Gangrene

views updated May 29 2018

Gangrene

Definition

Gangrene is the death of tissue caused by the lack of blood supply.

Description

The severity of gangrene is wide-ranging. It can affect a minuscule skin area or a finger or toe, or even an entire limb such as an arm, a foot, or a leg. Gangrene is usually classified into two categories, dry gangrene and wet gangrene.

Dry gangrene

Dry gangrene occurs when a portion of bodily tissue dies because its blood supply has been decreased or completely cut off. This type of gangrene will not spread to other healthy tissue, and infection is not present. It is usually a slow process, with the affected area gradually becoming cold, discolored, and eventually totally black. Shrinkage and withering away of the affected tissue occurs as the tissue dies.

Wet gangrene

Dry and wet gangrene are two terms often applied to different phases of the same death of tissue. Wet gangrene (also called moist gangrene) occurs when dry gangrene becomes infected, often due to injury, and the infection causes the tissue to die.

In the United States, approximately 50% of moist gangrene cases are the result of a severe traumatic injury; 40% occur following surgery. Car and industrial accidents, crush injuries, and gunshot wounds are the most common traumatic causes. Because of prompt surgical management of wounds with the removal of dead tissue, the incidence of gangrene from trauma has significantly diminished. Surgeries involving the bile ducts or intestine are the most frequent procedures causing gangrene. Approximately two-thirds of cases affect the extremities, and the remaining one-third involve the abdominal wall.

One particularly dangerous type of wet gangrene is termed gas gangrene, or myonecrosis. This particular type is caused by the infection of injured tissue or surgical wounds from the Clostridium species of bacteria , an especially virulent pathogen. In anaerobic conditions, that is, conditions in which oxygen levels are low, Clostridium can rapidly produce poisonous substances called toxins that cause tissue to die. Four of the Clostridium toxins, Alpha, Beta, Epsilon, and Iota, are capable of causing death.

Gas gangrene differs from other wet gangrenes because it is more involved with muscle than skin tissue. Not only do the toxins manufactured by Clostridium cause the death of tissue, but they also destroy blood cells, constrict blood vessels , thus decreasing circulation, and damage blood vessels so that they leak. Fortunately, in peacetime, and with improvements in medical care, gas gangrene is not a frequently occurring phenomenon. (It occurs in only between one and three thousand people in the United States each year.) However, in the past, in wartime, gas gangrene has killed literally millions.

Causes and symptoms

Dry gangrene

Some of the most common causes of dry gangrene include:

  • arterial obstruction, or occlusion of an artery, caused by arteriosclerosis, diabetes mellitus , AIDS or blood clot
  • severe blunt trauma to a part of the body causing damage and therefore obstruction of an artery
  • frostbite, which occurs when tissue becomes so cold that it is literally deprived of blood and therefore oxygen, and dies
  • diseases that affect the blood vessels, and especially the arteries, such as Buerger's disease or Raynaud's disease
  • traumatic occurrences such as crushing injuries, fractures , burns , and even injections given into skin or muscle

Wet gangrene

Causative organisms for wet gangrene infection include:

  • Streptococcus
  • Staphylococcus

A serious but rare form of infection with Group A Streptococcus can impede blood flow and, if untreated, can progress to gangrene caused by chemical reaction. This type of gangrene is more commonly called necrotizing fasciitis, or infection of the skin and tissues directly beneath the skin.

Gas gangrene, the most serious form of wet gangrene, often is caused by Clostridium bacteria, which are normal inhabitants of the gastrointestinal, respiratory, and female genital tracts. They often infect thigh amputation wounds, especially in those individuals who have lost control of their bowel function (incontinence). Gangrene, incontinence, and debility are often combined in patients with diabetes, and it is in the amputation stumps of diabetic patients that gas gangrene often occurs.

Areas of either dry or moist gangrene are initially characterized by a red line on the skin that marks the border of the affected tissues. The onset of dry gangrene is normally characterized by dull, aching pain at the site. The skin usually develops an abnormal, unhealthyappearing pallor and is cold to the touch. As tissues begin to die, dry gangrene may continue to cause some pain; but it may go unnoticed, especially in the elderly or in those individuals with diminished sensation to the affected area. As more tissue dies, its color changes to brown, and finally purplish-black. This dead tissue will gradually separate from the healthy tissue and fall off.

Gas gangrene has a dramatically sudden, rapid onset. It is frequently first noticed as a marked swelling and either a pallid or brownish-red colored area surrounding the wound site. The borders of the infected site can expand literally within minutes. Symptoms of gas gangrene include:

  • edema, or swelling, at the injury site that expands quickly
  • pain in the area surrounding the skin injury
  • crepitus, a bubbly, crackling sound often heard upon palpation
  • pallor at the injury site, then increasingly dusky discoloration
  • low-grade to moderate temperature elevation
  • tachycardia, or increased heart rate
  • diaphoresis, or clammy, sweaty skin
  • formation of blisters filled with rust-colored fluid
  • wound drainage, foul-smelling and rusty or bloody in appearance
  • in severe cases, shock (Symptoms of shock include generalized pallor, hypotension, rapid pulse, and cold hands and feet.)

Diagnosis

A diagnosis of gangrene is based on a combination of the patient history, a physical examination , and the results of blood and other laboratory tests. A physician will look for a history of recent trauma, surgery, cancer , or chronic disease. Blood tests will be used to determine whether infection is present and determine the extent to which an infection has spread.

A sample of drainage from a wound, possibly obtained through surgical exploration, may be cultured with oxygen (aerobic) and without oxygen (anaerobic) to identify the microorganism causing the infection and to aid in determining which antibiotic will be most effective. A gangrenous sample will contain few if any white blood cells and, when stained (with Gram stain ) and examined under the microscope , will show the presence of purple (Gram-positive) rod-shaped bacteria.

X ray studies and more sophisticated imaging techniques, such as computed tomography scans (CT) or magnetic resonance imaging (MRI), may be helpful in making a diagnosis, since gas accumulation and muscle death (myonecrosis) may be visible. These techniques, however, are not sufficient alone to provide an accurate diagnosis of gangrene.

Precise diagnosis of gas gangrene often requires surgical exploration of the wound. During such a procedure, the exposed muscle may appear pale, beefy-red, or in the most advanced stages, black. If infected, the muscle will fail to contract with stimulation, and the cut surface will not bleed.

Treatment

Gas gangrene is a potentially lethal condition requiring immediate action. It is recommended that anyone having any or all of the symptoms of gas gangrene contact a health provider immediately. Generally, once a diagnosis of gas gangrene is made, infected, gangrenous tissue must be removed surgically. To assure its complete removal, it is often necessary to remove all tissue surrounding the infection or even to amputate a portion of the body. Aggressive use of antibiotics , usually intravenously to start, is also begun as soon as possible. Pain medication will also usually be necessary.

Areas of dry gangrene that remain free from infection (aseptic) in the extremities are most often left to wither and fall off. Treatments applied to the wound externally (topically) are generally not effective without adequate blood supply to support wound healing. Assessment by a vascular surgeon, along with x rays to determine blood supply and circulation to the effected area, can help determine whether surgical intervention would be beneficial.

Once the causative organism has been identified, moist gangrene requires the prompt initiation of intravenous, intramuscular, and/or topical broad-spectrum antibiotic therapy. In addition, the infected tissue must be removed surgically (debridement), and amputation of the affected extremity may be necessary. Pain medications (analgesics ) are prescribed to control discomfort. Intravenous fluids and, occasionally, blood transfusions are indicated to counteract shock and replenish red blood cells and electrolytes. Adequate hydration and nutrition are vital to wound healing.

Although still controversial, some cases of gangrene are treated by administering oxygen under pressure greater than that of the atmosphere (hyperbaric) to the patient in a specially designed chamber. The theory behind using hyperbaric oxygen is that more oxygen will dissolve in the patient's bloodstream, and therefore more oxygen will be delivered to the gangrenous areas. By providing optimal oxygenation, the body's ability to fight off the bacterial infection is believed to be improved, and there is a direct toxic effect on the bacteria that thrive in an oxygen-free environment. Some studies have shown that the use of hyperbaric oxygen produces marked pain relief, reduces the number of amputations required, and reduces the extent of surgical debridement required. Patients receiving hyperbaric oxygen treatments must be monitored closely for evidence of oxygen toxicity. Symptoms of this toxicity include slow heart rate; profuse sweating; ringing in the ears; shortness of breath; nausea and vomiting; twitching of the lips, cheeks, eyelids, nose; and convulsions.

The emotional needs of the patient suffering from gangrene are also a large component of treatment. The individual with gangrene should be offered moral support, along with an opportunity to share questions and concerns about changes in body image. In addition, particularly in cases where amputation is required, physical, vocational, and rehabilitation therapy will also be required.

Prognosis

Except in cases where the infection has been allowed to spread through the blood stream, as in the case of severe gas gangrene, prognosis for survival is generally favorable. Anaerobic wound infection can progress quickly from initial injury to gas gangrene and the spread of the infection to the blood stream within one to two days. Between 20 and 25% of gas gangrene victims do not survive. If recognized and treated early, however, approximately 80% of patients survive, and only 15 to 20% require any form of amputation. Unfortunately, the individual with dry gangrene most often has multiple other health problems that complicate recovery, and it is usually these health problems that can prove fatal.

Health care team roles

  • In most cases, gangrene is discovered while the patient is still in a healthcare facility following trauma, surgery, or treatment of serious medical conditions. A diagnosis of gangrene is generally made by a primary care physician or surgeon.
  • Both registered nurses (RNs) and licensed practical nurses (LPNs) must complete a prescribed course in nursing and pass a state examination. RNs typically have a degree in nursing. Both RNs and LPNs care for patients afflicted by gangrene both in general hospitals, homes, or other healthcare facilities. Good nursing care and observation are primary requirements. These will include taking vital signs , monitoring surgical wounds or injuries for signs and symptoms of infection, providing aseptic (germ-free) treatment to wounds and injuries, collecting specimens of wound drainage to be tested, and making all efforts necessary to keep the patient as comfortable as possible. Education about the underlying cause of the gangrene (diabetes, infection, etc.) is an important aspect of caring for these patients.

KEY TERMS


Aerobic —A type of organism that grows and thrives only in environments containing oxygen.

Anaerobic —A type of organism that grows and thrives in an oxygen-free environment.

Arteriosclerosis —Build-up of fatty plaques within the arteries that can lead to the obstruction of blood flow.

Aseptic —Without contamination with bacteria or other microorganisms.

Crepitus —A crackling sound.

Gram stain —A staining procedure used to visualize and classify bacteria. The Gram stain procedure allows the identification of purple (Gram-positive) organisms and red (Gram-negative) organisms.

Hyperbaric oxygen —Medical treatment in which oxygen is administered in specially designed chambers under pressures greater than that of the atmosphere in order to treat specific medical conditions.

Incontinence —A condition characterized by the inability to control urination or bowel functions.

Myonecrosis —The destruction or death of muscle tissue.

Sepsis —The spreading of an infection in the bloodstream.

Thrombosis —The formation of a blood clot in a vein or artery that may obstruct local blood flow; or may dislodge, travel downstream, and obstruct blood flow at a remote location.


  • Clinical laboratory scientists have specialized training and must pass a state examination. They do the necessary tests on wound drainage specimens to determine the organism involved in the infection.
  • Radiologic technologists have specialized training and must pass a state examination. They take X rays and other tests to visualize and monitor the course of the gangrene.
  • Physical therapists must complete a prescribed course and pass a state examination in order to be licensed. Typically they have a degree. Physical therapists work with patients that have sustained an amputation because of gangrene to maintain and maximize mobility in walking, wheelchair use, and transferring (from wheelchair to toilet or from standing to sitting, for example). The physical therapist advises on such mobility aids as wheelchairs, braces, and canes.
  • Social workers have a degree in social work. A social worker may help coordinate services and ease the transition out of the hospital back into the home or extended care facility, if necessary. Social workers may help counsel the patient and the family during the difficult rehabilitation period.
  • Occupational therapists must complete a prescribed course and pass a state examination in order to be licensed. Typically they have a degree. They help people disabled after an amputation or loss of function caused by gangrene to relearn necessary functions needed to carry out normal activities of daily living such as bathing, dressing, and preparing meals.

All healthcare team members need to be aware that the person with gangrene, and possibly an amputation, and the family members who may care at home for the person will need to learn an entirely new set of skills and adaptations. Both the patient and family often experience stress , anxiety , and depression. Both may need teaching regarding both physical and mental symptoms that often follow gangrene or amputation, and the family may need to be taught how to deliver necessary care. For the patient with gangrene, finding other individuals or a support group composed of people that have had similar illness or injury can be one of the most important steps in the rehabilitation process.

Prevention

Patients with diabetes or severe arteriosclerosis need to take particular care of their hands and feet because of the risk of infection associated with even a minor injury. Education about proper foot care is vital. Diminished blood flow as a result of narrowed vessels will not lessen the body's defenses against invading bacteria. Measures taken towards the reestablishment of circulation are recommended whenever possible. Any abrasion, break in the skin, or infected tissue should be cared for immediately. Any dying or infected skin must be removed promptly to prevent the spread of bacteria.

Penetrating abdominal wounds should be surgically explored and drained, any tears in the intestinal walls closed, and antibiotic treatment begun early. Patients undergoing elective intestinal surgery should receive preventive antibiotic therapy. Use of antibiotics prior to and directly following surgery has been shown to significantly reduce the rate of infection from 20-30% to between 4 and 8%.

Resources

BOOKS

Berkow, Robert and Andrew Fletcher. The Merck Manual of Diagnosis and Therapy. Merck Research Laboratories, 1992.

Nettina, Sandra. The Lippincott Manual of Nursing Practice. Philadelphia: J.B. Lippincott Company, 2001.

Wyngaarden, James B., Lloyd H. Smith, and J. Claude Bennett. Cecil Textbook of Medicine. Philadelphia: W.B. Saunders Company, 1992.

OTHER

"Gas Gangrene." Medline, U.S. Department of Health and Human Services, National Institutes of Health. <http://www.nlm.nih.gov/medlingplus>. May 16, 2001.

Joan M. Schonbeck

Gangrene

views updated May 29 2018

Gangrene

Definition

Gangrene is the death of tissue caused by the lack of blood supply.

Description

The severity of gangrene is wide-ranging. It can affect a minuscule skin area or a finger or toe, or even an entire limb such as an arm, a foot, or a leg. Gangrene is usually classified into two categories, dry gangrene and wet gangrene.

Dry gangrene

Dry gangrene occurs when a portion of bodily tissue dies because its blood supply has been decreased or completely cut off. This type of gangrene will not spread to other healthy tissue, and infection is not present. It is usually a slow process, with the affected area gradually becoming cold, discolored, and eventually totally black. Shrinkage and withering away of the affected tissue occurs as the tissue dies.

Wet gangrene

Dry and wet gangrene are two terms often applied to different phases of the same death of tissue. Wet gangrene (also called moist gangrene) occurs when dry gangrene becomes infected, often due to injury, and the infection causes the tissue to die.

In the United States, approximately 50% of moist gangrene cases are the result of a severe traumatic injury; 40% occur following surgery. Car and industrial accidents, crush injuries, and gunshot wounds are the most common traumatic causes. Because of prompt surgical management of wounds with the removal of dead tissue, the incidence of gangrene from trauma has significantly diminished. Surgeries involving the bile ducts or intestine are the most frequent procedures causing gangrene. Approximately two-thirds of cases affect the extremities, and the remaining one-third involve the abdominal wall.

One particularly dangerous type of wet gangrene is termed gas gangrene, or myonecrosis. This particular type is caused by the infection of injured tissue or surgical wounds from the Clostridium species of bacteria, an especially virulent pathogen. In anaerobic conditions, that is, conditions in which oxygen levels are low, Clostridium can rapidly produce poisonous substances called toxins that cause tissue to die. Four of the Clostridium toxins, Alpha, Beta, Epsilon, and Iota, are capable of causing death.

Gas gangrene differs from other wet gangrenes because it is more involved with muscle than skin tissue. Not only do the toxins manufactured by Clostridium cause the death of tissue, but they also destroy blood cells, constrict blood vessels, thus decreasing circulation, and damage blood vessels so that they leak. Fortunately, in peacetime, and with improvements in medical care, gas gangrene is not a frequently occurring phenomenon. (It occurs in only between one and three thousand people in the United States each year.) However, in the past, in wartime, gas gangrene has killed literally millions.

Causes and symptoms

Dry gangrene

Some of the most common causes of dry gangrene include:

  • arterial obstruction, or occlusion of an artery, caused by arteriosclerosis, diabetes mellitus, AIDS, or blood clot
  • severe blunt trauma to a part of the body causing damage and therefore obstruction of an artery
  • frostbite, which occurs when tissue becomes so cold that it is literally deprived of blood and therefore oxygen, and dies
  • diseases that affect the blood vessels, and especially the arteries, such as Buerger's disease or Raynaud's disease
  • traumatic occurrences such as crushing injuries, fractures, burns, and even injections given into skin or muscle

Wet gangrene

Causative organisms for wet gangrene infection include:

  • Streptococcus
  • Staphylococcus

A serious but rare form of infection with Group A Streptococcus can impede blood flow and, if untreated, can progress to gangrene caused by chemical reaction. This type of gangrene is more commonly called necrotizing fasciitis, or infection of the skin and tissues directly beneath the skin.

Gas gangrene, the most serious form of wet gangrene, often is caused by Clostridium bacteria, which are normal inhabitants of the gastrointestinal, respiratory, and female genital tracts. They often infect thigh amputation wounds, especially in those individuals who have lost control of their bowel function (incontinence). Gangrene, incontinence, and debility often are combined in patients with diabetes, and it is in the amputation stumps of diabetic patients that gas gangrene often occurs.

Areas of either dry or moist gangrene are initially characterized by a red line on the skin that marks the border of the affected tissues. The onset of dry gangrene is normally characterized by dull, aching pain at the site. The skin usually develops an abnormal, unhealthy-appearing pallor and is cold to the touch. As tissues begin to die, dry gangrene may continue to cause some pain, but it may go unnoticed, especially in the elderly or in those individuals with diminished sensation to the affected area. As more tissue dies, its color changes to brown, and finally purplish-black. This dead tissue will gradually separate from the healthy tissue and fall off.

Gas gangrene has a dramatically sudden, rapid onset. It is frequently first noticed as a marked swelling and either a pallid or brownish-red colored area surrounding the wound site. The borders of the infected site can literally expand within minutes. Symptoms of gas gangrene include:

  • edema, or swelling, at the injury site that expands quickly
  • pain in the area surrounding the skin injury
  • crepitus, a bubbly, crackling sound often heard upon palpation
  • pallor at the injury site, then increasingly dusky discoloration
  • low-grade to moderate temperature elevation
  • tachycardia, or increased heart rate
  • diaphoresis, or clammy, sweaty skin
  • formation of blisters filled with rust-colored fluid
  • wound drainage, foul-smelling and rusty or bloody in appearance
  • in severe cases, shock (symptoms of shock include generalized pallor, hypotension, or low blood pressure, rapid pulse, and cold hands and feet)

Diagnosis

A diagnosis of gangrene is based on a combination of the patient history, a physical examination, and the results of blood and other laboratory tests. A physician will look for a history of recent trauma, surgery, cancer, or chronic disease. Blood tests will be used to determine whether infection is present and determine the extent to which an infection has spread.

A sample of drainage from a wound, possibly obtained through surgical exploration, may be cultured with oxygen (aerobic) and without oxygen (anaerobic) to identify the microorganism causing the infection and to aid in determining which antibiotic will be most effective. A gangrenous sample will contain few if any white blood cells and, when stained (with Gram stain ) and examined under the microscope, will show the presence of purple (Gram-positive), rodshaped bacteria.

X-ray studies and more sophisticated imaging techniques, such as computed tomography scans (CT) or magnetic resonance imaging (MRI), may be helpful in making a diagnosis, since gas accumulation and muscle death (myonecrosis) may be visible. These techniques, however, are not sufficient alone to provide an accurate diagnosis of gangrene.

Precise diagnosis of gas gangrene often requires surgical exploration of the wound. During such a procedure, the exposed muscle may appear pale, beefy-red, or in the most advanced stages, black. If infected, the muscle will fail to contract with stimulation, and the cut surface will not bleed.

Treatment

Gas gangrene is a potentially lethal condition requiring immediate action. It is recommended that anyone having any or all of the symptoms of gas gangrene contact a health provider immediately. Generally, once a diagnosis of gas gangrene is made, infected, gangrenous tissue must be removed surgically. To assure its complete removal, it is often necessary to remove all tissue surrounding the infection or even to amputate a portion of the body. Aggressive use of antibiotics, usually intravenously to start, is also begun as soon as possible. Pain medication will also usually be necessary.

Areas of dry gangrene that remain free from infection (aseptic) in the extremities are most often left to wither and fall off. Treatments applied to the wound externally (topically) are generally not effective without adequate blood supply to support wound healing. Assessment by a vascular surgeon, along with x rays to determine blood supply and circulation to the affected area, can help determine whether surgical intervention would be beneficial.

Once the causative organism has been identified, moist gangrene requires the prompt initiation of intravenous, intramuscular, and/or topical broadspectrum antibiotic therapy. In addition, the infected tissue must be removed surgically (debridement), and amputation of the affected extremity may be necessary. Pain medications (analgesics ) are prescribed to control discomfort. Intravenous fluids and, occasionally, blood transfusions are indicated to counteract shock and replenish red blood cells and electrolytes. Adequate hydration and nutrition are vital to wound healing.

Although still controversial, some cases of gangrene are treated by administering oxygen under pressure greater than that of the atmosphere (hyperbaric) to the patient in a specially designed chamber. The theory behind using hyperbaric oxygen is that more oxygen will dissolve in the patient's bloodstream, and therefore more oxygen will be delivered to the gangrenous areas. By providing optimal oxygenation, the body's ability to fight off the bacterial infection is believed to be improved, and there is a direct toxic effect on the bacteria that thrive in an oxygen-free environment. Some studies have shown that the use of hyperbaric oxygen produces marked pain relief, reduces the number of amputations required, and reduces the extent of surgical debridement required. Patients receiving hyperbaric oxygen treatments must be monitored closely for evidence of oxygen toxicity. Symptoms of this toxicity include slow heart rate; profuse sweating; ringing in the ears; shortness of breath; nausea and vomiting; twitching of the lips, cheeks, eyelids, nose; and convulsions.

The emotional needs of the patient suffering from gangrene are also a large component of treatment. The individual with gangrene should be offered moral support, along with an opportunity to share questions and concerns about changes in body image. In addition, particularly in cases where amputation is required, physical, vocational, and rehabilitation therapy will also be required.

Prognosis

Except in cases where the infection has been allowed to spread through the blood stream, as in the case of severe gas gangrene, prognosis for survival is generally favorable. Anaerobic wound infection can progress quickly from initial injury to gas gangrene and spread the infection in the blood stream within one to two days. Between 20 and 25% of gas gangrene victims do not survive. If recognized and treated early, however, approximately 80% of patients survive, and only 15-20% require any form of amputation. Unfortunately, the individual with dry gangrene most often has multiple other health problems that complicate recovery, and it is usually these health problems that can prove fatal.

Health care team roles

  • In most cases, gangrene is discovered while the patient is still in a healthcare facility, following trauma, surgery, or treatment of serious medical conditions. A diagnosis of gangrene is generally made by a primary care physician or surgeon.
  • Both registered nurses (RNs) and licensed practical nurses (LPNs) must complete a prescribed course in nursing and pass a state examination. RNs typically have a degree in nursing. Both RNs and LPNs care for patients afflicted by gangrene both in general hospitals, homes, or other healthcare facilities. Good nursing care and observation are primary requirements. These will include taking vital signs, monitoring surgical wounds or injuries for signs and symptoms of infection, providing aseptic (germfree) treatment to wounds and injuries, collecting specimens of wound drainage to be tested, and making all efforts necessary to keep the patient as comfortable as possible. Education about the underlying cause of the gangrene (diabetes, infection, etc.) is an important aspect of caring for these patients.
  • Clinical laboratory scientists have specialized training and must pass a state examination. They do the necessary tests on wound drainage specimens to determine the organism involved in the infection.
  • Radiologic technologists have specialized training and must pass a state examination. They take X rays and other tests to visualize and monitor the course of the gangrene.
  • Physical therapists must complete a prescribed course and pass a state examination in order to be licensed. Typically they have a degree. Physical therapists work with patients that have sustained an amputation because of gangrene to maintain and maximize mobility in walking, wheelchair use, and transferring (from wheelchair to toilet or from standing to sitting, for example). The physical therapist advises on mobility aids such as wheelchairs, braces, and canes.
  • Social workers have a degree in social work. A social worker may help coordinate services and ease the transition out of the hospital back into the home or extended care facility, if necessary. Social workers may help counsel the patient and the family during the difficult rehabilitation period.
  • Occupational therapists must complete a prescribed course and pass a state examination in order to be licensed. Typically they have a degree. They help people disabled after an amputation or loss of function caused by gangrene to relearn necessary functions needed to carry out normal activities of daily living such as bathing, dressing, and preparing meals.

All healthcare team members need to be aware that the person with gangrene, and possibly an amputation, and the family members who may care at home for the person will need to learn an entirely new set of skills and adaptations. Both the patient and family often experience stress, anxiety, and depression. Both may need teaching regarding both physical and mental symptoms that often follow gangrene or amputation, and the family may need to be taught how to deliver necessary care. For the patient with gangrene, finding other individuals or a support group composed of people that have had similar illness or injury can be one of the most important steps in the rehabilitation process.

Prevention

Patients with diabetes or severe arteriosclerosis need to take particular care of their hands and feet because of the risk of infection associated with even a minor injury. Education about proper foot care is vital. Diminished blood flow as a result of narrowed vessels will not lessen the body's defenses against invading bacteria. Measures taken towards the reestablishment of circulation are recommended whenever possible. Any abrasion, break in the skin, or infected tissue should be cared for immediately. Any dying or infected skin must be removed promptly to prevent the spread of bacteria.

Penetrating abdominal wounds should be surgically explored and drained, any tears in the intestinal walls closed, and antibiotic treatment begun early. Patients undergoing elective intestinal surgery should receive preventive antibiotic therapy. Use of antibiotics prior to and directly following surgery has been shown to significantly reduce the rate of infection from 20-30% to between 4 and 8%.

KEY TERMS

Aerobic— A type of organism that grows and thrives only in environments containing oxygen.

Anaerobic— A type of organism that grows and thrives in an oxygen-free environment.

Arteriosclerosis— Build-up of fatty plaques within the arteries that can lead to the obstruction of blood flow.

Aseptic— Without contamination with bacteria or other microorganisms.

Crepitus— A crackling sound.

Gram stain— A staining procedure used to visualize and classify bacteria. The Gram stain procedure allows the identification of purple (Gram-positive) organisms and red (Gram-negative) organisms.

Hyperbaric oxygen— Medical treatment in which oxygen is administered in specially designed chambers under pressures greater than that of the atmosphere in order to treat specific medical conditions.

Incontinence— A condition characterized by the inability to control urination or bowel functions.

Myonecrosis— The destruction or death of muscle tissue.

Sepsis— The spreading of an infection in the bloodstream.

Thrombosis— The formation of a blood clot in a vein or artery that may obstruct local blood flow or may dislodge, travel downstream, and obstruct blood flow at a remote location.

Resources

BOOKS

Berkow, Robert and Andrew Fletcher. The Merck Manual of Diagnosis and Therapy. Merck Research Laboratories, 1992.

Nettina, Sandra. The Lippincott Manual of Nursing Practice. Philadelphia: J.B. Lippincott Company, 2001.

Wyngaarden, James B., Lloyd H. Smith, and J. Claude Bennett. Cecil Textbook of Medicine. Philadelphia: W.B. Saunders Company, 1992.

OTHER

"Gas Gangrene." Medline, U.S. Department of Health and Human Services, National Institutes of Health. 〈http://www.nlm.nih.gov/medlingplus〉. May 16, 2001.

Gangrene

views updated May 23 2018

Gangrene

Definition

Gangrene is the death of tissue caused by the lack of blood supply.

Description

The severity of gangrene is wide-ranging. It can affect a minuscule skin area or a finger or toe, or even an entire limb such as an arm, a foot, or a leg. Gangrene is usually classified into two categories, dry gangrene and wet gangrene.

Dry gangrene

Dry gangrene occurs when a portion of bodily tissue dies because its blood supply has been decreased or completely cut off. This type of gangrene will not spread to other healthy tissue, and infection is not present. It is usually a slow process, with the affected area gradually becoming cold, discolored, and eventually totally black. Shrinkage and withering away of the affected tissue occurs as the tissue dies.

Wet gangrene

Dry and wet gangrene are two terms often applied to different phases of the same death of tissue. Wet gangrene (also called moist gangrene) occurs when dry gangrene becomes infected, often due to injury, and the infection causes the tissue to die.

In the United States, approximately 50% of moist gangrene cases are the result of a severe traumatic injury; 40% occur following surgery. Car and industrial accidents, crush injuries, and gunshot wounds are the most common traumatic causes. Because of prompt surgical management of wounds with the removal of dead tissue, the incidence of gangrene from trauma has significantly diminished. Surgeries involving the bile ducts or intestine are the most frequent procedures causing gangrene. Approximately two-thirds of cases affect the extremities, and the remaining one-third involve the abdominal wall.

One particularly dangerous type of wet gangrene is termed gas gangrene, or myonecrosis. This particular type is caused by the infection of injured tissue or surgical wounds from the Clostridium species of bacteria, an especially virulent pathogen. In anaerobic conditions, that is, conditions in which oxygen levels are low, Clostridium can rapidly produce poisonous substances called toxins that cause tissue to die. Four

of the Clostridium toxins, Alpha, Beta, Epsilon, and Iota, are capable of causing death.

Gas gangrene differs from other wet gangrenes because it is more involved with muscle than skin tissue. Not only do the toxins manufactured by Clostridium cause the death of tissue, but they also destroy blood cells, constrict blood vessels, thus decreasing circulation, and damage blood vessels so that they leak. Fortunately, in peacetime, and with improvements in medical care, gas gangrene is not a frequently occurring phenomenon. (It occurs in only between one and three thousand people in the United States each year.) However, in the past, in wartime, gas gangrene has killed literally millions.

Causes and symptoms

Dry gangrene

Some of the most common causes of dry gangrene include:

  • arterial obstruction, or occlusion of an artery, caused by arteriosclerosis, diabetes mellitus, AIDS, or blood clot
  • severe blunt trauma to a part of the body causing damage and therefore obstruction of an artery
  • frostbite, which occurs when tissue becomes so cold that it is literally deprived of blood and therefore oxygen, and dies
  • diseases that affect the blood vessels, and especially the arteries, such as Buerger's disease or Raynaud's disease
  • traumatic occurrences such as crushing injuries, fractures, burns, and even injections given into skin or muscle

Wet gangrene

Causative organisms for wet gangrene infection include:

  • Streptococcus
  • Staphylococcus

A serious but rare form of infection with Group A Streptococcus can impede blood flow and, if untreated, can progress to gangrene caused by chemical reaction. This type of gangrene is more commonly called necrotizing fasciitis, or infection of the skin and tissues directly beneath the skin.

Gas gangrene, the most serious form of wet gangrene, often is caused by Clostridium bacteria, which are normal inhabitants of the gastrointestinal, respiratory, and female genital tracts. They often infect thigh amputation wounds, especially in those individuals who have lost control of their bowel function (incontinence). Gangrene, incontinence, and debility often are combined in patients with diabetes, and it is in the amputation stumps of diabetic patients that gas gangrene often occurs.

Areas of either dry or moist gangrene are initially characterized by a red line on the skin that marks the border of the affected tissues. The onset of dry gangrene is normally characterized by dull, aching pain at the site. The skin usually develops an abnormal, unhealthy-appearing pallor and is cold to the touch. As tissues begin to die, dry gangrene may continue to cause some pain, but it may go unnoticed, especially in the elderly or in those individuals with diminished sensation to the affected area. As more tissue dies, its color changes to brown, and finally purplish-black. This dead tissue will gradually separate from the healthy tissue and fall off.

Gas gangrene has a dramatically sudden, rapid onset. It is frequently first noticed as a marked swelling and either a pallid or brownish-red colored area surrounding the wound site. The borders of the infected site can literally expand within minutes. Symptoms of gas gangrene include:

  • edema, or swelling, at the injury site that expands quickly
  • pain in the area surrounding the skin injury
  • crepitus, a bubbly, crackling sound often heard upon palpation
  • pallor at the injury site, then increasingly dusky discoloration
  • low-grade to moderate temperature elevation
  • tachycardia, or increased heart rate
  • diaphoresis, or clammy, sweaty skin
  • formation of blisters filled with rust-colored fluid
  • wound drainage, foul-smelling and rusty or bloody in appearance
  • in severe cases, shock (symptoms of shock include generalized pallor, hypotension, or low blood pressure, rapid pulse, and cold hands and feet)

Diagnosis

A diagnosis of gangrene is based on a combination of the patient history, a physical examination, and the results of blood and other laboratory Gangrene tests. A physician will look for a history of recent trauma, surgery, cancer , or chronic disease. Blood tests will be used to determine whether infection is present and determine the extent to which an infection has spread.

A sample of drainage from a wound, possibly obtained through surgical exploration, may be cultured with oxygen (aerobic) and without oxygen (anaerobic) to identify the microorganism causing the infection and to aid in determining which antibiotic will be most effective. A gangrenous sample will contain few if any white blood cells and, when stained (with Gram stain) and examined under the microscope, will show the presence of purple (Gram-positive), rod-shaped bacteria.

X-ray studies and more sophisticated imaging techniques, such as computed tomography scans (CT) or magnetic resonance imaging (MRI), may be helpful in making a diagnosis, since gas accumulation and muscle death (myonecrosis) may be visible. These techniques, however, are not sufficient alone to provide an accurate diagnosis of gangrene.

Precise diagnosis of gas gangrene often requires surgical exploration of the wound. During such a procedure, the exposed muscle may appear pale, beefy-red, or in the most advanced stages, black. If infected, the muscle will fail to contract with stimulation, and the cut surface will not bleed.

Treatment

Gas gangrene is a potentially lethal condition requiring immediate action. It is recommended that anyone having any or all of the symptoms of gas gangrene contact a health provider immediately. Generally, once a diagnosis of gas gangrene is made, infected, gangrenous tissue must be removed surgically. To assure its complete removal, it is often necessary to remove all tissue surrounding the infection or even to amputate a portion of the body. Aggressive use of antibiotics , usually intravenously to start, is also begun as soon as possible. Pain medication will also usually be necessary.

Areas of dry gangrene that remain free from infection (aseptic) in the extremities are most often left to wither and fall off. Treatments applied to the wound externally (topically) are generally not effective without adequate blood supply to support wound healing. Assessment by a vascular surgeon, along with x rays to determine blood supply and circulation to the affected area, can help determine whether surgical intervention would be beneficial.

Once the causative organism has been identified, moist gangrene requires the prompt initiation of intravenous, intramuscular, and/or topical broadspectrum antibiotic therapy. In addition, the infected tissue must be removed surgically (debridement), and amputation of the affected extremity may be necessary. Pain medications (analgesics) are prescribed to control discomfort. Intravenous fluids and, occasionally, blood transfusions are indicated to counteract shock and replenish red blood cells and electrolytes. Adequate hydration and nutrition are vital to wound healing.

Although still controversial, some cases of gangrene are treated by administering oxygen under pressure greater than that of the atmosphere (hyperbaric) to the patient in a specially designed chamber. The theory behind using hyperbaric oxygen is that more oxygen will dissolve in the patient's bloodstream, and therefore more oxygen will be delivered to the gangrenous areas. By providing optimal oxygenation, the body's ability to fight off the bacterial infection is believed to be improved, and there is a direct toxic effect on the bacteria that thrive in an oxygen-free environment. Some studies have shown that the use of hyperbaric oxygen produces marked pain relief, reduces the number of amputations required, and reduces the extent of surgical debridement required. Patients receiving hyperbaric oxygen treatments must be monitored closely for evidence of oxygen toxicity. Symptoms of this toxicity include slow heart rate; profuse sweating; ringing in the ears; shortness of breath; nausea and vomiting; twitching of the lips, cheeks, eyelids, nose; and convulsions.

The emotional needs of the patient suffering from gangrene are also a large component of treatment. The individual with gangrene should be offered moral support, along with an opportunity to share questions and concerns about changes in body image. In addition, particularly in cases where amputation is required, physical, vocational, and rehabilitation therapy will also be required.

Prognosis

Except in cases where the infection has been allowed to spread through the blood stream, as in the case of severe gas gangrene, prognosis for survival is generally favorable. Anaerobic wound infection can progress quickly from initial injury to gas gangrene and spread the infection in the blood stream within one to two days. Between 20 and 25% of gas gangrene victims do not survive. If recognized and treated early approximately 80% of patients survive, and only 15–20% require any form of amputation. Unfortunately, the individual with dry gangrene most often has multiple other health problems that complicate recovery, and it is usually these health problems that can prove fatal.

Caregiver concerns

  • In most cases, gangrene is discovered while the patient is still in a healthcare facility, following trauma, surgery, or treatment of serious medical conditions. A diagnosis of gangrene is generally made by a primary care physician or surgeon.
  • Both registered nurses (RNs) and licensed practical nurses (LPNs) must complete a prescribed course in nursing and pass a state examination. RNs typically have a degree in nursing. Both RNs and LPNs care for patients afflicted by gangrene both in general hospitals, homes, or other healthcare facilities. Good nursing care and observation are primary requirements. These will include taking vital signs, monitoring surgical wounds or injuries for signs and symptoms of infection, providing aseptic (germ-free) treatment to wounds and injuries, collecting specimens of wound drainage to be tested, and making all efforts necessary to keep the patient as comfortable as possible. Education about the underlying cause of the gangrene (diabetes, infection, etc.) is an important aspect of caring for these patients.
  • Clinical laboratory scientists have specialized training and must pass a state examination. They do the necessary tests on wound drainage specimens to determine the organism involved in the infection.
  • Radiologic technologists have specialized training and must pass a state examination. They take x rays and other tests to visualize and monitor the course of the gangrene.
  • Physical therapists must complete a prescribed course and pass a state examination in order to be licensed. Typically they have a degree. Physical therapists work with patients that have sustained an amputation because of gangrene to maintain and maximize mobility in walking, wheelchair use, and transferring (from wheelchair to toilet or from standing to sitting, for example). The physical therapist advises on mobility aids such as wheelchairs, braces, and canes.
  • Social workers have a degree in social work. A social worker may help coordinate services and ease the transition out of the hospital back into the home or extended care facility, if necessary. Social workers may help counsel the patient and the family during the difficult rehabilitation period.
  • Occupational therapists must complete a prescribed course and pass a state examination in order to be licensed. Typically they have a degree. They help people disabled after an amputation or loss of function caused by gangrene to relearn necessary functions needed to carry out normal activities of daily living such as bathing, dressing, and preparing meals.

KEY TERMS

Aerobic —A type of organism that grows and thrives only in environments containing oxygen.

Anaerobic —A type of organism that grows and thrives in an oxygen-free environment.

Aseptic —Without contamination with bacteria or other microorganisms.

Crepitus —A crackling sound.

Gram stain —A staining procedure used to visualize and classify bacteria. The Gram stain procedure allows the identification of purple (Grampositive) organisms and red (Gram-negative) organisms.

Hyperbaric oxygen —Medical treatment in which oxygen is administered in specially designed chambers under pressures greater than that of the atmosphere in order to treat specific medical conditions.

Myonecrosis —The destruction or death of muscle tissue.

Sepsis —The spreading of an infection in the bloodstream.

All healthcare team members need to be aware that the person with gangrene, and possibly an amputation, and the family members who may care at home for the person will need to learn an entirely new set of skills and adaptations. Both the patient and family often experience stress, anxiety , and depression . Both may need teaching regarding both physical and mental symptoms that often follow gangrene or amputation, and the family may need to be taught how to deliver necessary care. For the patient with gangrene, finding other individuals or a support group composed of people that have had similar illness or injury can be one of the most important steps in the rehabilitation process.

Prevention

Patients with diabetes or severe arteriosclerosis need to take particular care of their hands and feet because of the risk of infection associated with even a minor injury. Education about proper foot care is vital. Diminished blood flow as a result of narrowed vessels will not lessen the body's defenses against invading bacteria. Measures taken towards the reestablishment of circulation are recommended whenever possible. Any abrasion, break in the skin, or infected tissue should be cared for immediately. Any dying or infected skin must be removed promptly to prevent the spread of bacteria.

Penetrating abdominal wounds should be surgically explored and drained, any tears in the intestinal walls closed, and antibiotic treatment begun early. Patients undergoing elective intestinal surgery should receive preventive antibiotic therapy. Use of antibiotics prior to and directly following surgery has been shown to significantly reduce the rate of infection from 20–30% to between 4 and 8%.

Resources

BOOKS

Berkow, Robert, and Andrew Fletcher. The Merck Manual of Diagnosis and Therapy. Merck Research Laboratories, 1992.

Nettina, Sandra. The Lippincott Manual of Nursing Practice. Philadelphia: J.B. Lippincott Company, 2001.

Wyngaarden, James B., Lloyd H. Smith, and J. Claude Bennett. Cecil Textbook of Medicine. Philadelphia:W.B. Saunders Company, 1992.

OTHER

“Gas Gangrene.” Medline, U.S. Department of Health and Human Services, National Institutes of Health. http://www.nlm.nih.gov/medlingplus. May 16, 2001.

Joan M. Schonbeck

Gangrene

views updated Jun 11 2018

Gangrene

Definition

Gangrene is the term used to describe the decay or death of an organ or tissue caused by a lack of blood supply. It is a complication resulting from infectious or inflammatory processes, injury, or degenerative changes associated with chronic diseases, such as diabetes mellitus.

Description

Gangrene may be caused by a variety of chronic diseases and post-traumatic, post-surgical, and spontaneous causes. There are three major types of gangrene: dry, moist, and gas (a type of moist gangrene).

Dry gangrene is a condition that results when one or more arteries become obstructed. In this type of gangrene, the tissue slowly dies, due to receiving little or no blood supply, but does not become infected. The affected area becomes cold and black, begins to dry out and wither, and eventually drops off over a period of weeks or months. Dry gangrene is most common in persons with advanced blockages of the arteries (arteriosclerosis) resulting from diabetes.

Moist gangrene may occur in the toes, feet, or legs after a crushing injury or as a result of some other factor that causes blood flow to the area to suddenly stop. When blood flow ceases, bacteria begin to invade the muscle and thrive, multiplying quickly without interference from the body's immune system.

Gas gangrene, also called myonecrosis, is a type of moist gangrene that is commonly caused by bacterial infection with Clostridium welchii, Cl. perfringes, Cl. septicum, Cl. novyi, Cl. histolyticum, Cl. sporogenes, or other species that are capable of thriving under conditions where there is little oxygen (anaerobic). Once present in tissue, these bacteria produce gasses and poisonous toxins as they grow. Normally inhabiting the gastrointestinal, respiratory, and female genital tract, they often infect thigh amputation wounds, especially in those individuals who have lost control of their bowel functions (incontinence). Gangrene, incontinence, and debility often are combined in patients with diabetes, and it is in the amputation stump of diabetic patients that gas gangrene is often found to occur.

Other causative organisms for moist gangrene include various bacterial strains, including Streptococcus and Staphylococcus. A serious, but rare form of infection with Group A Streptococcus can impede blood flow and, if untreated, can progress to synergistic gangrene, more commonly called necrotizing fasciitis, or infection of the skin and tissues directly beneath the skin.

Chronic diseases, such as diabetes mellitus, arteriosclerosis, or diseases affecting the blood vessels, such as Buerger's disease or Raynaud's disease, can cause gangrene. Post-traumatic causes of gangrene include compound fractures, burns, and injections given under the skin or in a muscle. Gangrene may occur following surgery, particularly in individuals with diabetes mellitus or other long-term (chronic) disease. In addition, gas gangrene can be also be a complication of dry gangrene or occur spontaneously in association with an underlying cancer.

In the United States, approximately 50% of moist gangrene cases are the result of a severe traumatic injury, and 40% occur following surgery. Car and industrial accidents, crush injuries, and gunshot wounds are the most common traumatic causes. Because of prompt surgical management of wounds with the removal of dead tissue, the incidence of gangrene from trauma has significantly diminished. Surgeries involving the bile ducts or intestine are the most frequent procedures causing gangrene. Approximately two-thirds of cases affect the extremities, and the remaining one-third involve the abdominal wall.

Symptoms

Areas of either dry or moist gangrene are initially characterized by a red line on the skin that marks the border of the affected tissues. As tissues begin to die, dry gangrene may cause some pain in the early stages or may go unnoticed, especially in the elderly or in those individuals with diminished sensation to the affected area. Initially, the area becomes cold, numb, and pale before later changing in color to brown, then black. This dead tissue will gradually separate from the healthy tissue and fall off.

Moist gangrene and gas gangrene are distinctly different. Gas gangrene does not involve the skin as much, but usually only the muscle. In moist or gas gangrene, there is a sensation of heaviness in the affected region that is followed by severe pain. The pain is caused by swelling resulting from fluid or gas accumulation in the tissues. This pain peaks, on average, between one to four days following the injury, with a range of eight hours to several weeks. The swollen skin may initially be blistered, red, and warm to the touch before progressing to a bronze, brown, or black color. In approximately 80% of cases, the affected and surrounding tissues may produce crackling sounds (crepitus), as a result of gas bubbles accumulating under the skin. The gas may be felt beneath the skin (palpable). In wet gangrene, the pus is foul-smelling, while in gas gangrene, there is no true pus, just an almost "sweet" smelling watery discharge.

Fever, rapid heart rate, rapid breathing, altered mental state, loss of appetite, diarrhea, vomiting, and vascular collapse may also occur if the bacterial toxins are allowed to spread in the bloodstream. Gas gangrene can be a life-threatening condition and should receive prompt medical attention

Diagnosis

A diagnosis of gangrene will be based on a combination of the patient history, a physical examination, and the results of blood and other laboratory tests. A physician will look for a history of recent trauma, surgery, cancer, or chronic disease. Blood tests will be used to determine whether infection is present and determine the extent to which an infection has spread.

A sample of drainage from a wound, or obtained through surgical exploration, may be cultured with oxygen (aerobic) and without oxygen (anaerobic) to identify the microorganism causing the infection and to aid in determining which antibiotic will be most effective. The sample obtained from a person with gangrene will contain few, if any, white blood cells and, when stained (with Gram stain) and examined under the microscope, will show the presence of purple (Gram positive), rod-shaped bacteria.

X-ray studies and more sophisticated imaging techniques, such as computed tomography scans (CT) or magnetic resonance imaging (MRI), may be helpful in making a diagnosis since gas accumulation and muscle death (myonecrosis) may be visible. These techniques, however, are not sufficient alone to provide an accurate diagnosis of gangrene.

Precise diagnosis of gas gangrene often requires surgical exploration of the wound. During such a procedure, the exposed muscle may appear pale, beefy-red, or in the most advanced stages, black. If infected, the muscle will fail to contract with stimulation, and the cut surface will not bleed.

Treatment

Gas gangrene is a medical emergency because of the threat of the infection rapidly spreading via the bloodstream and infecting vital organs. It requires immediate surgery and administration of antibiotics.

Areas of dry gangrene that remain free from infection (aseptic) in the extremities are most often left to wither and fall off. Treatments applied to the wound externally (topically) are generally not effective without adequate blood supply to support wound healing. Assessment by a vascular surgeon, along with x rays to determine blood supply and circulation to the affected area, can help determine whether surgical intervention would be beneficial.

Once the causative organism has been identified, moist gangrene requires the prompt initiation of intravenous, intramuscular, and/or topical broad-spec-trum antibiotic therapy. In addition, the infected tissue must be removed surgically (debridement ), and amputation of the affected extremity may be necessary. Pain medications (analgesics ) are prescribed to control discomfort. Intravenous fluids and, occasionally, blood transfusions are indicated to counteract shock and replenish red blood cells and electrolytes. Adequate hydration and nutrition are vital to wound healing.

Although still controversial, some cases of gangrene are treated by administering oxygen under pressure greater than that of the atmosphere (hyperbaric) to the patient in a specially designed chamber. The theory behind using hyperbaric oxygen is that more oxygen will become dissolved in the patient's bloodstream, and therefore, more oxygen will be delivered to the gangrenous areas. By providing optimal oxygenation, the body's ability to fight off the bacterial infection are believed to be improved, and there is a direct toxic effect on the bacteria that thrive in an oxygen-free environment. Some studies have shown that the use of hyperbaric oxygen produces marked pain relief, reduces the number of amputations required, and reduces the extent of surgical debridement required. Patients receiving hyperbaric oxygen treatments must be monitored closely for evidence of oxygen toxicity. Symptoms of this toxicity include slow heart rate, profuse sweating, ringing in the ears, shortness of breath, nausea and vomiting, twitching of the lips/cheeks/eyelids/nose, and convulsions.

The emotional needs of the patient must also be met. The individual with gangrene should be offered moral support, along with an opportunity to share questions and concerns about changes in body image. In addition, particularly in cases where amputation was required, physical, vocational, and rehabilitation therapy will also be required.

Prognosis

Except in cases where the infection has been allowed to spread through the blood stream, prognosis is generally favorable. Anaerobic wound infection can progress quickly from initial injury to gas gangrene within one to two days, and the spread of the infection in the blood stream is associated with a 20-25% mortality rate. If recognized and treated early, however, approximately 80% of those with gas gangrene survive, and only 15-20% require any form of amputation. Unfortunately, the individual with dry gangrene most often has multiple other health problems that complicate recovery, and it is usually those other system failures that can prove fatal.

Prevention

Patients with diabetes or severe arteriosclerosis should take particular care of their hands and feet because of the risk of infection associated with even a minor injury. Education about proper foot care is vital. Diminished blood flow as a result of narrowed vessels will not lessen the body's defenses against invading bacteria. Measures taken towards the reestablishment of circulation are recommended whenever possible. Any abrasion, break in the skin, or infection tissue should be cared for immediately. Any dying or infected skin must be removed promptly to prevent the spread of bacteria.

KEY TERMS

Aerobic Organism that grows and thrives only in environments containing oxygen.

Anaerobic Organism that grows and thrives in an oxygen-free environment.

Arteriosclerosis Build-up of fatty plaques within the arteries that can lead to the obstruction of blood flow.

Aseptic Without contamination with bacteria or other microorganisms.

Crepitus A crackling sound.

Gram stain A staining procedure used to visualize and classify bacteria. The Gram stain procedure allows the identification of purple (Gram positive) organisms and red (Gram negative) organisms.

Hyperbaric oxygen Medical treatment in which oxygen is administered in specially designed chambers, under pressures greater than that of the atmosphere, in order to treat specific medical conditions.

Incontinence A condition characterized by the inability to control urination or bowel functions.

Myonecrosis The destruction or death of muscle tissue.

Sepsis The spreading of an infection in the bloodstream.

Thrombosis The formation of a blood clot in a vein or artery that may obstruct local blood flow or may dislodge, travel downstream, and obstruct blood flow at a remote location.

Penetrating abdominal wounds should be surgically explored and drained, any tears in the intestinal walls closed, and antibiotic treatment begun early. Patients undergoing elective intestinal surgery should receive preventive antibiotic therapy. Use of antibiotics prior to and directly following surgery has been shown to significantly reduce the rate of infection from 20-30% to 4-8%.

Resources

BOOKS

Berktow, Robert, editor. The Merck Manual of Diagnosis and Therapy. 17th ed. Rahway, NJ: Merck Research Laboratories, 1997.

PERIODICALS

Basoglu, M., et al. "Fournier's Gangrene: Review of Fifteen Cases." American Surgeon November 1997: 1019-1021.

Gangrene

views updated Jun 11 2018

Gangrene

Definition

Gangrene is a term used to describe the decay or death of an organ, tissue, or bone caused by a lack of oxygen and nutrients. It is a complication resulting from tissue injuries (such as frostbite), the obstruction of blood flow, or the processes of chronic diseases such as diabetes mellitus . Externally, the hands and feet are the areas most often affected by gangrene; internally, it is most likely to affect the gallbladder and the intestines. Gangrene is referred to as wet, or moist, if a bacterial infection is involved. In dry gangrene, there is no infection.

Description

Gangrene is often characterized by pain followed by numbness. The infection may first go unnoticed, especially in the elderly or those individuals with a loss of sensation. The area affected by gangrene may be cold and pale, especially early in the disease. Blisters may be apparent and the patient may experience an increased heart rate and profuse sweating. As the tissue dies, the skin begins to darken. The dead tissue gradually separates and falls away from the healthy tissue.

Dry gangrene is often seen in advanced cases of diabetes and arteriosclerosis. The tissue doesn't become infected, rather it dries out and shrivels over a period of weeks or months. Wet gangrene progresses much more rapidly. The affected area becomes swollen and gives off a foul smelling discharge. Death may occur within a matter of hours or days. Fever , rapid heart rate, rapid breathing, altered mental state, loss of appetite, diarrhea, vomiting , and vascular collapse may occur as the infection progresses.

Causes & symptoms

The primary cause of gangrene is often an injury to the blood vessels, causing either an interruption of blood flow, the introduction of a bacterial infection, or both. Such injuries may include burns , infected bedsores, boils , frostbite, compound fractures , deep cuts, or gunshot wounds . Gangrene can also develop due to the poor circulation and obstructions in the blood vessels associated with abnormal blood clots , torsion of organs, and diseases such as diabetes, heart disease , and Raynaud's disease. Gangrene of the internal organs may be attributed to a ruptured appendix, internal wounds, or the complications of surgery.

The bloodstream is the body's main transport system. When blood flow is diminished, the flow of the oxygen and nutrients needed to keep tissues healthy is greatly decreased. The white blood cells needed to fight infection are not readily available. In such an environment, invading bacteria thrive and multiply quickly. Streptococcus spp. and Staphylococcus spp. are the most common agents of external skin infection.

Gas gangrene, also called progressive or clostridial myonecrosis, is a type of moist gangrene most commonly caused by an infection of Clostridium perfringens, or other species that are capable of thriving under conditions where there is little oxygen. These bacteria produce gases and poisonous toxins as they grow in the tissues. Gas gangrene

causes the death of tissue, the destruction of red blood cells, and the damaging of the walls of the blood vessels and parts of the kidneys. Early symptoms include sweating, fear, and anxiety . Gas gangrene is a life-threatening condition and should receive prompt medical attention.

Diagnosis

A diagnosis of gangrene will be based on a combination of patient history, a physical examination, blood test results, and other laboratory findings. A physician will look for a history of recent trauma, surgery, cancer , or chronic disease. Blood tests will be used to determine whether infection is present and to determine how much the infection has spread. A sample of drainage from a wound or obtained through surgery may be tested to identify the bacteria causing the infection and to aid in determining treatment. In the case of gas gangrene, the gas produced by the bacteria may be detected beneath the skin by pressing into the swollen areas. The crackling sounds of gas bubbles may also be heard in the affected area and the surrounding tissues.

X-ray studies and other imaging techniques, such as computed tomography (CT) scans or magnetic resonance imaging (MRI), may be helpful in making a diagnosis by showing evidence of gas accumulation or muscle tissue death. These techniques, however, are not sufficient alone to provide an accurate diagnosis of gangrene. Precise diagnosis often requires surgical exploration of the wound.

Treatment

Chelation therapy is a treatment that uses an intravenous solution containing the drug ethylenediamine tetra-acetic acid (EDTA), among other substances. In the bloodstream, EDTA binds and removes toxins and plaque formation on arterial walls. It promotes circulation throughout the body, and is reportedly, although not proven, able to reverse the processes leading to gangrene. Early intervention is necessary, however.

Other alternative and complementary treatments are used to treat gangrene. Herbal remedies such as goldenseal can be applied topically. Biofeedback and hypnosis can increase blood flow. Diabetics will receive herbal and traditional Chinese medicine remedies and nutritional supplements to help prevent gangrene.

Allopathic treatment

Pain medications and large amounts of intravenous antibiotics are given. Prompt surgical removal of infected and destroyed tissue is required for healing to take place. Gas gangrene is often treated with the antitoxin for clostridium as well. In a number of cases, amputation may have to be used to keep the infection under control.

In hyperbaric oxygen (HBO) therapy the patient is placed in a pressurized chamber and receives 100% pure oxygen to breathe. This has been shown useful in inhibiting the production of toxins in gas gangrene and for getting oxygen quickly to tissues, especially following a crushing injury that might lead to gangrene. HBO therapy must be carried out early in the process and used before any surgical removal. The therapy, though useful, does have adverse side effects. It requires skilled technicians and may not be widely available.

Expected results

The outcomes for gangrene are generally favorable if the infection is recognized and treated early in the progression of the disease. Left untreated, gas gangrene will result in a decrease in blood pressure, kidney failure, and coma. Overall, about 20% of those infected with gas gangrene die from the disease, and another 20% require an amputation. Gangrene is most dangerous to the elderly, those who are immuno-compromised, and those who have internal infections and chronic conditions such as diabetes. Individuals suffering from dry gangrene often have multiple health problems that complicate recovery and may prove fatal.

Prevention

Infections and injuries should be thoroughly cleaned and monitored; medical attention should be pursued if symptoms worsen or remain unresolved. Gastrointestinal wounds should be surgically explored, drained, and repaired. Use of antibiotic therapy prior to and directly following surgery has been shown to reduce the rates of infection.

Patients with diabetes or severe arteriosclerosis should take particular care of their hands and feet to avoid the decreased circulation and unchecked infection that may lead to gangrene. Any injury or infection, however slight, should be cared for promptly. There should be a focus on proper foot care, including keeping the feet clean, dry, and warm, wearing well-fitting shoes and not going barefoot. It is important to avoid smoking , since tobacco use constricts the blood vessels of the hands and feet, decreasing circulation.

Resources

BOOKS

Bunch, Bryan, ed. The Family Encyclopedia of Diseases: a Complete and Concise Guide to Illnesses and Symptoms. New York: Scientific Publishing, Inc., 1999.

The Burton Goldberg Group Alternative Medicine: The Definitive Guide. Tiburon, CA: Future Medicine Publishing, 1993.

OTHER

drkoop.com http://www.drkoop.com/conditions/foot_care/library/gangrene.asp.

drkoop.com http://www.drkoop.com/conditions/ency/article/000620.htm.

The Merck Manual http://www.merck.com/pubs/mmanual/section21/chapter292/292a.htm.

Patience Paradox

Gangrene

views updated May 23 2018

Gangrene

Gas gangrene

Resources

Gangrene is a disease that is caused most frequently by the bacterium Clostridium perfringens, which can live in the absence of oxygen. In an infected wound, growth of the bacterium and resulting production of a toxin results in the death of human tissue. Tissue death is usually due to ischemia, which is an interruption in the blood supply to a particular area. Loss of blood supply means loss of oxygen delivery to that tissue, as well as loss of other nutritive factors usually carried in the blood circulation. Tissue deprived in this manner will die, and often becomes even further infected with bacteria during this process.

Gangrene was a disease associated with wartime, particularly with ill-attended wounds that became exposed to dirt (a habitat of C. perfringens ). Nowadays, in the developed world gangrene is more typically associated with the presence of atherosclerotic disease (disease in which arteries are stiff and hard, with fatty deposits blocking blood flow). The interrupted blood flow to toes, feet, and legs, as well as the lack of pain sensation that can accompany the impeded circulation, is a major predisposing factor to gangrene, particularly of the toes, feet, and legs.

In addition, people with diabetes often have advanced, severe cases of atherosclerosis, as well as a condition called neuropathy. Neuropathy is a type of nerve disease, which results in a significant decrease in sensation. Diabetics may not be able to feel any pain from a relatively minor injury (for example, a developing blister) to their foot or leg. Because the diabetic patient does not feel the blister, due to neuropathy, and because the blood supply to the area is so severely compromised, a small initial area of damage can be

extremely difficult to heal, and can rapidly spread. Furthermore, any small opening in the skin, such as a blister, can provide an entry point for bacteria (most commonly staphylococcal and/or streptococcal bacteria) The combination of tissue damage from a blister, along with lack of blood supply to the area to either help in healing the blister or in delivering immune cells to fight infection, can result in the ultimate development of gangrene from a seemingly insignificant injury. This can be severe enough to require amputation of part or all of the affected body part.

Gas gangrene

The scenario most frequently called to mind by the word gangrene is of an extremely rapidly progressing disorder, classically affecting a leg wounded in battle, and resulting in a blackening of the limb which leads either to death of the individual or amputation of the limb to save that persons life. In fact, this scenario is due to a very specific form of gangrene called gas gangrene. Individuals who suffer bullet wounds during the course of battle are very likely to have had these wounds contaminated with dirt or with shreds of their own clothing. This can introduce C. perfringens or related clostridia into the wound. Some types of extreme injury in civilian life can also result in C. perfringens infection. Because C. perfringens bacteria sometimes reside within the gallbladder, spillage of gallbladder contents during surgery can result in gas gangrene of the abdominal muscles.

C. perfringens causes much of its effect due to its ability to produce toxins, or poisons. In fact, C. perfringens is a close cousin to the bacteria which cause tetanus (C. tetani ) and food poisoning, called botulism

KEY TERMS

Atherosclerosis Abnormal narrowing of the arteries of the body that generally originates from the buildup of fatty plaque on the artery wall.

Ischemia Decreased blood, and therefore oxygen, supply to a particular area.

Neuropathy Decreased functioning of the peripheral nervous system. In diabetes, neuropathy leads to decreased sensory perception, and starts in the feet and lower legs.

(C. botulinum ). These bacteria also produce their effects through the production of toxins.

Gas gangrene receives its name from another characteristic of the C. perfringens bacteria. These bacteria ferment (breakdown) certain chemical components of muscle, giving off gas in the process. During examination of the affected area, one can actually feel bubbles of gas which have risen up just under the layers of skin.

C. perfringens bacteria multiply so quickly that gas gangrene can develop in a few hours. An individual with gas gangrene will note severe pain at the wound site (if the pain sensation has not been dulled), with increasing swelling of the area. The wound will begin to give off a watery, sometimes frothy fluid, which has a unique sweet odor, probably due to the digestion of muscle carbohydrate by the bacteria. As muscle breakdown progresses, the muscle feels cooler and appears paler than normal. The muscle feels softer and more liquid, as the bacterial toxins actually work to liquefy it. Ultimately, the area turns a deep blue-black, the classic color of gangrenous tissue. Low blood pressure, kidney failure, and a state of shock (severely decreased blood circulation to all major organ systems) may set in. Survival time for an individual with untreated gas gangrene can be as short as a single day.

Treatment of gas gangrene is with massive doses of antibiotics, in particular Penicillin G. Surgical removal of infected tissue, with a wide margin around it, is necessary to hal the spread of infection, and gangrenous limbs may require amputation.

A fascinating type of treatment for gas gangrene is hyperbaric oxygen therapy. The therapy involves placing an individual in a completely closed, carefully pressurized space, within which the patient will breathe 100% oxygen (much higher than the 21% oxygen

present in normal room air). This high level of oxygen reaches the tissues, where it slows the multiplication of the bacteria, inactivates toxin, and decreases further toxin production.

Resources

BOOKS

Freeman, Frank R. Gangrene and Glory: Medical Care during the American Civil War. Chicago: University of Illinois Press, 2001.

Icon Health Publications. Gangrene: A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. San Diego: Icon Health Publications, 2004.

Kobayashi, G., Patrick R. Murray, Ken Rosenthal, and Michael Pfaller. Medical Microbiology. St. Louis, MO: Mosby, 2003.

Rosalyn Carson-DeWitt

Gangrene

views updated May 09 2018

Gangrene

What Is Gangrene?

How Do Doctors Diagnose and Treat Gangrene?

Can Gangrene Be Prevented?

Resource

Gangrene (GANG-green) is the decay or death of living tissue caused by a lack of oxygen supply to the tissue and/or bacterial infection of the tissue.

KEYWORDS

for searching the Internet and other reference sources

Clostridium perfringens

Debridement

Frostbite

Hyperbaric chamber

What Is Gangrene?

Gangrene is not a contagious disease. It is a condition in which living tissue (e.g., skin, muscle, or bone) begins to decay and die because blood flow (and oxygen) to an area is blocked or because harmful bacteria invade the bodys tissues after entering through a wound or sore. Gangrene most commonly affects the feet, toes, hands, and fingers. Gangrene can also occur inside the body in abdominal organs such as the intestines.

Doctors recognize three major forms of gangrene: dry, wet, and gas gangrene.

Dry gangrene

Dry gangrene is the most common form of gangrene, and it occurs most frequently in the feet of people with diabetes*. Dry gangrene results from the gradual loss of blood supply to a part of the body. The tissue slowly dies because it receives little or no oxygen and nutrients from the blood, but it does not become infected. The first symptoms of dry gangrene are often numbness and tingling in the affected area. This is usually followed by severe pain as the condition progresses and the tissue begins to die; the skin temperature drops, and the color of the tissue changes, eventually turning black.

*diabetes
(dye-uh-BEE-teez) is a condition in which the bodys pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.

Dry gangrene is most often a complication of diabetes, arteriosclerosis*, or frostbite*. Because this condition usually develops gradually, it may go unnoticed for weeks or months, especially in elderly people. Dry gangrene usually is not life threatening, but it needs to be treated promptly.

*arteriosclerosis
(ar-teer-e-o-sklah-RO-sis) is a condition in which arteries of the body have become narrowed and hardened from the buildup of calcium, cholesterol, and other substances, causing decreased blood flow through these vessels.
*frostbite
is damage to tissues resulting from exposure to low environmental temperatures. It is also called congelation (kon-jeh-LAY-shun).

Wet gangrene

Wet gangrene is caused by a bacterial infection from severe wounds or burns or by a crushing injury that causes blood to stop flowing to a certain part of the body. When blood flow stops, bacteria begin to invade the damaged tissue. In wet gangrene, there is pain, swelling, and blistering of the skin, and the wound gives off a foul smell. Organisms that are commonly involved in wet gangrene include Streptococcus (strep-tuh-KAH-kus) and Staphylococcus (stah-fih-lo-KAH-kus) bacteria. Without treatment, wet gangrene can be fatal.

People with poor circulation may experience dry gangrene from loss of oxygen and nutrients carried by blood to the extremities. If the tissue turns black and dies, it must be removed surgically. Photo Researchers, Inc

Gas gangrene

Gas gangrene, which is a form of wet gangrene, involves infection of body tissue by certain types of bacteria (such as Clostridium perfringens, klah-STRIH-de-um per-FRING-enz) that are capable of thriving in anaerobic (ah-nuh-RO-bik) conditions (in which there is little or no oxygen). Once present in the tissue, these bacteria release toxins* and gas. Gas gangrene is marked by a high fever, brownish pus*, gas bubbles under the skin, skin discoloration, and a foul odor. It is the rarest form of gangrene, and only 1,000 to 3,000 cases occur in the United States each year. Like wet gangrene, gas gangrene can be fatal if not treated immediately.

*toxins
are poisons that harm the body.
*pus
is a thick, creamy fluid, usually yellow or greenish in color, that forms at the site of an infection. Pus contains infection-fighting white cells and other substances.

How Do Doctors Diagnose and Treat Gangrene?

A doctor will make the diagnosis of gangrene based on a physical examination, the patients medical history, and the results of blood and other laboratory tests. Cultures from the gangrenous area may be taken and laboratory tests performed to identify the type of bacterial infection and determine the extent to which an infection has spread.

Dead gangrenous tissue must be removed surgically by a procedure called debridement (deh-BREED-ment) so that the wound can heal and healthy new tissue can grow. People with gangrene caused by bacterial infections are treated with antibiotics. In more severe cases, amputation* of a finger, toe, or part of a limb may be necessary. Sometimes patients with gangrene are treated in a hyperbaric chamber, where they are exposed to oxygen at a high pressure to help the affected tissue heal.

*amputation
(am-pyoo-TAY-shun) is the removal of a limb or other appendage or outgrowth of the body.

The outcome for gangrene is usually favorable if the condition is recognized and treated early. Full recovery and new tissue growth can take several weeks to months. Sepsis, a potentially serious spread of infection through the bloodstream and body, can result from wet and gas gangrene. If left untreated, sepsis can result in shock* or death.

*shock
is a serious condition in which blood pressure is very low and not enough blood flows to the bodys organs and tissues. Untreated, shock may result in death.

Can Gangrene Be Prevented?

Carefully cleaning and watching wounds for signs of infection can help prevent gangrene. It is wise to seek medical attention for any wounds that are not healing well or look infected. People who are susceptible to dry gangrene, such as those with decreased circulation in their legs and feet from diabetes or arteriosclerosis, are advised to pay attention to any skin infection in those areas (because such infections could lead to the development of wet gangrene) and to avoid smoking (because smoking constricts the blood vessels, further decreasing circulation). Daily foot care and hygiene is very important in people with advanced diabetes. Treatment with antibiotics before and after abdominal surgery has been shown to reduce the rate of infection and the possibility of developing wet or gas gangrene.

See also

Sepsis

Staphylococcal Infections

Streptococcal Infections

Resource

Organization

U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894. The National Library of Medicine has a website packed with information on diseases (including gangrene) and drugs, consumer resources, dictionaries and encyclopedias of medical terms, and directories of doctors and helpful organizations.

Telephone 888-346-3656 http://www.nlm.nih.gov

Gangrene

views updated May 29 2018

Gangrene

Gangrene involves the death of human tissue , usually due to ischemia, which is an interruption in the blood supply to a particular area. Loss of blood supply means loss of oxygen delivery to that tissue, as well as loss of other nutritive factors usually carried in the blood circulation. Tissue deprived in this manner will die, and often becomes infected with bacteria during this process.


Gangrene in the setting of atherosclerotic disease

The presence of atherosclerotic disease (disease in which arteries are stiff and hard, with fatty deposits blocking blood flow), is a major predisposing factor to gangrene, particularly of the toes, feet, and legs.

People with diabetes often have advanced, severe cases of atherosclerosis, as well as a condition called neuropathy. Neuropathy is a type of nerve disease which results in a significant decrease in sensation. Diabetics, then, may be unable to feel any pain from a relatively minor injury (for example, a developing blister) to their foot or leg. Because the diabetic patient does not feel the blister, due to neuropathy, and because the blood supply to the area is so severely compromised, a small initial area of damage can be extremely difficult to heal, and can rapidly spread. Furthermore, any small opening in the skin, such as a blister, can provide an entry point for bacteria (most commonly staphylococcal and/or streptococcal bacteria) The combination of tissue damage from a blister, along with lack of blood supply to the area to either help in healing the blister or in delivering immune cells to fight infection , can result in the ultimate development of gangrene from a seemingly insignificant injury. This can be severe enough to require amputation of part or all of the affected body part.

Gas gangrene

The scenario most frequently called to mind by the word gangrene is of an extremely rapidly progressing disorder, classically affecting a leg wounded in battle, and resulting in a blackening of the limb which leads either to death of the individual or amputation of the limb to save that person's life. In fact, this scenario (courtesy of all those old war movies on late at night) is due to a very specific form of gangrene called "gas gangrene." Gas gangrene is a wound infection caused most frequently by the bacteria Clostridium perfringens, spores of which are present in soil . Individuals who suffer bullet wounds during the course of battle are very likely to have had these wounds contaminated with dirt or with shreds of their own clothing. This introduces the bacteria C. perfringens (or certain other clostridia cousins), into the wound. Some types of extreme injury in civilian life can also result in C. perfringens infection. Because C. perfringens bacteria sometimes reside within the gallbladder, spillage of gallbladder contents during surgery can result in gas gangrene of the abdominal muscles.

C. perfringens causes much of its effect due to its ability to produce toxins, or poisons. In fact, C. perfringens is a close cousin to the bacteria which cause tetanus (C. tetani) and botulism food poisoning (C. botulinum). These bacteria also produce their effects through the production of toxins.

Gas gangrene receives its name from another characteristic of the C. perfringens bacteria. These bacteria ferment (breakdown) certain chemical components of muscle, giving off gas in the process. During examination of the affected area, one can actually feel bubbles of gas which have risen up just under the layers of skin.

C. perfringens bacteria multiply so quickly that gas gangrene can develop in just a matter of hours. An individual with gas gangrene will note severe pain at the wound site, with increasing swelling of the area. The wound will begin to give off a watery, sometimes frothy fluid which has a unique sweet odor, probably due to the digestion of muscle carbohydrate by the bacteria. As muscle breakdown progresses, the muscle feels cooler and appears paler than normal. The muscle feels softer and more liquid, as the bacterial toxins actually work to liquefy it. Ultimately, the area turns a deep blue-black, the classic color of gangrenous tissue. Low blood pressure , kidney failure, and a state of shock (severely decreased blood circulation to all major organ systems) may set in. Survival time for an individual with untreated gas gangrene can be as short as a single day.

Diagnosis is by examination of tissue under a microscope , where the clostridia can be definitively identified. Certainly, gas gangrene has enough unique characteristics to allow a high level of suspicion based just on the appearance of the wound and the presence of gas as noted by the examiner's hand or as revealed by x ray of the area.

Treatment of gas gangrene is with massive doses of antibiotics , in particular Penicillin G. Surgical removal of infected tissue, with a wide margin around it, is necessary to halt the spread of infection, and gangrenous limbs may require amputation.

A fascinating type of treatment for gas gangrene is hyperbaric oxygen therapy (HBO). HBO involves placing an individual in a completely closed, carefully pressurized space, within which the patient will breathe 100% oxygen (as opposed to the 21% oxygen present in normal room air). This high level of oxygen reaches the tissues, where it slows the multiplication of the bacteria, inactivates toxin, and decreases further toxin production.


Resources

books

Andreoli, Thomas E., et al. Cecil Essentials of Medicine. Philadelphia: W. B. Saunders Company, 1993.

Berkow, Robert, and Andrew J. Fletcher. The Merck Manual ofDiagnosis and Therapy. Rahway, NJ: Merck Research Laboratories, 1992.

Cotran, Ramzi S., et al. Robbins Pathologic Basis of Disease. Philadelphia: W. B. Saunders Company, 1994.

Isselbacher, Kurt J., et al. Harrison's Principles of InternalMedicine. New York: McGraw Hill, 1994.

Kobayashi, G., Patrick R. Murray, Ken Rosenthal, and Michael Pfaller. Medical Microbiology. St. Louis, MO: Mosby, 2003.


Rosalyn Carson-DeWitt

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Atherosclerosis

—Abnormal narrowing of the arteries of the body that generally originates from the buildup of fatty plaque on the artery wall.

Ischemia

—Decreased blood, and therefore oxygen, supply to a particular area.

Neuropathy

—Decreased functioning of the peripheral nervous system. In diabetes, neuropathy leads to decreased sensory perception, and starts in the feet and lower legs.

gangrene

views updated May 29 2018

gan·grene / ˈganggrēn; gangˈgrēn/ • n. Med. localized death and decomposition of body tissue, resulting from either obstructed circulation or bacterial infection.• v. [intr.] become affected with gangrene.DERIVATIVES: gan·gre·nous / ˈganggrənəs/ adj.

gangrene

views updated May 14 2018

gangrene (gang-reen) n. death and decay of part of the body due to deficiency or cessation of blood supply. The causes include disease, injury, or atheroma in major blood vessels, frostbite or severe burns, and diseases such as diabetes mellitus and Raynaud's disease. dry g. death and withering of tissues caused simply by a cessation of local blood circulation. moist (or wet) g. death and putrefactive decay of tissue caused by bacterial infection. See also gas gangrene.