Intravenous (IV) therapy is the administration of therapeutic solutions directly into a vein.
Intravenous therapy is one of the most frequently used health care therapies. It is performed in emergency response settings, hospitals, clinics, nursing homes, and, under some circumstances, at an individual's home.
IV therapy is used for many reasons. One of the most common is to restore fluids in dehydrated patients. In patients with severe vomiting and/or diarrhea, especially children, dehydration can be rapid and severe. IV therapy replaces fluids and electrolytes and gives the digestive system a rest. IV fluids are also given to prevent dehydration in patients who can take nothing by mouth because they are undergoing medical or surgical procedures. Fluids can also be administered to keep a vein open.
IV therapy is also a method of used for the administration of medications. The simplest form of IV therapy is a single dose of medication administered by injection directly in a vein. More commonly, a physician will order a medication to be added to IV fluids already being infused into a vein. Commonly infused medications include antibiotics to treat infections, anticoagulants to prevent blood clots, thrombolytics to dissolve already established blood clots, and chemotherapy drugs to treat cancer. Anesthetics, blood pressure and heart medications, and anticonvulsant drugs can also be given using IV therapy. Other medications that are given IV are ones that would either harm the digestive system or be inactivated by digestive enzymes and the high acidity in gastric juice.
IV therapy is also used to transfuse blood or blood products such as plasma or packed red blood cells. Finally, IV therapy is used to provide nutritional support. This support can range from short-term infusion of a mixture of sugar (dextrose, glucose), water, and minerals (called electrolytes) such as sodium, potassium, magnesium, calcium, chloride, and bicarbonate, to meeting the individual's complete nutritional needs by administering IV therapy on a long term basis. Complete nutrition by IV is called total parenteral nutrition (TPN). TPN is used when an individual's digestive system is blocked, when nutrient absorption fails to occur, and when the GI tract needs to rest because of conditions such as Crohn's disease, ulcerative colitis, or recent bowel surgery. Because of its complete form of nutrition, TPN is also used for individuals with severe burns.
Before inserting an IV catheter, the health care provider should inquire about any allergies to antiseptics, especially iodine, or to latex. The insertion site should be selected based on the condition of the patient's veins, the expected length of IV therapy, type of fluid to be infused, and the potential need for future insertion sites. The health care provider should practice universal precautions against blood contamination. In the United States, federal Occupational Safety and Health Administration (OSHA) regulations require that IV catheters have a safety mechanism such as catheter-over-needle to reduce the likelihood of accidental needle stick injuries to the healthcare worker.
IV therapy can be short term or long term. Short-term IV therapy is administered through peripheral veins located on the hands and arms (legs and scalp for infants) that are close to the surface of the skin. Long-term IV therapy is usually given through larger, deeper central veins.
All IV therapy requires a sharp needle to pierce the skin and a catheter, (a thin, flexible tube) to deliver the fluids, a bag or bottle that contains the fluids, and a delivery system that controls the rate of flow of fluids coming out of the bag and into the patient.
Needles to pierce the skin come in sizes called gauges. The larger the gauge, the smaller the diameter of the needle, thus a 14-gauge needle has a diameter larger than a 23-gauge needle. Choice of needle size depends on the size of the vein to be punctured and the type of fluid to be given. Blood, for example, needs to be administered through a fairly large diameter (small gauge number) needle.
Three types of needles/catheter combinations are in common use. A butterfly catheter consists of an inflexible sharp steel needle with a catheter attached to it. This type of catheter is used to deliver a single injection into a vein, or when the therapy will take no more than four hours. Use of a butterfly needle/catheter combination is more likely to result in accidental needle sticks to the health care worker than other needle/catheter combinations.
An over-the-needle catheter is used for short-term IV therapy using peripheral veins. Using this combination, the needle is inserted into the vein (venipuncture). The catheter is then slid over the needle into the vein and the needle is withdrawn. An inside-the-needle catheter is similar, however, the catheter is inside the needle. It remains in the vein after the needle is withdrawn. Inside-the-needle catheters are larger than over-the-needle catheters and are used more often in central veins for long-term IV therapy.
IV fluid is usually supplied in sterile bags or sometimes in glass bottles. IV Bags may contain a port through which supplemental medications can be injected. The composition of the fluid to be infused depends on its purpose. Fluids can be isotonic, hypotonic, or hypertonic. Isotonic fluids have about the same number of molecules in them (same osmolarity) as blood serum. This prevents any major shifts in fluid balance. Isotonic fluids are often used to maintain hydration during surgery. Examples include normal saline (NS) and lactated Ringer's (LR) solution. Hypotonic solutions have fewer molecules in them than are in the surrounding blood serum. These solutions cause water to move out of the blood vessels and into the surrounding tissue and are often used to carefully rehydrate dehydrated individuals. Examples include 0.45% NaCl (sodium chloride) and 2.5% dextrose (a sugar solution). Hypertonic solutions have more molecules in them than exist in the surrounding blood serum. These solutions cause water to move out of the tissues and into the blood vessels. These solutions are useful in increasing urine output and reducing tissue swelling (edema ). TPN fluids contain a complex mix of protein molecules, fatty acids, and micronutrients to meet the patient's nutritional needs. Whole blood or blood products such as platelets or plasma can also be transfused intravenously.
Regulating flow is critical in successful IV therapy. Fluids can be infused either by a continuous or an intermittent drip. Medications can be added to the fluid or injected all at once (called IV push or IV bolus). Fluid is moved into the veins either through gravity or by a mechanical pump. In either case, the rate at which the fluid is delivered must be set by the nurse either mechanically through a stopcock valve or by setting the pump to the desired flow rate. Flow rate is calculated based on how much fluid should be delivered each hour.
For peripheral (short-term) IV therapy, the health care professional selects the correct needle gauge and readies the necessary equipment, including the tubing, IV fluid, and delivery system. Next, a vein is selected. In infants and toddlers, veins in the scalp, legs, and arms can be used. In older children and adults, the veins of choice are on the back of the hand or in the arm. The choice of vein depends on the type of catheter to be utilized, the type of solution that will be infused, and the condition of the patient's veins. A tourniquet is tightened between the insertion site and the heart a 5-6 inches (12-15 cm) above the insertion site. The skin is cleaned with an antiseptic. Sometimes a local anesthetic is given. The needle is then used to pierce the skin and enter the vein. The catheter position is confirmed by observing a backflow of blood into the catheter casing, or by drawing up blood in a syringe attached to the needle. If a butterfly catheter is used, the needle is then taped in place. If an over-the-needle catheter is used, the catheter is slid over the needle into the vein, then the needle is withdrawn and the catheter tube is taped in place. The tourniquet is released and the rate of flow is set. The procedure is documented. The IV line and flow rate are rechecked and re-documented at regular intervals. Sterile procedure must be maintained at all times to prevent potentially serious infection.
A midline catheter is often inserted when IV therapy will last more than one week but less than one month. These catheters are inserted into a vein near the elbow and then guided into one of the large veins in the upper chest or in the neck. A peripherally inserted central catheter (PICC) is used when IV therapy will continue from one month to one year. These catheters often are placed in the superior vena cava, the main vein returning blood to the heart. Choice of placement depends at least in part on the reason for IV therapy. Insertion of these catheters is a surgical procedure. The patient is usually placed in a position with the head lower than the body. The site of insertion, (often a vein in the arm), is disinfected. A needle and syringe are used to penetrate the vein. Next, the syringe is removed and a guide wire is inserted through the needle and into the vein. The needle is removed, and the guide wire stays in place. The catheter is slipped over the guide wire and into the vein. The catheter is moved into its final position. The position is confirmed by chest x ray. The guide wire is withdrawn, and the catheter is sutured in place.
Vascular access devices provide semi-permanent access to veins for IV therapy. These are often used for cancer patients who must receive frequent IV chemotherapy. They are placed by a surgeon and radiologist (with support staff) in an operating room setting. The patient is prepared for surgery. An incision is made in a vein in the arm or the neck. Using a fluoroscope, the radiologist then guides the catheter to its final placement area, which is in a large vein returning blood to the heart. The catheter is then sutured in place.
IV therapy needs no special preparation by the patient. However, the nurse needs to prepare the equipment and check the four "rights" before puncturing the vein. These are: right patient, right solution, right medication, and right route of administration. The person doing the insertion also needs to take precautions against blood contamination and infection with diseases such as AIDS or hepatitis.
Sterility must be maintained during IV therapy. Once the IV line is in place, it needs to be monitored and flushed regularly. Peripheral IV lines need to be replaced every three or four days. Once the IV line is removed, the insertion site needs to be kept clean until it heals.
Complications with IV therapy are common. They fall into two categories: complications related to insertion of the line and complications related to the fluids administered. Infection is the most common serious complication related to insertion of the device. Other complications related to the device include:
- damage to the vein and leaking of blood into nearby tissues (infiltration)
- bruising at the insertion site (hematoma)
- mechanical irritation of the veins (phlebitis)
- formation of blood clots at the tip of the catheter
- accidental puncture of an artery during insertion
- air in the catheter
- catheter blockage
- accidental dislodgement of the catheter.
Complications associated with medications and fluids administered by IV include:
- medication irritating the vein
- allergic reactions to medications
- irregular heart beat resulting from too rapid infusion of fluids
- fluid, electrolyte, and sugar imbalances due to the composition of the fluid (especially TPN solution)
- fluid overload resulting in congestive heart failure
Results of IV therapy depend primarily on the cause for which the therapy was initiated.
Health care team roles
In emergency situations, IV therapy can be started by paramedical personnel. In a hospital setting, physicians order IV therapy and write orders for any medication to be added to the fluid. Registered nurses or specially trained technicians initiate the venipuncture and insertion of the catheter, and set the IV flow rate. A nutritionist works with the health care team when TPN is used. A surgeon, radiologist, and operating room support team are needed when a long-term catheter is implanted. Visiting nurses may assist with in-home IV therapy.
Electrolytes— A substance that when dissolved in water becomes an ion. Proper concentrations of electrolytes are critical to maintaining biological functions.
Fluoroscope— A special type of x-ray machine that makes it possible to see internal organs in motion.
Infuse— To drip into, as infusing fluids into a vein.
Peripheral veins— Any veins that are not on the trunk of the body.
Tourniquet— A tight band that hinders blood flow.
Weinstein, Sharon. Plumer's Principles and Practice of Intravenous Therapy, 7th ed. Philadelphia: Lippincott Williams & Wilkins, 2000.
Infusion Nurses Society. 220 Norwood Park South, Norwood, MA. 02062 (781) 440-9409. http://www.ins1.org
League of Intravenous Therapy Education (LITE). Empire Building, Suite 3, 3001 Jacks Run Road, White Oak, PA 15131. 412-678-5025. http://www.lite.org.
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