resuscitation

resuscitation Normal function of the body requires an adequate delivery of oxygen to the tissues, and removal of carbon dioxide and other waste products of tissue metabolism. These items are carried by the bloodstream which must have sufficient flow and pressure to service all parts of the different tissues. The process requires both sufficient breathing and also adequate pumping by the heart. The most important tissues are the vital organs — the brain, heart, liver, and kidneys. In particular, the brain requires a continuous supply of oxygen and glucose or the brain cells may die.

When a person loses consciousness it is often caused by the heart rate slowing down — as in a simple fainting attack. This leads to a reduced blood pressure, insufficient oxygen then reaches the brain. When the person falls and lies horizontally, the blood pressure is improved and recovery of consciousness occurs spontaneously. A patient who has ‘passed out’ for more serious reasons may require resuscitation when this process fails, and if breathing has stopped it is vital to apply artificial ventilation to ensure the delivery of oxygen. Similarly, when the heart has stopped, it is essential to provide cardiac massage to deliver oxygen-carrying blood to the vital organs. The aim of resuscitation is to ensure that both the breathing and the blood flow functions of the body are maintained so that the brain and other vital organs receive a sufficient supply of oxygen and nutrients to maintain their functions, and that waste products of metabolism are removed. Brain damage can begin if the oxygen supply stops for more than a few minutes. The standard aide memoire for resuscitation is ‘ABC’: airway, breathing, and circulation.

Airway

The first essential of resuscitation is to make certain that the person's airway (the passage from the mouth via the larynx to the trachea) is clear. This may simply require the jaw to be pulled forward, to prevent the tongue falling backwards and blocking the airway; or there may be false teeth or vomit which must be removed before air can pass down into the patient's lungs. By placing the patient in the ‘coma position’, the tongue naturally falls forward and helps to maintain a clear airway. Where skilled assistance is available, as in a hospital, an anaesthetist may pass an endotracheal tube into the windpipe (trachea). This will guarantee the clear passage of air into the lungs.

Breathing

Once the airway is clear, the patient may begin to breathe spontaneously. If oxygen is available, this will be used to supplement the normal 21% oxygen present in the atmosphere. Pure oxygen may be used in extreme cases. Where spontaneous respiration does not begin, air must be forced into the patient's lungs either by mouth-to-mouth respiration or by using medical apparatus which can deliver air via a mouthpiece or by connecting it to an endotracheal tube.

Circulation: cardiac massage

Once the airway is clear and the patient can receive air or oxygen into the lungs, the blood flow to the tissues must be maintained. Following a faint, the heart usually returns to a normal rate and produces a normal flow. However, after an event such as a heart attack, the normal rhythm of the heart may be disturbed. The heart may stop beating or may vibrate at a very rapid rate which is too fast to move the blood forward (fibrillation). In such cases, the patient will require urgent cardiac massage. This involves compressing the heart against the spine by pushing down rhythmically on the breast bone (sternum). Following several cardiac massages, a mouth-to-mouth breath is given if breathing has not started spontaneously. The sequence is repeated until pulse and breathing start or skilled help is obtained.

This form of cardiac massage can be very effective in maintaining the blood flow to the vital organs. Where the cause of cardiac arrest is reversible, such as sudden cooling after falling through ice, the patient may make a complete recovery. However, where the underlying disease process has already produced considerable damage to the heart, then cardiac massage may not be successful.

A defibrillator may be used if cardiac arrest occurs in a hospital or in some other places such as exercise laboratories which may be equipped with this apparatus and knowledge of its use. This may succeed in jolting the heart back into effective action.

Gavin Kenny

See also defibrillator; drowning; fainting; fibrillation; heart attack; hypothermia.