Resuscitation (Latin re-, again + suscitare, to revive) is a group of measures to restore life of anyone who is gravely collapsed or apparently dead. The task of resuscitation is to resume and maintain the function of the heart, lungs and metabolism in the patient's body. Resuscitation is most effective in acute cardiac arrest, when the residual compensatory mechanisms are still operable. If, however, cardiac arrest results from a severe incurable disease, in which all the compensatory mechanisms of the body are compromised, CPR is unlikely to be effective.
The three types of terminal conditions are identified: preagonal state, agony and apparent death.
Preagonal state is characterised by confusion, dyspnoea, skin pallor, cyanosis, low or undetectable systolic blood pressure (60-70 mm Hg), weak and rapid heartbeat.
Agony is a further stage of the dying characterised by unconsciousness, a thready or undetectable pulse and blood pressure with shallow, fast, convulsive or very rare breath movements.
Apparent death occurs immediately after breathing and circulation have ceased. It is a transition between life and death, which lasts 3-5 minutes. In apparent death the essential metabolic processes are inhibited and for the lack of oxygen these are mediated by anaerobic glycolysis. After 3 to 5 minutes irreversible changes (primarily in the central nervous system) occur with subsequent somatic, or true biologic death.
Cardiac arrest can either be sudden or gradual in onset or result from a number of chronic diseases. In the latter case a preagonal state and agony precede it.
The causes of sudden cardiac arrest are as follows:
• myocardial infarction;
• upper respiratory tract obstruction by a foreign body;
• injuries to the heart;
• anaphylactic or electric shock;
• drowning;
• severe metabolic disorders (e.g. hyperkalaemia, metabolic acidosis).