Interposed abdominal compression as an adjunct to cardiopulmonary resuscitation.

The addition of IAC to otherwise standard CPR provides for the application of external pressure over the abdomen in counterpoint to the rhythm of chest compression. Interposed abdominal compression is a simple manual technique that can supplement the use of adrenergic drugs to increase both coronary perfusion pressure and total blood flow during CPR. Mechanistically, manual abdominal compressions induce both central aortic and central venous pressure pulses. However, owing to differences in venous versus arterial capacitance, the former are usually greater than the latter, so that systemic perfusion pressure is enhanced. Moreover, practical experience and theoretical analysis have suggested subtle refinements in the hand position and technique for abdominal compression that may further improve the ratio of arterial to venous pressure augmentation. Clinical studies confirm that IAC-CPR can improve perfusion pressures and carbon dioxide excretion during CPR in humans. The incidence of abdominal trauma, regurgitation, or other complications is not increased by IAC. Recently, randomized trials have shown that short-term and long-term survival of patients resuscitated in the hospital by IAC-CPR are about twice that of control patients resuscitated by standard CPR. The technique of IAC has thus evolved to become a highly promising adjunct to normal CPR, which is likely to be implemented in an increasing number of clinical protocols in the 1990s.