Controversial issues in cardiopulmonary resuscitation

Cardiopulmonary resuscitation (CPR) has been the subject of both anecdotes and descriptive research studies, which have resulted in an important step forward in medicine. Unfortunately, few attempts have been made to dispute the dogma surrounding aspects of the physiology and drug management of CPR. Indeed, since the advent of CPR in 1960 when external chest compressions were described by Kouwenhoven and Jude at The Johns Hopkins Hospital until very recently, the techniques and theories behind its use went unquestioned. A number of questions and controversies about physiology and pharmacology of CPR have arisen in the last few years. For example, it is still not well understood why blood flows during CPR. As new information appears regarding mechanisms of blood flow, there is hot debate over how clinical guidelines for chest compression should be altered. Anatomic differences between infants, older children, and adults that affect their responses to CPR have just begun to be addressed. Again, the effect of these findings on clinical practice is yet to be determined. In addition, many researchers are investigating the effects of drugs such as calcium blockers on vital organ blood flow during ischemia, and the results of these studies may affect our practice of advanced CPR. New information regarding glucose metabolism and acid-base factors during ischemia may also alter the clinical practice of CPR. In fact, a number of changes were made in the American Heart Association's recommendations for CPR in 1986. These changes addressed both mechanical and pharmacological aspects of CPR. For example, the number of chest compressions per minute have been increased for adults from 60 to a minimum of 80 and preferably 100 per minute. This change is consistent with both the cardiac pump and thoracic pump theories of blood flow during CPR. Changes have been made also in recommendations covering the indiscriminate use of sodium bicarbonate and calcium chloride. For CPR in children, hand position for chest compressions have been altered to conform with the true anatomy of the child. All of these changes are discussed below in greater detail. We have not attempted to write an exhaustive repetition of the Standards and Guidelines of Cardiopulmonary Resuscitation and Emergency Cardiac Care, but to critically review the literature in order to elucidate some of the controversial issues of clinical CPR.