Metabolic cost and electrocardiographic changes in cardiac patients during cardiopulmonary resuscitation practice

Nine conditioned post-mycocardial infarction male subjects were studied to determine the energy cost of the chest compression phase of cardiopulmonary resuscitation. Subjects underwent a maximal Bruce treadmill test to determine maximal heart rates and maximal double products. Maximal oxygen uptake (V̇O₂ max) was estimated from treadmill time. Subjects performed chest compression (70 compression/min) for ten minutes on a Resuscianne using American Heart Association techniques. V̇O₂, telemetered heart rate, and blood pressure were obtained at the tenth minute. A 24-hour ambulatory electrocardiogram was begun approximately 12 hours before and continued 12 hours after cardiopulmonary resuscitation. Mean heart rate was 73% of maximal heart rate, V̇O₂ was 42% of estimated V̇O₂ max, and mean double product was 72% of maximal double product. Ambulatory electrocardiography indicated that although there was evidence of ventricular ectopic beats in eight subjects during the control period, there was no significant increase in ventricular ectopic beat frequenty or complexity during cardiopulmonary resuscitation. The data indicate that conditioned post-mycocardial infarction subjects may safely perform cardiopulmonary resuscitation without exacerbation of arrhythmias, and that the V̇O₂ heart rate, and double product levels required are within the range of normal exercise training limits.