Effect of vest cardiopulmonary resuscitation on cerebral and coronary perfusion in an infant porcine model.

OBJECTIVES

To determine cerebral and myocardial blood flow rates during vest cardiopulmonary resuscitation (CPR) without direct cardiac compression in an infant porcine model. Also, to determine if circumferential chest compression without the chest deformity ordinarily associated with precordial compression maintains cerebral and myocardial blood flow rates during prolonged CPR. Finally, to establish the effect of compression rate and duty cycle on cerebral and myocardial blood flow rates during vest CPR in this model.

DESIGN

Prospective, randomized comparison of two compression rates and two duty cycles in four groups during prolonged CPR.

SETTING

University cerebral resuscitation laboratory.

SUBJECTS

Thirty-two infant domestic swine.

INTERVENTIONS

Microsphere-determined cerebral and myocardial blood flow rates, perfusion pressures, and chest dimensions, were measured before and during prolonged vest CPR. Immediately after ventricular fibrillation, epinephrine administration was started and thoracic vest CPR was performed using a single combination of compression rates of 100 or 150/min and duty cycles of 30% or 60%. Measurements were made before and at 5, 10, 20, 35, and 50 mins of CPR.

MEASUREMENTS AND MAIN RESULTS

Five minutes into CPR, between-group comparisons showed that cerebral blood flow was 16 to 20 mL/min/100 g and myocardial blood flow was 34 to 45 mL/min/100 g (48% to 62% and 25% to 33% of prearrest values). When CPR was prolonged, cerebral blood flow deteriorated similarly in all groups. Myocardial blood flow decreased over time but was better maintained in the groups with a 30% duty cycle (24 vs. 4 mL/min/100 g; p < .006). There were no differences between the two compression rates. Chest deformity after cessation of 50 mins of compression was < 3%.

CONCLUSIONS

Cerebral and myocardial blood flow rates produced by vest CPR are comparable with rates reported using other types of CPR in this model. Deterioration in blood flow during prolonged CPR occurs despite a lack of chest deformation. The deterioration in myocardial blood flow during prolonged CPR is greater when a long duty cycle is used in this model.