External cardiopulmonary resuscitation preserves brain viability after prolonged cardiac arrest in dogs

Abstract

Standard external cardiopulmonary resuscitation (CPR) steps A-B-C produce a low blood flow that may or may not preserve brain viability during prolonged cardiac arrest. A dog model was used with ventricular fibrillation (VF) of 20 minutes, reperfusion with brief cardiopulmonary bypass, controlled ventilation to 20 hours, and intensive care to 96 hours. A retrospective comparison was made of the results of one series, now called “group I” (n = 10)—which received CPR basic life support interposed from VF 10 to 15 minutes, and CPR advanced life support with epinephrine (without defibrillation) from VF 15 to 20 minutes—to the results of another series, now “control group II” (n = 10)—which received VF no flow (no CPR) for 20 minutes. All 20 dogs within protocol were resuscitated. All 10 of group I and 7 of group II survived to 96 hours. Pupillary light reflex returned after the start of cardiopulmonary bypass at 7.7 ± 3.7 minutes in CPR group I, versus 16.3 ± 7.4 minutes in control group II ( P = .032). At 96 hours postarrest, final overall performance categories (1, normal; 5, brain death) were better in group I. Six of 10 dogs achieved normality (overall performance category 1) in group I, as compared with none of 10 in group II ( P = .004). Final neurologic doficit score (0%, best; 100% worst) was lower (better) in group I (15% ± 20%) than in group II (51% ± 6%; P < .001). Final canine coma score (15, best; 3, worst) was higher (better) in group I (13.0 ± 2.8) than in group II (8.0 ± 1.3; P = .002). It was concluded that optimal standard external CPR steps A-B-C can sustain cerebral viability during prolonged VF cardiac arrest, even after no flow of 10 minutes.