Rapid induction of cerebral hypothermia is enhanced with active compression-decompression plus inspiratory impedance threshold device cardiopulmonary resuscitation in a porcine model of cardiac arrest

OBJECTIVES A rapid, ice-cold saline flush combined with active compression-decompression (ACD) plus an inspiratory impedance threshold device (ITD) cardiopulmonary resusitation (CPR) will cool brain tissue more effectively than with standard CPR (S-CPR) during cardiac arrest (CA). BACKGROUND Early institution of hypothermia after CPR and return of spontaneous circulation improves survival and outcomes after CA in humans. METHODS Ventricular fibrillation (VF) was induced for 8 min in anesthetized and tracheally intubated pigs. Pigs were randomized to receive either ACD + ITD CPR (n = 8) or S-CPR (n = 8). After 2 min of CPR, 30 ml/kg ice-cold saline (3 degrees C) was infused over the next 3 min of CPR via femoral vein followed by up to three debrillation attempts (150 J, biphasic). If VF persisted, epinephrine (40 mu g/kg) and vasopressin (0.3 mu/kg) were administered followed by three additional defibrillation attempts. Hemodynamic variables and temperatures were continuously recorded. RESULTS All ACD + ITD CPR pigs (8 of 8) survived (defined as 15 min of return of spontaneous circulation [ROSC]) versus 3 of 8 pigs with S-CPR (p < 0.05). In survivors, brain temperature (degrees C) measured at 2-cm depth in brain cortex 1 min after ROSC decreased from 37.6 +/- 0.2 to 35.8 +/- 0.3 in ACD + ITD CPR versus 37.8 +/- 0.2 to 37.3 +/- 0.3 in S-CPR (p < 0.005). Immediately before defibrillation: 1) right atrial systolic/diastolic pressures (min Hg) were lower (85 +/- 19,4 +/- 1) in ACD + ITD CPR than S-CPR pigs (141 +/- 12, 8 +/- 3, p < 0.01); and 2) coronary perfusion pressures (mm Hg) were higher in ACD + ITD CPR (28.3 +/- 2) than S-CPR pigs (17.4 +/- 3, p < 0.01). CONCLUSIONS A rapid ice-cold saline infusion combined with ACD + ITD CPR during cardiac arrest induces cerebral hypothermia more rapidly immediately after ROSC than with S-CPR.