Effects of active compression-decompression resuscitation on myocardial and cerebral blood flow in pigs

Background. This study was designed to assess the effects of a modified cardiopulmonary resuscitation (CPR) technique that consists of both active compression and active decompression of the chest (ACD CPR) versus standard CPR (STD CPR) on myocardial and cerebral blood flow during ventricular fibrillation both before and after epinephrine administration. Methods and Results. During a 30-second period of ventricular fibrillation cardiac arrest, 14 pigs were randomized to receive either STD CPR (n=7) or ACD CPR (n=7). Both STD and ACD CPR were performed using an automated pneumatic piston device applied midsternum, designed to provide either active chest compression (1.5 to 2.0 in.) and decompression or only active compression of the chest at 80 compressions per minute and 50% duty cycle. Using radiolabeled microspheres, median total myocardial blood flow after 5 minutes of ventricular fibrillation was 14 (7 to 30, minimum to maximum) STD CPR versus 30 (9 to 46) mL · min^-1 · 100 g^-1 with ACD CPR (P<.05). Median cerebral blood flow was 15 (10 to 26) mL · min^-1 · 100 g^-1 with STD CPR and 30 (21 to 39) with ACD CPR (P<.01). When comparing STD with ACD CPR, aortic systolic (62 mm Hg [48 to 70] vs 80 [59 to 86]) and diastolic (22 [18 to 28] vs 28 [21 to 36]) pressures, calculated coronary systolic (30 [22 to 36] vs 49 [37 to 56]) and diastolic (18 [16 to 23] vs 26 [21 to 31]) perfusion pressures, end-tidal CO₂ (1.4% [0.8 to 1.8] vs 2.1 (1.8 to 2.4]), cerebral O₂ delivery (3.1 mL · min^-1 · 100 g^-1 [1.5 to 4.5] vs 5.3 [3.8 to 7.5]), and cerebral perfusion pressure (14 mm Hg [4 to 22] vs 26 [6 to 34]) were all significantly higher with ACD CPR. To compare these parameters before and after vasopressor therapy, a bolus of high-dose epinephrine (0.2 mg/kg) was given to all animals after 5 minutes of ventricular fibrillation. Organ blood flow and calculated perfusion pressures increased significantly in both the STD and ACD groups after epinephrine. The differences observed between STD and ACD CPR before epinephrine were diminished 90 seconds after epinephrine but were again statistically significant when assessed 5 minutes later, once the acute effects of epinephrine had decreased. No difference in short-term resuscitation success was found between the two groups. Conclusions. We conclude that ACD CPR significantly increases myocardial and cerebral blood flow during cardiac arrest in the absence of vasopressor therapy compared with STD CPR.