Tilting for perfusion: head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest

Abstract

Introduction: Cerebral perfusion is compromised during cardiopulmonary resuscitation (CPR). We hypothesized that beneficial effects of gravity on the venous circulation during CPR performed in the head-up tilt (HUT) position would improve cerebral perfusion compared with supine or head-down tilt (HDT).

Methods: Twenty-two pigs were sedated, intubated, anesthetized, paralyzed and placed on a tilt table. After 6min of untreated ventricular fibrillation (VF) CPR was performed on 14 pigs for 3min with an automated CPR device called LUCAS (L) plus an impedance threshold device (ITD), followed by 5min of L-CPR+ITD at 0° supine, 5min at 30° HUT, and then 5min at 30° HDT. Microspheres were used to measure organ blood flow in 8 pigs. L-CPR+ITD was performed on 8 additional pigs at 0°, 20°, 30°, 40°, and 50° HUT.

Results: Coronary perfusion pressure was 19±2mmHg at 0° vs. 30±3 at 30° HUT (p<0.001) and 10±3 at 30° HDT (p<0.001). Cerebral perfusion pressure was 19±3 at 0° vs. 35±3 at 30° HUT (p<0.001) and 4±4 at 30° HDT (p<0.001). Brain-blood flow was 0.19±0.04mlmin(-1)g(-1) at 0° vs. 0.27±0.04 at 30° HUT (p=0.01) and 0.14±0.06 at 30° HDT (p=0.16). Heart blood flow was not significantly different between interventions. With 0, 10, 20, 30, 40 and 50° HUT, ICP values were 21±2, 16±2, 10±2, 5±2, 0±2, -5±2 respectively, (p<0.001), CerPP increased linearly (p=0.001), and CPP remained constant.

Conclusion: During CPR, HDT decreased brain flow whereas HUT significantly lowered ICP and improved cerebral perfusion. Further studies are warranted to explore this new resuscitation concept.

Keywords: Cardiac arrest; Cardiopulmonary resuscitation; Cerebral perfusion; Impedance threshold device; Mechanical CPR.