Controlled progressive elevation rather than an optimal angle maximizes cerebral perfusion pressure during head up CPR in a swine model of cardiac arrest

Abstract

Aim of the study: Elevation of the head and thorax (HUP) during cardiopulmonary resuscitation (CPR) has been shown to double brain blood flow with increased cerebral perfusion pressures (CerPP) after active compression-decompression (ACD) CPR with an impedance threshold device (ITD). However, the optimal angle for HUP CPR is unknown.

Methods: In Study A, different angles were assessed (20°, 30°, 40°), each randomized over 5-min periods of ACD + ITD CPR, after 8 min of untreated ventricular fibrillation in an anesthetized swine model. Based upon Study A, Study B was performed, where animals were randomized to 1 of 2 sequences: 20°, 30°, 40° or 40°, 30°, 20° with a similar protocol. The primary endpoint was CerPP for both studies.

Results: In Study A, no optimal HUP angle was observed in 18 pigs. CerPPs for 30° and 40° (mmHg, mean ± SD) were equivalent (44 ± 22 and 47 ± 26, p = 0.18). However, CerPP appeared higher when 40° HUP was performed during the last 5-min of CPR, suggestive of a sequence effect. For Study B, after 17 min of CPR, CerPP (mmHg) were higher with the 20°, 30°, 40° sequence: 60 ± 17 versus 33 ± 18 (p = 0.035).

Conclusions: No optimal HUP CPR angle was observed. However, controlled progressive elevation of the head and thorax during CPR is more beneficial than an absolute angle or height to maximize CerPP. Further studies are needed to determine the optimal rate of rise during HUP ACD + ITD CPR.

Institutional protocol number: 17-06.

Keywords: Active compression-decompression CPR; Cardiac arrest; Cardiopulmonary resuscitation; Cerebral perfusion; Head and thorax elevation; Head up CPR; Impedance threshold device; Mechanical CPR.