The effect of the head-up position on cardiopulmonary resuscitation: a systematic review and meta-analysis

Objective Experimental studies of head-up positioning (HUP) during cardiopulmonary resuscitation (CPR) have had some degree of conflicting published results. The current study aim was to analyze and reconcile those discrepancies in order to better clarify the effects of HUP CPR compared to conventional supine (SUP) CPR. Methods Three databases (PubMed, EMBASE and Cochrane Library) were searched comprehensively (from each respective database's inception to May 2021) for articles addressing HUP CPR. The primary outcome to be observed was cerebral perfusion pressure (CerPP), and secondary outcomes were mean intracranial pressure (ICP), mean arterial pressure (MAP), coronary perfusion pressure (CoPP) and frequencies of return of spontaneous circulation (ROSC). Results Seven key studies involving 131 animals were included for analysis. Compared to SUP CPR, CerPP (MD 10.37; 95% CI 7.11-13.64; p < 0.01; I-2 = 58%) and CoPP (MD 7.56; 95% CI 1.84-13.27, p = 0.01; I-2 = 75%) increased significantly with HUP CPR, while ICP (MD - 13.66; 95% CI - 18.6 to -8.71; p < 0.01; I-2 = 96%) decreased significantly. Combining all study methodologies, there were no significant differences detected in MAP (MD - 1.63; 95% CI - 10.77-7.52; p = 0.73; I-2 = 93%) or frequency of ROSC (RR 0.9; 95% CI 0.31-2.60; p = 0.84; I-2 = 65%). However, in contrast to worse outcomes in studies using immediate elevation of the head in a reverse Trendelenburg position, study outcomes were significantly improved when HUP (head and chest only) was introduced in a steady, graduated manner following a brief period of basic CPR augmented by active compression-decompression (ACD) and impedance threshold (ITD) devices. Conclusion In experimental models, gradually elevating the head and chest following a brief interval of circulatory priming with ACD and ITD devices can enhance CoPP, lower ICP and improve CerPP significantly while maintaining MAP. This effect is immediate, remains sustained and is associated with improved outcomes.