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

Abstract

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; I2 = 58%) and CoPP (MD 7.56; 95% CI 1.84–13.27, p = 0.01; I2 = 75%) increased significantly with HUP CPR, while ICP (MD − 13.66; 95% CI − 18.6 to –8.71; p < 0.01; I2 = 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; I2 = 93%) or frequency of ROSC (RR 0.9; 95% CI 0.31–2.60; p = 0.84; I2 = 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.

Survival for Nonshockable Cardiac Arrests Treated With Noninvasive Circulatory Adjuncts and Head/Thorax Elevation*

“…This study provides strong evidence that, compared with traditional closed-chest manual CPR performed in the supine/horizontal plane, OHCA patients with NS presentations can now have far higher likelihoods of SURV when treated by first-in responders who can amplify the lifesaving effects of C-CPR with rapid deployment of AHUP-CPR. These results confirm recent investigational breakthroughs in understanding the pivotal, synergistic role that gradual head/thorax elevation can play when combined with ITD/ACD-CPR (15, 17–23, 30–33).…”

“…More recently, a comprehensive series of porcine ventricular fibrillation models identified a well-defined sequencing of interventions in which C-CPR is followed rapidly by ITD/ACD-CPR for 2 minutes, and then gradual head and thorax elevation over another 2 minutes. This well-studied cadence consistently results in near-normalization of cerebral perfusion pressures and profound improvements in neurologically favorable survival (17,19,20,(29)(30)(31)(32)(33). The pivotal adjuncts used to generate these synergistic physiologic benefits, including an automated head/thorax-up positioning (AHUP) device (Fig.…”

Head-up cardiopulmonary resuscitation

“…Another study confirmed two-fold higher cerebral blood flow in animals receiving ACD+ITD CPR with head and thorax elevation compared with ACD+ITD flat during a prolonged CPR period [7]. In a meta-analysis of 131 animals from 7 studies, compared with supine CPR, CerPP, and Coronary Perfusion Pressure (CoPP) were significantly higher, and ICP was significantly lower [8]. A human cadaver study additionally confirmed the significant reduction in ICP with HUP CPR [9].…”

“…None of these animals had ROSC [10]. In a meta-analysis of animal HUP CPR, CerPP, CorPP, and MAP were all significantly higher in animals that had cardiocerebral priming versus studies that did not perform priming [8]. Physiologically, this makes sense; after a long no-flow time, immediate whole-body elevation may result in blood volume dumping into the lower extremities.…”

Comparison Between Active Abdominal Compression-Decompression Cardiopulmonary Resuscitation and Standard Cardiopulmonary Resuscitation in Asphyctic Cardiac Arrest Rats With Multiple Rib Fractures

“…Furthermore, compression on the internal abdominal organs, such as the liver, could push the blood in these organs into the inferior vena cava, increasing blood flow back to the heart (7). Previous clinical studies (28,29) have reported that STD-CPR can only provide approximately 20% to 30% of prearrest cardiac output, even when optimally performed. However, effective AACD-CPR could result in a maximum cardiac output of approximately 6 L/min (7,30), which is far beyond that of STD-CPR (1.5-3 L/min) (31).…”