Abstract
ObjectiveExperimental 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.MethodsThree 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).ResultsSeven 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.ConclusionIn 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.
Highlights
Cardiac arrest is the most critical challenge faced by every clinical physician because it has varying etiologies and a high mortality rate [1]
Cerebral perfusion pressure (CerPP), which is calculated as the mean arterial pressure (MAP) minus the intracranial pressure (ICP), decreases dramatically during cardiac arrest for the following reasons
The reason for the lower ICP is that when elevating the head and body up to 30° during cardiopulmonary resuscitation (CPR), ICP will decrease by facilitating brain venous return and cerebrospinal fluid (CSF) movement into the spinal subarachnoid space, which is consistent with previous studies, even at different elevation angles ranging from 10° to 50° [15]
Summary
Cardiac arrest is the most critical challenge faced by every clinical physician because it has varying etiologies and a high mortality rate [1]. Insufficient brain perfusion is a key factor in poor neurological outcomes. Once cardiac arrest occurs, inflammatory systems are activated to respond to whole-body ischemia, which results in increased membrane permeability [5]. The blood–brain barrier (BBB) breaks down because of intracellular acidosis, stopping oxidative phosphorylation and leading to accumulation of lactate [6]. Due to these two effects, serum proteins and water pass from the blood to brain tissue, which leads to neuronal, glial or axonal injuries [7] and increases ICP. The rate of survival with good neurological outcomes is dismal
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