Systolic Blood Pressure Threshold for HEMS-Witnessed Arrests

Abstract Objective Defining vital sign thresholds has focused on mortality, which may be delayed for hours, days, or weeks after injury. This limits the immediate clinical significance in guiding therapy to avoid arrest. The aim of this study was to identify a systolic blood pressure (SBP) threshold indicating imminent cardiopulmonary arrest. Methods This was a retrospective, observational study analyzing physiological data from air medical patients suffering witnessed arrest. We limited the analysis to a subgroup of adult (> 14 years) patients with hypoperfusion-related arrest. Prearrest SBP values were plotted over time, with arrest defined as “time zero.” Multiple linear regression was used to define a best fit curve to identify an inflection point beyond which arrest was imminent. Results A total of 53 eligible patients were identified; 33 (62%) were trauma victims. A fifth-degree equation showed appropriate goodness of fit ( r = −.66, P Conclusion An inflection point below SBP 80 mm Hg was identified, suggesting a predictable physiological pattern for perfusion-related deterioration. This may help guide therapy to reverse deterioration and prevent arrest.