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Systolic Blood Pressure Threshold for HEMS-Witnessed Arrests

by

Aurore Richard, DOa

Jared Johns, DOa

Allen Wolfe, RN

David Olvera, EMT-P

Alin Gragossian, DOc

Eliana Vaezazizid

Daniel Davis, MDa, b, e

aArrowhead Regional Medical Center, Department of Emergency Medicine

bAir Methods Corporation

cDrexel University, Department of Emergency Medicine

dUniversity of California at San Diego

eCalifornia University of Science and Medicine

Abstract

Background:  Defining vital sign thresholds has focused on mortality, which may be delayed for hour, days, or weeks following injury, limiting the immediate clinical significance.

Objectives:  To identify a systolic blood pressure (SBP) threshold indicating imminent cardiopulmonary arrest.

Methods:  This was a retrospective, observational study using data from adult helicopter emergency medical service (HEMS) patients suffering HEMS-witnessed arrest.  We identified a subgroup of patients with shock-related arrest.  Pre-arrest SBP values were plotted over time, with multiple linear regression used to define a best-fit curve to identify a “terminal inflection point” (slope = -1.0) beyond which cardiopulmonary arrest was imminent.

Results:  A total of 53 patients with hypoperfusion-related arrest and complete data for analysis were identified.  Of these, 33 (62%) were traumatic arrest victims.  A fifth-degree equation demonstrated appropriate goodness-of-fit (r=-0.66, p<0.0001).  An inflection point was identified at SBP 78 mmHg, with arrest occurring approximately 3 min later.

Conclusions:  A terminal inflection point below SBP 80 mmHg was identified, with arrest occurring within 3-4 minutes, suggesting a predictable physiological pattern for perfusion-related deterioration.  This may help guide aggressive therapies to reverse deterioration and avoid arrest.

Click below to read the full research paper published by Air Medical Journal, Volume 37, Issue 2, P104-107, March 01, 2018