Abstract 15910: Evaluation of Prehospital Hypotension Depth-duration Dose and Mortality in Major Traumatic Brain Injury
Objective: Prehospital hypotension [systolic BP (SBP) <90 mmHg] dramatically increases mortality in Traumatic Brain Injury (TBI). The literature supporting this concept is based upon a simple dichotomy of whether or not patients had a hypotensive event. However, little is known about the impact of hypotension depth or duration on outcome. The EPIC Study (NIH 1R01NS071049) has statewide, comprehensive, linked EMS data with all recorded BPs and associated times and, hence, enabled us to evaluate the association between prehospital hypotension “depth-duration dose” (DDD) and mortality in TBI.
Methods: We evaluated the moderate/severe TBI cases (CDC Barell Matrix Type 1) enrolled in EPIC before TBI guideline implementation (16,711 cases; 1/07-3/14). Logistic regression was used to determine the association between the DDD of hypotension [mmHg <90 times minutes below 90 (Figure)] and odds of death, adjusted for important confounders.
Results: After exclusions [age <10 (6.8%), transfers (29.2%), only 1 recorded SBP (6.8%), missing SBP/time (10.1%)] 7835 cases remained (median age 41, 70% male). The model revealed a monotonically-increasing relationship between DDD and adjusted odds of death [aOR = 1.14 (95% CI 1.08-1.19)]. Without assuming any a priori functional form for the relationship of DDD vs log odds of death, we obtained a strikingly straight line with tight 95% CI bands. Thus, with other factors being equal, in hypotensive patients, a doubling of DDD yields a 14% increase in adjusted odds of death. Ex: a case where SBP drops to 80 for 10 min (DDD = 100 mmHg-min) has 14% higher odds of dying than one with DDD of only 50 (e.g. 85 for 10 min or 80 for 5 min).
Conclusion: Historically, in TBI, BP has been assessed dichotomously (hypotensive or not). However, it appears that the “dose” of prehospital hypotension is strongly associated with mortality. Hypotension may not be a single entity and its influence on outcome may be much more complex than is inferred by the current literature.
Author Disclosures: D.W. Spaite: None. C. Hu: None. B.J. Bobrow: None. V. Chikani: None. B.J. Barnhart: None. J.B. Gaither: None. K.R. Denninghoff: None. P. Adelson: None. S.M. Keim: None. C. Viscusi: None. T. Mullins: None. D. Sherrill: None.
- © 2016 by American Heart Association, Inc.