title: Brief episodes of intracranial hypertension and cerebral hypoperfusion are associated with poor functional outcome after severe traumatic brain injury.
abstract: BACKGROUND
  Management strategies after severe traumatic brain injury (TBI) target prevention and treatment of intracranial hypertension (ICH) and cerebral hypoperfusion (CH). We have previously established that continuous automated recordings of vital signs (VS) are more highly correlated with outcome than manual end-hour recordings. One potential benefit of automated vital sign data capture is the ability to detect brief episodes of ICH and CH. The purpose of this study was to establish whether a relationship exists between brief episodes of ICH and CH and outcome after severe TBI.
  
  
  METHODS
  Patients at the R Adams Cowley Shock Trauma Center were prospectively enrolled over a 2-year period. Inclusion criteria were as follows: age >14 years, admission within the first 6 hours after injury, Glasgow Coma Scale score <9 on admission, and placement of a clinically indicated ICP monitor. From high-resolution automated VS data recording system, we calculated the 5-minute means of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and Brain Trauma Index (BTI = CPP/ICP). Patients were stratified by mortality and 6-month Extended Glasgow Outcome Score (GOSE).
  
  
  RESULTS
  Sixty subjects were enrolled with a mean admission Glasgow Coma Scale score of 6.4 ± 3.1, a mean Head Abbreviated Injury Severity Scale score of 4.2 ± 0.7, and a mean Marshall CT score of 2.5 ± 0.9. Significant differences in the mean number of brief episodes of CPP <50 and BTI <2 in patients with a GOSE 1-4 versus GOSE 5-8 (9.4 vs. 4.7, p = 0.02 and 9.3 vs. 4.9, p = 0.03) were found. There were significantly more mean brief episodes per day of ICP >30 (0.52 vs. 0.29, p = 0.02), CPP <50 (0.65 vs. 0.28, p < 0.001), CPP <60 (1.09 vs. 0.7, p = 0.03), BTI <2 (0.66 vs. 0.31, p = 0.002), and BTI <3 (1.1 vs. 0.64, p = 0.01) in those patients with GOSE 1-4. Number of brief episodes of CPP <50, CPP <60, BTI <2, and BTI <3 all demonstrated high predictive power for unfavorable functional outcome (area under the curve = 0.65-0.75, p < 0.05).
  
  
  CONCLUSIONS
  This study demonstrates that the number of brief 5-minute episodes of ICH and CH is predictive of poor outcome after severe TBI. This finding has important implications for management paradigms which are currently targeted to treatment rather than prevention of ICH and CH. This study demonstrates that these brief episodes may play a significant role in outcome after severe TBI.
authors.affiliation: Division of Critical Care/Program in Trauma, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. dstein@umm.edu
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Stein
authors.forename: Peter F
authors.initials: PF
authors.lastname: Hu
authors.forename: Megan
authors.initials: M
authors.lastname: Brenner
authors.forename: Kevin N
authors.initials: KN
authors.lastname: Sheth
authors.forename: Keng-Hao
authors.initials: KH
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Xiong
authors.forename: Bizhan
authors.initials: B
authors.lastname: Aarabi
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Scalea
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply*; D001930:Brain Injuries / Q000150:complications* / Q000401:mortality; D005260:Female; D023261:Glasgow Outcome Scale; D006801:Humans; D019586:Intracranial Hypertension / Q000209:etiology* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D020127:Recovery of Function; D013997:Time Factors; D055815:Young Adult