Association between prehospital end-tidal carbon dioxide levels and mortality in patients with suspected severe traumatic brain injury

BRAIN-PROTECT collaborators., Sebastiaan M Bossers*, Floor Mansvelder, Stephan A Loer, Christa Boer, Frank W Bloemers, Esther M M Van Lieshout, Dennis Den Hartog, Nico Hoogerwerf, Joukje van der Naalt, Anthony R Absalom, Lothar A Schwarte, Jos W R Twisk, Patrick Schober

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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PURPOSE: Severe traumatic brain injury is a leading cause of mortality and morbidity, and these patients are frequently intubated in the prehospital setting. Cerebral perfusion and intracranial pressure are influenced by the arterial partial pressure of CO 2 and derangements might induce further brain damage. We investigated which lower and upper limits of prehospital end-tidal CO 2 levels are associated with increased mortality in patients with severe traumatic brain injury.

METHODS: The BRAIN-PROTECT study is an observational multicenter study. Patients with severe traumatic brain injury, treated by Dutch Helicopter Emergency Medical Services between February 2012 and December 2017, were included. Follow-up continued for 1 year after inclusion. End-tidal CO 2 levels were measured during prehospital care and their association with 30-day mortality was analyzed with multivariable logistic regression.

RESULTS: A total of 1776 patients were eligible for analysis. An L-shaped association between end-tidal CO 2 levels and 30-day mortality was observed (p = 0.01), with a sharp increase in mortality with values below 35 mmHg. End-tidal CO 2 values between 35 and 45 mmHg were associated with better survival rates compared to < 35 mmHg. No association between hypercapnia and mortality was observed. The odds ratio for the association between hypocapnia (< 35 mmHg) and mortality was 1.89 (95% CI 1.53-2.34, p < 0.001) and for hypercapnia (≥ 45 mmHg) 0.83 (0.62-1.11, p = 0.212).

CONCLUSION: A safe zone of 35-45 mmHg for end-tidal CO 2 guidance seems reasonable during prehospital care. Particularly, end-tidal partial pressures of less than 35 mmHg were associated with a significantly increased mortality.

Original languageEnglish
Pages (from-to)491-504
Number of pages14
JournalIntensive care medicine
Publication statusPublished - May-2023


  • Humans
  • Carbon Dioxide/analysis
  • Hypercapnia/complications
  • Brain Injuries, Traumatic/complications
  • Emergency Medical Services
  • Brain Injuries/complications

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