After a traumatic brain injury is confirmed, preventing secondary brain injury due to the effects of hypotension and hypoxia is standard clinical practice. Detecting and reversing hypoxia, hypotension and hyperventilation is thought to be critical for the prognosis of the patient following a traumatic brain injury. As a result, the Brain Trauma Foundation developed evidence-based guidelines outline that it is critical to prevent and reverse hypoxia, hypotension and hyperventilation in patients with suspected traumatic brain injuries (Lulla et al., 2022).

Maiga et al., (2025), recently published in JAMA Network Open, conducted a cohort study including 14,994 adults to investigate the association between clinical outcomes following a traumatic brain injury and the incidence of hypoxia, hypotension and hypocarbia. Authors defined hypoxia as prehospital Sao2 less than 90%. Hypotension was defined as prehospital systolic blood pressure less than 90 mm Hg. Hypocarbia included any end-tidal CO2 less than 35 mm HG after intubation.

Authors found that the incidence of prehospital hypoxia, hypotension and hypocarbia amongst individuals who experienced traumatic brain injuries was associated with a higher risk of death and disability. The presence of both hypoxia and hypotension was associated with significantly increased mortality rates.

These findings highlight the importance of the appropriate clinical management of traumatic brain injuries to prevent secondary injury due to the effects of hypoxia, hypotension and hyperventilation. These findings build on existing literature suggesting that the incidence of hypoxia, hypotension and hypocarbia can inform the clinical prognosis of a patient following a traumatic brain injury. These findings also have important implications for the assessment of medicolegal claims where clinical teams failed to properly assess and reverse hypoxia, hypotension and hypocarbia following a traumatic brain injury.

Dr McCorry comments that while most are familiar with the key features of a primary brain injury such as loss of consciousness, Glasgow coma score and imaging, few appreciate that secondary brain injuries can also develop. There are various mechanisms by which secondary brain injuries may occur. Thorough clinical assessments and a careful analysis of medical records is critical for the clinical management of both primary and secondary injuries following a traumatic brain injury.

References

• Lulla, A., Lumba-Brown, A., Totten, A. M., Maher, P. J., Badjatia, N., Bell, R., … Bobrow, B. J. (2023). Prehospital Guidelines for the Management of Traumatic Brain Injury – 3rd Edition. Prehospital Emergency Care,27(5), 507–538. https://doi.org/10.1080/10903127.2023.2187905.
• Maiga AW, Lin HS, Wisniewski SR, et al. Adverse Prehospital Events and Outcomes After Traumatic Brain Injury. JAMA Netw Open.2025;8(1):e2457506. doi:10.1001/jamanetworkopen.2024.57506.