Traumatic brain injury (TBI) is a major cause of death and disability, with 60 million cases annually and 8.1 million years of disability worldwide. Hypotension, a common secondary injury in TBI, often results from blood loss or neurogenic causes like myocardial depression or brainstem herniation disrupting autonomic control. Hypotension significantly worsens outcomes, including increased mortality, disability, and extended ICU stays, and is a key factor in the International Mission for Prognosis and Analysis of Clinical Trials score for TBI.
Studies highlight that systolic blood pressure (SBP) below 90 mm Hg correlates with poorer outcomes in TBI patients. The Brain Trauma Foundation recommends avoiding SBP under 100 mm Hg for patients aged 50-69 and under 110 mm Hg for those younger than 15 or older than 70. However, these guidelines are based on weak evidence due to insufficient data.
A recent review analysed the relationship between hypotension and adverse outcomes in TBI, refined SBP thresholds, and provided stronger evidence to enhance clinical guidelines, ultimately improving TBI management and patient care.
A search was conducted for primary research articles published before April 2024 across multiple databases. The inclusion criteria for the study were patients aged 10 years or older with moderate to severe TBI and hypotension.
The main outcomes of the study were the association of hypotension with death and/or vegetative state within six months and the incidence of hypotension. However, data on vegetative state was not reported due to a lack of relevant information from the included studies.
The search identified 17,676 unique articles, and the final review included 51 studies with 384,329 patients. Pooled analysis revealed a significant increase in mortality for patients with hypotension and moderate to severe TBI. The overall incidence of hypotension was 18%.
This review, encompassing over 380,000 patients across 51 studies, provides strong evidence linking hypotension with adverse outcomes in moderate to severe TBI. The findings show that hypotension increases the risk of mortality, with a crude odds ratio (OR) suggesting nearly a 4-fold risk and an adjusted OR showing more than a 2-fold risk. Subgroup analysis highlighted key variables influencing mortality, supporting the multifactorial nature of hypotension in TBI outcomes.
An SBP threshold of 90 mm Hg showed a significant increase in mortality, with a 2.64-fold increased risk, while a higher BP threshold (above 90 mm Hg) reduced mortality odds by 60%. Analysing the Brain Trauma Foundation's recommended SBP thresholds of 100 mm Hg and 110 mm Hg showed improved mortality outcomes, supporting these guidelines.
The study also found that isolated TBI was associated with higher mortality compared to multiple-trauma TBI, possibly due to neurogenic hypotension resulting from direct brain injury. Additionally, hypotension measured in the emergency department (ED) was linked to higher mortality than when measured by emergency medical services (EMS), possibly reflecting more sustained hypotension in the ED.
The overall incidence of hypotension was 18%, with variability in its definition across studies. The incidence was lower when defined as SBP below 90 mm Hg and lower in isolated TBI compared to multiple-trauma TBI. The study's findings underscore the importance of BP management in TBI, with the need for more aggressive control of hypotension to improve patient outcomes.
Overall, this analysis found a significant association between hypotension and more than twice the odds of mortality. The findings highlight the importance of blood pressure threshold management in reducing deaths and can help guide future treatment recommendations for TBI patients.
Source: JAMA
Image Credit: iStock
