A recent study examined whether low-tidal-volume ventilation (LTVV) is associated with lower mortality in mechanically ventilated patients with acute brain injury (ABI).
LTVV has become standard care in patients with acute respiratory distress syndrome (ARDS) but its use in the ABI population remains controversial due to concerns about intracranial hypertension and the need for additional sedation or neuromuscular blockade.
The researchers analysed data from 1,510 patients across 73 intensive care units in 18 countries. The cohort had a mean age of 52 years, with 34% being female. Traumatic brain injury was the most common cause of ABI (48.1%), followed by intracranial haemorrhage (34.5%). The median Glasgow Coma Scale score before intubation was 7, indicating severe brain injury. Only 9.2% of patients developed ARDS during their ICU admission, making this predominantly a non-ARDS cohort.
The study defined LTVV as a tidal volume of 8 millilitres per kilogram predicted body weight or less, compared with tidal volumes exceeding this threshold. The exposure was measured on days 1, 3, and 7 of mechanical ventilation. The primary outcome was ICU mortality up to 60 days.
The results demonstrated that on day 1 of mechanical ventilation, 76.8% of patients received LTVV, with this proportion remaining relatively stable through day 7. Mean tidal volumes in the LTVV group ranged from 6.7 to 6.8 millilitres per kilogram, whilst the control group received 9.0 to 9.3 millilitres per kilogram. There were no significant differences between groups in plateau pressure, positive end-expiratory pressure, driving pressure, or blood gas parameters.
By day 60, 122 patients (8.1%) had died. The analysis revealed that patients receiving LTVV had a cumulative mortality incidence of 40.2%, compared with 59.7% in those receiving higher tidal volumes. The marginal hazard ratio for mortality was 0.54, indicating a substantial protective association with LTVV. Subgroup analyses showed consistent results across patients with severe brain injury, older age groups, and those with baseline hypoxaemic respiratory failure.
Results remained similar when using machine learning methods to estimate treatment weights and when excluding patients with missing tidal volume data. However, when lower thresholds for defining LTVV were tested (7.5, 7, 6.5, and 6 millilitres per kilogram), associations with mortality became less clear. A negative control outcome analysis examining ventilator-associated pneumonia showed no association with LTVV.
Overall, these findings suggest that LTVV with tidal volumes at or below 8 millilitres per kilogram predicted body weight during the first week of mechanical ventilation is associated with lower ICU mortality in patients with acute brain injury. This supports limiting exposure to high tidal volumes in this population, consistent with evidence from other critically ill patients. However, the authors emphasise that adequately powered randomised controlled trials are needed to definitively establish optimal ventilator strategies while addressing potential risks related to hypercarbia and intracranial pressure.
Source: Chest
Image Credit: iStock
References:
Daza JF et al. (2025) Low-Tidal-Volume Ventilation and Mortality in Patients With Acute Brain Injury. Chest.
