Association between mechanical power and 28-day mortality in brain injury patients: a retrospective cohort analysis

Recent studies have shown associations between mechanical power (MP) and mortality in critical care populations. At present, there is insufficient evidence regarding the relationship between mechanical power and mortality in patients with acute brain injury (ABI). We aimed to investigate the association between mechanical power and 28-day mortality, ventilator-free days, duration of mechanical ventilation, and ICU length of stay (LOS) in mechanically ventilated patients with ABI. We conducted a retrospective study involving 950 participants with brain injuries receiving mechanical ventilation. Demographic, clinical, and ventilation parameters were collected. Associations between the first 24 h of MP and 28-day mortality were analyzed using multivariable Cox proportional-hazards models, with sequential adjustment for demographics, illness severity and comorbidities. Secondary outcomes (ventilator-free days through day 28 (VFDs), duration of ventilation, and ICU length of stay) were analyzed using multivariable linear regression. Non-survivors had significantly higher baseline MP compared to survivors (13.8 ± 4.5 vs. 10.8 ± 3.4 J/min, p < 0.001). In Cox regression, higher MP was consistently associated with increased mortality risk across all models. In the fully adjusted model, a per-unit increment in MP (J/min) was associated with an 18.5% higher risk of 28-day mortality (HR 1.185, 95% CI 1.1 ~ 1.28, p < 0.001). Higher MP was also significantly associated with fewer VFDs (β -0.41, 95% CI -0.55 ~ -0.27, p < 0.001), prolonged duration of ventilation (β 5.13, 95% CI 2.4 ~ 7.85, p < 0.001), and increased ICU LOS (β 0.58, 95% CI 0.19 ~ 0.98, p = 0.004). Elevated mechanical power during ventilation is independently associated with increased 28-day mortality risk, fewer ventilator-free days, prolonged duration of ventilation, and increased ICU stay in patients with acute brain injury. MP deserves attention in neurocritical care ventilation management.