Mechanical ventilation in patients with acute brain injury: a systematic review with meta-analysis

To describe the potential effects of ventilatory strategies on the outcome of acute brain-injured patients undergoing invasive mechanical ventilation. Systematic review with an individual data meta-analysis. Observational and interventional (before/after) studies published up to August 22nd, 2022, were considered for inclusion. We investigated the effects of low tidal volume Vt = 8 ml/Kg of IBW, positive end-expiratory pressure (PEEP) = 5 cmH O and protective ventilation (association of both) on relevant clinical outcomes. Patients with acute brain injury (trauma or haemorrhagic stroke) with invasive mechanical ventilation for ≥ 24 h. The primary outcome was mortality at 28 days or in-hospital mortality. Secondary outcomes were the incidence of acute respiratory distress syndrome (ARDS), the duration of mechanical ventilation and the partial pressure of oxygen (PaO )/fraction of inspired oxygen (FiO ) ratio. The meta-analysis included eight studies with a total of 5639 patients. There was no difference in mortality between low and high tidal volume [Odds Ratio, OR 0.88 (95%Confidence Interval, CI 0.74 to 1.05), p = 0.16, I = 20%], low and moderate to high PEEP [OR 0.8 (95% CI 0.59 to 1.07), p = 0.13, I = 80%] or protective and non-protective ventilation [OR 1.03 (95% CI 0.93 to 1.15), p = 0.6, I = 11]. Low tidal volume [OR 0.74 (95% CI 0.45 to 1.21, p = 0.23, I = 88%], moderate PEEP [OR 0.98 (95% CI 0.76 to 1.26), p = 0.9, I = 21%] or protective ventilation [OR 1.22 (95% CI 0.94 to 1.58), p = 0.13, I = 22%] did not affect the incidence of acute respiratory distress syndrome. Protective ventilation improved the PaO /FiO ratio in the first five days of mechanical ventilation (p