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

OBJECTIVE

To describe the potential effects of ventilatory strategies on the outcome of acute brain-injured patients undergoing invasive mechanical ventilation.

DESIGN

Systematic review with an individual data meta-analysis.

SETTING

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 versus Vt >  = 8 ml/Kg of IBW, positive end-expiratory pressure (PEEP) < or >  = 5 cmHO and protective ventilation (association of both) on relevant clinical outcomes.

POPULATION

Patients with acute brain injury (trauma or haemorrhagic stroke) with invasive mechanical ventilation for ≥ 24 h.

MAIN OUTCOME MEASURES

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.

RESULTS

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 < 0.01).

CONCLUSIONS

Low tidal volume, moderate to high PEEP, or protective ventilation were not associated with mortality and lower incidence of ARDS in patients with acute brain injury undergoing invasive mechanical ventilation. However, protective ventilation improved oxygenation and could be safely considered in this setting. The exact role of ventilatory management on the outcome of patients with a severe brain injury needs to be more accurately delineated.