Neurological and respiratory effects of lung protective ventilation in acute brain injury patients without lung injury: brain vent, a single centre randomized interventional study
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https://hdl.handle.net/10037/30615Date
2023-03-20Type
Journal articleTidsskriftartikkel
Peer reviewed
Author
Beqiri, Erta; Smielewski, Peter; Guérin, Claude; Czosnyka, Marek; Robba, Chiara; Bjertnæs, Lars Jakob; K Frisvold, ShirinAbstract
Methods - In a prospective, crossover study, 30 intubated ABI patients with normal ICP and no lung injury were randomly assigned to receive low VT [6 ml/kg/predicted (pbw)]/at either low (5 cmH2O) or high PEEP (12 cmH2O). Between each intervention, baseline ventilation (VT 9 ml/kg/pbw and PEEP 5 cmH2O) were resumed. The safety limit for interruption of the intervention was ICP above 22 mmHg for more than 5 min. Airway and transpulmonary pressures were continuously monitored to assess respiratory mechanics. We recorded ICP by using external ventricular drainage or a parenchymal probe. CA and brain compensatory reserve were derived from ICP waveform analysis.
Results - We included 27 patients (intracerebral haemorrhage, traumatic brain injury, subarachnoid haemorrhage), of whom 6 reached the safety limit, which required interruption of at least one intervention. For those without intervention interruption, the ICP change from baseline to “low VT/low PEEP” and “low VT/high PEEP” were 2.2 mmHg and 2.3 mmHg, respectively, and considered clinically non-relevant. None of the interventions affected CA or oxygenation significantly. Interrupted events were associated with high baseline ICP (p < 0.001), low brain compensatory reserve (p < 0.01) and mechanical power (p < 0.05).
The transpulmonary driving pressure was 5 ± 2 cmH2O in both interventions. Partial arterial pressure of carbon dioxide was kept in the range 34–36 mmHg by adjusting the respiratory rate, hence, changes in carbon dioxide were not associated with the increase in ICP.
Conclusions - The present study found that most patients did not experience any adverse effects of LPV, neither on ICP nor CA. However, in almost a quarter of patients, the ICP rose above the safety limit for interrupting the interventions. Baseline ICP, brain compensatory reserve, and mechanical power can predict a potentially deleterious effect of LPV and can be used to personalize ventilator settings.