The PreVent trial: bag-mask ventilation decreases hypoxia in patients undergoing tracheal intubation

1. For intensive care unit (ICU) patients undergoing tracheal intubation, bag-mask ventilation between induction and laryngoscopy resulted in less hypoxia during the procedure.

2. No difference in aspiration was reported for patients in the groups undergoing intubation with or without bag-mask ventilation.

Evidence Rating Level: 1 (Excellent)      

Study Rundown: A significant number of tracheal intubations in the ICU are complicated by patient hypoxia, which is associated with subsequent cardiac arrest. Between sedative induction and laryngoscopy the use of positive-pressure bag-mask ventilation is controversial, as its benefit of reducing hypoxia is weighed against the perceived increased risk of aspiration. The Preventing Hypoxemia with Manual Ventilation during Endo-tracheal Intubation (PreVent) trial compared the use of bag-mask ventilation between induction and laryngoscopy with not using ventilation. Patients randomized to the bag-mask group had higher oxygen saturation levels than those in the group not being ventilated, and aspiration reported by clinicians and as evidenced on chest x-ray showed no between group differences.

This study provides very pragmatic, clinically useful evidence to support the use of bag-mask ventilation in rapid sequence induction. It is limited as the study is not possible to blind and only evaluated ICU patients, so may not be generalizable to emergency department patients.

Click to read the study in NEJM

Relevant Reading: Positive-pressure ventilation with a face mask and a bag-valve device

In-Depth [randomized controlled trial]: This multicenter randomized controlled trial enrolled patients between 2017 and 2018. Eligible patients were adults undergoing tracheal intubation in an ICU setting, and excluded if they were pregnant or the clinician determined ventilation between induction and laryngoscopy was either required (severe hypoxia) or contraindicated (ongoing hemoptysis, emesis). Patients were randomized in a 1:1 ratio to either a bag-mask group (n=199) receiving best standard practices for ventilation or a group receiving no ventilation between sedative induction and laryngoscopy (n=202). The primary outcome was the lowest oxygen saturation between induction and 2 minutes after intubation, which showed a median lowest oxygen saturation of 96% in the ventilation group and 93% in the non-ventilated group (P=0.01). With prespecified subgroup analysis, all subgroups showed no difference or improved oxygenation with ventilation compared to the non-ventilated group. Severe hypoxia (<80%) was observed in 10.9% and 22.8% of patients in the bag-mask and non-ventilated groups, respectively (relative risk [RR], 0.48; 95% confidence interval [CI], 0.30 to 0.77). Few patients in the ventilated group had oxygen saturations lower than 70% or 90% compared to the non-ventilated group. Operator reported aspiration rates were not significantly different between the ventilated and non-ventilated groups (2.5% and 4.0%, respectively; absolute risk difference, −1.5 percentage points; 95% CI, −4.9 to 2.0; P=0.41). At 48 hours after intubation, there was no between group difference with the ventilated and non-ventilated groups for the presence of chest opacity (16.4% vs. 14.8%, respectively; absolute risk difference, 1.6 percentage points; 95% CI, −5.6 to 8.9; P=0.73).

Image: PD

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