In Reply Drs Slagt and van Eijk suggest that the ventilation protocol used in PReVENT, a randomized clinical trial comparing a low tidal volume ventilation strategy with an intermediate tidal volume strategy in critically ill patients without ARDS,1 was too complex, perhaps explaining why there was little difference in tidal volume between the 2 groups. Actually, the 2 ventilation protocols were simple2 and well understood and practiced by the caregivers in the participating centers. Volume-controlled ventilation and pressure support ventilation were the preferred modes of ventilation, but other modes could be used if deemed necessary by the attending physician, which happened in a minority of cases. In the low tidal volume group, the aim was to reach a tidal volume between 4 and 6 mL/kg PBW; however, this was not always possible, such as when the lowest allowed level of support (5 cm H2O) was reached, when unacceptable hypercarbia developed, or when a patient became too dyspneic. In the intermediate tidal volume group, the aim was to reach a tidal volume between 8 and 10 mL/kg PBW; however, this also was not always possible, such as when the highest allowed airway pressure (25 cm H2O) was reached. Additional use of sedation or muscle relaxants, with the purpose of allowing the assigned ventilation strategy, was not permitted. Of note, light sedation was practiced in all participating centers, resulting in early use of pressure support ventilation. This explains, at least in part, why tidal volume differences were less than differences in earlier studies that examined the effects of a low tidal volume strategy,3 including the pilot study for PReVENT.4
Neto AS, Simonis FD, Schultz MJ. Tidal Volume Ventilation Strategy in ICU Patients Without ARDS—Reply. JAMA. 2019;321(13):1312–1313. doi:10.1001/jama.2019.0306
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