Dear editor,
We congratulate Goyal et al. with their recent paper on the association between body mass index (BMI) and inappropriately sized tidal volumes in adult intubated and ventilated emergency department (ED) patients [1]. A staggering 20% of patients received ventilation with inappropriately large tidal volumes, and after adjusting for age and gender, patients in all three obesity categories had higher odds of receiving inappropriately large tidal volumes compared with patients with a normal BMI.
Goyal et al. chose to call a tidal volume ‘appropriate’ when it did not exceed 10 cm3/kg ideal body weight (IBW). Given that a tidal volume of 8 cm3/kg IBW is currently seen as ‘protective’ in patients with non–injured lungs, we suggest the authors recalculating the percentages and odds using this cutoff value. In doing so, the authors allow better comparisons with ventilation practices in operation rooms [2] and in intensive care units [3]. As we are uncertain whether using a too large tidal volume also translates into a higher incidence of acute respiratory distress syndrome (ARDS) in ED patients, the authors could also report the incidence of ARDS in their cohort as well.
One essential comment is that one should be careful calculating IBW based on estimated height and weight values. As this was a retrospective study, we assume that height and weight were not collected as precisely as it would have been done in a prospective study –usually these values are more ‘guesstimates’, and we recently showed that using ‘guesstimates’ results in inappropriate calculations of the IBW. Of note, this challenge is particularly important for extreme values, namely in underweight and overweight patients [4].
Despite all these comments, we very much applaud increasing interest in the way mechanical ventilators are set in the ED [5], [6], were peculiar working conditions and the acuteness of illness could bring the clinician to be less cautious in setting the ventilator and to focus more on other, more stringent, tasks. More studies are warranted to understand the potential role of protective ventilation in this setting.
References
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