Of 189 subjects included in the analysis, 166 were successfully extubated and 23 (12%) required re-intubation. Subjects were monitored for 48 h after extubation for escalation in respiratory support and need for re-intubation. Respiratory support upon extubation was based on the clinical team's judgment and defined as low (ie, room air or nasal cannula) or high (ie, high-flow nasal cannula, CPAP, or bi-level positive airway pressure). Using arterial blood gas analysis and mainstream volumetric capnography, daily V D/V T measurements were obtained on intubated subjects using an automated algorithm. All subjects were < 18 y old and were extubated in the pediatric multidisciplinary ICU or the cardiac ICU at an academic medical center from June 2016 through March 2017. This was a prospective, observational, cohort study. We hypothesized that a higher V D/V T value would be associated with extubation failure and higher postextubation respiratory support.

An elevated dead-space-to-tidal-volume ratio (V D/V T) has been proposed as a predictor of successful extubation in children. Extubation failure is associated with increased duration of mechanical ventilation, length of hospital stay, and mortality.

Dead space ventilation ratio