Monitoring Transcutaneously Measured Partial Pressure of C[O.sub.2] During Intubation in Critically Ill Subjects

BACKGROUND: The risk for severe hypoxemia during endotracheal intubation is a major concern in the ICU, but little attention has been paid to C[O.sub.2] variability. The objective of this study was to assess transcutaneously measured partial pressure of C[O.sub.2] ([Please download the PDF to view the mathematical expression]) throughout intubation in subjects in the ICU who received standard oxygen therapy, high-flow nasal cannula oxygen therapy, or noninvasive ventilation for preoxygenation. We hypothesized that the 3 methods differ in terms of ventilation and C[O.sub.2] removal. METHODS: In this single-center, prospective, observational study, we recorded [Please download the PDF to view the mathematical expression] from preoxygenation to 3 h after the initiation of mechanical ventilation among subjects requiring endotracheal intubation. Subjects were sorted into 3 groups according to the preoxygenation method. We then assessed the link between [Please download the PDF to view the mathematical expression] variability and the development of postintubation hypotension. RESULTS: A total of 202 subjects were included in the study. The [Please download the PDF to view the mathematical expression] values recorded at endotracheal intubation, at the initiation of mechanical ventilation, and after 30 min and 1 h of mechanical ventilation were significantly higher than those recorded during preoxygenation (P < .05). [Please download the PDF to view the mathematical expression] variability differed significantly according to the preoxygenation method (P < .001, linear mixed model). A decrease in [Please download the PDF to view the mathematical expression] by > 5 mm Hg within 30 min after the start of mechanical ventilation was independently associated with postintubation hypotension (odds ratio 5 2.14 [95% CI 1.03-4.44], P = .039) after adjustments for age, Simplified Acute Physiology Score II, COPD, cardiac comorbidity, the use of propofol for anesthetic induction, and minute ventilation at the start of mechanical ventilation. CONCLUSIONS: [Please download the PDF to view the mathematical expression] variability during intubation is significant and differs with the method of preoxygenation. A decrease in [Please download the PDF to view the mathematical expression] after the beginning of mechanical ventilation was associated with postintubation hypotension. (ClinicalTrials.gov registration NCT0388430.) Key words: intubation; transcutaneous blood gas monitoring;