Monitoring transcutaneously measured partial pressure of co2 during intubation in critically ill subjects

Abstract

BACKGROUND: The risk for severe hypoxemia during endotracheal intubation is a major concern in the ICU, but little attention has been paid to CO2 variability. The objective of this study was to assess transcutaneously measured partial pressure of CO2 (PtcCO2 ) 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 CO2 removal. METHODS: In this single-center, prospective, observational study, we recorded PtcCO2 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 PtcCO2 variability and the development of postintubation hypotension. RESULTS: A total of 202 subjects were included in the study. The PtcCO2 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). PtcCO2 variability differed significantly according to the preoxygenation method (P < .001, linear mixed model). A decrease in PtcCO2 by > 5 mm Hg within 30 min after the start of mechanical ventilation was independently associated with postintubation hypotension (odds ratio = 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: PtcCO2 variability during intubation is significant and differs with the method of preoxygenation. A decrease in PtcCO2 after the beginning of mechanical ventilation was associated with postintubation hypotension. (ClinicalTrials.gov registration NCT0388430.).