Peri-intubation adverse events in critically ill obese patients A secondary analysis of the INTUBE study cohort

IMPORTANCE: Endotracheal intubation is routinely done in the critical care setting. However, few data is available on the possible adverse peri-intubation events in the general population and even less in the obese population. Obese patients are usually associated with intubation respiratory physiological modifications such as cephalic ascension of the diaphragm, decreased FRC, decreased pulmonary and chest wall compliance and presence of OHS or OSA comorbidities. These factors impede good pre-oxygenation and decrease the safe apnea period. Furthermore, obese patients usually have anatomical risk factors that predict difficult intubation such as decreased neck mobility, neck masses, large tongue and are usually associated with a higher Mallampati and MACOCHA score. OBJECTIVE:The aim of this secondary analysis is to analyze if obese critically ill patients of the original INTUBE study on major adverse peri-intubation events are at higher risk to develop them versus non-obese critically ill patients. DESIGN, SETTING AND PARTICIPANTS: This is a secondary analysis of the INTUBE study, that was a prospective cohort study done in multiple centers at an international level. During 8 consecutive weeks (October 1, 2018 to July 31,2019) patients were enrolled in 197 sites across 29 countries. The reported intubations included in the study were in-hospital intubations in critically ill patients from emergency department, ICU department and medical wards. For the purposes of this secondary analysis, we classified patients according to their body mass index (BMI) following the WHO weight classification. MAIN OUTCOMES AND MEASURES: In the original INTUBE study, the primary outcomes were defined as the occurrence of at least one of the following major peri-intubation events within 30minutes from the start of the endotracheal intubation procedure: cardiovascular instability (42.6%), severe hypoxemia (9.3%) and cardiac arrest (3.1%). The goal of this secondary study was to analyze the differences that can be noticed in the intubation outcomes and the clinical characteristics of the obese patient group versus non-obese. Additionally, we tried to understand if there is an increased risk of occurrence in these major adverse peri-intubation events in the obese subgroup. RESULTS: In the original INTUBE studies, out of a total of 3659 intubations, 2964 were originally included in the study. For this secondary study, we stratified the participants in the obese and non-obese group, out of 2946 patients that fitted all study criteria (2307 non-obese patients and 639 obese patients). No significant association was detected between obesity and other major peri-intubation adverse events except from severe hypoxemia in univariate analysis. Indeed, incidence of cardiovascular collapse, cardiac arrest, airway injury, esophageal intubation and first pass intubation outcomes were not different between obese and not obese patients. The only adverse event that proved to be more present in the obese group was severe hypoxemia, originally defined as peripheral oxygen saturation <80%. In the multivariable analysis, obesity was not independently associated with increased first pass intubation failure nor severe hypoxemia. Indeed, the difficulty of airway management, both from anatomical and physiology perspectives, are driven by the underlying presence of hypoxemia and anatomical predictors of difficult intubation. CONCLUSION: Obesity is not a risk factor for difficult a