Endotracheal Tube Size Is Associated With Mortality in Patients With Status Asthmaticus

Abstract

Background: There is limited evidence on the clinical importance of the endotracheal tube (ETT) size selection in patients with status asthmaticus who require invasive mechanical ventilation. We set out to explore the clinical outcomes of different ETT internal diameter sizes in subjects mechanically ventilated with status asthmaticus.

Methods: This was a retrospective study of intubated and non-intubated adults admitted for status asthmaticus between 2014-2021. We examined in-hospital mortality across subgroups with different ETT sizes, as well as non-intubated subjects, using logistic and generalized linear mixed-effects models. We adjusted for demographics, Charlson comorbidities, the first Sequential Organ Failure Assessment score, intubating personnel and setting, COVID-19, and the first P_aCO2 . Finally, we calculated the post-estimation predictions of mortality.

Results: We enrolled subjects from 964 status asthmaticus admissions. The average age was 46.9 (SD 14.5) y; 63.5% of the encounters were women and 80.6% were Black. Approximately 72% of subjects (690) were not intubated. Twenty-eight percent (275) required endotracheal intubation, of which 3.3% (32) had a 7.0 mm or smaller ETT (ETT ≤ 7 group), 16.5% (159) a 7.5 mm ETT (ETT ≤ 7.5 group), and 8.6% (83) an 8.0 mm or larger ETT (ETT ≥ 8 group). The adjusted mortality was 26.7% (95% CI 13.2-40.2) for the ETT ≤ 7 group versus 14.3% ([(95% CI 6.9-21.7%], P = .04) for ETT ≤ 7.5 group and 11.0% ([95% CI 4.4-17.5], P = .02) for ETT ≥ 8 group, respectively.

Conclusions: Intubated subjects with status asthmaticus had higher mortality than non-intubated subjects. Intubated subjects had incrementally higher observed mortality with smaller ETT sizes. Physiologic mechanisms can support this dose-response relationship.

Keywords: airway resistance; diameter; dynamic hyperinflation; endotracheal tube size; mortality; status asthmaticus.

Fig. 1.

Post generalized linear mixed-effects (GLME) marginal estimation status asthmaticus mortality predictions for each endotracheal tube (ETT) group.

Fig. 2.

Post generalized mixed-effects (GLME) liner model estimation of model-predicted mortality, with endotracheal tube (ETT) analyzed as a continuous variable.

Fig. 3.

Sensitivity analysis of differential height groups, expressed in tertiles (top, middle, low). Post generalized linear mixed-effects (GLME) marginal estimation status asthmaticus mortality predictions of endotracheal tube (ETT) groups in each subject-height tertile group.