Are cardiac surgical patients at increased risk of difficult intubation?

Safe airway management is the cornerstone of contemporary anaesthesia practice, and difficult intubation (DI) remains a major cause of anaesthetic morbidity and mortality. The surgical category, particularly cardiac surgery as a risk factor for DI has not been studied extensively. The aim of this study was to test the hypothesis whether cardiac surgical patients are at increased risk of DI.

During the study, 627 patients (329 cardiac and 298 non-cardiac surgical) were enrolled. Pre-operative demographic and other variables associated with DI were assessed. Patients with Cormack Lehane grade III and IV or use of bougie in Cormack grade II were defined as DI. The incidence of anticipated and unanticipated DI was assessed. Factors associated with DI were described using univariate and multivariate logistic regression models.

The overall incidence of DI was 122/627 (19.46%). The incidence of DI was higher in cardiac surgery patients (24%) as compared to non-cardiac surgery patients (14.4% P = 0.002). On multivariate analysis, factors independently associated with DI were greater age, male sex, higher Mallampati grade, and anticipated DI, but not cardiac surgery. The incidence of unanticipated DI was 48.1% and 53.4% in cardiac and non-cardiac surgery patients, respectively.

Although there was a higher incidence of DI in cardiac surgical patients, cardiac surgery is not an independent risk factor for DI. Rather, other factors play more important role. About half of the DI both in cardiac and non-cardiac surgeries were unanticipated.