The assessment of risk factors associated with difficult intubation as endocrine, musculoskeletal diseases and intraoral cavity mass: A nested case control study.

Background: The predictive factors of difficult airway have been studied to reduce especially the incidence of unanticipating difficult intubation, provide patient safety, and avoid wasting resources. In this study, it was aimed to investigate whether endocrine, musculoskeletal diseases, presence of intraoral mass, and demographic factors have predictive values in the evaluation of difficult air-way as well as frequently used airway assessment tests.

Methods: This study was designed a nested-case control study. After eligibility criterions, totally 1012 patient data were collected, 92 of them were difficult intubation, 920 of them were non-difficult intubation patients (1: 10 ratio). Demographic characteristics of the patients (age, gender), body mass index (BMI), Mallampati, Cormack-Lehane Score (CLS), sternomental distance (SMD), inter incisor gap (IIG), type of surgery, endocrine, musculoskeletal and cardio-pulmonary diseases, and the presence of intraoral mass were compared between groups.

Results: Age >52 years, male gender, ASA 3-4, higher BMI, CLS 3-4, Mallampati 3-4, IIG <4 cm, and SMD <10 cm were found statistically significant in terms of difficult intubation. Besides, a statistically significant relationship was found when the groups were compared in the presence of intraoral mass (17.57 times higher, p<0.05), endocrine diseases (3.51 times more common, p<0.05) and musculoskeletal system diseases (4.5 times higher, p<0.05).

Conclusion: In this study, it was demonstrated that endocrine disorders such as diabetes mellitus and thyroid disorders, musculoskeletal system diseases, and the presence of intraoral cavity mass should be used as predictors for difficult intubation with commonly used airway assessment tests.