Difficult laryngoscopy and intubation in the Indian population: An assessment of anatomical and clinical risk factors

Abstract

Background and aim: Differences in patient characteristics due to race or ethnicity may influence the incidence of difficult airway. Our purpose was to determine the incidence of difficult laryngoscopy and intubation, as well as the anatomical features and clinical risk factors that influence them, in the Indian population.

Methods: In 330 adult patients receiving general anaesthesia with tracheal intubation, airway characteristics and clinical factors were determined and their association with difficult laryngoscopy (Cormack and Lehane grade 3 and 4) was analysed. Intubation Difficulty Scale score was used to identify degree of difficult laryngoscopy.

Results: The incidence of difficult laryngoscopy and intubation was 9.7% and 4.5%, respectively. Univariate analysis showed that increasing age and weight, male gender, modified Mallampati class (MMC) 3 and 4 in sitting and supine positions, inter-incisor distance (IID) ≤3.5 cm, thyromental (TMD) and sternomental distance, ratio of height and TMD, short neck, limited mandibular protrusion, decreased range of neck movement, history of snoring, receding mandible and cervical spondylosis were associated with difficult laryngoscopy. Multivariate analysis identified four variables that were independently associated with difficult laryngoscopy: MMC class 3 and 4, range of neck movement <80°, IID ≤ 3.5 cm and snoring.

Conclusions: We found an incidence of 9.7% and 4.5% for difficult laryngoscopy and difficult intubation, respectively, in Indian patients with apparently normal airways. MMC class 3 and 4, range of neck movement <80°, IID ≤ 3.5 cm and snoring were independently related to difficult laryngoscopy. There was a high incidence (48.5%) of minor difficulty in intubation.

Keywords: Airway evaluation; difficult intubation; difficult laryngoscopy; intubation difficulty scale.