title: Difficult laryngoscopy and intubation in the Indian population: An assessment of anatomical and clinical risk factors.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India.
authors.forename: Smita
authors.initials: S
authors.lastname: Prakash
authors.affiliation: Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India.
authors.forename: Amitabh
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India.
authors.forename: Shyam
authors.initials: S
authors.lastname: Bhandari
authors.affiliation: Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India.
authors.forename: Parul
authors.initials: P
authors.lastname: Mullick
authors.affiliation: Medical Research Cardiology, HMC, Doha, Qatar.
authors.forename: Rajvir
authors.initials: R
authors.lastname: Singh
authors.affiliation: Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India.
authors.forename: Anoop Raj
authors.initials: AR
authors.lastname: Gogia
keywords: Airway evaluation; difficult intubation; difficult laryngoscopy; intubation difficulty scale