Airway assessment: Predictors for difficult intubation – A prospective observational study

Abstract

Airway management remains an important challenge in the contemporary practice of anaesthesia and preoperative airway assessment facilitates appropriate preparation when difficulty with intubation or ventilation is anticipated prior to induction of anaesthesia.: Aim: To study the important predictors for difficult laryngeal intubation. To determine the predictors of difficult laryngeal intubation. Secondary: To determine the most significant predictor for difficult intubation and to determine the incidence of unanticipated difficult intubation.This single centre prospective observational study done in Bangalore Baptist hospital (after obtaining clearance from ethical committee) included adult patients posted for elective surgeries who received general anaesthesia. Patients of either gender in the 18 – 65 year age group, with an American Society of Anaesthesiologists physical status classification of I or II, who required endotracheal intubation for general anaesthesia. The sample size was 413 with confidence level 95%. In our study the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Mallampati class were found to be 75.8%, 78.06%, 37.90%, 94.80% respectively. The sensitivity, specificity, PPV and NPV of mouth opening were found to be 33.87%, 81.19%, 24.13%, 87.42% respectively. The sensitivity, specificity, PPV and NPV of upper lip bite test found to be 27.41%, 96.29%, 56.66%, 88.25% respectively. The sensitivity, specificity, PPV and NPV of neck extension found to be 54.83%, 92.59%, 56.66%, 92.06% respectively. The sensitivity, specificity, PPV and NPV of BMI found to be 53.22%, 75.49%, 27.73%, 90.13% respectively. The incidence of difficult intubation was 15%.:In conclusion, no single predictor is sufficient for prediction of difficult intubation on its own. All the studied bedside tests are poor to moderate predictors of difficult intubation. All the tests showed poor positive predictive values and high negative predictive values which suggests that they can be more useful predictors of easy intubation than difficult intubation.