Abstract PR542

Abstract

Background & Objectives: Difficult intubation is an undesirable situation for an anaesthesiologist particularly if it is not anticipated. Although considered a surrogate indicator, difficult laryngoscopy is not the true measure of difficult intubation. The objectives of this study were (i) to determine the association between difficult laryngoscopy and difficult intubation and to determine their prevalence. (ii) to determine the usefulness of routinely used airway measurements for prediction of difficult laryngoscopy. Materials & Methods: This prospective study involved 314, ASA I/II adult patients requiring endotracheal intubation for various routine surgical procedure. A value of sternomental distance < 12 cm, thyromental distance < 6.5cm, inter-incisor distance < 3.5 cm, mandibular protrusion grade >2 and Modified Mallampati class III or IV were defined as the predictors of difficult laryngoscopy.1 Cormack and Lehane grade III or IV of laryngoscopic view was defined as difficult laryngoscopy.2 Requirement of more than three attempts for insertion of the tracheal tube with conventional laryngoscopy was defined as difficult intubation.3 Alternate techniques were applied only after three attempts of intubation. Results: Twelve (3.8%) patients had grade III laryngoscopic view and none had a grade of IV. Increased age (p=0.014) and higher Mallampati score (p<0.001) were associated with difficult laryngoscopy as compared to easy laryngoscopy. Of all the airway measurements, Modified Mallampati class had the highest sensitivity (83.3%) and negative predictive values (99%). Significant association was found between Modified Mallampati Class and Cormack and Lehane laryngoscopic view (p<0.001). No intubations failed. More than three attempts of intubation were required in 7(2.2%) patients. Of these, stylet was used in four patients and Mc-coy laryngoscope was used in two patients as an alternate technique. Strong association was observed between difficult laryngoscopy and an increased attempts (>3) of intubation (p<0.001). Conclusion: The prevalence of difficult laryngoscopy and difficult intubation was 3.8% and 2.2%. Strong association was observed between difficult laryngoscopy and difficult intubation. Of the airway measurements, Modified Mallampati Test had the highest sensitivity and negative predictive values and showed strong association with difficult laryngoscopy.