Prediction of Difficult Airway by Correlating Physical Indices with Maxillo-Pharyngeal Angle, Measured on Lateral Cervical Radiograph-an Analytical Study
Prediction of Difficult Airway
Background: The ability to predict difficult laryngoscopy preoperatively allows anaesthesiologists to take precautions to reduce the anesthesia-related risks but till now, no single airway test can provide a high index of sensitivity and specificity for prediction of difficult airway. The present analytical study was aimed to correlate the various physical indices with maxillo-pharyngeal angle, measured on lateral cervical radiograph, for preoperative prediction of difficult airway. Subjects and Methods: After approval from Institutional Ethical Committee and written informed consent, 200 patients of ASA physical status I and II, aged between 18 to 58 years of either gender with BMI <25 Kg/m2, were studied. Patients with any obvious airway related abnormality, restricted mouth opening, short and thick neck, fixation of the trachea, malformation of the skull, teeth or mandible were excluded. Preoperatively, they were assessed for Modified Mallampati grading, thyromental distance, protrusion of jaw and head-neck movements along with Maxillo-pharyngeal angle, measured on lateral cervical radiograph. These parameters were correlated with Cormack Lehane grading during direct laryngoscopy. The observed data were analyzed by using one way analysis of variance (ANOVA) and Pearson’s correlating co-efficient. Results: Modified Mallampati test sensitivity and specificity was found as 39.29% and 65.12% respectively with accuracy of 61.5%. The sensitivity and specificity of Maxillo- Pharyngeal Angle was 85.71 % and 97.09% respectively with accuracy of 95.50 %. Conclusion: The combination of various physical indices along with maxillo-pharyngeal angle in parallel is more sensitive and specific with clinically relevant higher discriminative power.