NECK CIRCUMFERENCE TO THYROMENTAL DISTANCE RATIO IN COMPARISON WITH MALLAMPATI TEST: A STUDY TO PREDICT DIFFICULT INTUBATION

Dr. Samiksha Khanooja* and Dr. Madhusudan Upadya

ABSTRACT

Background: Difficult visualization of larynx, which might lead to difficult intubation is a major concern for anesthesiologists. By utilizing different predictors for difficult airway assessment, the airway can be secured without adverse consequences. Objectives: This study was performed to assess and compare the ratio of the neck circumference to thyromental distance (NC/TMD) with modified Mallampati score in predicting difficult intubation. Methods: The incidence of difficult tracheal intubation in 288 patients were studied. Difficult intubation was determined using the intubation difficulty scale (IDS≥5). The NC/TMD ratio was calculated and it was compared with the patient’s modified Mallampati score to predict difficult intubation .Other factors like TMJ mobility, neck movement, presence of abnormal teeth etc were considered. Statistical analysis: The differences between the two predictors, modified Mallampati score and NC/TMD ratio were analysed using a Chi square test and Student’s unpaired t-test. Results: Difficult intubation was reported in 18 out of 288 patients (6.25%). Multivariate analysis revealed that the modified Mallampati score and NC/TMD can be used independently to predict difficult intubation, (IDS≥5). Among these two indices, NC/TMD showed the higher sensitivity and a negative predictive value. Conclusion: The NC/TMD is a reliable method for predicting difficult intubation like modified Mallampati score.

Keywords: Airway management, laryngoscopy, tracheal intubation, Mallampati, NC/TMD.