Prakash T. S. N1, Ravi Vasupalli2
BACKGROUND
The significance of difficult or failed tracheal intubation was well recognised as a major cause of morbidity and mortality in anaesthetic practice as per ASA closed claim study. The need to predict potentially difficult tracheal intubation has received more importance, but with limited success. Unanticipated difficult intubation is a risk to patient’s life and a challenge to the skill of the anaesthesiologist. Many anatomical and pathological variables have been identified and have been suggested to be useful in anticipating a difficult airway. These factors have limitations because of wide variations in the incidence of difficult intubation, interobserver variability and inadequate statistical power of the currently measured variables.
METHODS
After obtaining institutional ethical committee clearance and written informed consent, the present study was conducted in 200 patients aged between 16 yrs. and 65 yrs. at King George Hospital, Andhra Medical College, Visakhapatnam, in the Department of Anaesthesiology. All the 200 patients undergoing elective surgical procedures under general anaesthesia were enrolled in the study. A thorough preanaesthetic evaluation was carried out in all the patients and the procedure was explained in detail to the patients.
RESULTS
Of the entire two hundred patients, a total of ten patients had difficult intubation, all of them had Cormack-Lehane class III on laryngoscopy. None of them had Cormack-Lehane class IV on laryngoscopy. The incidence of difficult intubation was 5% in the present study. There were no cases of failed intubation. One hundred and eighty seven patients predicted to be easy for intubation by ULBT (i.e. patients who had ULBT class I and II) out of whom, however, we encountered difficult intubation in 5 patients. Out of the eight patients predicted to have difficult airway by ULBT III, only one patient had CL III difficult airway and subsequently difficult intubation.
CONCLUSIONS
MMT has high sensitivity, specificity, PPV and NPV compared to other two tests. So, it can be used as a simple bedside screening test for difficult laryngoscopy/intubation. ULBT is more accurate than TMD and probably 2nd most important test in prediction of difficult airway. MMT has high specificity and moderate sensitivity and should never be used as a single bedside screening test and it should be combined with other airway assessment tests for prediction of difficult laryngoscopy/intubation. In spite of various airway assessment tests, no single test is 100% accurate. So, it is advisable to use combination of different tests or the use of various scoring systems for predicting difficult laryngoscopy/intubation.
