Evaluation of Airway Parameters to Predict Difficult Laryngoscopy in Paediatric Patients Undergoing Surgery.

INTRODUCTION: Predicting difficult airway in children is very important as unexpected difficulties in intubation may be diminished by proper pre-operative assessment. OBJECTIVES: To evaluate & compare different airway parameters in predicting difficult laryngoscopy in children. Comparing each airway parameter with Cormack-Lehane Grading for assessing difficult laryngoscopy, Sensitivity, Specificity, NPV & PPV of all airway parameters. MATERIALS AND METHODS: This was a Prospective study,100 Children ASA grade I & II, either gender of age 6 to 12 yrs undergoing elective surgery were included. Children with reactive airway, swelling/mass in neck/limited neck extension/BMI >35 & craniofacial abnormalities were excluded. All children were evaluated in the pre-operative room & following parameters were measured. Ratio of Height to Thyromental distance (RHTMD), Ratio of weight to Interincisor distance, Tragus to nares distance, Sternomental distance (SMD), Nose to chin distance, Mallampati grading (MMPG) (I/II/III/IV), Upper lip bite test (ULBT) (I/II/III), Head Circumference. RESULTS: It was found that mean RHTMD was 19.6 ± 2.26, mean ratio of weight to Interincisor distance was 7.35±3.5, mean SMD was 12.9±1.62, mean Tragus to nares distance was 8.34 ± 0.69, mean nose to chin distance 1.2±0.53 and mean head circumference was 52.02±1.3. It was observed that RHTMD (p = 0.001), SMD (p=0.001), ULBT (p = 0.001) & MMPG (p = 0.02) had significant correlation with difficult laryngoscopy. RHTMD >23 cm had sensitivity of 100% & specificity of 92.86%. SMD <11.5 cm was found to have 100% sensitivity with 81.63%. ULBT > I grade had sensitivity of 100% and specificity of 80.88%. MMPG >II, was found to have sensitivity of 50% & specificity of 100%. Tragus to nares distance, Nose to chin distance, Head circumference and ratio of weight to Interincisor distance did not correlate significantly with difficult laryngoscopy (p>0.05).(1) DISCUSSIONS: Ray et al compared the RHTMD & ratio of height to SMD for predicting laryngoscopy, found that RHTMD was a better predictor in children of age 6 to 12 yrs & found a cut off of >18.6 had a sensitivity of 100% with specificity of 70% to predict a restricted view during laryngoscopy. In our study cut off of 19.6 had sensitivity of 100%, specificity of 92.86% to predict difficult laryngoscopy. Santos AP et al studied MMPG in Age of 4 to 8 yrs & found a sensitivity of 75.8% and specificity of 96.2%. In our study MMPG >2 had sensitivity of 50% and specificity of 100% to predict laryngoscopy. Inal et al in children of 5 to 11 yrs, ULBT was found to have sensitivity of 76.92% with specificity of 97.32%. They found that ULBT had better predictive power than TMD, RHTMD and MMT. In our study results were comparable with sensitivity of 100%, specificity of 80.88% & NPV of 100%. Aggarwal et al found that SMD did not significantly correlate with difficult laryngoscopy (p = 0.07). In our study SMD <11.5 cm had a significant correlation (p = 0.001) with predicting difficult laryngoscopy with sensitivity of 100% & specificity of 81.63%. CONCLUSIONS: We recommend that a thorough preoperative assessment including RHTMD, SMD, ULBT and MM in Airway assessment protocol for children, which would help in anticipating difficult airway making it safer for the children undergoing anaesthesia.