A prospective comparative cross-sectional study between the modified Mallampati classification and the upper lip bite test for the prediction of difficult endotracheal intubation.

Kamzi Ahmar; Baksi Adrita; Basu Swapnil; Dr. Ravi Kumar

doi:10.51168/vpcc8t50

Authors

Dr. Ahmar Kazmi 3rd Year PG Resident, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India1
Dr. Adrita Baksi 2nd year PG Resident, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India
Dr. Swapnil Basu 1st Year PG Resident, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India
Dr. Ravi Kumar Assistant Professor, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India

DOI:

https://doi.org/10.51168/vpcc8t50

Keywords:

Difficult direct laryngoscopy, Upper Lip Bite Test, Modified Mallampati Classification, Difficult airway, Preoperative airway assessment, Cormack–Lehane grading, Endotracheal intubation, Airway prediction, Diagnostic accuracy, Anaesthesia

Abstract

Background:

Accurate prediction of difficult endotracheal intubation is essential for preventing airway-related complications during general anaesthesia. This study compared the diagnostic performance of the Modified Mallampati Classification (MMT) and Upper Lip Bite Test (ULBT).

Objective: To compare MMT and ULBT for predicting difficult endotracheal intubation in adults undergoing elective surgery under general anaesthesia.

Methods:

This prospective comparative cross-sectional study was conducted in the Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, from July 2024 to June 2025. One hundred adults scheduled for elective surgery requiring oral endotracheal intubation were enrolled by consecutive sampling. Preoperative airway assessment was performed using MMT and ULBT. Direct laryngoscopy with a Macintosh laryngoscope was subsequently performed, with Cormack–Lehane grades III–IV considered difficult laryngoscopy. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratios, and diagnostic accuracy were calculated. Fisher's exact test and McNemar's exact test were used for statistical comparisons.

Results:

Difficult laryngoscopy occurred in 9 (9.0%) patients. ULBT showed higher sensitivity (66.7% vs. 44.4%), specificity (87.9% vs. 85.7%), diagnostic accuracy (86.0% vs. 82.0%), PPV (35.3% vs. 23.5%), and NPV (96.4% vs. 94.0%) than MMT. Both ULBT (p=0.0006) and MMT (p=0.0429) were significantly associated with difficult laryngoscopy. However, McNemar's test showed no significant difference between the two tests (p=0.541). Combining either test increased sensitivity to 77.8%, while requiring both increased specificity to 97.8%.

Conclusion:

ULBT demonstrated better observed diagnostic performance than MMT, although statistical superiority was not established. Both tests should be used as complementary components of comprehensive preoperative airway assessment.

Recommendation:

Routine airway assessment should incorporate ULBT alongside MMT. Larger multicentre studies are warranted to validate these findings.

Author Biographies

Dr. Ahmar Kazmi, 3rd Year PG Resident, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India1

is a third-year postgraduate resident in the Department of Anaesthesia and Critical Care at Narayan Medical College and Hospital, Sasaram, Bihar. His academic interests include airway management, regional anaesthesia, and perioperative critical care.
Dr. Adrita Baksi, 2nd year PG Resident, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India

is a second-year postgraduate resident in the Department of Anaesthesia and Critical Care at Narayan Medical College and Hospital, Sasaram, Bihar. Her research interests include difficult airway assessment, perioperative medicine, and patient safety
Dr. Swapnil Basu, 1st Year PG Resident, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India

is a first-year postgraduate resident in the Department of Anaesthesia and Critical Care at Narayan Medical College and Hospital, Sasaram, Bihar. His interests include airway management, anaesthesia education, and emergency airway care.
Dr. Ravi Kumar, Assistant Professor, Department of Anaesthesia and Critical Care, Narayan Medical College and Hospital, Sasaram, Bihar, India

is an Assistant Professor in the Department of Anaesthesia and Critical Care at Narayan Medical College and Hospital, Sasaram, Bihar. His research focuses on airway management, critical care anaesthesia, perioperative patient safety, and clinical observational research.

References

1. Mallampati SR, Gatt SP, Gugino LD, Desai SP, Waraksa B, Freiberger D, et al. A clinical sign to predict difficult tracheal

intubation: a prospective study. Can Anaesth Soc J. 1985;32(4):429-34. https://doi.org/10.1007/BF03011357

2. Samsoon GLT, Young JRB. Difficult tracheal intubation: a retrospective study. Anaesthesia. 1987;42(5):487-90.

https://doi.org/10.1111/j.1365-2044.1987.tb04039.x

3. Benumof JL. Difficult laryngoscopy and the intubation problem. Anesthesiol Clin North Am. 1995;13(4):755-76.

4. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology. 2005;103(2):429-37.

https://doi.org/10.1097/00000542-200508000-00023

5. Merah NA, Wong DT, Ffoulkes-Crabbe DJ, Kushimo OT, Bode CO. Modified Mallampati test, thyromental distance and inter-incisor gap are the best predictors of difficult laryngoscopy in West Africans. Can J Anaesth. 2005;52(3):291-6. https://doi.org/10.1007/BF03016066

6. El-Ganzouri AR, McCarthy RJ, Tuman KJ, Tanck EN, Ivankovich AD. Preoperative airway assessment: predictive value of a multivariate risk index. Anesth Analg. 1996;82(6):1197-204. https://doi.org/10.1213/00000539-199606000-00017

7. Mallampati SR, Seshagiri RK, Varshney R. A modified Mallampati test for predicting difficult intubation: a prospective study. Anesth Analg. 1987;66:S126.

8. Merah NA, Wong DT, Ffoulkes-Crabbe DJ, Kushimo OT, Bode CO. Modified Mallampati test, thyromental distance and inter-incisor gap are the best predictors of difficult laryngoscopy in West Africans. Can J Anaesth. 2005;52(3):291-6. https://doi.org/10.1007/BF03016066

9. Bindra A, Prabhakar H, Bithal PK, Singh GP, Chowdhury T. Predicting difficult laryngoscopy in acromegalic patients undergoing surgery for excision of pituitary tumors: a comparison of extended Mallampati score with modified Mallampati classification. J Anaesthesiol Clin Pharmacol. 2013;29(2):187-90. https://doi.org/10.4103/0970-9185.111694

10. Khan ZH, Kashfi A, Ebrahimkhani E. A comparison of the upper lip bite test with modified Mallampati classification in predicting difficulty in endotracheal intubation: a prospective blinded study. Anesth Analg. 2003;96(2):595-9. https://doi.org/10.1213/00000539-200302000-00053

11. Khan ZH, Maleki A, Makarem J. A comparison of the upper lip bite test with hyomental/thyrosternal distances and mandible length in predicting difficulty in intubation: a prospective study. Indian J Anaesth. 2011;55(1):43-6. https://doi.org/10.4103/0019-5049.76603

12. Shah PJ, Dubey KP, Yadav JP. Predictive value of upper lip bite test and ratio of height to thyromental distance compared with other multivariate airway assessment tests for difficult laryngoscopy in apparently normal patients. J Anaesthesiol Clin Pharmacol. 2013;29(2):191-5. https://doi.org/10.4103/0970-9185.111700

13. Badheka JP, Doshi PM, Vyas AM, Kacha NJ, Parmar VS. Comparison of upper lip bite test and ratio of height to thyromental distance with other airway assessment tests for predicting difficult endotracheal intubation. Indian J Crit Care Med. 2016;20(1):3-8. https://doi.org/10.4103/0972-5229.173678

14. Faramarzi E, Soleimanpour H, Khan ZH, Mahmoodpoor A, Sanaie S. Upper lip bite test for prediction of difficult airway: a systematic review. Pak J Med Sci. 2018;34(4):1019-23. https://doi.org/10.12669/pjms.344.15364

15. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia. 1984;39(11):1105-11. https://doi.org/10.1111/j.1365-2044.1984.tb08932.x

16. Kar S, Senapati LK, Samanta P, Satapathy GC. Predictive value of modified Mallampati test and upper lip bite test concerning Cormack and Lehane's laryngoscopy grading in the anticipation of difficult intubation: a cross-sectional study at a tertiary care hospital, Bhubaneswar, India. Cureus. 2022;14(9):e28754. https://doi.org/10.7759/cureus.28754

17. Wang LY, Zhang KD, Zhang ZH, Zhang DX, Wang HL, Qi F. Evaluation of the reliability of the upper lip bite test and the modified Mallampati test in predicting difficult intubation under direct laryngoscopy in apparently normal patients: a prospective observational clinical study. BMC Anesthesiol. 2022;22(1):314. https://doi.org/10.1186/s12871-022-01855-7

18. Honarmand A, Safavi M, Ansari N. A comparison between hyomental distance ratios, ratio of height to thyromental distance, modified Mallampati classification test, and upper lip bite test in predicting difficult laryngoscopy. Adv Biomed Res. 2014;3:166. https://doi.org/10.4103/2277-9175.139130

19. Safavi M, Honarmand A, Amoushahi M. Prediction of difficult laryngoscopy: extended Mallampati score versus the modified Mallampati test, upper lip bite test and ratio of height to thyromental distance. Adv Biomed Res. 2014;3:133. https://doi.org/10.4103/2277-9175.139130

20. Tang X, Dong Z, Xu J, Cheng P, et al. Observation of the validity of the upper lip bite test in predicting difficult intubation. Sci Rep. 2023;13:22160. https://doi.org/10.1038/s41598-023-49642-9