Pediatricians and acute care physicians caring for ill patients with respiratory failure often encounter the decision to intubate children for respiratory support and/or to protect the airway. There are several Standard Operating Procedures (SOPs) or protocols such as the 3-3-2 Rule, Mallampati Score, Modified Mallampati Test, and Lemon Criteria, to evaluate whether a difficult airway exists so that preparedness for successful intubation can be ensured. Pediatricians are particularly concerned that there are usually no tailor-made tools or protocols to follow. The authors think that there are a few issues associated with the 3-3-2, Mallampati, and LEMON approaches. The Mallampati approach is only part of the more comprehensive LEMON approach to oropharyngeal patency, and patient cooperation is often required. The LEMON approach amalgamates the 3-3-2 and Mallampati approaches, together with the intrinsic problems associated with these two methods. We present a novel NIMO approach that consolidates existing techniques for intubating difficult airways. By integrating assessments of the Neck (3-3-2), Incisors (Inter-incisor distance), Mouth (Mallampati), and Oropharynx (LEMON), this systematic framework optimizes and streamlines clinical workflow and minimizes the limitations of current tools.

Keywords: LEMON, mallampati score, difficult airway, NIMO protocols, standard operating procedure, upper lip bite test (ULBT), systematic approach.

1. Zimmermann L. Maiellare F. Veyckemans F. Airway management in pediatrics: Improving safety. J Anesth 2025 39 1 123 33 10.1007/s00540‑024‑03428‑z 39556153
2. Disma N. Asai T. Cools E. Airway management in neonates and infants: European Society of Anaesthesiology and Intensive Care and British Journal of Anaesthesia joint guidelines. Br J Anaesth 2024 132 1 124 44 10.1016/j.bja.2023.08.040 38065762
3. Ahmad I. El-Boghdadly K. Iliff H. Difficult Airway Society 2025 guidelines for management of unanticipated difficult tracheal intubation in adults. Br J Anaesth 2026 136 1 283 307 10.1016/j.bja.2025.10.006 41203471
4. Braude D. McLaughlin S. Difficult airways are "LEMONS": Updating the LEMON mneumonic to account for time and oxygen reserve. Ann Emerg Med 2006 47 6 581 10.1016/j.annemergmed.2006.02.030 16713792
5. Barlas Ü.K. Özel A. Tosun V. Bozkurt E.U. Kıhtır H.S. Comparison of the efficacies of high-flow nasal cannula oxygen therapy and non-invasive nasal cannula ventilation in preventing intubation. Turk Pediatri Ars 2024 59 2 214 220 10.5152/TurkArchPediatr.2024.23301 38454232
6. Derakhshan P. Nikoubakht N. Alimian M. Mohammadi S. Relationship between airway examination with LEMON criteria and difficulty of tracheal intubation with IDS criteria. Anesth Pain Med 2024 13 6 e142921 10.5812/aapm‑142921 38721441
7. Soyuncu S. Eken C. Cete Y. Bektas F. Akcimen M. Determination of difficult intubation in the ED. Am J Emerg Med 2009 27 8 905 910 10.1016/j.ajem.2008.07.003 19857405
8. Jagannathan N. Shivazad A. Kolan M. Tracheal extubation in children with difficult airways: A descriptive cohort analysis. Paediatr Anaesth 2016 26 4 372 7 10.1111/pan.12837 26715011
9. Matsumoto T. de Carvalho W.B. Tracheal intubation. J Pediatr 2007 83 2 S83 90 10.1590/S0021‑75572007000300010 17530140
10. Nuckton T.J. Glidden D.V. Browner W.S. Claman D.M. Physical examination: Mallampati score as an independent predictor of obstructive sleep apnea. Sleep 2006 29 7 903 8 10.1093/sleep/29.7.903 16895257
11. Mallampati S.R. Gatt S.P. Gugino L.D. A clinical sign to predict difficult tracheal intubation; A prospective study. Can Anaesth Soc J 1985 32 4 429 434 10.1007/BF03011357 4027773
12. Ouchi K. Hosokawa R. Yamanaka H. Nakajima Y. Nakamura Y. Kishimoto J. Mallampati test with phonation, tongue protrusion and supine position is most correlated with Cormack–Lehane test. Odontology 2020 108 4 617 25 10.1007/s10266‑020‑00490‑3 32040653
13. Oates J.D.L. Oates P.D. Pearsall F.J. McLeod A.D. Howie J.C. phonation affects Mallampati class. Anaesthesia 1990 45 11 984 10.1111/j.1365‑2044.1990.tb14639.x
14. Samsoon G.L.T. Young J.R.B. Difficult tracheal intubation: A retrospective study. Anaesthesia 1987 42 5 487 90 10.1111/j.1365‑2044.1987.tb04039.x 3592174
15. Tham E.J. Gildersleve C.D. Sanders L.D. Mapleson W.W. Vaughan R.S. Effects of posture, phonation and observer on Mallampati classification. Br J Anaesth 1992 68 1 32 8 10.1093/bja/68.1.32 1739564
16. Nair D.J. Varma S.N.K. Ghosh P. Ajith V.V. Reliability of friedman staging system and modified mallampati scoring as clinical assessment methods for obstructive sleep apnea – A cross sectional study. Cranio 2025 43 4 543 550 10.1080/08869634.2023.2221618 37345746
17. Hanouz J.L. Lefrançois V. Boutros M. Fiant A.L. Simonet T. Buléon C. Comparison of the modified Mallampati classification score versus the best visible Mallampati score in the prediction of difficult tracheal intubation: A single-centre prospective observational study. Can J Anaesth 2024 71 10 1353 62 10.1007/s12630‑024‑02815‑0 39147992
18. Roth D. Pace N.L. Lee A. Airway physical examination tests for detection of difficult airway management in apparently normal adult patients. Cochrane Database Syst Rev 2018 3 CD008874 10.1002/14651858.CD008874.pub2
19. Khongkaew J. Sahasthas D. Potat T. Thammawirat P. Modified mallampati classification in determining the success of unsedated transesophageal echocardiography procedure in patients with heart disease: Simple but efficient. Cardiovasc Ultrasound 2016 14 1 42 10.1186/s12947‑016‑0086‑z 27716227
20. Greeshma S. Jayakumar C. Devi K.S. Sumanyu S. Predictive accuracy of modified mallampati classification and thyromental distance for difficult laryngoscopy and intubation. Eur J Cardiovasc Med 2025 15 127 131 10.61336/EJCM/25‑08‑26
21. Lee A. Fan L.T.Y. Gin T. Karmakar M.K. Ngan Kee W.D. A systematic review (meta-analysis) of the accuracy of the Mallampati tests to predict the difficult airway. Anesth Analg 2006 102 6 1867 78 10.1213/01.ane.0000217211.12232.55 16717341
22. Reed M.J. Rennie L.M. Dunn M.J.G. Gray A.J. Robertson C.E. McKeown D.W. Is the 'LEMON' method an easily applied emergency airway assessment tool? Eur J Emerg Med 2004 11 3 154 7 10.1097/01.mej.0000127645.46457.b9 15167176
23. Ohnishi S. Hagiwara Y. Amagasa S. Uematsu S. Validating the performance of the modified LEMON criteria in predicting difficult intubation among pediatric emergency patients. Am J Emerg Med 2025 93 115 9 10.1016/j.ajem.2025.03.067 40184661
24. Hagiwara Y. Watase H. Okamoto H. Goto T. Hasegawa K. Prospective validation of the modified LEMON criteria to predict difficult intubation in the ED. Am J Emerg Med 2015 33 10 1492 6 10.1016/j.ajem.2015.06.038 26166379
25. Yu T. Wang B. Jin X.J. Predicting difficult airways: 3-3-2 rule or 3-3 rule? Ir J Med Sci 2015 184 3 677 83 10.1007/s11845‑015‑1276‑7 25740093
26. Hendrix J.M. Patel R. Friede R. 3-3-2 rule. In: StatPearls [Internet] Treasure Island (FL) StatPearls Publishing 2023 Available from: https://www.ncbi.nlm.nih.gov/books/
27. Sitot M. Amare W. Aregawi A. Predictive values of the modified Mallampati test, upper lip bite test, thyromental distance and ratio of height to thyromental distance to predict difficult laryngoscopy in pediatric elective surgical patients 5–12 years old at selected Addis Ababa governmental hospitals, Ethiopia: A multicenter cross-sectional study. BMC Anesthesiol 2022 22 1 364 10.1186/s12871‑022‑01901‑4 36443701
28. Jackson J.S. Rondeau B. Mallampati score. In: StatPearls [Internet] Treasure Island (FL) StatPearls Publishing 2025 Available from: https://www.ncbi.nlm.nih.gov/books/
29. Lundstrøm L.H. Vester-Andersen M. Møller A.M. Charuluxananan S. L’Hermite J. Wetterslev J. Poor prognostic value of the modified Mallampati score: A meta-analysis involving 177 088 patients. Br J Anaesth 2011 107 5 659 667 10.1093/bja/aer292 21948956