"NECK CIRCUMFERENCE TO THYROMENTAL DISTANCE RATIO AS A PREDICTOR OF DIFFICULT INTUBATION IN OBESE PATIENTS: A PROSPECTIVE OBSERVATIONAL STUDY"
Main Article Content
Keywords
Obesity, Difficult Intubation, Neck Circumference, Thyromental Distance, NC/TMD Ratio
Abstract
Background: Obesity has become a widespread health concern, and obese individuals are at a higher risk of airway-related complications. Difficult laryngoscopy and intubation are major challenges for anesthesiologists, contributing to significant perioperative morbidity and mortality. Several predictors for difficult intubation in obese patients have been studied, but the role of the neck circumference (NC) to thyromental distance (TMD) ratio as a predictor remains under-explored. This study aims to assess the predictive value of NC, TMD, and NC/TMD ratio for difficult intubation in obese versus non-obese individuals.
Methods: A prospective observational study was conducted in the ENT department of our institute after ethical approval. Patients requiring general anesthesia and tracheal intubation were included, with exclusions for restricted cervical movement, neck contractures, visible neck swelling, or oropharyngeal pathology. Demographic data, body mass index (BMI), NC (measured at the cricoid level), TMD, and modified Mallampati scores were recorded.
Results: The study included 200 patients (117 males, 83 females) with a mean age of 36.36 ± 8.04 years. The mean NC was significantly higher in obese (36.06 ± 1.92 cm) than in non-obese (34.21 ± 1.85 cm) (p = 0.00). The mean TMD was lower in obese (7.43 ± 0.66 cm) compared to non-obese (7.89 ± 0.65 cm) (p = 0.00). The NC/TMD ratio was significantly higher in obese patients (4.94 ± 0.49) compared to non-obese (4.35 ± 0.40) (p = 0.00). Among 200 patients, 18 had difficult intubation (4 non-obese, 14 obese), with a significant association between obesity and difficult intubation (p = 0.013).
Conclusion: The NC/TMD ratio is a reliable, cost-effective, and non-invasive predictor of difficult intubation in obese individuals. It provides better predictive accuracy than NC or TMD alone and can serve as an essential screening tool in preoperative airway assessment.
Methods: A prospective observational study was conducted in the ENT department of our institute after ethical approval. Patients requiring general anesthesia and tracheal intubation were included, with exclusions for restricted cervical movement, neck contractures, visible neck swelling, or oropharyngeal pathology. Demographic data, body mass index (BMI), NC (measured at the cricoid level), TMD, and modified Mallampati scores were recorded.
Results: The study included 200 patients (117 males, 83 females) with a mean age of 36.36 ± 8.04 years. The mean NC was significantly higher in obese (36.06 ± 1.92 cm) than in non-obese (34.21 ± 1.85 cm) (p = 0.00). The mean TMD was lower in obese (7.43 ± 0.66 cm) compared to non-obese (7.89 ± 0.65 cm) (p = 0.00). The NC/TMD ratio was significantly higher in obese patients (4.94 ± 0.49) compared to non-obese (4.35 ± 0.40) (p = 0.00). Among 200 patients, 18 had difficult intubation (4 non-obese, 14 obese), with a significant association between obesity and difficult intubation (p = 0.013).
Conclusion: The NC/TMD ratio is a reliable, cost-effective, and non-invasive predictor of difficult intubation in obese individuals. It provides better predictive accuracy than NC or TMD alone and can serve as an essential screening tool in preoperative airway assessment.
References
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3. Misra A, Chowbey P, Makkar BM, Vikram NK, Wasir JS, et al. (2009) Consensus statement for diagnosis of obesity, abdominal obesity and the metabolic syndrome for Asian Indians and recommendations for physical activity, medical and surgical management. J Assoc Physicians India 57: 163-170.
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5. Benumof JL (1991) management of difficult adult airway with special emphasis on awake tracheal intubation. Anaesthesiology 75(6): 1087- 1110.
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8. Horner RL, Mohiaddin RH, Lowell DG, Shea SA, Burman ED, et al. (1989) Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. Eur Respir J 2(7): 613-622.
9. Ezri T, Gewurtz G, Sessler DI, Medalion B, Szmuk P, et al. (2003) Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue. Anaesthesia 58(11): 1111- 1148.
10. Basil P M. The Importance of Neck Circumference to Thyromental Distance Ratio (Nc/Tm Distance Ratio) as a Predictor of Difficult Intubation in Obese Patients Coming for Elective Surgery under General Anaesthesia in a Teritatry Care Hospital – A Prospective Observational Study. J Anest & Inten Care Med. 2017; 4(1) : 555628
11. Rose N, Maya G, Sathyadas A. Comparison of Difficult Intubation and Neck Circumference to Thyromental Distance Ratio, in Obese and Non-Obese: A Clinical Study.
12. Gonzalez H, Minville V, Delanoue K, Mazerolles M, Concina D. The importance of increased neck circumference to intubation difficulties in obese patients. Anesth Analg 2008;106(4):1132-1136.
13. Brodsky JB, Lemmens HJ, Brock- Utne JG, Vierra M, Saidman LJ. Morbid obesity and tracheal intubation. Anesth Analg 2002;94(3):732-736.
14. Juvin P, Lavaut E, Dupont H, Lefevre P, Demetriou M, et al. Difficult tracheal intubation is more common in obese than in lean patients. Anesth Analg 2003;97(2):595-600.
15. Nadia R. Comparison of Difficult Intubation and Neck Circumference to Thyromental Distance Ratio, in Obese and Non- Obese: A Clinical Study. J Med Sci Clin Res 2017;5(3):19670-19679.
16. Kim WH, Ahn HJ, Lee CJ, Shin BS, KO JS. Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients. Br J Anesth 2011;106(5):743-748.
17. Hiremath AS, Hillman DR, James AL, Noffsinger WJ, Platt PR, Singer SL. Relationship between difficult tracheal intubation and obstructive sleep apnoea. British Journal of Anaesthesia. 1998 May 1;80(5):606-11.
2. WHO Expert Consultation (2004) appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet 363(9403): 157-163.
3. Misra A, Chowbey P, Makkar BM, Vikram NK, Wasir JS, et al. (2009) Consensus statement for diagnosis of obesity, abdominal obesity and the metabolic syndrome for Asian Indians and recommendations for physical activity, medical and surgical management. J Assoc Physicians India 57: 163-170.
4. Miller CG (2000) management of difficult intubation in closed malpractice claims. ASA Newsletter 64(6): 13-16 and 19.
5. Benumof JL (1991) management of difficult adult airway with special emphasis on awake tracheal intubation. Anaesthesiology 75(6): 1087- 1110.
6. Bond A. Obesity and difficult intubation. Anaesth Intensive Care. 1993;21:828–30
7. Smita Prakash, Amitabh Kumar, Shyam Bhandari, ParulMullick, Rajvir Singh,1 and Anoop Raj Gogia. Difficult laryngescopy and intubation in the Indian population: An assessment of anatomical and clinical risk factors. Indian J Anaesth. 2013 Nov-Dec; 57(6): 569–575.
8. Horner RL, Mohiaddin RH, Lowell DG, Shea SA, Burman ED, et al. (1989) Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. Eur Respir J 2(7): 613-622.
9. Ezri T, Gewurtz G, Sessler DI, Medalion B, Szmuk P, et al. (2003) Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue. Anaesthesia 58(11): 1111- 1148.
10. Basil P M. The Importance of Neck Circumference to Thyromental Distance Ratio (Nc/Tm Distance Ratio) as a Predictor of Difficult Intubation in Obese Patients Coming for Elective Surgery under General Anaesthesia in a Teritatry Care Hospital – A Prospective Observational Study. J Anest & Inten Care Med. 2017; 4(1) : 555628
11. Rose N, Maya G, Sathyadas A. Comparison of Difficult Intubation and Neck Circumference to Thyromental Distance Ratio, in Obese and Non-Obese: A Clinical Study.
12. Gonzalez H, Minville V, Delanoue K, Mazerolles M, Concina D. The importance of increased neck circumference to intubation difficulties in obese patients. Anesth Analg 2008;106(4):1132-1136.
13. Brodsky JB, Lemmens HJ, Brock- Utne JG, Vierra M, Saidman LJ. Morbid obesity and tracheal intubation. Anesth Analg 2002;94(3):732-736.
14. Juvin P, Lavaut E, Dupont H, Lefevre P, Demetriou M, et al. Difficult tracheal intubation is more common in obese than in lean patients. Anesth Analg 2003;97(2):595-600.
15. Nadia R. Comparison of Difficult Intubation and Neck Circumference to Thyromental Distance Ratio, in Obese and Non- Obese: A Clinical Study. J Med Sci Clin Res 2017;5(3):19670-19679.
16. Kim WH, Ahn HJ, Lee CJ, Shin BS, KO JS. Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients. Br J Anesth 2011;106(5):743-748.
17. Hiremath AS, Hillman DR, James AL, Noffsinger WJ, Platt PR, Singer SL. Relationship between difficult tracheal intubation and obstructive sleep apnoea. British Journal of Anaesthesia. 1998 May 1;80(5):606-11.
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Published
Feb 19, 2025
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How to Cite
Dr Sandeep Dilip Veer, & Dr Bhagwat Khillari. (2025). "NECK CIRCUMFERENCE TO THYROMENTAL DISTANCE RATIO AS A PREDICTOR OF DIFFICULT INTUBATION IN OBESE PATIENTS: A PROSPECTIVE OBSERVATIONAL STUDY". Journal of Population Therapeutics and Clinical Pharmacology, 32(1), 1068-1072. https://doi.org/10.53555/f64tew88
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Author Biographies
Dr Sandeep Dilip Veer
Assistant Professor, Department of Anesthesia, Dr DY Patil Medical College Hospital and Research Centre, DPU(Deemed to be University) Pimpri Pune Maharashtra, India.
Dr Bhagwat Khillari
Senior Consultant, Department of Anesthesia, Indrayani Hospital and Cancer Institute, Chakan - Alandi Road Alandi, Devachi, Charholi Budruk, Pune, Maharashtra, India.
How to Cite
Dr Sandeep Dilip Veer, & Dr Bhagwat Khillari. (2025). "NECK CIRCUMFERENCE TO THYROMENTAL DISTANCE RATIO AS A PREDICTOR OF DIFFICULT INTUBATION IN OBESE PATIENTS: A PROSPECTIVE OBSERVATIONAL STUDY". Journal of Population Therapeutics and Clinical Pharmacology, 32(1), 1068-1072. https://doi.org/10.53555/f64tew88