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Will This Patient Be Difficult to Intubate?The Rational Clinical Examination Systematic Review

Educational Objective
To recognize patients who may be difficult to intubate.
1 Credit CME
Key Points

Question  Which risk factors and physical findings can help predict difficult endotracheal intubation?

Findings  In this systematic review, several physical findings increased the likelihood of difficult intubation. The best predictors were an inability to bite the upper lip with the lower incisors, a short hyomental distance, retrognathia, or a combination of findings based on the Wilson score. No risk factor or physical finding consistently ruled out a potentially difficult intubation.

Meaning  Although a variety of tests are helpful in identifying a potentially difficult intubation, the inability to bite the upper lip with the lower teeth was the best predictor.

Abstract

Importance  Recognizing patients in whom endotracheal intubation is likely to be difficult can help alert physicians to the need for assistance from a clinician with airway training and having advanced airway management equipment available.

Objective  To identify risk factors and physical findings that predict difficult intubation.

Data Sources  The databases of MEDLINE and EMBASE were searched from 1946 to June 2018 and from 1947 to June 2018, respectively, and the reference lists from the retrieved articles and previous reviews were searched for additional studies.

Study Selection  Sixty-two studies with high (level 1-3) methodological quality that evaluated the accuracy of clinical findings for identifying difficult intubation were reviewed.

Data Extraction and Synthesis  Two authors independently abstracted data. Bivariate random-effects meta-analyses were used to calculate summary positive likelihood ratios across studies or univariate random-effects models when bivariate models failed to converge.

Results  Among the 62 high-quality studies involving 33 559 patients, 10% (95% CI, 8.2%-12%) of patients were difficult to intubate. The physical examination findings that best predicted a difficult intubation included a grade of class 3 on the upper lip bite test (lower incisors cannot extend to reach the upper lip; positive likelihood ratio, 14 [95% CI, 8.9-22]; specificity, 0.96 [95% CI, 0.93-0.97]), shorter hyomental distance (range of <3-5.5 cm; positive likelihood ratio, 6.4 [95% CI, 4.1-10]; specificity, 0.97 [95% CI, 0.94-0.98]), retrognathia (mandible measuring <9 cm from the angle of the jaw to the tip of the chin or subjectively short; positive likelihood ratio, 6.0 [95% CI, 3.1-11]; specificity, 0.98 [95% CI, 0.90-1.0]), and a combination of physical findings based on the Wilson score (positive likelihood ratio, 9.1 [95% CI, 5.1-16]; specificity, 0.95 [95% CI, 0.90-0.98]). The widely used modified Mallampati score (≥3) had a positive likelihood ratio of 4.1 (95% CI, 3.0-5.6; specificity, 0.87 [95% CI, 0.81-0.91]).

Conclusions and Relevance  Although several simple clinical findings are useful for predicting a higher likelihood of difficult endotracheal intubation, no clinical finding reliably excludes a difficult intubation. An abnormal upper lip bite test, which is easily assessed by clinicians, raises the probability of difficult intubation from 10% to greater than 60% for the average-risk patient.

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Article Information

Corresponding Author: Damon C. Scales, MD, PhD, 2075 Bayview Ave, Room D108, Toronto, ON M4N 3M5, Canada (damon.scales@sunnybrook.ca).

Accepted for Publication: December 13, 2018.

Author Contributions: Drs Detsky and Scales had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Detsky, Adhikari, Friedrich, Wijeysundera, Scales.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Detsky, Jivraj, Simel, Scales.

Critical revision of the manuscript for important intellectual content: Jivraj, Adhikari, Friedrich, Pinto, Simel, Wijeysundera, Scales.

Statistical analysis: Detsky, Pinto, Simel, Scales.

Administrative, technical, or material support: Jivraj, Scales.

Supervision: Adhikari, Simel, Scales.

Conflict of Interest Disclosures: Dr Simel reported receiving honoraria for contributions to JAMAEvidence.com; and is supported by the Durham Center of Innovation to Accelerate Discovery and Practice Transformation (CIN 13-410) at the Durham VA Health Care System. Dr Wijeysundera is supported in part by a New Investigator Award from the Canadian Institutes of Health Research and an Excellence in Research Award from the Department of Anesthesia at the University of Toronto. No other disclosures were reported.

Additional Contributions: We acknowledge Jamie Spiegelman, MD (Humber River Hospital, Toronto, Ontario, Canada), for help with a preliminary search and related data abstraction and we thank Daniel Nishijima, MD (University of California-Davis School of Medicine), Karen Welty-Wolf, MD (Durham Veterans Affairs Medical Center and Duke University), and Jonathan Mark, MD (Durham Veterans Affairs Medical Center and Duke University, Durham, NC) for helpful comments on an earlier version of the manuscript. None of those acknowledged were compensated for contributing.

References
1.
Caplan  RA, Posner  KL, Ward  RJ, Cheney  FW.  Adverse respiratory events in anesthesia: a closed claims analysis.  Anesthesiology. 1990;72(5):828-833. doi:10.1097/00000542-199005000-00010PubMedGoogle ScholarCrossref
2.
Cook  TM, Woodall  N, Frerk  C; Fourth National Audit Project.  Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society, part 1: anaesthesia.  Br J Anaesth. 2011;106(5):617-631. doi:10.1093/bja/aer058PubMedGoogle ScholarCrossref
3.
Law  JA, Broemling  N, Cooper  RM,  et al; Canadian Airway Focus Group.  The difficult airway with recommendations for management—part 1—difficult tracheal intubation encountered in an unconscious/induced patient.  Can J Anaesth. 2013;60(11):1089-1118. doi:10.1007/s12630-013-0019-3PubMedGoogle ScholarCrossref
4.
Cook  TM, Woodall  N, Harper  J, Benger  J; Fourth National Audit Project.  Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society, part 2: intensive care and emergency departments.  Br J Anaesth. 2011;106(5):632-642. PubMedGoogle ScholarCrossref
5.
Cook  TM, MacDougall-Davis  SR.  Complications and failure of airway management.  Br J Anaesth. 2012;109(suppl 1):i68-i85. doi:10.1093/bja/aes393PubMedGoogle ScholarCrossref
6.
Nagaro  T, Yorozuya  T, Sotani  M,  et al.  Survey of patients whose lungs could not be ventilated and whose trachea could not be intubated in university hospitals in Japan.  J Anesth. 2003;17(4):232-240. PubMedGoogle ScholarCrossref
7.
Cormack  RS, Lehane  J.  Difficult tracheal intubation in obstetrics.  Anaesthesia. 1984;39(11):1105-1111. doi:10.1111/j.1365-2044.1984.tb08932.xPubMedGoogle ScholarCrossref
8.
Yentis  SM, Lee  DJ.  Evaluation of an improved scoring system for the grading of direct laryngoscopy.  Anaesthesia. 1998;53(11):1041-1044. doi:10.1046/j.1365-2044.1998.00605.xPubMedGoogle ScholarCrossref
9.
Adnet  F, Borron  SW, Racine  SX,  et al.  The Intubation Difficulty Scale (IDS): proposal and evaluation of a new score characterizing the complexity of endotracheal intubation.  Anesthesiology. 1997;87(6):1290-1297. PubMedGoogle ScholarCrossref
10.
Apfelbaum  JL, Hagberg  CA, Caplan  RA,  et al; American Society of Anesthesiologists Task Force on Management of the Difficult Airway.  Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway.  Anesthesiology. 2013;118(2):251-270. doi:10.1097/ALN.0b013e31827773b2PubMedGoogle ScholarCrossref
11.
Myers  KA, Mrkobrada  M, Simel  DL.  Does this patient have obstructive sleep apnea?: the Rational Clinical Examination systematic review.  JAMA. 2013;310(7):731-741. doi:10.1001/jama.2013.276185PubMedGoogle ScholarCrossref
12.
Joshi  GP, Ankichetty  SP, Gan  TJ, Chung  F.  Society for Ambulatory Anesthesia consensus statement on preoperative selection of adult patients with obstructive sleep apnea scheduled for ambulatory surgery.  Anesth Analg. 2012;115(5):1060-1068. doi:10.1213/ANE.0b013e318269cfd7PubMedGoogle ScholarCrossref
13.
Roth  D, Pace  NL, Lee  A,  et al.  Airway physical examination tests for detection of difficult airway management in apparently normal adult patients.  Cochrane Database Syst Rev. 2018;5(5):CD008874.PubMedGoogle Scholar
14.
Vannucci  A, Cavallone  LF.  Bedside predictors of difficult intubation: a systematic review.  Minerva Anestesiol. 2016;82(1):69-83.PubMedGoogle Scholar
15.
Khan  ZH, Kashfi  A, Ebrahimkhani  E.  A comparison of the upper lip bite test (a simple new technique) with modified Mallampati classification in predicting difficulty in endotracheal intubation: a prospective blinded study.  Anesth Analg. 2003;96(2):595-599.PubMedGoogle Scholar
16.
Khan  ZH, Arbabi  S, Yekaninejad  MS, Khan  RH.  Application of the upper lip catch test for airway evaluation in edentulous patients: an observational study.  Saudi J Anaesth. 2014;8(1):73-77. doi:10.4103/1658-354X.125942PubMedGoogle ScholarCrossref
17.
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):1197-1204.PubMedGoogle Scholar
18.
Huh  J, Shin  HY, Kim  SH, Yoon  TK, Kim  DK.  Diagnostic predictor of difficult laryngoscopy: the hyomental distance ratio.  Anesth Analg. 2009;108(2):544-548. doi:10.1213/ane.0b013e31818fc347PubMedGoogle ScholarCrossref
19.
Mashour  GA, Stallmer  ML, Kheterpal  S, Shanks  A.  Predictors of difficult intubation in patients with cervical spine limitations.  J Neurosurg Anesthesiol. 2008;20(2):110-115. doi:10.1097/ANA.0b013e318166dd00PubMedGoogle ScholarCrossref
20.
Savva  D.  Prediction of difficult tracheal intubation.  Br J Anaesth. 1994;73(2):149-153. doi:10.1093/bja/73.2.149PubMedGoogle ScholarCrossref
21.
Mallampati  SR, Gatt  SP, Gugino  LD,  et al.  A clinical sign to predict difficult tracheal intubation: a prospective study.  Can Anaesth Soc J. 1985;32(4):429-434. doi:10.1007/BF03011357PubMedGoogle ScholarCrossref
22.
Samsoon  GL, Young  JR.  Difficult tracheal intubation: a retrospective study.  Anaesthesia. 1987;42(5):487-490. doi:10.1111/j.1365-2044.1987.tb04039.xPubMedGoogle ScholarCrossref
23.
Nadal  JL, Fernandez  BG, Escobar  IC, Black  M, Rosenblatt  WH.  The palm print as a sensitive predictor of difficult laryngoscopy in diabetics.  Acta Anaesthesiol Scand. 1998;42(2):199-203. doi:10.1111/j.1399-6576.1998.tb05109.xPubMedGoogle ScholarCrossref
24.
Erden  V, Basaranoglu  G, Delatioglu  H, Hamzaoglu  NS.  Relationship of difficult laryngoscopy to long-term non-insulin-dependent diabetes and hand abnormality detected using the ‘prayer sign’.  Br J Anaesth. 2003;91(1):159-160. doi:10.1093/bja/aeg583PubMedGoogle ScholarCrossref
25.
Ayuso  MA, Sala  X, Luis  M, Carbó  JM.  Predicting difficult orotracheal intubation in pharyngo-laryngeal disease: preliminary results of a composite index.  Can J Anaesth. 2003;50(1):81-85. doi:10.1007/BF03020193PubMedGoogle ScholarCrossref
26.
Mahmoodpoor  A, Soleimanpour  H, Nia  KS,  et al.  Sensitivity of palm print, modified Mallampati score and 3-3-2 rule in prediction of difficult intubation.  Int J Prev Med. 2013;4(9):1063-1069.PubMedGoogle Scholar
27.
Ezri  T, Weisenberg  M, Khazin  V,  et al.  Difficult laryngoscopy: incidence and predictors in patients undergoing coronary artery bypass surgery versus general surgery patients.  J Cardiothorac Vasc Anesth. 2003;17(3):321-324. doi:10.1016/S1053-0770(03)00052-1PubMedGoogle ScholarCrossref
28.
Juvin  P, Lavaut  E, Dupont  H,  et al.  Difficult tracheal intubation is more common in obese than in lean patients.  Anesth Analg. 2003;97(2):595-600. PubMedGoogle ScholarCrossref
29.
Nath  G, Sekar  M.  Predicting difficult intubation—a comprehensive scoring system.  Anaesth Intensive Care. 1997;25(5):482-486.PubMedGoogle Scholar
30.
Wilson  ME, Spiegelhalter  D, Robertson  JA, Lesser  P.  Predicting difficult intubation.  Br J Anaesth. 1988;61(2):211-216. doi:10.1093/bja/61.2.211PubMedGoogle ScholarCrossref
31.
Simel  D. Update: primer on precision and accuracy. In: Simel  D, ed.  The Rational Clinical Examination. New York, NY: McGraw Hill; 2009.
32.
Takwoingi  Y, Deeks  JJ. MetaDAS: a SAS macro for meta-analysis of diagnostic accuracy studies. In: User Guide, version 1.3; 2010. https://methods.cochrane.org/sdt/software-meta-analysis-dta-studies. Accessed December 20, 2018.
33.
Chhina  AK, Jain  R, Gautam  PL, Garg  J, Singh  N, Grewal  A.  Formulation of a multivariate predictive model for difficult intubation: a double blinded prospective study.  J Anaesthesiol Clin Pharmacol. 2018;34(1):62-67.PubMedGoogle Scholar
34.
Hanouz  J-L, Bonnet  V, Buléon  C,  et al.  Comparison of the Mallampati classification in sitting and supine position to predict difficult tracheal intubation: a prospective observational cohort study.  Anesth Analg. 2018;126(1):161-169. doi:10.1213/ANE.0000000000002108PubMedGoogle ScholarCrossref
35.
Prakash  S, Kumar  A, Bhandari  S, Mullick  P, Singh  R, Gogia  AR.  Difficult laryngoscopy and intubation in the Indian population: an assessment of anatomical and clinical risk factors.  Indian J Anaesth. 2013;57(6):569-575. doi:10.4103/0019-5049.123329PubMedGoogle ScholarCrossref
36.
Honarmand  A, Safavi  MR.  Prediction of difficult laryngoscopy in obstetric patients scheduled for Caesarean delivery.  Eur J Anaesthesiol. 2008;25(9):714-720. doi:10.1017/S026502150800433XPubMedGoogle ScholarCrossref
37.
Ali  MA, Qamar-ul-Hoda  M, Samad  K.  Comparison of upper lip bite test with Mallampati test in the prediction of difficult intubation at a tertiary care hospital of Pakistan.  J Pak Med Assoc. 2012;62(10):1012-1015.PubMedGoogle Scholar
38.
Eberhart  LH, Arndt  C, Cierpka  T, Schwanekamp  J, Wulf  H, Putzke  C.  The reliability and validity of the upper lip bite test compared with the Mallampati classification to predict difficult laryngoscopy: an external prospective evaluation.  Anesth Analg. 2005;101(1):284-289. PubMedGoogle ScholarCrossref
39.
Shah  AA, Rafique  K, Islam  M.  Can difficult intubation be accurately predicted using upper lip bite test?  J Postgrad Med Inst. 2014;28(3):282-287.Google Scholar
40.
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. doi:10.4103/0972-5229.173678PubMedGoogle ScholarCrossref
41.
Hester  CE, Dietrich  SA, White  SW, Secrest  JA, Lindgren  KR, Smith  T.  A comparison of preoperative airway assessment techniques: the modified Mallampati and the upper lip bite test.  AANA J. 2007;75(3):177-182.PubMedGoogle Scholar
42.
Khan  ZH, Maleki  A, Makarem  J, Mohammadi  M, Khan  RH, Zandieh  A.  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):43-46. doi:10.4103/0019-5049.76603PubMedGoogle ScholarCrossref
43.
Khan  ZH, Mohammadi  M, Rasouli  MR, Farrokhnia  F, Khan  RH.  The diagnostic value of the upper lip bite test combined with sternomental distance, thyromental distance, and interincisor distance for prediction of easy laryngoscopy and intubation: a prospective study.  Anesth Analg. 2009;109(3):822-824. doi:10.1213/ane.0b013e3181af7f0dPubMedGoogle ScholarCrossref
44.
Min  JJ, Kim  G, Kim  E, Lee  J-H.  The diagnostic validity of clinical airway assessments for predicting difficult laryngoscopy using a grey zone approach.  J Int Med Res. 2016;44(4):893-904. doi:10.1177/0300060516642647PubMedGoogle ScholarCrossref
45.
Salimi  A, Farzanegan  B, Rastegarpour  A, Kolahi  AA.  Comparison of the upper lip bite test with measurement of thyromental distance for prediction of difficult intubations.  Acta Anaesthesiol Taiwan. 2008;46(2):61-65. doi:10.1016/S1875-4597(08)60027-2PubMedGoogle ScholarCrossref
46.
Selvi  O, Kahraman  T, Senturk  O, Tulgar  S, Serifsoy  E, Ozer  Z.  Evaluation of the reliability of preoperative descriptive airway assessment tests in prediction of the Cormack-Lehane score: a prospective randomized clinical study.  J Clin Anesth. 2017;36:21-26. doi:10.1016/j.jclinane.2016.08.006PubMedGoogle ScholarCrossref
47.
Shah  PJ, Dubey  KP, Yadav  JP.  Predictive value of upper lip bite test and ratio of height to thyromental distance compared to other multivariate airway assessment tests for difficult laryngoscopy in apparently normal patients.  J Anaesthesiol Clin Pharmacol. 2013;29(2):191-195. PubMedGoogle ScholarCrossref
48.
Balakrishnan  KP, Chockalingam  PA.  Ethnicity and upper airway measurements: a study in South Indian population.  Indian J Anaesth. 2017;61(8):622-628. doi:10.4103/ija.IJA_247_17PubMedGoogle ScholarCrossref
49.
Mahmoodpoor  A, Soleimanpour  H, Golzari  SE,  et al.  Determination of the diagnostic value of the Modified Mallampati score, upper lip bite test and facial angle in predicting difficult intubation: a prospective descriptive study.  J Clin Anesth. 2017;37:99-102. doi:10.1016/j.jclinane.2016.12.010PubMedGoogle ScholarCrossref
50.
Mehta  T, Jayaprakash  J, Shah  V.  Diagnostic value of different screening tests in isolation or combination for predicting difficult intubation: a prospective study.  Indian J Anaesth. 2014;58(6):754-757. doi:10.4103/0019-5049.147176PubMedGoogle ScholarCrossref
51.
Gupta  S, Pareek  S, Dulara  SC.  Comparison of two methods for predicting difficult intubation in obstetric patients.  Middle East J Anaesthesiol. 2003;17(2):275-285.PubMedGoogle Scholar
52.
Kim  WH, Ahn  HJ, Lee  CJ,  et al.  Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients.  Br J Anaesth. 2011;106(5):743-748. doi:10.1093/bja/aer024PubMedGoogle ScholarCrossref
53.
Topcu  I, Ovali  GY, Yentur  EA, Kefi  A, Tuncyurek  O, Pabuscu  Y.  Clinical and radiologic evaluations for predicting difficult tracheal intubation.  Acta Anaesth Italica. 2006;57:285-300.Google Scholar
54.
Krishna  HM, Munisha  A, Dali  JS, Prashant  R, Dua  CK.  Prediction of difficult laryngoscopy in indian population: role of ratio of patient’s height to thyromental distance.  J Anaesthesiol Clin Pharmacol. 2005;21(3):257-260.Google Scholar
55.
Oates  JD, Macleod  AD, Oates  PD, Pearsall  FJ, Howie  JC, Murray  GD.  Comparison of two methods for predicting difficult intubation.  Br J Anaesth. 1991;66(3):305-309. doi:10.1093/bja/66.3.305PubMedGoogle ScholarCrossref
56.
Siddiqi  R, Kazi  WA.  Predicting difficult intubation—a comparison between Mallampati classification and Wilson risk-sum.  J Coll Physicians Surg Pak. 2005;15(5):253-256.PubMedGoogle Scholar
57.
Yamamoto  K, Tsubokawa  T, Shibata  K, Ohmura  S, Nitta  S, Kobayashi  T.  Predicting difficult intubation with indirect laryngoscopy.  Anesthesiology. 1997;86(2):316-321. doi:10.1097/00000542-199702000-00007PubMedGoogle ScholarCrossref
58.
Guo  Y, Feng  Y, Liang  H, Zhang  R, Cai  X, Pan  X.  Role of flexible fiberoptic laryngoscopy in predicting difficult intubation.  Minerva Anestesiol. 2018;84(3):337-345.PubMedGoogle Scholar
59.
Yu  T, Wang  B, Jin  XJ,  et al.  Predicting difficult airways: 3-3-2 rule or 3-3 rule?  Ir J Med Sci. 2015;184(3):677-683. doi:10.1007/s11845-015-1276-7PubMedGoogle ScholarCrossref
60.
Yildiz  TS, Korkmaz  F, Solak  M,  et al.  Prediction of difficult tracheal intubation in Turkish patients: a multi-center methodological study.  Eur J Anaesthesiol. 2007;24(12):1034-1040. doi:10.1017/S026502150700052XPubMedGoogle ScholarCrossref
61.
Sahin  SH, Yilmaz  A, Gunday  I,  et al.  Using temporomandibular joint mobility to predict difficult tracheal intubation.  J Anesth. 2011;25(3):457-461. doi:10.1007/s00540-011-1126-3PubMedGoogle ScholarCrossref
62.
Ul Haq  MI, Ullah  H.  Comparison of Mallampati test with lower jaw protrusion maneuver in predicting difficult laryngoscopy and intubation.  J Anaesthesiol Clin Pharmacol. 2013;29(3):313-317. PubMedGoogle ScholarCrossref
63.
Khatiwada  S, Bhattarai  B, Pokharel  K, Acharya  R.  Prediction of difficult airway among patients requiring endotracheal intubation in a tertiary care hospital in Eastern Nepal.  JNMA J Nepal Med Assoc. 2017;56(207):314-318. doi:10.31729/jnma.2918PubMedGoogle ScholarCrossref
64.
Kuriakose  R, Mathew  A, Koshy  CR.  Screening tests for predicting difficult endotracheal intubation—a clinical assessment in facio-oro-maxillary and neck malignancy patients.  J Anaesthesiol Clin Pharmacol. 2003;19(1):37-44.Google Scholar
65.
Tse  JC, Rimm  EB, Hussain  A.  Predicting difficult endotracheal intubation in surgical patients scheduled for general anesthesia: a prospective blind study.  Anesth Analg. 1995;81(2):254-258.PubMedGoogle Scholar
66.
Wong  SH, Hung  CT.  Prevalence and prediction of difficult intubation in Chinese women.  Anaesth Intensive Care. 1999;27(1):49-52.PubMedGoogle Scholar
67.
Al Ramadhani  S, Mohamed  LA, Rocke  DA, Gouws  E.  Sternomental distance as the sole predictor of difficult laryngoscopy in obstetric anaesthesia  [published correction appears in Br J Anaesth. 1996;77(5):701].  Br J Anaesth. 1996;77(3):312-316. doi:10.1093/bja/77.3.312PubMedGoogle ScholarCrossref
68.
Eiamcharoenwit  J, Itthisompaiboon  N, Limpawattana  P, Suwanpratheep  A, Siriussawakul  A.  The performance of neck circumference and other airway assessment tests for the prediction of difficult intubation in obese parturients undergoing cesarean delivery.  Int J Obstet Anesth. 2017;31:45-50. doi:10.1016/j.ijoa.2017.01.011PubMedGoogle ScholarCrossref
69.
Iohom  G, Ronayne  M, Cunningham  AJ.  Prediction of difficult tracheal intubation.  Eur J Anaesthesiol. 2003;20(1):31-36. doi:10.1097/00003643-200301000-00006PubMedGoogle ScholarCrossref
70.
Badhe  VK, Deogaonkar  SG, Tambe  MV, Singla  A, Shidhaye  RV.  Clinical comparison of five different predictor tests for difficult intubation.  Anaesth Pain Intensive Care. 2014;18(1):31-37.Google Scholar
71.
Etezadi  F, Ahangari  A, Shokri  H,  et al.  Thyromental height: a new clinical test for prediction of difficult laryngoscopy.  Anesth Analg. 2013;117(6):1347-1351. doi:10.1213/ANE.0b013e3182a8c734PubMedGoogle ScholarCrossref
72.
Reddy  PB, Punetha  P, Chalam  KS.  Ultrasonography—a viable tool for airway assessment.  Indian J Anaesth. 2016;60(11):807-813. doi:10.4103/0019-5049.193660PubMedGoogle ScholarCrossref
73.
Han  Y-Z, Tian  Y, Xu  M,  et al.  Neck circumference to inter-incisor gap ratio: a new predictor of difficult laryngoscopy in cervical spondylosis patients.  BMC Anesthesiol. 2017;17(1):55. doi:10.1186/s12871-017-0346-yPubMedGoogle ScholarCrossref
74.
Choi  JW, Kim  JA, Kim  HK, Oh  MS, Kim  DK.  Chest anteroposterior diameter affects difficulty of laryngoscopy for non-morbidly obese patients.  J Anesth. 2013;27(4):563-568. doi:10.1007/s00540-013-1572-1PubMedGoogle ScholarCrossref
75.
Pinto  J, Cordeiro  L, Pereira  C, Gama  R, Fernandes  HL, Assunção  J.  Predicting difficult laryngoscopy using ultrasound measurement of distance from skin to epiglottis.  J Crit Care. 2016;33:26-31. doi:10.1016/j.jcrc.2016.01.029PubMedGoogle ScholarCrossref
76.
Yao  W, Wang  B.  Can tongue thickness measured by ultrasonography predict difficult tracheal intubation?  Br J Anaesth. 2017;118(4):601-609. doi:10.1093/bja/aex051PubMedGoogle ScholarCrossref
77.
Aktas  S, Atalay  YO, Tugrul  M.  Predictive value of bedside tests for difficult intubations.  Eur Rev Med Pharmacol Sci. 2015;19(9):1595-1599.PubMedGoogle Scholar
78.
Ambesh  SP, Singh  N, Rao  PB, Gupta  D, Singh  PK, Singh  U.  A combination of the modified Mallampati score, thyromental distance, anatomical abnormality, and cervical mobility (M-TAC) predicts difficult laryngoscopy better than Mallampati classification.  Acta Anaesthesiol Taiwan. 2013;51(2):58-62. doi:10.1016/j.aat.2013.06.005PubMedGoogle ScholarCrossref
79.
Baig  MM, Khan  FH.  To compare the accuracy of prayer’s sign and Mallampatti test in predicting difficult intubation in diabetic patients.  J Pak Med Assoc. 2014;64(8):879-883.PubMedGoogle Scholar
80.
Bindra  A, Prabhakar  H, Singh  GP, Ali  Z, Singhal  V.  Is the modified Mallampati test performed in supine position a reliable predictor of difficult tracheal intubation?  J Anesth. 2010;24(3):482-485. doi:10.1007/s00540-010-0905-6PubMedGoogle ScholarCrossref
81.
Kamalipour  H, Bagheri  M, Kamali  K, Taleie  A, Yarmohammadi  H.  Lateral neck radiography for prediction of difficult orotracheal intubation.  Eur J Anaesthesiol. 2005;22(9):689-693. doi:10.1017/S0265021505001146PubMedGoogle ScholarCrossref
82.
Khan  ZH, Eskandari  S, Yekaninejad  MS.  A comparison of the Mallampati test in supine and upright positions with and without phonation in predicting difficult laryngoscopy and intubation: a prospective study.  J Anaesthesiol Clin Pharmacol. 2015;31(2):207-211. doi:10.4103/0970-9185.155150PubMedGoogle ScholarCrossref
83.
Savva  D.  Sternomental distance—a useful predictor of difficult intubation in patients with cervical spine disease?  Anaesthesia. 1996;51(3):284-285. doi:10.1111/j.1365-2044.1996.tb13653.xPubMedGoogle ScholarCrossref
84.
Gao  YX, Song  YB, Gu  ZJ,  et al.  Video versus direct laryngoscopy on successful first-pass endotracheal intubation in ICU patients.  World J Emerg Med. 2018;9(2):99-104. PubMedGoogle ScholarCrossref
85.
Qudaisat  IY, Al-Ghanem  SM.  Short thyromental distance is a surrogate for inadequate head extension, rather than small submandibular space, when indicating possible difficult direct laryngoscopy.  Eur J Anaesthesiol. 2011;28(8):600-606. doi:10.1097/EJA.0b013e328347cdd9PubMedGoogle ScholarCrossref
86.
Reissell  E, Orko  R, Maunuksela  EL, Lindgren  L.  Predictability of difficult laryngoscopy in patients with long-term diabetes mellitus.  Anaesthesia. 1990;45(12):1024-1027. doi:10.1111/j.1365-2044.1990.tb14879.xPubMedGoogle ScholarCrossref
87.
Sachdeva  KP, Singh  A, Kathuria  S,  et al.  Prediction of difficult laryngoscopy in diabetics by palm print and interphalangeal gap.  J Anaesthesiol Clin Pharmacol. 2005;21(3):261-264.Google Scholar
88.
Deeks  JJ, Macaskill  P, Irwig  L.  The performance of tests of publication bias and other sample size effects in systematic reviews of diagnostic test accuracy was assessed.  J Clin Epidemiol. 2005;58(9):882-893. doi:10.1016/j.jclinepi.2005.01.016PubMedGoogle ScholarCrossref
89.
Toshniwal  G, McKelvey  GM, Wang  H.  STOP-Bang and prediction of difficult airway in obese patients.  J Clin Anesth. 2014;26(5):360-367. PubMedGoogle ScholarCrossref
90.
De Jong  A, Molinari  N, Terzi  N,  et al; AzuRéa Network for the Frida-Réa Study Group.  Early identification of patients at risk for difficult intubation in the intensive care unit: development and validation of the MACOCHA score in a multicenter cohort study.  Am J Respir Crit Care Med. 2013;187(8):832-839.PubMedGoogle ScholarCrossref
91.
Frerk  C, Mitchell  VS, McNarry  AF,  et al; Difficult Airway Society Intubation Guidelines Working Group.  Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults.  Br J Anaesth. 2015;115(6):827-848.PubMedGoogle ScholarCrossref
92.
Law  JA, Broemling  N, Cooper  RM,  et al; Canadian Airway Focus Group.  The difficult airway with recommendations for management—part 2—the anticipated difficult airway.  Can J Anaesth. 2013;60(11):1119-1138. doi:10.1007/s12630-013-0020-xPubMedGoogle ScholarCrossref
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