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Meta-Analysis
. 2018 May 15;5(5):CD008874.
doi: 10.1002/14651858.CD008874.pub2.

Airway physical examination tests for detection of difficult airway management in apparently normal adult patients

Dominik Roth  1 , Nathan L Pace, Anna Lee, Karen Hovhannisyan, Alexandra-Maria Warenits, Jasmin Arrich, Harald Herkner
Affiliations
Meta-Analysis

Airway physical examination tests for detection of difficult airway management in apparently normal adult patients

Dominik Roth et al. Cochrane Database Syst Rev. .

Abstract

Background: The unanticipated difficult airway is a potentially life-threatening event during anaesthesia or acute conditions. An unsuccessfully managed upper airway is associated with serious morbidity and mortality. Several bedside screening tests are used in clinical practice to identify those at high risk of difficult airway. Their accuracy and benefit however, remains unclear.

Objectives: The objective of this review was to characterize and compare the diagnostic accuracy of the Mallampati classification and other commonly used airway examination tests for assessing the physical status of the airway in adult patients with no apparent anatomical airway abnormalities. We performed this individually for each of the four descriptors of the difficult airway: difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, and failed intubation.

Search methods: We searched major electronic databases including CENTRAL, MEDLINE, Embase, ISI Web of Science, CINAHL, as well as regional, subject specific, and dissertation and theses databases from inception to 16 December 2016, without language restrictions. In addition, we searched the Science Citation Index and checked the references of all the relevant studies. We also handsearched selected journals, conference proceedings, and relevant guidelines. We updated this search in March 2018, but we have not yet incorporated these results.

Selection criteria: We considered full-text diagnostic test accuracy studies of any individual index test, or a combination of tests, against a reference standard. Participants were adults without obvious airway abnormalities, who were having laryngoscopy performed with a standard laryngoscope and the trachea intubated with a standard tracheal tube. Index tests included the Mallampati test, modified Mallampati test, Wilson risk score, thyromental distance, sternomental distance, mouth opening test, upper lip bite test, or any combination of these. The target condition was difficult airway, with one of the following reference standards: difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, and failed intubation.

Data collection and analysis: We performed screening and selection of the studies, data extraction and assessment of methodological quality (using QUADAS-2) independently and in duplicate. We designed a Microsoft Access database for data collection and used Review Manager 5 and R for data analysis. For each index test and each reference standard, we assessed sensitivity and specificity. We produced forest plots and summary receiver operating characteristic (ROC) plots to summarize the data. Where possible, we performed meta-analyses to calculate pooled estimates and compare test accuracy indirectly using bivariate models. We investigated heterogeneity and performed sensitivity analyses.

Main results: We included 133 (127 cohort type and 6 case-control) studies involving 844,206 participants. We evaluated a total of seven different prespecified index tests in the 133 studies, as well as 69 non-prespecified, and 32 combinations. For the prespecified index tests, we found six studies for the Mallampati test, 105 for the modified Mallampati test, six for the Wilson risk score, 52 for thyromental distance, 18 for sternomental distance, 34 for the mouth opening test, and 30 for the upper lip bite test. Difficult face mask ventilation was the reference standard in seven studies, difficult laryngoscopy in 92 studies, difficult tracheal intubation in 50 studies, and failed intubation in two studies. Across all studies, we judged the risk of bias to be variable for the different domains; we mostly observed low risk of bias for patient selection, flow and timing, and unclear risk of bias for reference standard and index test. Applicability concerns were generally low for all domains. For difficult laryngoscopy, the summary sensitivity ranged from 0.22 (95% confidence interval (CI) 0.13 to 0.33; mouth opening test) to 0.67 (95% CI 0.45 to 0.83; upper lip bite test) and the summary specificity ranged from 0.80 (95% CI 0.74 to 0.85; modified Mallampati test) to 0.95 (95% CI 0.88 to 0.98; Wilson risk score). The upper lip bite test for diagnosing difficult laryngoscopy provided the highest sensitivity compared to the other tests (P < 0.001). For difficult tracheal intubation, summary sensitivity ranged from 0.24 (95% CI 0.12 to 0.43; thyromental distance) to 0.51 (95% CI 0.40 to 0.61; modified Mallampati test) and the summary specificity ranged from 0.87 (95% CI 0.82 to 0.91; modified Mallampati test) to 0.93 (0.87 to 0.96; mouth opening test). The modified Mallampati test had the highest sensitivity for diagnosing difficult tracheal intubation compared to the other tests (P < 0.001). For difficult face mask ventilation, we could only estimate summary sensitivity (0.17, 95% CI 0.06 to 0.39) and specificity (0.90, 95% CI 0.81 to 0.95) for the modified Mallampati test.

Authors' conclusions: Bedside airway examination tests, for assessing the physical status of the airway in adults with no apparent anatomical airway abnormalities, are designed as screening tests. Screening tests are expected to have high sensitivities. We found that all investigated index tests had relatively low sensitivities with high variability. In contrast, specificities were consistently and markedly higher than sensitivities across all tests. The standard bedside airway examination tests should be interpreted with caution, as they do not appear to be good screening tests. Among the tests we examined, the upper lip bite test showed the most favourable diagnostic test accuracy properties. Given the paucity of available data, future research is needed to develop tests with high sensitivities to make them useful, and to consider their use for screening difficult face mask ventilation and failed intubation. The 27 studies in 'Studies awaiting classification' may alter the conclusions of the review, once we have assessed them.

PubMed Disclaimer

Conflict of interest statement

Dominik Roth: none known

Nathan L Pace: none known

Anna Lee: is the first author of a previously published diagnostic test accuracy review of the Mallampati score (Lee 2006).

Karen Hovhannisyan: none known

Alexandra‐Maria Warenits: none known

Jasmin Arrich: none known

Harald Herkner: none known

This review was selected for the third Cochrane Review Support Programme.

Figures

1
1
Study flow diagram.
2
2
Risk of bias and applicability concerns graph for difficult laryngoscopy: review authors' judgements about each domain presented as percentages across included studies.
3
3
Risk of bias and applicability concerns graph for difficult tracheal intubation: review authors' judgements about each domain presented as percentages across included studies.
4
4
Risk of bias and applicability concerns graph for failed intubation: review authors' judgements about each domain presented as percentages across included studies.
5
5
Risk of bias and applicability concerns graph for difficult face mask ventilation: review authors' judgements about each domain presented as percentages across included studies.
6
6
Forest plot of modified Mallampati test for difficult laryngoscopy, sorted by descending sensitivity. Summary sensitivity 0.53 (95% confidence interval (CI) 0.47 to 0.59); summary specificity 0.80 (95% CI 0.74 to 0.85).
7
7
Forest plot of thyromental distance for difficult laryngoscopy, sorted by descending sensitivity. Summary sensitivity 0.37 (95% CI 0.28 to 0.47); summary specificity 0.89 (95% CI 0.84 to 0.93).
8
8
Forest plot of mouth opening for difficult laryngoscopy, sorted by descending sensitivity. Summary sensitivity 0.22 (95% CI 0.13 to 0.33); summary specificity 0.94 (95% CI 0.90 to 0.97).
9
9
Forest plot of upper lip bite test for difficult laryngoscopy, sorted by descending sensitivity. Summary sensitivity 0.67 (95% CI 0.45 to 0.83); summary specificity 0.92 (95% CI 0.86 to 0.95).
10
10
Summary receiver operating characteristic (ROC) plot of modified Mallampati test, thyromental distance, mouth opening, and upper lip bite test for difficult laryngoscopy. For each index test, the summary point with the 95% confidence region is displayed.
11
11
Forest plot of modified Mallampati test for difficult tracheal intubation, sorted by descending sensitivity. Summary sensitivity 0.51 (95% CI 0.40 to 0.61); summary specificity 0.87 (95% CI 0.82 to 0.91).
12
12
Forest plot of thyromental distance for difficult tracheal intubation, sorted by descending sensitivity. Summary sensitivity 0.24 (95% CI0.12 to 0.43); summary specificity 0.90 (95% CI 0.80 to 0.96).
13
13
Forest plot of mouth opening for difficult tracheal intubation, sorted by descending sensitivity. Summary sensitivity 0.27 (95% CI 0.16 to 0.41); summary specificity 0.93 (95% Cl 0.87 to 0.96).
14
14
Summary receiver operating characteristic (ROC) plot of modified Mallampati test, thyromental distance, and mouth opening test for difficult tracheal intubation. For each index test the summary point with the 95% confidence region is displayed.
15
15
Forest plot of modified Mallampati test for difficult face mask ventilation, sorted by descending sensitivity. Summary sensitivity 0.17 (95% CI 0.06 to 0.39); summary specificity 0.90 (95% CI 0.81 to 0.95).
16
16
Risk of bias and applicability concerns summary for Mallampati test: review authors' judgements about each domain for each included study.
17
17
Risk of bias and applicability concerns summary for modified Mallampati test (part 1): review authors' judgements about each domain for each included study.
18
18
Risk of bias and applicability concerns summary for modified Mallampati test (part 2): review authors' judgements about each domain for each included study.
19
19
Risk of bias and applicability concerns summary for mouth opening: review authors' judgements about each domain for each included study.
20
20
Risk of bias and applicability concerns summary for sternomental distance: review authors' judgements about each domain for each included study.
21
21
Risk of bias and applicability concerns summary for thyromental distance: review authors' judgements about each domain for each included study.
22
22
Risk of bias and applicability concerns summary for upper lip bite test: review authors' judgements about each domain for each included study.
23
23
Risk of bias and applicability concerns summary for Wilson risk score: review authors' judgements about each domain for each included study.
24
24
Risk of bias and applicability concerns summary for combination of tests (part 1): review authors' judgements about each domain for each included study.
25
25
Risk of bias and applicability concerns summary for combination of tests (part 2): review authors' judgements about each domain for each included study.
See this image and copyright information in PMC

Update of

  • doi: 10.1002/14651858.CD008874

References

References to studies included in this review

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Ittichaikulthol 2010 {published data only}
    1. Ittichaikulthol W, Chanpradub S, Amnoundetchakorn S, Arayajarernwong N, Wongkum W. Modified Mallampati test and thyromental distance as a predictor of difficult laryngoscopy in Thai patients. Journal of the Medical Association of Thailand = Chotmaihet Thangphaet 2010;93(1):84‐9. [PUBMED: 20196416] - PubMed
Juvin 2003 {published data only}
    1. Juvin P, Lavaut E, Dupont H, Lefevre P, Demetriou M, Dumoulin JL, et al. Difficult tracheal intubation is more common in obese than in lean patients. Anesthesia and Analgesia 2003;97(2):595‐600. [PUBMED: 12873960 ] - PubMed
Kalezic 2016 {published data only}
    1. Kalezić N, Lakićević M, Miličić B, Stojanović M, Sabljak V, Marković D. Hyomental distance in the different head positions and hyomental distance ratio in predicting difficult intubation. Bosnian Journal of Basic Medical Sciences / Udruženje Basičnih Mediciniskih Znanost 2016;16(3):232‐6. [PUBMED: 27299374 ] - PMC - PubMed
Kamalipour 2005 {published data only}
    1. Kamalipour H, Bagheri M, Kamali K, Taleie A, Yarmohammadi H. Lateral neck radiography for prediction of difficult orotracheal intubation. European Journal of Anaesthesiology 2005;22(9):689‐93. [PUBMED: 16163916] - PubMed
Kamranmanesh 2013 {published data only}
    1. Kamranmanesh MR, Jafari AR, Gharaei B, Aghamohammadi H, Poor Zamany NKM, Kashi AH. Comparison of acromioaxillosuprasternal notch index (a new test) with modified Mallampati test in predicting difficult visualization of larynx. Acta Anaesthesiologica Taiwanica 2013;51(4):141‐4. [PUBMED: 24529668 ] - PubMed
Khan 2003 {published data only}
    1. 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. Anesthesia and Analgesia 2003;96(2):595‐9. [PUBMED: 12538218] - PubMed
Khan 2009a {published data only}
    1. 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. Anesthesia and Analgesia 2009;109(3):822‐4. [PUBMED: 19690252] - PubMed
Khan 2009b {published data only}
    1. Khan ZH, Mofrad MK, Arbabi S, Javid MJ, Makarem J. Upper lip bite test as a predictor of difficult mask ventilation: a prospective study. Middle East Journal of Anaesthesiology 2009;20(3):377‐82. [PUBMED: 19950730] - PubMed
Khan 2011 {published data only}
    1. 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 Journal of Anaesthesia 2011;55(1):43‐6. [PUBMED: 21431052 ] - PMC - PubMed
Khan 2013 {published data only}
    1. Khan ZH, Arbabi S. Diagnostic value of the upper lip bite test in predicting difficulty in intubation with head and neck landmarks obtained from lateral neck X‐ray. Indian Journal of Anaesthesia 2013;57(4):381‐6. [PUBMED: 24163453 ] - PMC - PubMed
Khan 2014 {published data only}
    1. 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 Journal of Anaesthesia 2014;8(1):73‐7. [PUBMED: 24665244 ] - PMC - PubMed
Khan 2015 {published data only}
    1. 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. Journal of Anaesthesiology, Clinical Pharmacology 2015;31(2):207‐11. [PUBMED: 25948902 ] - PMC - PubMed
Kheterpal 2009 {published data only}
    1. Kheterpal S, Martin L, Shanks AM, Tremper KK. Prediction and outcomes of impossible mask ventilation: a review of 50,000 anesthetics. Anesthesiology 2009;110(4):891‐7. [PUBMED: 19293691 ] - PubMed
Kim 2011 {published data only}
    1. Kim WH, Ahn HJ, Lee CJ, Shin BS, Ko JS, Choi SJ, et al. Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients. British Journal of Anaesthesia 2011;106(5):743‐8. [PUBMED: 21354999 ] - PubMed
K Nasa 2014 {published data only}
    1. K Nasa V, S Kamath S. Risk factors assessment of the difficult intubation using intubation difficulty scale (IDS). Journal of Clinical and Diagnostic Research: JCDR 2014;8(7):GC01‐3. [PUBMED: 25177576 ] - PMC - PubMed
Knudsen 2014 {published data only}
    1. Knudsen K, Högman M, Larsson A, Nilsson U. The best method to predict easy intubation: a quasi‐experimental pilot study. Journal of Perianesthesia Nursing 2014;29(4):292‐7. [PUBMED: 25062573 ] - PubMed
Koh 2002 {published data only}
    1. Koh LK, Kong CE, Ip‐Yam PC. The modified Cormack‐Lehane score for the grading of direct laryngoscopy: evaluation in the Asian population. Anaesthesia and Intensive Care 2002;30(1):48‐51. [PUBMED: 11939440 ] - PubMed
Kolarkar 2015 {published data only}
    1. Kolarkar P, Badwaik G, Watve A, Abhishek K, Bhangale N, Bhalerao A, et al. Upper lip bite test: A novel test of predicting difficulty in intubation. Journal of Evolution of Medical and Dental Sciences 2015;4(24):4149‐56.
Komatsu 2007 {published data only}
    1. Komatsu R, Sengupta P, Wadhwa A, Akça O, Sessler DI, Ezri T, et al. Ultrasound quantification of anterior soft tissue thickness fails to predict difficult laryngoscopy in obese patients. Anaesthesia and Intensive Care 2007;35(1):32‐7. [PUBMED: 17323663 ] - PubMed
Konwar 2015 {published data only}
    1. Konwar C, Baruah ND, Saikia P, Chakrabartty A. A prospective study of the usefulness of upper lip bite test in combination with sternomental distance, thyromental distance and inter‐incisor distance as predictor of ease of laryngoscopy. Journal of Evolution of Medical and Dental Sciences 2015;4(97):16286‐89.
Krobbuaban 2005 {published data only}
    1. Krobbuaban B, Diregpoke S, Kumkeaw S. An assessment of the ratio of height to thyromental distance compared to thyromental distance as a predictive test for prediction of difficult tracheal intubation in Thai patients. Journal of the Medical Association of Thailand = Chotmaihet Thangphaet 2006;89(5):638‐42. [PUBMED: 16756049] - PubMed
    1. Krobbuaban B, Diregpoke S, Kumkeaw S, Tanomsat M. The predictive value of the height ratio and thyromental distance: four predictive tests for difficult laryngoscopy. Anesthesia and Analgesia 2005;101(5):1542‐5. [PUBMED: 16244029 ] - PubMed
Langeron 2000 {published data only}
    1. Langeron O, Masso E, Huraux C, Guggiari M, Bianchi A, Coriat P, et al. Prediction of difficult mask ventilation. Anesthesiology 2000;92(5):1229‐36. [PUBMED: 10781266 ] - PubMed
Lee 2015 {published data only}
    1. Lee SL, Hosford C, Lee QT, Parnes SM, Shapshay SM. Mallampati class, obesity, and a novel airway trajectory measurement to predict difficult laryngoscopy. Laryngoscope 2015;125(1):161‐6. [PUBMED: 25042696 ] - PubMed
Liaskou 2014 {published data only}
    1. Liaskou C, Vouzounerakis E, Moirasgenti M, Trikoupi A, Staikou C. Anatomic features of the neck as predictive markers of difficult direct laryngoscopy in men and women: A prospective study. Indian Journal of Anaesthesia 2014;58(2):176‐82. [PUBMED: 24963183 ] - PMC - PubMed
Lundstrom 2009 {published data only}
    1. Lundstrøm LH, Møller AM, Rosenstock C, Astrup G, Gätke MR, Wetterslev J, et al. A documented previous difficult tracheal intubation as a prognostic test for a subsequent difficult tracheal intubation in adults. Anaesthesia 2009;64(10):1081‐8. [PUBMED: 19735399 ] - PubMed
    1. Lundstrøm LH, Møller AM, Rosenstock C, Astrup G, Gätke MR, Wetterslev J, et al. Avoidance of neuromuscular blocking agents may increase the risk of difficult tracheal intubation: a cohort study of 103,812 consecutive adult patients recorded in the Danish Anaesthesia Database. British Journal of Anaesthesia 2009;103(2):283‐90. [PUBMED: 19457894] - PubMed
    1. Lundstrøm LH, Møller AM, Rosenstock C, Astrup G, Wetterslev J. High body mass index is a weak predictor for difficult and failed tracheal intubation: a cohort study of 91,332 consecutive patients scheduled for direct laryngoscopy registered in the Danish Anesthesia Database. Anesthesiology 2009;110(2):266‐74. [PUBMED: 19194154] - PubMed
Mallat 2010 {published data only}
    1. Mallat J, Robin E, Pironkov A, Lebuffe G, Tavernier B. Goitre and difficulty of tracheal intubation. Annales Françaises d'anesthèsie et de Rèanimation 2010;296(6):436‐9. [PUBMED: 20547033] - PubMed
Mashour 2008 {published data only}
    1. Mashour GA, Kheterpal S, Vanaharam V, Shanks A, Wang LY, Sandberg WS, et al. The extended Mallampati score and a diagnosis of diabetes mellitus are predictors of difficult laryngoscopy in the morbidly obese. Anesthesia and Analgesia 2008;107(6):1919‐23. [PUBMED: 19020139 ] - PubMed
Mehta 2014 {published data only}
    1. Mehta T, Jayaprakash J, Shah V. Diagnostic value of different screening tests in isolation or combination for predicting difficult intubation: A prospective study. Indian Journal of Anaesthesia 2014;58(6):754‐7. [PUBMED: 25624545 ] - PMC - PubMed
Merah 2004 {published data only}
    1. Merah NA, Foulkes‐Crabbe DJ, Kushimo OT, Ajayi PA. Prediction of difficult laryngoscopy in a population of Nigerian obstetric patients. West African Journal of Medicine 2004;23(1):38‐41. [PUBMED: 15171524 ] - PubMed
    1. 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. Canadian Journal of Anesthesia 2005;52(3):291‐6. [PUBMED: 15753502 ] - PubMed
Mishra 2009 {published data only}
    1. Mishra SK, Bhat RR, Sudeep K, Nagappa M, Badhe AS. Comparison of upper lip bite test with modified Mallampati classification for prediction of difficult obstetric intubation. The Internet Journal of Anesthesiology 2010;19(1):1‐3.
Montemayor‐Cruz 2015 {published data only}
    1. Montemayor‐Cruz JM, Guerrero‐Ledezma RM. Diagnostic utility of the hyomental distance ratio as predictor of difficult intubation at UMAE 25. Gaceta Médica de México 2015;151(5):599‐607. [PUBMED: 26526473 ] - PubMed
Myneni 2010 {published data only}
    1. Myneni N, O'Leary AM, Sandison M, Roberts K. Evaluation of the upper lip bite test in predicting difficult laryngoscopy. Journal of Clinical Anesthesia 2010;22(3):174‐8. [PUBMED: 20400002] - PubMed
Nadal 1998 {published data only}
    1. Nadal JL, Fernandez BG, Escobar IC, Black M, Rosenblatt WH. The palm print as a sensitive predictor of difficult laryngoscopy in diabetics. Acta Anaesthesiologica Scandinavica 1998;42(2):199‐203. [PUBMED: 9509203 ] - PubMed
    1. Rae R, Kinsella J, Daniel M, Booth M. The palm print as predictor of difficult intubation. Acta Anaesthesiologica Scandinavica 2001;45(8):1053. [PUBMED: 11576065 ] - PubMed
Naguib 1999 {published data only}
    1. Naguib M, Malabarey T, AlSatli RA, Al Damegh S, Samarkandi AH. Predictive models for difficult laryngoscopy and intubation. A clinical, radiologic and three‐dimensional computer imaging study. Canadian Journal of Anaesthesia = Journal Canadien d'anesthésie 1999;46(8):748‐59. [PUBMED: 10451134 ] - PubMed
Naguib 2006 {published data only}
    1. Naguib M, Scamman FL, O'Sullivan C, Aker J, Ross AF, Kosmach S, et al. Predictive performance of three multivariate difficult tracheal intubation models: a double‐blind, case‐controlled study. Anesthesia and Analgesia 2006;102(3):818‐24. [PUBMED: 16492835 ] - PubMed
Nasir 2011 {published data only}
    1. Nasir KK, Shahani AS, Maqbool MS. Correlative value of airway assessment by Mallampati classification and Cormack and Lehane grading. Rawal Medical Journal 2011;36:2‐4.
Nasiri 2013 {published data only}
    1. Nasiri E, Akbari H, Farrokhi H, Ebrahimi F, Nasiri R. A comparison of the Upper Lip Bite Test with Inter Incisor Distance in predicting difficult laryngoscopy and tracheal intubation. Journal of Mazandaran University of Medical Sciences 2013;23(105):71‐9.
Nath 1997 {published data only}
    1. Nath G, Sekar M. Predicting difficult intubation ‐ a comprehensive scoring system. Anaesthesia and Intensive Care 1997;25(5):482‐6. [PUBMED: 9352759 ] - PubMed
Noorizad 2006 {published data only}
    1. Noorizad S, Mahdian M. Mallampati and thyromental distance to predict difficult intubation. Journal of Medical Sciences 2006;6(2):169‐72.
Oates 1990 {published data only}
    1. Oates JD, Oates PD, Pearsall FJ, McLeod AD, Howie JC. Phonation affects Mallampati class. Anaesthesia 1990;45(11):984. [PUBMED: 2082969 ] - PubMed
Oates 1991 {published data only}
    1. Oates JD, Macleod AD, Oates PD, Pearsall FJ, Howie JC, Murray GD. Comparison of two methods for predicting difficult intubation. British Journal of Anaesthesia 1991;66(3):305‐9. [PUBMED: 2015145 ] - PubMed
Pottecher 1991 {published data only}
    1. Pottecher T, Velten M, Galani M, Forrler M. Comparative value of clinical signs of difficult tracheal intubation in women. Annales Françaises d'anesthèsie et de Rèanimation 1991;10(5):430‐5. [PUBMED: 1755552 ] - PubMed
Prakash 2013 {published data only}
    1. 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 Journal of Anaesthesia 2013;57(6):569‐75. [PUBMED: 24403616 ] - PMC - PubMed
Qudaisat 2011 {published data only}
    1. 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. European Journal of Anaesthesiology 2011;28(8):600‐6. [PUBMED: 21610502] - PubMed
Reghunathan 2016 {published data only}
    1. Reghunathan U, Raghavan RK, Veetil BM. Airway assessment for anticipation of difficult intubation: a double blind comparative study. Journal of Evolution Medical and Dental Sciences 2016;5(40):2466‐9.
Rocke 1992 {published data only}
    1. Rocke DA, Murray WB, Rout CC, Gouws E. Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia. Anesthesiology 1992;77(1):67‐73. [PUBMED: 1610011 ] - PubMed
Safavi 2014 {published data only}
    1. Safavi M, Honarmand A, Amoushahi M. Prediction of difficult laryngoscopy: Extended mallampati score versus the MMT, ULBT and RHTMD. Advances in Biomedical Engineering Research 2014;3:133. [PUBMED: 24949304 ] - PMC - PubMed
Sahin 2011 {published data only}
    1. Sahin SH, Yilmaz A, Gunday I, Kargi M, Sut N, Taskinalp O, et al. Using temporomandibular joint mobility to predict difficult tracheal intubation. Journal of Anesthesia 2011;25(3):457‐61. [PUBMED: 21451975 ] - PubMed
Salimi 2008 {published data only}
    1. 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 Anaesthesiologica Taiwanica 2008;46(2):61‐5. [PUBMED: 18593650 ] - PubMed
Samra 1995 {published data only}
    1. Samra SK, Schork MA, Guinto FC Jr. A study of radiologic imaging techniques and airway grading to predict a difficult endotracheal intubation. Journal of Clinical Anesthesia 1995;7(5):373‐9. [PUBMED: 7576671] - PubMed
Savva 1994 {published data only}
    1. Savva D. Prediction of difficult tracheal intubation. British Journal of Anaesthesia 1994;73(2):149‐53. [PUBMED: 7917726 ] - PubMed
Schmitt 2000 {published data only}
    1. Schmitt H, Buchfelder M, Radespiel‐Tröger M, Fahlbusch R. Difficult intubation in acromegalic patients: incidence and predictability. Anesthesiology 2000;93(1):110‐4. [PUBMED: 10861153 ] - PubMed
Seo 2012 {published data only}
    1. Seo SH, Lee JG, Yu SB, Kim DS, Ryu SJ, Kim KH. Predictors of difficult intubation defined by the intubation difficulty scale (IDS): predictive value of 7 airway assessment factors. Korean Journal of Anesthesiology 2012;63(6):491‐7. [PUBMED: 23277808 ] - PMC - PubMed
Shah 2013 {published data only}
    1. 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. Journal of Anaesthesiology, Clinical Pharmacology 2013;29(2):191‐5. [PUBMED: 23878440 ] - PMC - PubMed
Shah 2014 {published data only}
    1. Shah AA, Rafique K, Islam M. Can difficult intubation be accurately predicted using upper lip bite test?. Journal of Postgraduate Medical Institute 2014;28(3):282‐7.
Sharma 2010 {published data only}
    1. Sharma D, Prabhakar H, Bithal PK, Ali Z, Singh GP, Rath GP, et al. Predicting difficult laryngoscopy in acromegaly: a comparison of upper lip bite test with modified Mallampati classification. Journal of Neurosurgical Anesthesiology 2010;22(2):138‐43. [PUBMED: 20118795 ] - PubMed
Singh 2009 {published data only}
    1. Singh R, Jain A, Swatantra M, Kohli P. Clinical evaluation of predicting difficult laryngoscopy in obstetric patients. Journal of Anaesthesiology, Clinical Pharmacology 2009;25(1):38‐42.
Soyuncu 2009 {published data only}
    1. Soyuncu S, Eken C, Cete Y, Bektas F, Akcimen M. Determination of difficult intubation in the ED. The American Journal of Emergency Medicine 2009;27(8):905‐10. [PUBMED: 19857405 ] - PubMed
Tantri 2016 {published data only}
    1. Tantri AR, Firdaus R, Salomo ST. Predictors of difficult intubation among Malay patients in Indonesia. Anesthesiology and Pain Medicine 2016;6(2):e34848. [PUBMED: 27252905 ] - PMC - PubMed
Thompson 2009 {published data only}
    1. Thompson J, O'Neill SS, Hutchings L, Jones R. Retrospective study of 1602 obstetric intubations: predicting difficult and failed intubation using the Mallampati test. International Journal of Obstetric Anesthesia 2009;18:S1‐63. [DOI: ]
Tse 1995 {published data only}
    1. Tse JC, Rimm EB, Hussain A. Predicting difficult endotracheal intubation in surgical patients scheduled for general anesthesia: a prospective blind study. Anesthesia and Analgesia 1995;81(2):254‐8. [PUBMED: 7618711 ] - PubMed
Tuzuner‐Oncul 2008 {published data only}
    1. Tuzuner‐Oncul AM, Kucukyavuz Z. Prevalence and prediction of difficult intubation in maxillofacial surgery patients. Journal of Oral and Maxillofacial Surgery 2008;66(8):1652‐8. [PUBMED: 18634954 ] - PubMed
Ul Haq 2013 {published data only}
    1. Ul Haq MI, Ullah H. Comparison of Mallampati test with lower jaw protrusion maneuver in predicting difficult laryngoscopy and intubation. Journal of Anaesthesiology, Clinical Pharmacology 2013;29(3):313‐7. [PUBMED: 24106353 ] - PMC - PubMed
Uribe 2015 {published data only}
    1. Uribe AA, Zvara DA, Puente EG, Otey AJ, Zhang J, Bergese SD. BMI as a predictor for potential difficult tracheal intubation in males. Frontiers in Medicine (Lausanne) 2015;2(38):e. [PUBMED: 26137460 ] - PMC - PubMed
Vallem 2015 {published data only}
    1. Vallem B, Thalisetty J, Challapalli SR, Israel N, Gudise S, Murthigari S. Comparison of upper lip bite test with other four predictors for predicting difficulty in intubation. Journal of Evolution of Medical and Dental Sciences 2015;4(39):6811‐7. [DOI: 10.14260/jemds/2015/988] - DOI
Vani 2000 {published data only}
    1. Vani V, Kamath SK, Naik LD. The palm print as a sensitive predictor of difficult laryngoscopy in diabetics: a comparison with other airway evaluation indices. Journal of Postgraduate Medicine 2000;46(2):75‐9. [PUBMED: 11013469 ] - PubMed
Wajekar 2015 {published data only}
    1. Wajekar AS, Chellam S, Toal PV. Prediction of ease of laryngoscopy and intubation‐role of upper lip bite test, modified mallampati classification, and thyromental distance in various combination. Journal of Family Medicine and Primary Care 2015;4(1):101‐5. [PUBMED: 25810998 ] - PMC - PubMed
Wilson 1988 {published data only}
    1. Wilson ME, Spiegelhalter D, Robertson JA, Lesser P. Predicting difficult intubation. British Journal of Anaesthesia 1988;61(2):211‐6. [PUBMED: 3415893 ] - PubMed
Wong 1999 {published data only}
    1. Wong SH, Hung CT. Prevalence and prediction of difficult intubation in Chinese women. Anaesthesia and Intensive Care 1999;27(1):49‐52. [PUBMED: 10050224 ] - PubMed
Wong 2009 {published data only}
    1. Wong P, Parrington S. Difficult intubation in ENT and maxillofacial surgical patients: a prospective survey. The Internet Journal of Anesthesiology 2009;21(1):1‐3.
Yamamoto 1997 {published data only}
    1. Yamamoto K, Tsubokawa T, Shibata K, Ohmura S, Nitta S, Kobayashi T. Predicting difficult intubation with indirect laryngoscopy. Anesthesiology 1997;86(2):316‐21. [PUBMED: 9054250 ] - PubMed
Yildiz 2005 {published data only}
    1. Yildiz TS, Solak M, Toker K. The incidence and risk factors of difficult mask ventilation. Journal of Anesthesia 2005;19(1):7‐11. [PUBMED: 15674508 ] - PubMed
Yildiz 2007 {published data only}
    1. Yildiz TS, Korkmaz F, Solak M, Toker K, Erciyes N, Bayrak F, et al. Prediction of difficult tracheal intubation in Turkish patients: a multi‐center methodological study. European Journal of Anaesthesiology 2007;24(12):1034‐40. [PUBMED: 17555609 ] - PubMed
Yu 2015 {published data only}
    1. Yu T, Wang B, Jin XJ, Wu RR, Wu H, He JJ, et al. Predicting difficult airways: 3‐3‐2 rule or 3‐3 rule?. Irish Journal of Medical Science 2015;184(3):677‐83. [PUBMED: 25740093 ] - PubMed

References to studies excluded from this review

Acer 2011 {published data only}
    1. Acer N, Akkaya A, Tugay BU, Öztürk A. A comparison of Cormack‐Lehane and Mallampati tests with mandibular and neck measurements for predicting difficult intubation [Zor Entübasyonu Tahmin Etmek İçin Cormeck‐Lehane ve Mallampati Testleri İle Mandibula ve Boyun Ölçümlerinin Karşılaştırılması]. Balkan Medical Journal 2011;28:157‐63. [DOI: 10.5174/tutfd.2010.03475.1] - DOI
Acikgoz 2015 {published data only}
    1. Acikgoz AO, Karagoz H, Yilbas AA, Akca B, Uzumcugil F, Pamuk G. Difficult airway and risk factors in bariatric surgery patients. Bariatric Surgical Practice and Patient Care 2015;10(4):145‐9. [DOI: 10.1089/bari.2015.0026] - DOI
Beyus 2010 {published data only}
    1. Beyus C, Mort T. Challenges of airway management in obesity. Thirty‐Ninth Critical Care Congress of the Society of Critical Care Medicine; 2010 Jan 9‐13; Miami Beach (FL). Miami Beach, FL: Society of Critical Care Medicine, 2010.
Hiremath 1998 {published data only}
    1. 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;80:606‐11. - PubMed
Lewis 1994 {published data only}
    1. Lewis M, Keramati S, Benumof JL, Berry CC. What is the best way to determine oropharyngeal classification and mandibular space length to predict difficult laryngoscopy?. Anaesthesiology 1994;81:69‐75. - PubMed
Meininger 2010 {published data only}
    1. Meininger D, Strouhal U, Weber CF, Fogl D, Holzer L, Zacharowski K, et al. Direct laryngoscopy or C‐MAC video laryngoscopy? Routine tracheal intubation in patients undergoing ENT surgery [Direkte laryngoskopie oder C‐MAC‐ Vvdeolaryngoskopie? Routineintubation von patienten in der HNO‐heilkunde]. Anaesthesist 2010;59:806‐11. - PubMed
Moon 2013 {published data only}
    1. Moon HY, Baek CW, Kim JS, Koo GH, Kim JY, Woo YC, et al. The causes of difficult tracheal intubation and preoperative assessments in different age groups. Korean Journal of Anesthesiology 2013;64(4):308‐14. [PUBMED: 23646239 ] - PMC - PubMed
Oriol‐López 2009 {published data only}
    1. Oriol‐Lopez SA, Hernandez‐Bernal CE. Assessment, prediction and presence of difficult intubation [Valoración, predicción y presencia de intubación difícil]. Revista Mexicana de Anestesiologica 2009;32(1):41‐9.
Orozco‐Díaz 2010 {published data only}
    1. Orozco‐Díaz E, Alvarez‐Ríos JJ, Arceo‐Díaz JL, Ornelas‐Aguirre JM. Predictive factors of difficult airway with known assessment scales. Cirugia y Cirujanos 2010;78(5):393‐9. [PUBMED: 21219809] - PubMed
Reed 2005 {published data only}
    1. Reed MJ, Dunn MJ, McKeown DW. Can an airway assessment score predict difficulty at intubation in the emergency department?. Emergency Medicine Journal 2005;22(2):99‐102. [PUBMED: 15662057 ] - PMC - PubMed
Safavi 2011 {published data only}
    1. Safavi M, Honarmand A, Zare N. A comparison of the ratio of patient's height to thyromental distance with the modified Mallampati and the upper lip bite test in predicting difficult laryngoscopy. Saudi Journal of Anaesthesia 2011;5(3):258‐63. [PUBMED: 21957403 ] - PMC - PubMed
Siyam 2002 {published data only}
    1. Siyam MA, Benhamou D. Difficult endotracheal intubation in patients with sleep apnea syndrome. Anesthesia and Analgesia 2002;95(4):1098‐102. [PUBMED: 12351303 ] - PubMed
Tripathi 2006 {published data only}
    1. Tripathi M, Pandey M. Short thyromental distance: a predictor of difficult intubation or an indicator for small blade selection?. Anesthesiology 2006;104(6):1131‐6. [PUBMED: 16732082 ] - PubMed

References to studies awaiting assessment

Akhlaghi 2017 {published data only}
    1. Akhlaghi M, Abedinzadeh M, Ahmadi A, Heidari Z. Predicting difficult laryngoscopy and intubation with laryngoscopic exam test: a new method. Acta Medica Iranica 2017;55:453‐8. - PubMed
Andrade 2017 {published data only}
    1. Andrade R, Lima BL, Lopes DK, Couceiro Filho RO, Lima LC, Couceiro TC. Difficult laryngoscopy and tracheal intubation: observational study. Revista Brasileira de Anestesiologia 2017;20:20.
Awan 2017 {published data only}
    1. Awan A, Rehman A. Comparison of neck circumference to thyromental distance ratio with modified Mallampati score for prediction of difficult intubation in obese patients. Acta Anaesthesiologica Scandinavica 2017;61:997.
Banik 2017 {published data only}
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References to other published versions of this review

Lee 2010
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