Elsevier

Journal of Clinical Anesthesia

Volume 36, February 2017, Pages 21-26
Journal of Clinical Anesthesia

Original Contribution
Evaluation of the reliability of preoperative descriptive airway assessment tests in prediction of the Cormack-Lehane score: A prospective randomized clinical study

https://doi.org/10.1016/j.jclinane.2016.08.006Get rights and content

Highlights

  • TMH is a practical method but clinical practice is controversial.

  • Final Cormack-Lehane scores are concordant with IDS.

  • Validity of airway screening tests is variable.

  • Age-, sex-, and race-dependent variables can affect the results of these tests.

Abstract

Study objective

In this study we investigated and compared the predictive values of different airway assessments tests including thyromental height measurement test, which has been recently suggested, in difficult laryngoscopy (Cormack and Lehane [C-L] scores 3 and 4). In addition, we compared the effectiveness of methods and C-L scores, by IDS, in terms of predicting difficult intubation.

Design

Prospective, blinded study.

Setting

Maltepe University.

Patients

Four hundred fifty-one patients selected randomly who underwent general anesthesia.

Interventions

In this study we compared predictive value of thyromental height measurement test (TMH), which has been recently suggested, modified Mallampati test (MMT), upper lip bite test (ULBT), and thyromental distance measurement test (TMD) in difficult laryngoscopy. Final C-L scores were compared with intubation difficulty scale (IDS) in terms of predicting difficult intubation.

Measurements

Patient's American Society of Anesthesiology score, age and weight were recorded. TMH, TMD, MMT, ULBT, IDS and C-L scores were measured and determined.

Main results

The optimal cut-off point for TMH for predicting difficult laryngoscopy was 43.5 mm and for TMD was 82.06 mm. Use of TMH <43.5 with MMT has the highest sensitivity for predicting difficult intubation (78.38) with 75.36% specificity and 97.50% negative predictive value. TMH showed sensitivity of 91.89% and specificity 52.17% at 50 mm cut-off value. In the comparison of the area under the receiver operating characteristic curve values, none of the tests came forth individually or in combination with MMT test.

Conclusions

The present study demonstrates the practicality of TMH as a digitalized test however the clinical benefits of TMH in daily medical practice are drawn into question. The additional variable of race may have had some bearing on this and further studies, larger in patient sample size, may need to use different methodology concerning age-, sex-, and race-dependent variables in evaluating these tests.

Section snippets

Introductıon

Appropriate management of the difficult airway constitutes an important place in the prevention of mortality and morbidity associated with anesthesia. The prevalence of difficult laryngoscopy has been reported to range between 1.5% and 20%, and a variety of physical examination tests have been used to estimate its presence [1]. One of the most frequently used tests in the assessment of airway is Mallampati scoring, while a variety of methods including thyromental distance, mouth opening,

Materials and methods

This study was conducted between February 2015 and August 2015 after obtaining approval from Maltepe University Medical Faculty (Istanbul) ethics committee on 29 May 2014 with protocol number 23. A total of 451 male and female patients over 18 years of age, who would undergo surgical operation under general anesthesia were included in the study; written consents of the patients were obtained. The patients were selected in the preoperative according to a randomization principle of “the first

Results

The demographic data of the participants are shown in Table 1. A total of 451 patients (221 women and 230 men, age 17–94 y) were included in the study. A total of 37 (8.2%) patients were defined as difficult intubation according to the C-L grade 3 and grade 4 laryngeal views. None of the patients had failed endotracheal intubation. Age and American Society of Anesthesiologists (ASA) score scores of the patients who were classified as difficult intubation were significantly higher (Table 2).

Discussion

The tests that are used to predict difficult intubation are expected to have high sensitivity and specificity and minimal false positive and false negative values [6]. There is still no available single standard method that meets the criteria or a consensus regarding the reliability of the ideally preferred tests [7], [8]. Etezadi et al [1] suggested that TMH was a promising single anatomical measurement technique with high sensitivity, specificity, PPV and NPV (82.6%, 99.31%, 90.47% and 98.63%

Conclusion

Airway screening tests should be simple, convenient and practical. They are an essential tool for anesthesiologists despite the fact that their validity is variable and their ability to predict unexpected difficult intubations remains restricted.

The present study demonstrates the practicality of TMH as a digitalized test. It also confirms the relatively high sensitivity of TMH for predicting difficult intubation; however, in not replicating the clear-cut results of the previous study, the

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Disclosure: There is no funding for this study and we do not have any conflict of interest.

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