Thyromental Height Test Research Articles

Thyromental Height Test (TMHT) as a Predictor of Difficult Airway in Obese Patients

Thyromental Height Test (TMHT) as a Predictor of Difficult Airway in Obese Patients

Accuracy of thyromental height test for predicting difficult intubation in elderly.

Studies of the accuracy of different airway tests are lacking in elderly. We evaluated and compared the accuracy of thyromental height in predicting difficult intubation in relation to the other traditional airway tests in elderly. We included 120 patients aged ≥ 65years scheduled for general anesthesia with tracheal intubation. Thyromental height, modified Mallampati test, thyromental distance and sternomental distance were evaluated. Cormack-Lehane grade > 2 was considered difficult laryngoscopy. Difficult tracheal intubation was considered if successful intubation required more than 2 attempts. The accuracy of different tests in predicting difficult intubation and difficult laryngoscopy were evaluated through area under receiver operating characteristic (AUROC) curves. Univariate and multivariate analyses were conducted to identify risk factors for difficult intubation and difficult laryngoscopy. Our cohort had a mean age of 71(7) years. We encountered difficult laryngoscopy in 15/120 (12%) patients, difficult intubation in 20/120 (17%) patients, and failed laryngoscopy requiring alternative methods for securing the airway in 3/120 (3%) patients. For predicting difficult intubation, thyromental height and modified Mallampati test showed the highest accuracy AUROC (95% confidence interval): 0.9 (0.83-0.95), cut-off value ≤ 5.9cm, and AUROC (95% confidence interval): 0.89 (0.82-0.94), cut-off value > 2, respectively. Low thyromental height and high modified Mallampati test were the only independent risk factors for difficult laryngoscopy and difficult intubation. In elderly scheduled for elective procedure, both thyromental height and modified Mallampati tests showed good accuracy in predicting difficult intubation and difficult laryngoscopy, whilst thyromental distance and sternomental distance were poor predictors.

Comparison of thyromental height test with ratio of height to thyromental distance, thyromental distance, and modified Mallampati test in predicting difficult laryngoscopy: A prospective study.

Background and Aims:Preoperative airway assessment to predict patients with difficult laryngoscopy is always crucial for anesthesiologists. Several predictive tests have been studied by various authors in quest of finding the best airway predictor. Recently, a new airway predictor, thyromental height test (TMHT) has been reported to have good predictive value in assessing difficult airway. We conducted this study with primary aim to evaluate the diagnostic accuracy of TMHT and to compare it with other established airway predictors, such as ratio of height to thyromental distance (RHTMD), thyromental distance (TMD), and modified Mallampati test (MMT) for predicting difficult laryngoscopy.Material and Methods:This prospective, observational study was conducted in 550 patients of either sex aged >18 years scheduled for elective surgery under general anesthesia. The patients’ airway was assessed preoperatively by two anesthetists. Standard anesthetic protocol was followed in all the patients. The laryngoscopic view was graded according to Cormack–Lehane scale. The receiver operating characteristic (ROC) curve was used to calculate the ideal cut off values for TMHT and RHTMD. Standard formulae were used to calculate validity indexes.Results:The incidence of difficult laryngoscopy was 10%. The cut-off value for TMHT and RHTMD were 5.1 cm and 19.5, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TMHT were 78.18%, 93.94%, 58.90%, and 97.48%, respectively. The highest sensitivity, PPV, and NPV were observed with TMHT as compared with RHTMD, TMD, and MMT (P < 0.0001).Conclusions:TMHT is the best predictive test with highest accuracy and odds ratio for predicting difficult airway out of all predictive tests evaluated.

Reliability of the thyromental height test for prediction of difficult visualisation of the larynx: A prospective external validation.

Background and Aims:Thyromental height (TMH) has been reported to be useful for prediction of difficult visualisation of the larynx (DVL), defined as Cormack--Lehane (C&L) grade III or IV. The aim of this study was to compare the diagnostic accuracy of the TMH test for DVL with that of other clinically used tests in Japanese patients.Methods:Six hundred and nine surgical patients undergoing endotracheal intubation under general anaesthesia were enrolled in this prospective observational study. TMH, thyromental distance (TMD), and Samsoon and Young's modified Mallampati (MMT) tests were performed in all patients. The C&L grades for the laryngoscopic view with and without external backward, upward, rightward pressure (BURP) were determined by designated airway assessors. The cutoff value for the TMH test was calculated using receiver-operating characteristic (ROC) curve analysis. The sensitivity, specificity, positive predictive value, accuracy, positive likelihood ratio, and area under the ROC curve (AUROC) for each predictive test were calculated and compared.Results:ROC curve analysis indicated that 54 mm is the optimal cutoff value for the TMH test. However, both this value and the conventional cutoff value of 50 mm, which has been reported as having good diagnostic accuracy in the literature, had poor diagnostic accuracy. The AUROC for the TMH test was 0.631 without BURP and 0.592 with BURP; these values were not superior to those for the TMD test or MMT.Conclusion:The TMH test is not a good predictor of DVL in Japanese patients.

Prediction of difficult airway by thyromental height test- a comparison with modified mallampati test.

Background: Management of airway is central to the Practice of anaesthesia. One of the anaesthesiologist fundamental roles is to maintain a patent airway at a all times.Maintaining a patent airway is essential for adequate oxygenation and ventilation and failure to do so, even for a brief period of time, can be life threatening. Recently, thyromental height test (TMHT) has been proposed as one of the highly sensitive and specific bedside tests to predict difficult airway.Objective: To assess the predictivity of thyromental height test in comparison to modified Mallampati test.Methods: This cross sectional study was carried out in Anesthesiology department of ISMCH during the period of January, 2015 to December, 2016. A total number of 139 consecutive patients scheduled for elective surgical procedure under general anaesthesia requiring intubation having American Society of Anesthesiologists grading I-II. Statistical analyses of the results were obtained by SPSS-20. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value of Thyromental height test and Modified mallampati scoring in diagnosis of difficult airway were calculated.Results: Most (74.4) of the patients belonged to age ≤50 years. Male to female ratio was 1.01:1. Majority 91(65.5%) patients had thyromental height of ≥50 mm. In the diagnosis of difficult airway, Thyromental height test was 92.7% sensitivity, 93.5% specificity, 93.5% accuracy and 85.4% positive predictive values, 97.8% negative predictive value, 13.1% positive likelihood ratio, 0.05 negative likelihood ratio. On the other hand Modified mallampati scoring was 48.8% sensitivity, 92.7% specificity, 79.1% accuracy, 75.0% positive predictive values, 80.2% negative predictive value, 6.7% positive likelihood ratio, 0.55 negative likelihood ratio for prediction of difficult airway.Conclusions: It can be concluded that the thyromental height is useful diagnostic modality for predicting difficult airway.Bangladesh Journal of Medical Science Vol.17(3) 2018 p.455-461

Validity of thyromental height test as a predictor of difficult laryngoscopy: A prospective evaluation comparing modified Mallampati score, interincisor gap, thyromental distance, neck circumference, and neck extension.

Background and Aims:Thyromental height test (TMHT) is a recently described anatomical bedside screening tool in predicting difficult laryngoscopy. It has been shown to be more accurate than the modified Mallampati score, thyromental distance (TMD), and sternomental distance with regard to sensitivity and positive predictive value (PPV). Airway assessment studies based on the anatomic parameters of the upper airway are limited in the subcontinent population. We attempted this study to evaluate and validate the predictive value of TMHT at 50 mm in an Indian population in predicting difficult laryngoscopy.Methods:This prospective observational study was conducted in a tertiary teaching hospital on 340 patients. TMHT along with other bedside predictors of difficult intubation, including modified Mallampati score, interincisor gap (IIG), TMD, neck circumference (NC), and neck extension were assessed. We compared the sensitivity, specificity, PPV, negative predictive value (NPV), and diagnostic accuracy of TMHT with other bedside tests such as the modified Mallampati score, IIG, TMD, NC, and neck extension individually in predicting difficult laryngoscopy. Any Cormack and Lehane's intubation grade II b and above was considered to be difficult laryngoscopy.Results:TMHT had the highest sensitivity (84.62%) and specificity (98.97%), and had the most PPV (88%) and NPV (98.63%) when compared with the modified Mallampati score, IIG, TMD, NC, and neck extension. TMHT was followed by the modified Mallampati score and IIG.Conclusion:TMHT appears promising as a single anatomical measure to predict the risk of difficult laryngoscopy, however, validation will require further studies in more diverse patient populations.

Thyromental height test for prediction of difficult laryngoscopy in patients undergoing coronary artery bypass graft surgical procedure.

Background:Patients undergoing coronary artery bypass graft (CABG) procedures have higher incidence of difficult laryngoscopy and intubation than general surgery population. Accurate prediction of difficult laryngoscopy in CABG patients is desirable to reduce the hemodynamic response and myocardial oxygen requirements. Recently, thyromental height test (TMHT) has been proposed as one of the highly sensitive and specific bedside tests to predict difficult airway. We, in our prospective observational study, evaluated the accuracy of the TMHT in predicting difficult laryngoscopy.Methodology:A total of 345 patients undergoing CABG of either sex, in the age group of 35–80 years, American Society of Anesthesiologists 111, undergoing CABG, were studied. Airway assessment was performed with modified Mallampati test with the addition of thyromental distance, sternomental distance, and TMHT. Intraoperatively, direct laryngoscopy was done in accordance with Cormack and Lehane grade of laryngoscopy. The preoperative data and laryngoscopic findings were used together to evaluate the accuracy of TMHT. The sensitivity, specificity, positive and negative predictive values of other three tests were calculated according to standard formula.Results:A total of 345 patients were in the group with mean age of study population at 56.7 (standard deviation 9.1) years (35–80 years). This study showed that almost all tests had good specificity, but sensitivity was poor. However, sensitivity of TMHT was 75% with accuracy of 95%. Receiver operating characteristic curve analysis of TMHT-derived cutoff was 52.17 which increased sensitivity to 81.25% and specificity to 92.3%.Conclusion:TMHT had a higher sensitivity compared to other tests along with good positive and negative predictive value and a very high specificity.

Thyromental Height

The incidence of difficult laryngoscopy is reported in the range of 1.5% to 20%. We hypothesized that there is a close association between the occurrence of difficult laryngoscopy and the height between the anterior borders of the mentum and thyroid cartilage, while the patient lies supine with her/his mouth closed. We have termed this the "thyromental height test" (TMHT). Our aim in this study was to determine its utility in predicting difficult laryngoscopy. Three hundred fourteen consecutive male and female patients aged ≥ 16 years scheduled to undergo general anesthesia were invited to participate. Airway assessments were performed with the modified Mallampati test, thyromental distance and sternomental distance, and TMHT in the preoperative clinic. Afterward, Cormack and Lehane grade of laryngoscopy views was assessed during intubation. The laryngoscopist was unaware of airway assessments. As a primary end point, the validity and prediction indexes for the TMHT were calculated. Calculation of validity indexes for the 3 other methods of airway assessment was a secondary objective of this study. The optimal sensitivity and specificity values were in the range of 47.46 to 51.02 mm. To facilitate clinical application, a cutoff value equal to 50 mm was chosen. TMHT was more accurate than the other tests (all P < 0.0001). The TMHT appears to be a more accurate predictor of difficult laryngoscopy than the existing anatomical measurements.