Panjiar Pratibha, Kochhar Anjali, Bhat Kharat M, Bhat Mudassir A
Department of Anesthesiology and Critical Care, Hamdard Institute of Medical Sciences and Research, New Delhi, India.
J Anaesthesiol Clin Pharmacol. 2019 Jul-Sep;35(3):390-395. doi: 10.4103/joacp.JOACP_276_18.
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.
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.
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 ( < 0.0001).
TMHT is the best predictive test with highest accuracy and odds ratio for predicting difficult airway out of all predictive tests evaluated.
术前气道评估以预测喉镜检查困难的患者对麻醉医生来说始终至关重要。多位作者研究了多种预测试验，以寻找最佳气道预测指标。最近，一种新的气道预测指标，即颏甲距离试验（TMHT），据报道在评估困难气道方面具有良好的预测价值。我们开展本研究的主要目的是评估TMHT的诊断准确性，并将其与其他既定的气道预测指标，如身高与颏甲距离比值（RHTMD）、颏甲距离（TMD）和改良Mallampati试验（MMT）进行比较，以预测喉镜检查困难情况。
本前瞻性观察性研究纳入了550例年龄大于18岁、计划接受全身麻醉下择期手术的患者，性别不限。由两名麻醉医生在术前对患者气道进行评估。所有患者均遵循标准麻醉方案。喉镜视野根据Cormack-Lehane分级标准进行分级。采用受试者操作特征（ROC）曲线计算TMHT和RHTMD的理想截断值。使用标准公式计算有效性指标。
喉镜检查困难的发生率为10%。TMHT和RHTMD的截断值分别为5.1 cm和19.5。TMHT的敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）分别为78.18%、93.94%、58.90%和97.48%。与RHTMD、TMD和MMT相比，TMHT的敏感性、PPV和NPV最高（<0.0001）。
在所有评估的预测试验中，TMHT是预测困难气道准确性最高、比值比最大的最佳预测试验。
