Jeong Il Man, Seo Won Goo, Woo Chul Ho, Bae Ji Young, Mun Sung Ha, Kim Kwang Min
Department of Anesthesiology and Pain Medicine, Hangang Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Korea.
Korean J Anesthesiol. 2009 Sep;57(3):290-295. doi: 10.4097/kjae.2009.57.3.290.
Postburn sternomental contractures cause various changes in mouth, oral cavity, pharynx, larynx and related structures. Although there are many methods to predict difficult intubation, the modified Mallampati test (mMT) and the El-Ganzouri multivariate risk index (EGRI) are popular tests. The authors wanted to compare modified Onah class with these 2 tests and also explored the possibility that Onah class could be an adequate independent predictor for difficult intubation.
One hundred and nine patients, aged 18 to 60 years of age, scheduled for elective surgery for reconstruction of postburn sternomental contractures were divided according to the modified Onah class. We made assessments prior to general anesthesia with respect to mouth opening, thyromental distance, mMT, neck movement, ability to prognath, body weight, and history of difficult tracheal intubation. The accuracy, specificity, positive and negative predictive values were calculated from the data of the 3 tests, and as the 3 tests were compared with patient's laryngoscopic view grade according to Cormack and Lehane criteria by using the Chi-square test.
The incidence of Cormack and Lehane grade III, IV was 39.4%. Onah class showed significantly higher accuracy, specificity, and positive predictive value than mMT and EGRI. There were significant correlations between modified Onah class 2b, 3 and the Cormack and Lehane grade III, IV.
Application of modified Onah class for preoperative prediction of the degree of difficulty with laryngeal visualization can reduce the frequency of both an unanticipated failure to visualize laryngeal structures as well as potential unnecessary interventions related to over-prediction of airway difficulty in patients with postburn sternomental contractures.
烧伤后胸骨颏部挛缩会导致口腔、口咽、喉及相关结构发生各种变化。尽管有多种预测困难插管的方法，但改良马兰帕蒂试验（mMT）和埃尔 - 甘祖里多因素风险指数（EGRI）是常用的检测方法。作者希望将改良奥纳分级与这两种检测方法进行比较，并探讨奥纳分级是否可能成为困难插管的充分独立预测指标。
109例年龄在18至60岁之间、计划择期行烧伤后胸骨颏部挛缩重建手术的患者，根据改良奥纳分级进行分组。在全身麻醉前，我们对患者的张口度、甲状软骨 - 颏距离、mMT、颈部活动度、前伸下颌能力、体重以及困难气管插管史进行评估。根据这三种检测方法的数据计算其准确性、特异性、阳性和阴性预测值，并使用卡方检验将这三种检测方法与根据科马克和莱汉内标准划分的患者喉镜视野分级进行比较。
科马克和莱汉内III级、IV级的发生率为39.4%。奥纳分级显示出比mMT和EGRI更高的准确性、特异性和阳性预测值。改良奥纳分级2b、3级与科马克和莱汉内III级、IV级之间存在显著相关性。
应用改良奥纳分级对烧伤后胸骨颏部挛缩患者术前预测喉镜视野显露困难程度，可减少意外无法显露喉部结构的频率以及与气道困难过度预测相关的潜在不必要干预。
