Iohom G, Ronayne M, Cunningham A J
Beaumont Hospital, Department of Anaesthesia and Intensive Care, Dublin, Ireland.
Eur J Anaesthesiol. 2003 Jan;20(1):31-6. doi: 10.1017/s0265021503000061.
Preoperative bedside screening tests for difficult tracheal intubation may be neither sensitive nor specific enough for clinical use. The aim was to investigate if a combination of the Mallampati classification of the oropharyngeal view with either the thyromental or sternomental distance measurement improved the predictive value.
A total of 212 (109 male, 103 female) non-obstetric surgical patients, aged >18 yr, undergoing elective surgical procedures requiring tracheal intubation were assessed preoperatively with respect to the oropharyngeal (modified Mallampati) classification, thyromental and sternomental distances. An experienced anaesthetist, blinded to the preoperative airway assessment, performed laryngoscopy and graded the view according to Cormack and Lehane's classification.
Twenty tracheal intubations (9%) were difficult as defined by a Cormack and Lehane Grade 3 or 4, or the requirement for a bougie in patients with Cormack and Lehane Grade 2. Used alone, the Mallampati oropharyngeal view, and thyromental and sternomental distances were associated with poor sensitivity, specificity and positive predictive values. Combining the Mallampati Class III or IV with either a thyromental distance <6.5cm or a sternomental distance <12.5cm decreased the sensitivity (from 40 to 25 and 20%, respectively), but maintained a negative predictive value of 93%. The specificity and positive predictive values increased from 89 and 27% respectively for Mallampati alone to 100%.
The findings suggest that the Mallampati classification, in conjunction with measurement of the thyromental and sternomental distances, may be a useful routine screening test for preoperative prediction of difficult tracheal intubation.
术前用于困难气管插管的床旁筛查试验在临床应用中可能既不够敏感也不够特异。本研究旨在探讨将口咽视像的Mallampati分级与甲状软骨-颏下距离或胸骨上切迹-颏下距离测量相结合是否能提高预测价值。
选取212例（男109例，女103例）年龄>18岁、接受需要气管插管的择期手术的非产科手术患者，术前对其进行口咽（改良Mallampati）分级、甲状软骨-颏下距离及胸骨上切迹-颏下距离评估。由一位对术前气道评估不知情的经验丰富的麻醉医生进行喉镜检查，并根据Cormack和Lehane分级对视野进行分级。
按照Cormack和Lehane分级为3级或4级，或Cormack和Lehane分级为2级的患者需要使用探条确定为困难气管插管20例（9%）。单独使用时，Mallampati口咽视像、甲状软骨-颏下距离和胸骨上切迹-颏下距离的敏感性、特异性和阳性预测值均较差。将MallampatiⅢ级或Ⅳ级与甲状软骨-颏下距离<6.5cm或胸骨上切迹-颏下距离<12.5cm相结合，敏感性降低（分别从40%降至25%和20%），但阴性预测值维持在93%。特异性和阳性预测值分别从单独使用Mallampati分级时的89%和27%增至100%。
研究结果表明，Mallampati分级结合甲状软骨-颏下距离和胸骨上切迹-颏下距离测量，可能是术前预测困难气管插管的一种有用的常规筛查试验。
