困难气道患者上气道三维CT图像的改变

Changes in three-dimensional computer tomography images of upper airway in patients with difficult tracheal intubation

目的评价困难气道患者上气道三维CT图像的改变，为困难气道的预测提供客观依据。方法择期全麻手术男性患者17例，年龄25～60岁，身高165～185cm，体重55～110kg，体重指数19～33kg／m^2，ASAⅠ或Ⅱ级。术前行Mallampati评分、Willson综合评分，并进行上气道三维CT扫描，分别测量伸舌前和伸舌时口咽腔内空腔容积（分别为Va1和Va2）、舌体体积（分别为Vt1和Vt2）、硬腭后缘所在冠状位口咽腔内空腔截面积（分别为Aa1和Aa2）和舌体截面积（分别为At1，和At2），于正中矢状位测量上门齿与舌根部连线与水平线的夹角即直接喉镜视角，测量下颌骨平面与舌骨平面的垂直距离（MHD）。患者均行清醒盲探气管插管，麻醉诱导后采用直接喉镜暴露，根据Cormack—Lehane分级分为2组：非困难气道组（NDI组）Cormack—Lehane分级为Ⅰ或Ⅱ级；困难气道组（DI组）Cormack—Lehane分级为Ⅲ或Ⅳ级。结果NDI组8例，DI组9例。与NDI组比较，DI组伸舌前各指标比较差异无统计学意义（P〉0．05），Va2、Va1—Va2、Aa2、Aa1-Aa2、At1-At2减小，MHD延长，Va1／Vt1—Va2／Vt2增大（P〈0．05或0．01）；与Va1或Aa1比较，DI组va2、Aa2减小（P〈0．05）。结论困难气道患者上气道三维CT图像的改变主要表现为伸舌时口咽腔内空腔容积和截面积减小，伸舌前与伸舌时空腔容积，舌体体积比的差值增大，MHD延长。

Objective To evaluate the changes in three-dimensional computer tomography （3DCT） images of upper airway in patients with difficult tracheal intubation and provide theoretical evidence for predicting the difficult tracheal intubation. Methods Seventeen ASA Ⅰ or Ⅱ male patients, 25-60 yr old , height 165-185 cm, weight 55-110 kg, body mass index 19-33 kg/m^2 , scheduled for elective surgery under general anesthesia, were studied. The airway condition was evaluated with Mallampati classification and Willson score system in all patients before the operation. The patients underwent 3DCT scanning under 2 different statuses： with or without tongue protruding while opening his mouth maximally. The volume of the oropharyngeal cavity （ Val , Va2 ） and tongue body （Vt1, Vt2 ）, and area of the oropharyngeal cavity （ Aa1, Aa2 ） and tongue body （ At1 , At2 ） in the coronal position were measured before and during tongue protruding. The midline sagittal images of the upper airway were made on computer to measure the direct laryngoscope angle and vertical distance between the mandible and hyoid （MHD）. Awake blind tracheal intubation was performed in all patients. The exposure of the glottis was performed after anesthesia induction and evaluated with Cormack-Lehane classification. The patients were divided into non-difficult intubation group （group NDI, Cormack-Lehane grade Ⅰ or Ⅱ ） and difficult intubation group （group DI, Cormack-Lehane grade Ⅲ or Ⅳ）according to Cormack-Lehane classification. Results There were 8 patients in group NDI, and 9 patients in group DI. There was no significant difference in the indices before tongue protruding between group DI and NDI （P 〉0.05）. Va2, Va1 - Va2, Aa2, Aa1 - Aa2, and At1 - At2 were significantly smaller, MHD was significantly longer and Va1/Vt1 - Va2/Vt2 was significantly larger in group DI than in group NDI （P 〈 0.05 or 0.01 ）. Va2 and Aa2 were significantly smaller than Va1 and Aal in group DI respectively （ P 〈 0.05）. Conclusion The changes in 3DCT images of the upper airway in patients with difficult tracheal intubation are mainly presented as smaller volume and area of the oropharyngeal cavity, larger difference value of the ratio of cavity volume to tongue volume and prolonged MHD.