双相气道正压无创机械通气时阻塞性睡眠呼吸暂停综合征患者上呼吸道影像分析

Imageological analysis of upper airway during noninvasive mechanical ventilation with bi-level positive airway pressure in obstructive sleep apnea syndrome patients

目的应用多层螺旋CT对阻塞性睡眠呼吸暂停综合征（OSAS）患者不同通气状态下上呼吸道行放射学成像，分析在全身麻醉无自主呼吸条件下双相气道正压（BiPAP）无创机械通气是否能克服上呼吸道阻力达到有效的机械通气。方法选择拟行咽腭成形术的OSAS患者10例，手术前常规实施麻醉诱导睡眠。分别对患者清醒状态下自主呼吸（清醒期）、睡眠诱导后意识消失（诱导期）、BiPAP无创机械通气后5min（通气期）时头部正位和侧位作螺旋CT扫描，测量上呼吸道各软组织区[软腭后区（RP）、舌根后区（RG）、会厌区（EPG）]的最窄气道横截面左右径、前后径长度及相应横截面积，并监测扫描过程中的无创血压（NIBP）、脉搏血氧饱和度（SpO2）、心率（HR）、自主呼吸频率（RR）。结果头颈部正位扫描显示诱导期RP区和EPG区最窄气道横截面左右径、前后径线长度比清醒期明显缩短，各区横截面积明显缩小[RP区：0．00（0．00，0．60）mm^2比38．34（10．57，72．76）mm^2，RG区：145．16（0．00，183．72）mm^2比177．79（111．05，216．27）mm^2，EPG区：39．02（7．55，86．36）mm^2比154．69（124．74，322．00）mm^2，均P〈0．05]。通气期各横截面径线和面积较清醒期仍明显缩小（均P〈0．05），但与诱导期差异无统计学意义（均P〉0．05）。头部侧位诱导期除RG区左右径外，各区最窄气道横截面左右径、前后径线长度均短于清醒期，横截面积亦缩小[RP区：0．00（0．00，18．74）mm^2比61．46（36．77，141．46）mm^2，RG区：69．75（35．74，214．83）mm^2比287．68（197．01，393．18）mm^2，EPG区：17．28（437，65．45）mm^2比293．76（254．63，374．83）mm^2，均P〈0．05]。BiPAP通气时各区横截面径线与清醒期比较尚明显缩短，横截面积虽缩小却较诱导期明显回升（均P〈0．05）。各期正、侧位NIBP、HR无明显变化，诱导期RR明显受抑制，SpO2降低（均P〈0．05），通气期RR、SpO2与诱导期比较虽有所改善，但差异无统计学意义（均P〉0．05），仍未回复到清醒期水平（均P〈0．05）。结论OSAS患者睡眠诱导后上呼吸道通畅度明显下降，即使将头部侧位后仍未能改善上呼吸道的通畅度，无自主呼吸的状态下应用BiPAP无创机械通气不能克服上呼吸道阻力达到有效通气，需特殊处理保证安全。

Objective Multislice spiral CT scanning was used for radiological imaging of upper airway under various ventilation in obstructive sleep apnea syndrome （OSAS） patients in order to study whether hi-level positive airway pressure （BiPAP） noninvasive mechanical vetilation can overcome upper airway resistance and provide effective ventilation under general anesthesia and non-spontenuous breathing. Methods Ten OSAS patients scheduled for uvulopalatopharyngoplasty were enrolled in the study. General anesthesia inducing sleep was routinely performed before operation. Computer tomography of cephal-neck in orthophoric and lateral position was performed under spontaneous respiration （lucid interval） , non- consciousness after sleep induction （induction period）, and noninvasively ventilation with BiPAP for 5 min （ventilation period）. Narrowest transverse and anteroposterior diameters of transverse section, and correlative cross section areas over each soft tissue region of upper respiratory tract [retropalatal （RP） , retroglossal （RG） and epiglottal （EPG） region] were tested. Noninvasive blood pressure （NIBP） , oxygen saturation by pulse oximeter （SpO2） , heart rate （HR） and spontaneous respiratory rate （RR） during scanning were monitored. Results In orthophorie position, transverse diameter and anteroposterior diameter of RP and EPG regions shortened during anesthesia induction. Cross section area of all regions decreased during anesthesia induction [RP region： 0.00（0.00, 0.60） mm^2 vs 38.34（10.57, 72.76） mm^2, RG region： 145.16 （0.00, 183.72） mm^2 vs 177.79 （111.05, 216.27） mm^2, EPG region： 39.02 （7.55, 86.36） mm^2 vs 154.69 （124.74, 322.00） mm^2, all P〈0.05]. The diameters shortened and area decreased as well under BiPAP ventilation when comparing with those in spontaneous respiration （all P〉0.05） , however, no statistical significance was found when comparing with those in induction period （all P〉0.05）. In lateral position, diameters and areas under BiPAP ventilation were smaller than those during spontaneous respiration except for transverse diameter of RG region[areas, RP region： 0.00（0.00, 18.74） mm^2 vs 61.46 （36.77, 141.46） mm^2, RG region： 69.75 （35.74, 214.83） mm^2 vs 287.68 （197.01, 393.18） mm^2, EPG region： 17.28 （4.37, 65.45） mm^2 vs 293.76（254.63, 374.83） mm^2, all P〈0.05] The transverse diameter, anteroposterior diameter and transverse section area during BiPAP ventilation decreased also when comparing with those in spontaneous respiration, however, transverse section area increased significantly during induction period （all P〉0.05）. Neither NIBP nor HR changed both in orthophoric and lateral position. RR at induction period was obviously inhibited and SpO2 decreased （all P〈0.05）. Though RR and SpO2 during ventilation period improved as compared to induction period, however no statistical significance was observed （all P〉0.05） , none of them returned to normal range （all P〈0.05）. Conclusion The ventilation of upper airway is not smooth after sleep induction in OSAS patients, though their heads are in lateral postion. By BiPAP noninvasive ventilation, effective ventilation still can not be achieved since airway resistance is not relieved, so special handling is advised to ensure safety.