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

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 bi-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 orthophofic and lateral position was performed under spontaneous respiration (lucid interval) , nonconsciousness 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 orthophoric 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) mm2 vs 38.34(10.57, 72.76) mm2, RG region:145.16(0.00, 183.72) mm2 vs 177.79(111.05, 216.27) mm2, EPG region: 39.02(7.55, 86.36) mm2 vs 154.69 (124.74, 322.00) mm2, 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 regionareas, BP region: 0.00(0.00, 18.74) mm2 vs 61.46(36.77, 141.46) mm2, RG region: 69.75 (35.74, 214.83) mm2 vs 287.68 (197.01, 393.18) mm2, EPG region: 17.28 (4.37, 65.45) mm2 vs 293.76(254.63, 374.83) mm2, 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.

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