Comparative Study Of Determining The Sites Of Airway Obstruction In Obstructive Sleep Apnea Hypopnea Syndrome Between Real-time CT Imaging And Laryngoifherscope Technology

Objective To investigate methods of256-layer spiral computed tomography (CT)scanning of upper airway in patients with obstructive sleep apnea hypopneasyndrome(OSAHS) during awake and drug-induced sleep states, and compare real-timeCT with laryngofiberscope technology for locating obstructive sites of upper airway,and analyze their advantages and disadvantages and discuss the clinical applicationvalues.Methods1.Establishing methods of real-time CT and induced sleep Four patients withOSAHS underwent spiral CT scan during awake state,and the scanning range extendedfrom superior wall of nasopharynx to the level of cricoid cartilage, with scanning timeabout3s. Then, propofol intravenous injection was given according to0.5~1.0mg/kgby the specialized responsible anesthesiologist,waiting for patients to sleep. Real-timeCT scanning began with the same scanning parameters and range as soon as PSGshowed sleep apnea occuring.2.Real-time CT imaging and laryngofiberscope59patients with OSAHS underwent CT scanning of upper airway during awake anddrug-induced sleep states.The minimum section area, diameter and volume of pharynxcavity were measured on reconstructed3-dimensional computed tomography. Then, thesites of airway obstruction were assessed by laryngofiberscope examination duringawake state, which were compared with results of real-time CT scanning.Results1. Sleep apnea episodes were observed during drug-induced sleep state in all offour patients, and real-time CT images were obtained,without any accident.2. Real-time CT scanning was completed successfully in all patients.(1)There were airwayobstruction at isolated retropalatal regions (real-time CT revealing n=26,laryngofiberscope revealing n=34), retropalatal&retroglottal regions simultaneously(real-time CT revealing n=19, laryngofiberscope revealing n=10), retropalatal&epiglottal regions simultaneously (real-time CT revealing n=6, laryngofiberscoperevealing n=2), retropalatal&retroglottal&epiglottal regions simultaneously (real-timeCT revealing n=7, laryngofiberscope revealing n=3) and no airway obstruction(real-time CT revealing n=1, laryngofiberscope revealing n=10). There was not solitaryairway obstruction at retroglottal or epiglottal regions.(2)The results of real-time CTscans and laryngofiberscope examination were statistically significant different in allregions, and real-time CT scanning compared with laryngofiberscope found moreobstructive sites of upper airway [retropalatal regions:98.3%(n=58)/83.1%(n=49),X~2=5.82, P<0.05; retroglottal regions:44.1%(n=26)/22.0%(n=13), X~2=9.60, P<0.05;epiglottal regions:22.0%(n=13)/8.5%(n=5), X~2=4.90, P<0.05].(3) The minimumsection area, volume, minimum anteroposterior diameter and left-right diameter ofpharynx cavity between awake and drug-induced sleep apnea state were statisticallysignificant difference in all of regions(P<0.05).(4) The real-time CT results showed thatrate of single region airway obstruction is44.1%(26/59)，and rate of multiple regionsairway obstruction54.2%(32/59). Starting from Friedman tongue position I to IV, thepercentage of obstruction at retroglottal and(or) retroglottal region were increasing, andthe percentage of obstruction was0/6,8/25,13/20,11/11, respectively (P<0.05).Conclusion (1)Propofol short-term induced sleep can maximize the simulation (orrepresentation) of natural sleep state, during which obstructive sites of upper airway inOSAHS can be observed and located.(2)For OSAHS localization diagnosis, awakeexaminations can only reflect the anatomical abnormalities, but it is difficult todetermine the obstructive sites during sleep.(3)There is obvious correlation between Friedman tongue position and airway stenosis of retroglottal or epiglottal region, whichis applicable to evaluation airway obstruction of retroglottal or epiglottal region.(4)Theupper airway structure and morphology change were observed dynamically bylaryngoscopy combined with Müller test during awake states, which has limitations inthe diagnosis of hypopharynx obstruction.(5)Compared with laryngofiberscopeexamination，real-time dynamic CT scans during drug-induced sleep state could getmore information about anatomy changes of upper airway, providing relativelyobjective morphological basis for diagnosis and treatment of patients with OSAHS.