拔管困难除了结构因素之外,不少病人完全由功能因素所致。适当肺泡通气需要随膈肌下降,声带同步外展。据认为,声带外展期相系由脑干呼吸中枢通过喉返神经控制的。实验资料表明:在施行过气管切开术后的病人,通气阻力减少,致使声带外展期相消失。因此,突然拔管可由于声带暂时不能外展,发生严重喘鸣、胸骨凹陷和恐慌。通过逐渐增加通气阻力,声带外展期相可随吸气得以重新 Extubation difficulties In addition to structural factors, many patients are entirely due to functional factors. Appropriate alveolar ventilation with the diaphragmatic decline, simultaneous outreach vocal cords. It is believed that the vocal cord outreach phase is controlled by the recurrent laryngeal nerve from the brainstem respiratory center. Experimental data show that: after the implementation of tracheotomy patients, ventilation resistance decreased, resulting in disappearance of vocal cord outreach phase. Therefore, sudden extubation can temporarily outreach due to vocal cords, severe wheezing, sternum depression and panic. By gradually increasing ventilation resistance, the vocal cord phase can be renewed with inspiration