肌無力症(myasthenia gravis, MG)病人出現肌無力危象時，病人在拔除氣管内管完後再回插氣管内管的比例可高達26%。在考量肌無力危象病人的呼吸器脫離標準時，必需特別著重於MG病人的肌力不穩定性。本研究於一年内收集4例肌無力危象病人，以傳統的呼吸器脫離標準評估後拔除氣管内管，之後施以連續性、整合性肌力評估，以評估拔管前後的肌力及呼吸功能變化。全部4例使用氣管内管合併傳統呼吸器中位天數為5.5天(4至6天）。其中1例在拔管後再度病情惡化，以致必須改以雙階正壓呼吸器來維持穩定的呼吸。因此，此案例可以清楚佐證傳統拔管標準在MG病人身上的妥適性欠佳。在拔管後連續監控指標中：血中最大CO2分壓值，在白天時，拔管後有輕微上升現象，在夜眠時則顯著上升。至於MG分數、頸部肌力、最大吸氣壓(Pimax)、肺活量及白天〇2最低飽和度則都呈現直線上升，穩定進步趨勢。不過在病人呼吸衰竭時與拔管時頸部肌力差值及Pimax進步值卻是最明顯。總結，以傳統的呼吸器脫離標準來協助MG危象病人拔除氣管内管仍未臻理想，必須搭配頸部肌力、Pimax、及夜眠時C〇2監控來提供全面性的安全防護。

The reintubation rate is up to 26% of patients with myasthenia gravis (MG) in crisis after extubation. Easy fatigability and diurnal worsening of weakness were the major determinants for the weaning criteria designed for the patients with myasthenic crisis. In the past one year, we enrolled 4 patients with myasthenic crisis to be extubated objectively after passing a series of tests of a standard weaning protocol. An integrated set of clinical assessment were tested sequentially starting from the day before extubation till the fifth day after extubation on daily basis to evaluate the changes of the respiratory muscle power during the critical period of extubation. The median duration of endotracheal intubation was 5.5 days (4-6 days) in all 4 cases. One of them deteriorated again after extubation, who must be supported by Bilevel Positive Airway Pressure ventilator subsequently. Therefore, this weaning failure case clearly demonstrated the pitfall of traditional weaning methods applied for MG patients. Among the sequential parameters monitored after extubation, the maximum CO2 partial pressures increased modestly at daytime but significantly rose during night sleep. MG score, neck muscle power, maximum inspiratory pressure (Pimax), vital capacity and the minimum O2 saturations improved steadily after extubation. However, the changes in the peri-extubation period were remarkably evident in the neck muscle strength and Pimax. In conclusion, the traditional weaning criteria for myasthenic crisis were not ideal enough. Concomitantly monitoring with neck muscle power, Pimax, and CO2 monitoring during night sleep could provide more comprehensive assessment and timely assistance.