肌無力症危象病人拔除氣管內管標準之驗證性研究

Validation of the Current Extubation Criteria in the Myasthenic Crisis

肌無力症（myasthenia gravis, MG）病人出現肌無力危象時，病人在拔除氣管內管完後再回插氣管內管的比例可高達26%。在考量肌無力危象病人的呼吸哭脫離標準時，必需特別著重於MG病人的肌力不穩定性。本研究於一年內收集4例肌無力危象病人，以傳統的呼吸器脫離標雀評估後拔除氣管內管，之後施以連續性、合性股力評估，以評估拔管前後的肌力和乎吸功能變化。

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.