The role of non-invasive ventilation and factors predicting extubation outcome in myasthenic crisis.
BACKGROUND
Myasthenic crisis is a great threat to patients with myasthenia gravis. Usage of non-invasive ventilation (NIV) to prevent intubation and timing of extubating of patients in myasthenic crisis are important issues though not well documented.


METHODS
To explore the factors predicting NIV success and extubation outcome in myasthenic crisis, we reviewed the records of 41 episodes of myasthenia crisis.


RESULTS
NIV was applied to 14 episodes of myasthenic crisis and eight (57.1%) of them were successfully prevented from intubation. An Acute Physiology and Chronic Health Evaluation (APACHE) II score of <6 and a serum bicarbonate level of <30 mmol/l were independent predictors of NIV success. For patients undergoing invasive mechanical ventilation, extubation failure was observed in 13 (39.4%) of 33 episodes, and the most common cause was sputum impaction due to a poor cough strength (61.5%). A maximal expiratory pressure (Pemax) of > or = 40 cmH(2)O was a good predictor of extubation success. Extubation failure led to poorer outcomes.


CONCLUSIONS
NIV may be applied to those patients with a low APACHE II score and a lesser degree of metabolic compensation for respiratory acidosis. For patients undergoing invasive mechanical ventilation, extubation failure is associated with significant in-hospital morbidity in myasthenic crisis. Adequate levels of Pemax and cough strength correlate significantly with extubation success.
Wu
Jenn-Yu
JY
Department of Internal Medicine, National Taiwan University Hospital Yun-Lin Branch, Yun-Lin, Taiwan.
Kuo
Ping-Hung
PH
Fan
Pi-Chuan
PC
Wu
Huey-Dong
HD
Shih
Fuh-Yuan
FY
Yang
Pan-Chyr
PC
D000368:Aged; D015331:Cohort Studies; D003422:Critical Care; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000150:complications* / Q000628:therapy; D011237:Predictive Value of Tests; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000209:etiology / Q000628:therapy*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome