Q: What is the 20-30-40 rule in myasthenic crisis? 


 Answer: The 20-30-40 rule is the most helpful and reliable indicator to decide when intubation is necessary in Myasthenia Crisis. 

•  vital capacity less than 20ml/kg; 
•  peak inspiratory pressure less than −30 cm H2O 
•  peak expiratory pressure less than 40 cm H20