Lawn et al identified clinical and pulmonary function findings in patients with Guillain-Barre Syndrome associated with the need for mechanical ventilation. Patients with these findings may benefit from closer monitoring and/or elective intubation. The authors are from the Mayo Clinic in Rochester, Minnesota.


Clinical findings:

(1) rapid disease progression

(2) bulbar dysfunction (includes impaired gag reflex, dysarthria, and/or dysphagia)

(3) bilateral facial weakness

(4) dysautonomia (autonomic dysfunction includes unexplained dysrhythmia, blood pressure fluctuations, significant bowel involvement or bladder involvement)


"Threshold" pulmonary function findings:

(1) vital capacity < 20 mL per kg

(2) maximal inspiratory pressure < 30 cm H2O

(3) maximal expiratory pressure < 40 cm H2O



• The change in vital capacity, maximal inspiratory pressure and maximal expiratory pressure is referred to as the "20/30/40 rule".


Serial pulmonary function findings (performed 3 or more times daily to detect deterioration):

(1) reduction > 30% in vital capacity from baseline levels

(2) reduction > 30% in maximal inspiratory pressure from baseline levels

(3) reduction > 30% in maximal expiratory pressure from baseline levels


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