Weakness in the ICU: GBS & MG

• Myasthenic crisis: intubate when FVC falls below 15–20 mL/kg (or by 30%), NIF is weaker than −20 to −30 cm H₂O, or bulbar weakness threatens the airway; treat with IVIG or PLEX; on the ventilator hold pyridostigmine; steer clear of crisis drugs (aminoglycosides, Mg, β-blockers).
• GBS: PLEX ×5 and IVIG 2 g/kg work equally; track FVC/NIF (20/30/40 rule) — autonomic swings kill.
• Botulism: early antitoxin plus supportive ventilation; descending paralysis with pupils.
• ICU-acquired weakness: cut steroids/NMB/sedation; mobilize early.
• Steroids are NOT recommended in GBS (2023 EAN/PNS).

Guillain–Barré syndrome

First tests: Serial respiratory muscle assessment, 12-lead ECG.

Only if indicated: Lumbar puncture and CSF studies, Nerve conduction studies / EMG, MRI spine.

Repeat monitoring: Serial respiratory muscle assessment, BP and cardiac rhythm monitoring.

Myasthenic crisis

First tests: Serial respiratory and bulbar assessment, Sodium, potassium, bicarbonate, urea and creatinine.

Only if indicated: Chest X-ray, Respiratory culture, AChR / MuSK antibodies and neurophysiology, Arterial blood gas.

Repeat monitoring: Serial respiratory and bulbar assessment.

• Management of Neuromuscular Respiratory Failure