Respiratory · Year 1 · from Respiratory

Case 3: Neuromuscular Respiratory Failure - Guillain-Barre Syndrome

Clinical Image

Source: Clinical illustration of respiratory muscle function testing - Educational use

Patient Presentation

A 45-year-old man presents with progressive weakness that began in his legs 5 days ago and has now spread to involve his arms. He had a diarrheal illness 2 weeks ago that resolved. Over the past 24 hours, he has noticed increasing difficulty breathing, especially when lying flat. His voice sounds weak and he has difficulty coughing.

Demographics

  • Age: 45 years
  • Sex: Male
  • Past Medical History: None significant
  • Medications: None
  • Social History: No smoking, social alcohol
  • Recent history: Acute diarrheal illness 2 weeks ago (likely Campylobacter)

Chief Complaint

Progressive ascending weakness and difficulty breathing

Physical Examination

  • Blood pressure: 168/95 mmHg (autonomic instability)
  • Heart rate: 52-110 bpm (labile)
  • Respiratory rate: 24/min
  • Oxygen saturation: 94% on room air
  • General: Anxious, speaking in shorter sentences than normal
  • Neurological:
  • Power: 2/5 bilateral hip flexion, 3/5 knee extension, 3/5 shoulder abduction, 4/5 grip
  • Reflexes: Areflexia throughout
  • Sensation: Mildly diminished distally
  • Facial weakness present bilaterally
  • Respiratory: Shallow breathing, weak cough, paradoxical abdominal breathing when supine
  • Bulbar: Weak voice, mild dysarthria, intact gag reflex

Workup

  • Bedside respiratory monitoring:
  • Negative inspiratory force (NIF): -28 cmH2O (normal > -60)
  • Forced vital capacity (FVC): 1.8 L (42% predicted) - repeated q4h
  • FVC in 6 hours: 1.4 L (declining)
  • ABG: pH 7.44, PaCO2 32 mmHg, PaO2 72 mmHg (compensatory hyperventilation)
  • Lumbar puncture: Protein 185 mg/dL, WBC 3 cells/μL (albuminocytologic dissociation)
  • Nerve conduction studies: Prolonged distal latencies, conduction block, features of acute inflammatory demyelinating polyneuropathy (AIDP)

Diagnosis

Guillain-Barre Syndrome (AIDP variant) with Impending Respiratory Failure

Treatment

  1. ICU admission for respiratory monitoring
  2. Serial FVC and NIF measurements every 4-6 hours
  3. Elective intubation indicated for:
  • FVC <20 mL/kg or <1 L
  • NIF weaker than -30 cmH2O
  • Rapid decline in FVC (>30% decline)
  • Bulbar dysfunction with aspiration risk
  1. Immunotherapy:
  • IVIG 0.4 g/kg/day x 5 days OR
  • Plasmapheresis x 5 sessions
  1. DVT prophylaxis
  2. Autonomic monitoring (BP, HR fluctuations)
  3. Pain management (neuropathic pain common)
  4. Early physical/occupational therapy
  5. Avoid succinylcholine if intubation needed (hyperkalemia risk)

Physiological Principles Demonstrated

  • "20-30-40 rule" for intubation in neuromuscular disease: Intubate if FVC <20 mL/kg, NIF < -30 cmH2O, or FVC decline >30% from baseline.
  • Early intubation rationale: Waiting for hypercapnia is dangerous - by the time CO2 rises, respiratory muscles are exhausted and emergent intubation carries higher risk. The patient compensates by increasing rate until sudden decompensation.
  • Paradoxical breathing: In neuromuscular weakness, the weak diaphragm is pulled upward by negative pleural pressure during inspiration, causing the abdomen to move inward (opposite of normal).
  • Albuminocytologic dissociation: Elevated CSF protein with normal cell count is classic for GBS, reflecting inflammation at the nerve root level with protein leakage into CSF.

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