When should intubation be considered in patients with Guillain Barre syndrome (GBS)?

When to Intubate Patients with Guillain-Barré Syndrome

Intubate GBS patients when forced vital capacity (FVC) falls below 20 mL/kg, maximum inspiratory pressure is less than 30 cmH₂O, maximum expiratory pressure is less than 40 cmH₂O, or when the single breath count is ≤15-19. 1, 2, 3

Objective Respiratory Criteria: The "20/30/40 Rule"

The most reliable indicators for intubation are objective pulmonary function measurements, not clinical appearance or blood gases 1, 2:

• FVC < 20 mL/kg - strongly associated with need for mechanical ventilation 1, 4
• Maximum inspiratory pressure < 30 cmH₂O - indicates inadequate inspiratory muscle strength 1, 4
• Maximum expiratory pressure < 40 cmH₂O - suggests inability to clear secretions effectively 1, 4
• >30% decline in any of these parameters from baseline also predicts respiratory failure 4

Bedside Clinical Assessment

The single breath count test is the most ominous bedside physical sign for imminent respiratory failure 2, 3:

• Have the patient take a deep breath and count at 2 numbers per second
• Count ≤15-19 predicts need for mechanical ventilation and should trigger immediate ICU admission 2, 3, 5
• Each counted number correlates with approximately 116 mL of vital capacity 1, 3

High-Risk Clinical Features Requiring Close Monitoring

Certain clinical features dramatically increase the likelihood of requiring intubation 1, 2, 4:

• Bulbar dysfunction (dysphagia, dysarthria) - present in 81.8% of intubated patients 5
• Bilateral facial weakness - present in 78% of intubated patients 4, 5
• Rapid disease progression (≤3 days from onset to admission) 1, 4
• Severe weakness at presentation (inability to lift arms from bed) 1, 5
• Autonomic dysfunction - present in 56.8% of intubated patients 4, 5

Prognostic Risk Stratification

Use the Erasmus GBS Respiratory Insufficiency Score (EGRIS) to calculate the probability (1-90%) that a patient will require ventilation within 1 week 1, 2. The score incorporates:

• Days from weakness onset to admission (≤3 days = 2 points; 4-7 days = 1 point) 1
• Presence of facial/bulbar weakness (1 point if present) 1
• MRC sum score at admission (lower scores = higher points, maximum 4 points) 1

Critical Monitoring Pitfalls to Avoid

Do not rely on pulse oximetry or arterial blood gases as early indicators of respiratory failure 1, 2, 3. These parameters remain normal until late-stage respiratory failure because gas diffusion is unimpaired in neuromuscular disorders 1. Hypoxia and hypercapnia develop only after significant respiratory muscle weakness has occurred 1.

Do not wait for the patient to appear dyspneic - patients with GBS may not exhibit obvious respiratory distress despite severe respiratory muscle weakness 2.

Monitoring Frequency and ICU Admission

• Serial respiratory function testing every 2-4 hours is essential in patients with risk factors 2, 3
• Immediate ICU admission is indicated for 2:
  • Evolving respiratory distress with imminent respiratory insufficiency
  • Severe autonomic cardiovascular dysfunction
  • Severe swallowing dysfunction or diminished cough reflex
  • Rapid progression of weakness

Timing and Approach to Intubation

Perform elective intubation before emergency intubation becomes necessary 4, 6. The median time from hospitalization to intubation is 4 days 5, but deterioration can be rapid 1.

• Consider early tracheostomy in patients unable to lift arms from bed at 1 week after intubation, or those with axonal subtypes on nerve conduction studies, as these predict prolonged mechanical ventilation 1
• Average duration of mechanical ventilation is 37-50 days 7, 6
• Use neuromuscular blocking agents with sedative-hypnotic agents during intubation for improved first-pass success 1

Additional Respiratory Monitoring Tools

While the 20/30/40 rule and single breath count are primary, additional monitoring may include 1:

• Sniff nasal inspiratory pressure - values > -70 cmH₂O (males) or > -60 cmH₂O (females) suggest absence of significant weakness 1
• End-tidal CO₂ monitoring - rising pCO₂ strongly predicts need for ventilation 1
• Assessment for use of accessory respiratory muscles 2

Epidemiology

Up to 20-30% of GBS patients develop respiratory failure requiring mechanical ventilation, with 22% requiring it within the first week of admission 2, 3, 4. Mortality from respiratory complications occurs in 3-10% of cases 1.