Ventilatory drive and carbon dioxide response in ventilatory failure due to myasthenia gravis and Guillain-Barré syndrome

Crit Care Med. 1993 Nov;21(11):1717-26. doi: 10.1097/00003246-199311000-00022.


Objective: To test the hypothesis that either decreased ventilatory drive or decreased CO2 responsiveness accounts for the hypoventilation observed in patients during acute ventilatory failure from myasthenia gravis or Guillain-Barré syndrome.

Design: Prospective, consecutive case series evaluating trials of ventilatory muscle performance, ventilatory drive, and CO2 response in patients during recovery from ventilatory failure until they were weaned from mechanical ventilation.

Setting: Neurosciences critical care unit in a university hospital.

Patients: Seven intubated, mechanically ventilated patients with myasthenia gravis or Guillain-Barré syndrome.

Interventions: Patients repeatedly performed mechanically unsupported, spontaneous breathing trials to the limits of endurance. After spontaneous breathing trials, patients underwent CO2 rebreathing studies.

Measurements and main results: Seventy-three breathing trials were performed in three patients with Guillain-Barré syndrome and four patients with myasthenia gravis. Patients were unable to sustain spontaneous ventilation in 55 trials averaging 27 +/- 5 mins. In these trials, significant increases occurred in mean end-tidal CO2 (41 +/- 1 to 44 +/- 1 torr [5.6 +/- 0.1 to 6.0 +/- 0.1 kPa]) and respiratory rate (31 +/- 1 to 35 +/- 1 breaths/min, p < .01). Ventilatory drive (as measured by airway occlusion pressure for 100 msecs) increased significantly p < .01 from 3.7 +/- 0.3 to 4.9 +/- 0.3 cm H2O. The response of airway occlusion pressure to CO2 rebreathing after these trials was 0.33 +/- 0.07 cm H2O/sec/mm Hg, while the minute ventilation response to CO2 rebreathing was only 0.30 +/- 0.06 L/min/mm Hg.

Conclusions: These results suggest that ventilatory drive increases during acute hypoventilation, and the ventilatory drive response to CO2 remains intact, even when the minute ventilation response to CO2 is poor. Therefore, a decrease in ventilatory drive or CO2 response is unlikely to account for hypoventilation during ventilatory failure in patients with myasthenia gravis or Guillain-Barré syndrome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Aged
  • Carbon Dioxide* / physiology*
  • Female
  • Humans
  • Hypoventilation / etiology
  • Hypoventilation / physiopathology
  • Linear Models
  • Male
  • Middle Aged
  • Myasthenia Gravis / complications
  • Myasthenia Gravis / epidemiology
  • Myasthenia Gravis / physiopathology*
  • Polyradiculoneuropathy / epidemiology
  • Polyradiculoneuropathy / etiology
  • Polyradiculoneuropathy / physiopathology*
  • Proportional Hazards Models
  • Respiration / physiology
  • Respiratory Function Tests / statistics & numerical data
  • Respiratory Insufficiency / epidemiology
  • Respiratory Insufficiency / etiology
  • Respiratory Insufficiency / physiopathology*
  • Respiratory Mechanics*
  • Respiratory Muscles / physiopathology


  • Carbon Dioxide