Severe weakness complicating status asthmaticus despite minimal duration of neuromuscular paralysis

Mechanically ventilated patients with status asthmaticus who undergo prolonged paralysis are at risk for severe weakness due to myopathy. In the mid-1990s, we changed our usual method of achieving tolerance of ventilatory support in asthmatic patients from continuous paralysis to deep sedation. This study examines the impact of this change in practice on the development of clinically significant weakness in status asthmaticus.

Retrospective cohort study in university-affiliated county hospital.

Mechanically ventilated asthmatic patients seen before (n = 96) and after (n = 74) a clinical practice change in 1995 that markedly restricted use of paralytics.

The duration of neuromuscular paralysis declined sharply after 1995 (23.7 +/- 42.2 vs. 1.8 +/- 4.0 h, P < 0.001), but this was not associated with a significant difference in the incidence of weakness (21 vs. 14%, P = 0.23). Within the post-1995 cohort, there was no significant difference in the duration of paralysis for weak and non-weak patients (3.5 +/- 6.2 vs. 1.5 +/- 3.5 h, P = 0.10). However, weak patients had a much longer duration of mechanical ventilation than did patients without weakness (11.9 +/- 3.6 vs. 1.9 +/- 1.8 days, P < 0.001).

Mechanically ventilated patients with status asthmaticus who are immobilized for prolonged periods of time by deep sedation remain at risk for clinically significant weakness.