Background: Acute myopathy following mechanical
ventilation for near-fatal asthma (NFA) has been described recently,
and some researchers have suggested that this complication is related
to the use of neuromuscular blocking agents (NMBAs) and corticosteroids
Objectives: To determine the incidence
of acute myopathy in a group of patients and to examine the most
important predictors of its development.
methods: A retrospective cohort study over a 10-year period (1985
to 1995) of all asthma patients who received mechanical ventilation at
two centers in Vancouver (designated center 1 and center 2).
Results: In center 1, there were 58 patients who had 64
episodes of NFA, and in center 2, there were 28 patients who had 30
episodes. NMBAs were used in 30 of 86 admissions for acute severe
asthma (35%). The mean (± SD) duration of muscle paralysis was
3.1 ± 2.3 days. A total of 9 patients (10.4%) developed significant
myopathy. The incidence of myopathy was 9 of 30 (30%) among patients
who received NMBAs. In a multiple logistic regression model, the
development of myopathy was only significantly associated with the
duration of muscle relaxation. The odds ratio for the development of
myopathy increased by 2.1 (95% confidence interval, 1.4 to 3.2) with
each additional day of muscle relaxation. The dose and the type of the
CS were not significantly associated with the myopathy in the multiple
logistic regression analysis.
Conclusion: Our study
showed that there is a high incidence of acute myopathy when NMBAs are
used for NFA. The incidence of myopathy increases with each additional
day of muscle relaxation.