Does ICU-acquired paresis lengthen weaning from mechanical ventilation?

Objective. To determine whether ICU-acquired paresis (ICUAP) is an independent risk factor of prolonged weaning. Design. Second study of a prospective cohort of 95 patients who were enrolled in an incidence and risk factor study of ICUAP. Setting. Three medical and two surgical ICUs in four hospitals. Patients and participants. Ninety-five patients without pre-existing neuromuscular disease recovering from the acute phase of critical illness after greater than or equal to7 days of mechanical ventilation. Interventions. None. Measurements and results. Duration of weaning from mechanical ventilation was defined as the duration of mechanical ventilation between awakening (day 1) and successful weaning. Muscle strength was evaluated at day 7 after awakening using the Medical Research Council (MRC) score. Patients with an MRC <48 were considered to have ICUAP. Among the 95 patients (mean age 62.0+/-15.3 years, SAPS 2 on admission 48.7+/-17.4) who regained satisfactory awakening after 7 or more days of mechanical ventilation, 67 (70.5%) were hospitalized in a medical ICU and 28 (29.5%) in a surgical ICU. Median duration (25th-75th percentiles) of weaning was longer in patients with ICUAP than in those without ICUAP: 6 days (1-22 days) vs 3 days (1-7 days); p=0.01; log-rank analysis. In multivariate analysis, the two independent predictors of prolonged weaning were ICUAP [hazard ratio (HR): 2.4; 95% confidence interval (CI): 1.4-4.2] and chronic obstructive pulmonary disease (HR: 2.7; 95% CI: 1.6-4.5) Conclusions. ICU-acquired paresis is an independent predictor of prolonged weaning. Prevention of ICU-acquired neuromuscular abnormalities in patients recovering from severe acute illness should result in shorter weaning duration.