Does ICU-acquired paresis lengthen weaning from mechanical ventilation?

Abstract

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 > or =7 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.