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 > 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.