A prospective multicenter study of ICU acquired paralysis

Objectives

Although the incidence of electrophysiological and muscle histological abnormalities in ICU patients has been largely described, the clinical incidence of ICU acquired paralysis (ICUAP) remains poorly explored. The objective of this study was to assess clinical incidence, risk factors and outcome of ICUAP.

Method

All consecutive patients without pre-existent neuromuscular disease were daily screened for awakeness in the 5 participating ICUs after 7 days of mechanical ventilation (MV). The first day patient was considered awake (based on a specific awakeness scale) was Day 1. Patients with a neuromuscular score (NMS) < 48 (on a scale ranging from 0, totally paralyzed to 60, normal muscle strength) on Day 7 were considered as having ICUAP. These patients underwent an electrophysiologic (EP) examination within the next 72 hours. Patients with persistent paralysis (NMS < 48) on Day 14 underwent a muscle biopsy. Potential risk factors (including demographic, metabolic, drug-related and organ failure-related variables) were recorded between ICU admission and Day 1. Odd ratios (OR) with 95% CI were separately computed for each potential risk factor. Then, significant factors were simultaneously included in a multivariate logistic regression model (BMDP software).

Results

Among the 95 patients who satisfactorily woke up, the incidence rate of ICUAP was 25.3% (95% CI 16.9–35.2). EP examination showed a sensory-motor axonopathy in all cases. A specific muscle involvement, not exclusively related to the nerve involvement, was observed in all the patients who underwent a muscle biopsy. The median duration of ICUAP was 21 days. ICUAP patients had a significantly longer duration of MV after Day 1 (18.2 ± 36.3 vs 7.6 ± 19.2 days, P = 0.03) and longer ICU length of stay after Day 1 (27.6 ± 31.4 vs 14.6 ± 19.6 days, P = 0.02), compared to patients without ICUAP. Two patients remained paralyzed after 6 months. In multivariate logistic regression, the number of days with organ failure ≥ 2 (OR 1.28 [1.11–1.49]), duration of MV (OR 1.10 [1.00–1.22]), administration of corticosteroids (OR 14.90 [3.20–69.8]) prior to day 1, and female sex (OR 4.66 [1.19–18.3]) were independent predictors of ICUAP.

Conclusion

Clinically detected ICUAP was a frequent finding among patients mechanically ventilated ≥ 7 days and was associated with a prolonged duration of MV and ICU length of stay. Both the peripheral nerve and the muscle were involved in the paralysis. Some risk factors might be accessible to preventive measures.

Supported by GlaxoWellcome.