Incidence rate and risk factors for muscle weakness in emergency ICU

Objective: We retrospectively assessed the clinical incidence and risk factors for ICU-attributable muscle weakness by surveying the medical records of patients admitted to the emergency ICU. Materials and methods: We investigated the medical records of patients who required mechanical ventilation between 2006 and 2007. Muscle weakness was determined as Medical Research Council (MRC) score of <48, manual muscle test (MMT) level of <4 evaluated by nurses in at least one extremity, or medical recordings that indicated abnormal activities. Clinical factors and laboratory data that could influence the onset of muscle weakness were collected from the medical records. Results: Out of 916 patients admitted to the ICU who required mechanical ventilation over the 2-year study period, 495 were evaluable. Among these, 82 (16.6%) had muscle weakness. The incidence of muscle weakness was 47 (34.1%) among 138 patients who required ≥7 days of mechanical ventilation. Independent predictors of muscle weakness were duration of mechanical ventilation, use of muscle relaxants, neurological disease and blood urea nitrogen (BUN). Conclusions: ICU-attributable muscle weakness was some degree of feature in critically ill patients who required mechanical ventilation. The duration of mechanical ventilation, muscle relaxants, neurological disease and BUN was associated with ICU-attributable muscle weakness.