Peripheral muscle strength and correlates of muscle weakness in patients receiving mechanical ventilation.

BACKGROUND: Intensive care unit-acquired weakness is a frequent complication of critical illness because of patients' immobility and prolonged use of mechanical ventilation.
OBJECTIVES: To describe daily measurements of peripheral muscle strength in patients receiving mechanical ventilation and explore relationships among factors that influence intensive care unit-acquired weakness.
METHODS: Peripheral muscle strength of 120 critically ill patients receiving mechanical ventilation was measured daily by using a standardized handgrip dynamometry protocol. Three grip measurements for each hand were recorded in pounds-force; the mean of these 3 assessments was used in the analysis. Correlates of intensive care unit-acquired weakness (age, sex, illness severity, duration of mechanical ventilation, medications) were analyzed by using mixed models to explore the relationship to grip strength.
RESULTS: Median baseline grip strength was variable yet diminished (7.7 pounds-force), with either a pattern of diminishing grip strength or maintenance of the baseline low grip strength over time. With controls for days of measurement, female sex (β = -10.4; P < .001), age (β = -0.24; P = .004), and days receiving mechanical ventilation (β = -0.34; P = .005) explained a significant amount of variance in grip strength over time.
CONCLUSIONS: Patients receiving prolonged mechanical ventilation had marked decrements in grip strength, measured by hand dynamometry, a marker for peripheral muscle strength. Hand dynamometry is a reliable method for measuring muscle strength in cooperative critically ill patients and can be used to develop interventions to prevent intensive care unit-acquired weakness. ©2015 American Association of Critical-Care Nurses.