Use of actigraphy to characterize inactivity and activity in patients in a medical ICU.

BACKGROUND

In the intensive care unit (ICU), inactivity is common, contributing to ICU-acquired weakness and poor outcomes. Actigraphy may be useful for measuring activity in the ICU.

OBJECTIVES

To use actigraphy to characterize inactivity and activity in critically ill patients.

METHODS

This prospective observational study involved 48-h wrist actigraphy in medical ICU (MICU) patients, with activity data captured across 30-s epochs. Inactivity (zero-activity epochs) and activity (levels of non-zero activity) were summarized across key patient (e.g., age) and clinical (e.g., mechanical ventilation status) variables, and compared using multivariable regression.

RESULTS

Overall, 189,595 30-s epochs were collected in 34 MICU patients. Zero-activity (inactivity) comprised 122,865 (65%) of epochs; these epochs were 24% and 13% more prevalent, respectively, in patients receiving mechanical ventilation (versus none, p < 0.001) and in the highest (versus lowest) organ failure score tertile (p = 0.03). Ambulatory (versus non-ambulatory) patients exhibited more non-zero activity (35 more movements per epoch, p < 0.001), while those in the highest (versus lowest) organ failure score tertile exhibited less activity (22 fewer movements per epoch, p = 0.03). Significant inactivity/activity differences were not observed when evaluated based on age, sedation, or restraint status.

CONCLUSIONS

Actigraphy demonstrated that MICU patients are profoundly inactive, including those who are young, non-sedated and non-restrained. Hence, ICU-specific, non-patient-related factors may contribute to inactivity, an issue requiring further investigation.