Physical activity of patients with critical illness undergoing rehabilitation in intensive care and on the acute ward: An observational cohort study.

Background: There are limited published data on physical activity of survivors of critical illness engaged in rehabilitation in hospital, despite it plausibly influencing outcome.

Objective: The aims of this study were to measure physical activity of patients with critical illness engaged in rehabilitation in the intensive care unit (ICU) and on the acute ward and report discharge destination, muscle strength, and functional outcomes.

Methods: This was a single-centre, prospective observational study. Adults with critical illness, who received ≥48 h of invasive mechanical ventilation, and who were awake and able to participate in rehabilitation were eligible. To record physical activity, participants wore BodyMedia SenseWear Armbands (BodyMedia Incorporated, USA), during daylight hours, from enrolment until hospital discharge or day 14 of ward stay (whichever occurred first). The primary outcome was time (minutes) spent performing physical activity at an intensity of greater than 1.5 Metabolic Equivalent Tasks. Secondary outcomes included discharge destination, muscle strength, and physical function.

Results: We collected 807 days of physical activity data (363 days ICU, 424 days ward) from 59 participants. Mean (standard deviation) duration of daily physical activity increased from the ICU, 17.8 (22.8) minutes, to the ward, 52.8 (51.2) minutes (mean difference [95% confidence interval] = 35 [23.8-46.1] minutes, P < .001). High levels of activity in the ICU were associated with higher levels of activity on the ward (r = .728), n = 48, P < .001.

Conclusions: Patients recovering from critical illness spend less than 5% of the day being physically active throughout hospital admission, even when receiving rehabilitation. Physical activity increased after discharge from intensive care, but had no relationship with discharge destination. Only the absence of ICU-acquired weakness on awakening was associated with discharge directly home from the acute hospital. Future studies could target early identification of ICU-acquired weakness and the preservation of muscle strength to improve discharge outcomes.