Abstract
BACKGROUNDPoor sleep is associated with worse motor function in older adults. Sleep may affect motor function specifically among older adults recovering from critical illness after transfer out of an intensive care unit (ICU).
OBJECTIVESDescribe motor function (grip strength) of older ICU survivors and explore relationships between sleep and ICU-acquired weakness in the early post-ICU transition period.
METHODSWe enrolled 30 older adults who were functionally independent prior to hospitalization, mechanically ventilated while in ICU, and within 24–48 hours post-ICU discharge. Handgrip dynamometry assessed post-ICU motor function (fully corrected T score on the National Institutes of Health Motor Battery Grip Strength Test). Actigraphy estimated post-ICU sleep duration (total sleep time [TST]) and fragmentation (wake after sleep onset) over two consecutive nights from 22:00 p.m. to 06:00 a.m.. We identified differences in grip strength by history of obstructive sleep apnea (OSA) using independent-samples t tests. We examined associations between sleep duration and grip strength using exploratory multivariate regression analyses, after adjustment for clinically relevant covariates.
RESULTSGrip strength among this cohort of older ICU survivors was almost 2 SDs below the norm for healthy older adults, indicating considerable ICU-acquired weakness. Grip strength was lower among subjects with history of OSA than those without OSA. Greater TST was associated with worse grip strength, after adjusting for history of OSA and Pittsburgh Sleep Quality Index global score. Moreover, among the subset of male subjects (n = 19), greater TST was significantly and negatively associated with grip strength, after adjusting for Acute Physiology, Age, and Chronic Health Evaluation III score, and Pittsburgh Sleep Quality Index global score.
DISCUSSIONSleep promotion may be a potentially modifiable risk factor to mitigate ICU-acquired weakness in older ICU survivors. We propose that improving sleep throughout recovery from critical illness may indirectly promote better outcomes, as poor grip strength is linked to longer length of hospital stay, higher acuity of discharge disposition, and worsened functional decline in older adults.
