By Linda Chlan, PhD, RN, FAAN
Dean’s Distinguished Professor of Symptom Management Research,
The Ohio State University,
College of Nursing,
Columbus, OH

Dr. Chlan reports no financial relationships relevant to this field of study.

SYNOPSIS: Physical function after critical illness is influenced by clinical, physiological, and psychological factors that suggest a need for comprehensive interventions to promote recovery and quality of life.

SOURCE: Aitken LM, et al. Physical recovery in intensive care unit survivors: A cohort analysis. Am J Crit Care 2015;24:33-40.

As more and more patients survive critical illness or injury, there is increasing evidence that they leave the intensive care unit (ICU) with a number of impediments and impairments. These decrements occur in all of the quality-of-life domains: physical, functional, psychological, and emotional. Many of the decrements in these quality-of-life domains are influenced by factors that are not modifiable, such as age or illness severity. The challenge for researchers and clinicians is to identify modifiable factors that can be used to develop and test interventions to improve functioning and quality of life for patients after they leave the ICU.

The study by Aitken and colleagues aimed to identify physical factors associated with recovery from critical illness that may be modifiable. This cohort study examined a subset of patients enrolled in an Australian multi-site, randomized, controlled trial testing a home-based rehabilitation program of individualized endurance and strength training on physical function and quality of life. Participants in the parent study were recruited from 12 hospitals in three Australian cities that had ICUs stays > 48 hours and length of mechanical ventilator support > 24 hours. Patients (n = 195) were assessed at 1 week, 8 weeks, and again at 26 weeks after ICU discharge on quality of life, psychological well-being, and physical function by the 6-minute walk test. The primary outcome for the cohort sub-analysis (n = 145) reported here was whether the 6-minute walk distance improved from week 1 to the 26-week study endpoint. Participants were divided into three groups by the 6-minute walk results at week 26: those who improved, those who did not improve, and those who did not complete the walk test. Mean age was 56-59 years, with median ICU stays of 5-6 days and median hours mechanically ventilated at 72-92. Overall, 65% of participants increased their 6-minute walk distance by 40% or more. A series of logistic regression models were explored to determine independent relationships to the primary physical function outcome (6-minute walk test), including demographic and clinical variables, illness severity, quality of life, psychological well-being, sleep quality, and engagement in incidental exercise outside of the study rehabilitation protocol. Independent factors contributing to improvement in the 6-minute walk test from week 1 to week 26 were: sleep problems in the first week after ICU discharge, engagement in moderate to vigorous exercise, and higher ratings of vitality.

On the other hand, a lack of improvement in physical functioning at the 26-week assessment point was associated with a respiratory ICU admission diagnosis, higher social functioning, and greater 6-minute walk test during the first week after discharge, suggesting that participants in this cohort did not improve physically at the 26-week assessment point. The authors concluded that the meaning of these reported relationships is unclear. However, many complex factors contribute to recovery after critical illness, such as sleep quality, and interventions need to consider multiple influences to improve post-ICU physical function and quality of life.


The study by Aitken and colleagues reports on factors associated with an objective marker of post-ICU physical function, the 6-minute walk test, in a cohort of ICU survivors. Given that the aims of this study were to determine independent associations with an increase in physical function, no cause-and-effect conclusions can be drawn from the findings. The intriguing contributions of sleep quality and exercise outside of the home-based rehabilitation intervention require further investigation. The inter-relationships among sleep, vitality, exercise, and social functioning in enhancing recovery after ICU stays may be a complicated web to untangle; further investigation with additional cohorts of ICU survivors is needed.

A major limitation of this cohort study is the time lag between the two data collection points (week 1 to week 26 post-ICU discharge) considered in the analysis. There are a number of unknown factors that may have influenced the results, such as hospital readmission or cognitive impairment. Nevertheless, as more and more patients survive critical illness, comprehensive interventions are needed to promote optimal recovery to enhance quality of life.