Background: Functional outcomes and health-related quality of life are important measures for survivors of a critical illness. Studies have demonstrated debilitating physical effects for a significant proportion of surviving patients, particularly those with intensive care unit-acquired weakness. Contemporary practice changes include a focus on the continuum of critical illness, with less sedation and more physical activity including mobility while in ICU, and post-ICU and post-hospitalisation activ- ities to support optimal recovery. How to best assess the physical function of patients at different phases of their recovery and rehabilitation is therefore important. Purpose: This narrative review paper examined observational and functional assess- ment instruments used for assessing patients across the in-ICU, post-ICU and post-hospital continuum of critical illness.

Methods: Relevant papers were identified from a search of bibliographic databases and a review of the reference list of selected articles. The clinimetric properties of physical function and HRQOL measures and their relevance and utility in ICU were reported in narrative format.

Findings: The review highlighted many different instruments used to measure func- tion in survivors of ICU including muscle strength testing, functional tests and walk tests, and patient centred outcomes such as health related quality of life. In general, the sensitivity and validity of these instruments for use with survivors of a critical illness has not yet been established.