Repeatability of six-minute walk test and relation to physical function in survivors of a critical illness
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Background. The Six-Minute Walk Test (6MWT) is widely used as an outcome measure in exercise rehabilitation. However, the repeatability of the 6MWT performed at home in survivors of a critical illness has not been evaluated. Objective. The purpose of this study was to evaluate, in survivors of a critical illness: (1) the repeatability of the 6MWT performed at home, (2) the effect on estimates of change in functional exercise capacity if only one 6MWT was performed at follow-up assessments, and (3) the relationship between the physical functioning (PF) score of the 36-Item Short-Form Health Survey questionnaire (SF-36) and the 6MWT. Design. Repeated measures of the 6MWT and SF-36 were obtained. Methods. Eligible participants had an intensive care unit (ICU) length of stay of 48 hours and were mechanically ventilated for 24 hours. Two 6MWTs and the SF-36 were conducted in participants' homes at weeks 1, 8, and 26 after hospital discharge. Results. One hundred seventy-three participants completed the study. The participants had a mean age of 57 years (SD 16), a mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score on admission of 19 (SD 10), a mean ICU length of stay of 9 days (SD 8), and a mean mechanical ventilation time of 140 hours (SD 137). Of the 173 participants, 110 performed two 6MWTs at weeks 1, 8, and 26. There were significant mean increases in 6-minute walk distance in the second test of 15 m (P .0001) at week 1, 13 m (P .0001) at week 8, and 9 m (P .04) at week 26. If only one 6MWT was performed at weeks 8 and 26, the estimate of change in 6-minute walk distance from week 1 was 19 m less (P .001) at both weeks 8 and 26. There was a moderate to strong correlation between SF-36 PF score and 6-minute walk distance at each assessment (week 1: r .62, P .001; week 8: r .55, P .001; and week 26: r .47, P .001). Limitations. Some study participants were unable to perform a second 6MWT, and these participants may have differed in important aspects of function compared with those individuals who completed two 6MWTs. Conclusions. In survivors of a critical illness, the 6MWT in the home environment should be performed twice at each assessment to give an accurate reflection of change in exercise capacity over time. The SF-36 PF score was a strong indicator of 6-minute walk distance in early recovery from a critical illness.
Journal of Physical Therapy
© 2012 American Physical Therapy Association. The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Clinical Nursing: Secondary (Acute Care)