A New Test to Evaluate Functional Capacity in the Pre- and Immediate Postoperative Periods of Cardiac Surgery: Measurement Properties of the Six-Minute Cycle Ergometer Test.

BACKGROUND AND PURPOSE: The development and validation of a portable cycle ergometer test can facilitate functional capacity assessment of patients with walking difficulties and those in controlled environments. Our aim was to develop the six-minute cycle ergometer test (6MCET) and verify its validity and reliability for assessing functional capacity in the preoperative period of cardiac surgery and its ability to identify functional capacity changes in the postoperative period (PO).

METHODS

In this cross-sectional and prospective study, patients in the preoperative period of cardiac surgery underwent two 6MCET (6MCETPRE) and two six-minute walk tests (6MWT). In the PO period, two 6MCET (6MCETPOST) were performed.

RESULTS

Performance in the 6MCETPRE correlated with 6MWT performance (r = 0.68, p 0.004). A high reliability was found for performance in the 6MCETPRE and 6MCETPOST (ICC = 0.87, 95% CI: 0.71-0.96; and 0.95, 95% CI: 0.80 - 0.99; respectively; both p < 0.05). Performance on retest was higher compared with the first 6MCETPRE (mean difference = 58.8 ± 67.7 revolutions; p < 0.001) and 6MCETPOST (mean difference = 36.4 ± 55.6 revolutions; p = 0.03) with learning effects of 15% and 16%, respectively. All patients presented a reduced performance in the 6MCETPOST compared with 6MCETPRE (mean difference = 185 ± 92.6 revolutions; p < 0.001).

DISCUSSION: 6MCET is valid for assessing functional capacity in the preoperative period, reliable in the pre- and postoperative periods, and can identify a functional capacity reduction in the PO period of cardiac surgeries. Two tests are recommended due to the learning effect.