Relationship on walk test and pulmonary function tests with the length of hospitalization in cardiac surgery patients

The lung function is identified as a predictor of time of hospitalization in heart surgery. Meanwhile sixminute walk test has been used to establish functional capacity of cardiac patients, however there are few studies that correlate it with the length of hospital stay. The aim of this research was to determine whether there is correlation of preoperative and postoperative lung function and the ability of walking during the hospital stay.

A prospective cohort with 18 patients was performed, being 8 males and 10 females, with age above 40 years (medium 64.89 +/- 6.95 years). Patients where admitted for coronary artery bypass graft surgery and/or exchange valve. To characterize the pulmonary function, patients were submitted to spirometry in preoperative and the 5th postoperative day. In the latter period was also a test for 6 minutes walk (6MWT) to characterize the ability to walk.

There was not significant correlation of preoperative and postoperative pulmonary function with length of hospital stay. Only the distance covered in 6MWT showed a significant negative correlation (rho= 0.62) with length of stay. The distance in 6MWT obtained a significant positive correlation with forced vital capacity (r=0.59) and first second of a maximal forced expiratory manoeuvre (r=0.52).

These results suggest that patients with increased postoperative capacity to walk have a shorter time of hospitalization and it also suggest that the distance in the 6MWT can better represent the functional capacity of these patients than pulmonary function alone.