Physiological Characteristics of Surgical Patients With Obesity in Response to the 6-Min Walk Test

Abstract

Background: Overall health and fitness contribute to surgical experience and recovery. The aim of this study was to describe an array of physiological characteristics in a presurgical patient cohort with obesity as a function of their sustained walking speed. Methods: We performed a prospective single-center cohort study in Wollongong Hospital, Australia from 2016 to 2018. Patients (N = 293) with severe obesity completed a 6-min walk test and were classified as either slow or fast walkers according to the cut point of 0.9 m·s−1 (2 mph). These groups were compared for anthropometry, comorbidities, respiratory and cardiovascular physiology, blood biomarkers, patient-centered outcomes, and perception of effort. Results: Slow walkers (n = 115; age 65 [63 to 67] years; mean [95% confidence interval]) and fast walkers (n = 178; age 54 [52 to 56]; P < 0.05) were not different in body weight but were different for body mass index (slow 43.2 [42.0 to 44.4] versus fast 41.1 [40.5 to 41.8]; P < 0.05). Cardiovascular disease and renal disease were more prevalent in slow walkers. Respiratory physiology reflective of restrictive lung disease (force vial capacity [L] slow 2.61 [2.45 to 2.77] versus fast 3.34 [3.19 to 3.47]; P < 0.05) was more common in slow walkers, who also reported higher dyspnea ratings. Resting cardiovascular characteristics were not different, although N-terminal pro-B-type natriuretic peptide levels were higher in the slow group (P < 0.05). Quality of recovery at postoperative day 30 was higher in the fast walking group. Conclusion: In this Australian cohort, patients with obesity undergoing nonbariatric surgery differed in their physiological profiles according to walking speed. This study supports the need to appreciate the physical fitness of patients beyond simplified body weight and classification of obesity in the perioperative period.