Cardiopulmonary exercise testing among pediatric patients with severe obesity prior to bariatric surgery

Background: Cardiopulmonary exercise testing (CPET) is used prior to bariatric surgery in children with severe obesity to assess surgical risk factors. Lack of data for peak oxygen consumption (pVO2) for this population limits CPET interpretation and establishing surgical risk. Objectives: We aimed to use lean tissue mass (LM) to better define pVO2 and developed predictive equations for use in this cohort. Methods: Participants with obesity age 9-20 years underwent CPET, using Bruce treadmill protocol, prior to bariatric surgery from January 1, 2006, to December 31, 2019. Bioelectrical impedance analysis (BIA) helped calculate LM from total body weight (TBW). Achieving peak heart rate >= 90 % predicted, RER of >= 1.1, and patient volition were considered satisfactory effort. Results: Of tests performed by 446 participants, CPET studies (29 %) met inclusion criteria as peak exercise. For this group, body mass index was 45.2 +/- 6.1 kg/m2, body fat % 49.7 +/- 6.8, and LM 63 +/- 10 kg. Mean pVO2 was 22.2 +/- 3.2 mL/kg/min, which was 51 % +/- 7 % predicted when using conventional prediction methods. Mean pVO2 using LM was 44.8 +/- 8.7 mL/kg/min, which was 102.3 +/- 17.6 % predicted. Linear regression yielded reference equations pVO2 = 1571.6 + 12.2 * TBW (males) and pVO2 = 1301.8 + 10.6 * TBW (females). Conclusion: This report is the largest dataset of pVO2 in the pediatric population with severe obesity. Adolescents with severe obesity had normal pVO2 when LM was applied rather than TBW. Given BIA or other methods of calculating LM are not readily available to all labs, a novel set of predictive pVO2 equations using TBW was developed for labs to integrate into their CPET interpretations when evaluating youth with severe obesity prior to surgery.