Peak Oxygen Consumption and the Minute Ventilation/Carbon Dioxide Production Relation Slope in Morbidly Obese Men and Women: Influence of Subject Effort and Body Mass Index

The authors evaluated the minute ventilation/carbon dioxide production relation (V E /VCO 2 slope) as a complementary measure to peak oxygen consumption (peak VO 2 ) in 76 patients (mean ± SD age = 44.3±10.8 years, 69.7% female) with morbid obesity (mean ± SD body mass index BMI = 49.4±7.0 kg/m 2 ), as it is not limited by effort. Nearly one‐half (43%) of the patients achieved a peak respiratory exchange ratio <1.10. Mean peak VO 2 and V E /VCO 2 slope were 17.0±3.7 mL/kg/min and 27.8±4.0, respectively. Peak VO 2 correlated with BMI ( r =−0.45, P <.0001), while V E /VCO 2 slope did not ( r =−0.04, P =.73). There was a linear trend for declining mean peak VO 2 (P =.001) but not for V E /VCO 2 slope ( P =.59) with increasing BMI quintiles. The V E /VCO 2 slope is an effort‐independent measure that is also independent of BMI and may serve as an adjunctive cardiorespiratory variable when evaluating morbidly obese men and women.