Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas.
Arkansas Children's Research Institute, Little Rock, Arkansas.
Ann Am Thorac Soc. 2021 Jul;18(7):1167-1174. doi: 10.1513/AnnalsATS.202006-746OC.
Obesity presents a mechanical load to the thorax, which could perturb the generation of minute ventilation (V̇e) during exercise. Because the respiratory effects of obesity are not homogenous among all individuals with obesity and obesity-related effects could vary depending on the magnitude of obesity, we hypothesized that the exercise ventilatory response (slope of the V̇e and carbon dioxide elimination [V̇co] relationship) would manifest itself differently as the magnitude of obesity increases. To investigate the V̇e/V̇co slope in an obese population that spanned across a wide body mass index (BMI) range. A total of 533 patients who presented to a surgical weight loss center for pre-bariatric surgery testing performed an incremental maximal cycling test and were studied retrospectively. The V̇e/V̇co slope was calculated up to the ventilatory threshold. Patients were examined in groups based on BMI (category 1: 30-39.9 kg/m, category 2: 40-49.9 kg/m, and category 3: ≥50 kg/m). Because the respiratory effects of obesity could be sex and/or age specific, we further examined patients in groups by sex and age (younger: <50 yr and older: ≥50 yr). Differences in the V̇e/V̇co slope were then compared between BMI category, age, and sex using a three-way ANOVA. No significant BMI category by sex by age interactions was detected ( = 0.75). The V̇e/V̇co slope decreased with increases in BMI (category 1, 29.1 ± 4.0; category 2, 28.4 ± 4.1; and category 3, 27.1 ± 3.3) and was elevated in women (28.9 ± 4.1) compared with men (26.7 ± 3.2) (BMI category by sex interaction, < 0.05). No age-related differences were observed (BMI category by age interaction, = 0.55). The partial pressure for end-tidal CO was elevated at the ventilatory threshold in BMI category 3 compared with BMI categories 1 and 2 (both < 0.01). These findings suggest that obesity presents a unique challenge to augmenting ventilatory output relative to CO elimination, such that the increase in the exercise ventilatory response becomes blunted as the magnitude of obesity increases. Further studies are required to investigate the clinical consequences and the mechanisms that may explain the attenuation of exercise ventilatory response with increasing BMI in men and women with obesity.
肥胖会给胸部带来机械负荷，这可能会扰乱运动时的分钟通气量（V̇e）的产生。由于肥胖对呼吸的影响并非所有肥胖者都相同，并且肥胖相关的影响可能因肥胖程度的不同而有所不同，因此我们假设随着肥胖程度的增加，运动时的通气反应（V̇e 和二氧化碳排出量 [V̇co] 关系的斜率）会表现出不同。为了研究肥胖人群的 V̇e/V̇co 斜率，该研究纳入了一个跨越广泛体重指数（BMI）范围的肥胖人群。共有 533 名患者因拟行减重手术前来减重手术中心进行术前检查，他们进行了递增最大踏车测试，并进行了回顾性研究。V̇e/V̇co 斜率计算至通气阈值。根据 BMI 将患者分为三组（类别 1：30-39.9 kg/m，类别 2：40-49.9 kg/m，类别 3：≥50 kg/m）。由于肥胖对呼吸的影响可能具有性别和/或年龄特异性，因此我们还根据性别和年龄将患者分为两组（年轻组：<50 岁，老年组：≥50 岁）。然后使用三因素方差分析比较 BMI 类别、年龄和性别之间的 V̇e/V̇co 斜率差异。未检测到 BMI 类别与性别和年龄的显著交互作用（ = 0.75）。V̇e/V̇co 斜率随 BMI 的增加而降低（类别 1：29.1 ± 4.0；类别 2：28.4 ± 4.1；类别 3：27.1 ± 3.3），女性（28.9 ± 4.1）高于男性（26.7 ± 3.2）（BMI 类别与性别交互作用， < 0.05）。未观察到年龄相关差异（BMI 类别与年龄交互作用， = 0.55）。与 BMI 类别 1 和 2 相比，BMI 类别 3 在通气阈值时的终末潮气 CO 分压升高（均 < 0.01）。这些发现表明，肥胖对相对于 CO 清除增加通气输出提出了独特的挑战，因此，随着肥胖程度的增加，运动时通气反应的增加变得迟钝。需要进一步的研究来探讨肥胖男性和女性中 BMI 增加导致运动通气反应衰减的临床后果和可能的机制。
