在射血分数保留的心力衰竭患者中，运动期间肺泡死腔增加。
Alveolar Dead Space Is Augmented During Exercise in Patients With Heart Failure With Preserved Ejection Fraction.
机构信息
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
Department of Population and Data Sciences (Biostatistics) & Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX.
出版信息
Chest. 2022 Dec;162(6):1349-1359. doi: 10.1016/j.chest.2022.06.016. Epub 2022 Jun 23.
BACKGROUND
Patients with heart failure with preserved ejection fraction (HFpEF) exhibit many cardiopulmonary abnormalities that could result in V˙/Q˙ mismatch, manifesting as an increase in alveolar dead space (VD) during exercise. Therefore, we tested the hypothesis that VD would increase during exercise to a greater extent in patients with HFpEF compared with control participants.
RESEARCH QUESTION
Do patients with HFpEF develop VD during exercise?
STUDY DESIGN AND METHODS
Twenty-three patients with HFpEF and 12 control participants were studied. Gas exchange (ventilation [V˙], oxygen uptake [V˙o], and CO elimination [V˙co]) and arterial blood gases were analyzed at rest, twenty watts (20W), and peak exercise. Ventilatory efficiency (evaluated as the V˙/V˙co slope) also was measured from rest to 20W in patients with HFpEF. The physiologic dead space (VD) to tidal volume (VT) ratio (VD/VT) was calculated using the Enghoff modification of the Bohr equation. VD was calculated as: (VD / VT × VT) - anatomic dead space. Data were analyzed between groups (patients with HFpEF vs control participants) across conditions (rest, 20W, and peak exercise) using a two-way repeated measures analysis of variance and relationships were analyzed using Pearson correlation coefficient.
RESULTS
VD increased from rest (0.12 ± 0.07 L/breath) to 20W (0.22 ± 0.08 L/breath) in patients with HFpEF (P < .01), whereas VD did not change from rest (0.01 ± 0.06 L/breath) to 20W (0.06 ± 0.13 L/breath) in control participants (P = .19). Thereafter, VD increased from 20W to peak exercise in patients with HFpEF (0.37 ± 0.16 L/breath; P < .01 vs 20W) and control participants (0.19 ± 0.17 L/breath; P = .03 vs 20W). VD was greater in patients with HFpEF compared with control participants at rest, 20W, and peak exercise (main effect for group, P < .01). Moreover, the increase in VD correlated with the V˙/V˙co slope (r = 0.69; P < .01), which was correlated with peak V˙o (r = 0.46; P < .01) in patients with HFpEF.
INTERPRETATION
These data suggest that the increase in V˙/Q˙ mismatch may be explained by increases in VD and that increases in VD worsens ventilatory efficiency, which seems to be a key contributor to exercise intolerance in patients with HFpEF.
背景
射血分数保留的心力衰竭（HFpEF）患者表现出许多心肺异常，这可能导致 V˙/Q˙ 不匹配，在运动期间表现为肺泡死腔（VD）增加。因此，我们假设 HFpEF 患者在运动期间 VD 的增加程度大于对照组。
研究问题
HFpEF 患者在运动期间是否会出现 VD？
研究设计和方法
研究了 23 名 HFpEF 患者和 12 名对照组参与者。在休息、20 瓦（20W）和峰值运动时分析气体交换（通气[V˙]、氧气摄取[V˙o]和 CO 消除[V˙co]）和动脉血气。HFpEF 患者还从休息到 20W 测量通气效率（以 V˙/V˙co 斜率评估）。使用 Enghoff 对 Bohr 方程的修正来计算生理死腔（VD）与潮气量（VT）的比值（VD/VT）。VD 计算为：（VD / VT × VT）-解剖死腔。使用双向重复测量方差分析在组间（HFpEF 患者与对照组参与者）分析数据，在各组间分析数据（休息、20W 和峰值运动），并使用 Pearson 相关系数分析相关性。
结果
HFpEF 患者的 VD 从休息时（0.12 ± 0.07 L/breath）增加到 20W（0.22 ± 0.08 L/breath）（P<.01），而对照组参与者的 VD 从休息时（0.01 ± 0.06 L/breath）到 20W（0.06 ± 0.13 L/breath）没有变化（P=0.19）。此后，HFpEF 患者的 VD 从 20W 增加到峰值运动（0.37 ± 0.16 L/breath；P<.01 与 20W 相比），对照组参与者的 VD 也从 20W 增加到峰值运动（0.19 ± 0.17 L/breath；P=0.03 与 20W 相比）。HFpEF 患者在休息、20W 和峰值运动时的 VD 均大于对照组（组间主要效应，P<.01）。此外，VD 的增加与 V˙/V˙co 斜率相关（r=0.69；P<.01），而 V˙/V˙co 斜率与 HFpEF 患者的峰值 V˙o 相关（r=0.46；P<.01）。
解释
这些数据表明，V˙/Q˙ 不匹配的增加可能归因于 VD 的增加，而 VD 的增加会降低通气效率，这似乎是 HFpEF 患者运动不耐受的关键因素。
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