Van Iterson Erik H, Wheatley Courtney M, Baker Sarah E, Olson Thomas P, Morgan Wayne J, Snyder Eric M
Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America.
College of Pharmacy, University of Arizona, 1295 N Martin Ave, Tucson, AZ, United States of America.
PLoS One. 2016 Dec 20;11(12):e0168490. doi: 10.1371/journal.pone.0168490. eCollection 2016.
Cystic fibrosis (CF) is commonly recognized as a pulmonary disease associated with reduced airway function. Another primary symptom of CF is low exercise capacity where ventilation and gas-exchange are exacerbated. However, an independent link between pathophysiology of the pulmonary system and abnormal ventilatory and gas-exchange responses during cardiopulmonary exercise testing (CPET) has not been established in CF. Complicating this understanding, accumulating evidence suggests CF demonstrate abnormal peripheral vascular function; although, the clinical implications are unclear. We hypothesized that compared to controls, relative to total work performed (WorkTOT), CF would demonstrate increased ventilation accompanied by augmented systolic blood pressure (SBP) during CPET.
16 CF and 23 controls (age: 23±4 vs. 27±4 years, P = 0.11; FEV1%predicted: 73±14 vs. 96±5, P<0.01) participated in CPET. Breath-by-breath oxygen uptake ([Formula: see text]), ventilation ([Formula: see text]), and carbon dioxide output ([Formula: see text]) were measured continuously during incremental 3-min stage step-wise cycle ergometry CPET. SBP was measured via manual sphygmomanometry. Linear regression was used to calculate [Formula: see text] slope from rest to peak-exercise.
Compared to controls, CF performed less WorkTOT during CPET (90±19 vs. 43±14 kJ, respectively, P<0.01). With WorkTOT as a covariate, peak [Formula: see text] (62±8 vs. 90±4 L/min, P = 0.76), [Formula: see text] (1.8±0.3 vs. 2.7±0.1 L/min, P = 0.40), and SBP (144±13 vs. 152±6 mmHg, P = 0.88) were similar between CF and controls, respectively; whereas CF demonstrated increased [Formula: see text] slope (38±4 vs. 28±2, P = 0.02) but lower peak [Formula: see text] versus controls (22±5 vs. 33±4 mL/kg/min, P<0.01). There were modest-to-moderate correlations between peak SBP with [Formula: see text] (r = 0.30), [Formula: see text] (r = 0.70), and [Formula: see text] (r = 0.62) in CF.
These data suggest that relative to WorkTOT, young adults with mild-to-moderate severity CF demonstrate augmented [Formula: see text] slope accompanied by increased SBP during CPET. Although the underlying mechanisms remain unclear, the coupling of ventilatory inefficiency with increased blood pressure suggest important contributions from peripheral pathophysiology to low exercise capacity in CF.
囊性纤维化（CF）通常被认为是一种与气道功能下降相关的肺部疾病。CF的另一个主要症状是运动能力低下，运动时通气和气体交换会加剧。然而，CF患者的肺系统病理生理学与心肺运动试验（CPET）期间异常的通气和气体交换反应之间尚未建立独立的联系。使这种理解更加复杂的是，越来越多的证据表明CF患者存在外周血管功能异常；尽管其临床意义尚不清楚。我们假设，与对照组相比，相对于总做功量（WorkTOT），CF患者在CPET期间会表现出通气增加，同时收缩压（SBP）升高。
16例CF患者和23名对照组（年龄：23±4岁对27±4岁，P = 0.11；预计第一秒用力呼气容积（FEV1%predicted）：73±14对96±5，P<0.01）参与了CPET。在递增的3分钟阶段逐步进行的踏车运动CPET期间，连续测量逐次呼吸的摄氧量（[公式：见正文]）、通气量（[公式：见正文]）和二氧化碳排出量（[公式：见正文]）。通过手动血压计测量SBP。使用线性回归计算从静息到运动峰值的[公式：见正文]斜率。
与对照组相比，CF患者在CPET期间的WorkTOT较少（分别为90±19与43±14 kJ，P<0.01）。以WorkTOT作为协变量，CF患者和对照组的运动峰值[公式：见正文]（62±8与90±4 L/min，P = 0.76）、[公式：见正文]（1.8±0.3与2.7±0.1 L/min，P = 0.40）和SBP（144±13与152±6 mmHg，P = 0.88）相似；而CF患者的[公式：见正文]斜率增加（38±4与28±2，P = 0.02），但运动峰值[公式：见正文]低于对照组（22±5与33±4 mL/kg/min, P<0.01）。在CF患者中，运动峰值SBP与[公式：见正文]（r = 0.30）、[公式：见正文]（r = 0.70）和[公式：见正文]（r = 0.62）之间存在中度至高度相关性。
这些数据表明，相对于WorkTOT，轻度至中度严重程度的CF年轻成年人在CPET期间表现出[公式：见正文]斜率增加，同时SBP升高。尽管潜在机制尚不清楚，但通气效率低下与血压升高的关联表明外周病理生理学对CF患者运动能力低下有重要影响。
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