Pulmonary Hypertension and Vascular Biology Research Group, Quebec City, QC, Canada.
Quebec Heart and Lung Institute Research Center, Université Laval, Quebec City, QC, Canada.
Physiol Rep. 2020 Mar;8(6):e14389. doi: 10.14814/phy2.14389.
Patients with pulmonary arterial hypertension (PAH) have lower cerebral blood flow (CBF) and oxygenation compared to healthy sedentary subjects, the latter negatively correlating with exercise capacity during incremental cycling exercise. We hypothesized that patients would also exhibit altered CBF and oxygenation during endurance exercise, which would correlate with endurance time.
Resting and exercise cardiorespiratory parameters, blood velocity in the middle cerebral artery (MCAv; transcranial doppler) and cerebral oxygenation (relative changes in cerebral tissue oxygenation index (ΔcTOI) and cerebral deoxyhemoglobin (ΔcHHb); near-infrared spectroscopy) were continuously monitored in nine PAH patients and 10 healthy-matched controls throughout endurance exercise. Cardiac output (CO), systemic blood pressure (BP) and oxygen saturation (SpO ), ventilatory metrics and end-tidal CO pressure (P CO ) were also assessed noninvasively.
Despite a lower workload and endurance oxygen consumption, similar CO and systemic BP, ΔcTOI was lower in PAH patients compared to controls (p < .01 for interaction). As expected during exercise, patients were characterized by an altered MCAv response to exercise, a lower P CO and SpO , as wells as a higher minute-ventilation/CO production ratio ( ratio). An uncoupling between changes in MCAv and P CO during the cycling endurance exercise was also progressively apparent in PAH patients, but absent in healthy controls. Both cHHb and ΔcTOI correlated with ratio (r = 0.50 and r = -0.52; both p < .05 respectively), but not with endurance time.
PAH patients present an abnormal cerebrovascular profile during endurance exercise with a lower cerebral oxygenation that correlate with hyperventilation but not endurance exercise time. These findings complement the physiological characterization of the cerebral vascular responses to exercise in PAH patients.
与健康的久坐受试者相比，肺动脉高压 (PAH) 患者的脑血流量 (CBF) 和氧合水平较低，后者与递增循环运动中的运动能力呈负相关。我们假设患者在耐力运动期间也会表现出 CBF 和氧合的改变，并且这些改变与耐力时间相关。
在耐力运动期间，连续监测九名 PAH 患者和十名健康匹配对照者的静息和运动心肺参数、大脑中动脉血流速度 (MCAv；经颅多普勒) 和脑氧合 (脑氧合指数相对变化 (ΔcTOI) 和脑去氧血红蛋白 (ΔcHHb)；近红外光谱)。还通过无创方式评估心输出量 (CO)、全身血压 (BP) 和血氧饱和度 (SpO2)、通气指标和呼气末 CO2 分压 (P CO2)。
尽管 PAH 患者的工作负荷和耐力耗氧量较低，但 CO 和全身 BP 相似，与对照组相比，PAH 患者的 ΔcTOI 较低 (交互作用 p < 0.01)。正如运动期间所预期的那样，患者的 MCAv 对运动的反应、较低的 P CO2 和 SpO2，以及较高的分钟通气量/CO 产生比 ( 比值) 发生改变。在 PAH 患者中，循环耐力运动期间 MCAv 和 P CO2 之间的解耦也逐渐变得明显，但在健康对照组中不存在。cHHb 和 ΔcTOI 均与 比值相关 (r = 0.50 和 r = -0.52；两者均 p < 0.05)，但与耐力时间无关。
PAH 患者在耐力运动期间表现出异常的脑血管特征，脑氧合水平较低，与过度通气相关，但与耐力运动时间无关。这些发现补充了 PAH 患者运动时脑血管反应的生理特征。
