Division of Pulmonary and Critical Care Medicine, University of California, San Diego, San Diego, CA.
Harbor-UCLA Medical Center, Torrance, CA.
Chest. 2020 Apr;157(4):936-944. doi: 10.1016/j.chest.2019.10.047. Epub 2019 Nov 22.
Many patients with pulmonary embolism (PE) report dyspnea on exertion following long-term treatment. Increased physiological dead space proportion (V/V) and decreased cardiac stroke volume reserve may distinguish persistent effects of PE itself from symptoms reflecting comorbid conditions or deconditioning.
This retrospective study analyzed a consecutive series of incremental symptom-limited cardiopulmonary exercise tests that had been ordered to evaluate persistent dyspnea on exertion following long-term treatment for acute PE. Physiological V/V was determined at anaerobic threshold from exhaled CO and transcutaneous Pco (validated against Paco measurements). Cardiac stroke volume reserve was estimated at rest and at anaerobic threshold by using oxygen consumption/pulse and previously validated estimates of the arteriovenous oxygen content difference.
Cardiopulmonary exercise tests were performed on 40 patients with post-PE dyspnea. In 65.0% (95% CI, 50.2-79.8), V/V at anaerobic threshold was abnormally elevated, stroke volume reserve was decreased, or both defects occurred. V/V at anaerobic threshold was abnormally elevated (≥ 0.27) in 35.0% (95% CI, 20.2-49.8). V/V at anaerobic threshold significantly correlated with the extent of unmatched perfusion defects on subsequent ventilation-perfusion scans (P = .0085). In 55.0% (95% CI, 39.6-70.4), stroke volume reserve at anaerobic threshold was abnormally decreased (≤ 128% of the resting value). Both defects were present in 25.0% (95% CI, 11.6-38.4).
Increased V/V at anaerobic threshold and decreased stroke volume reserve during exercise are common among patients with dyspnea on exertion after long-term treatment of PE. The defects can be disclosed noninvasively by using cardiopulmonary exercise testing.
许多患有肺栓塞 (PE) 的患者在长期治疗后会报告运动时呼吸困难。生理死腔比例 (V/V) 增加和心输出量储备减少可能将 PE 本身的持续影响与反映合并症或去适应的症状区分开来。
这项回顾性研究分析了一系列连续的递增症状限制心肺运动测试，这些测试是为了评估急性 PE 长期治疗后持续运动时呼吸困难而进行的。生理 V/V 通过从呼出的 CO 和经皮 Pco 确定（通过 Paco 测量验证）在无氧阈值处确定。心输出量储备通过使用氧耗量/脉搏和先前验证的动静脉血氧含量差的估计值在休息和无氧阈值处进行估计。
对 40 例 PE 后呼吸困难的患者进行了心肺运动测试。在 65.0%（95%CI，50.2-79.8）的患者中，无氧阈值处的 V/V 异常升高、心输出量储备减少或两者均存在缺陷。35.0%（95%CI，20.2-49.8）的患者无氧阈值处的 V/V 异常升高（≥0.27）。无氧阈值处的 V/V 与随后通气灌注扫描中不匹配灌注缺陷的程度显著相关（P=0.0085）。在 55.0%（95%CI，39.6-70.4）的患者中，无氧阈值处的心输出量储备异常减少（≤休息值的 128%）。25.0%（95%CI，11.6-38.4）的患者存在两种缺陷。
在长期治疗 PE 后出现运动时呼吸困难的患者中，无氧阈值处的 V/V 增加和运动时的心输出量储备减少是常见的。这些缺陷可以通过心肺运动测试无创地揭示出来。
