Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Heart Lung. 2012 Mar-Apr;41(2):125-36. doi: 10.1016/j.hrtlng.2011.06.009. Epub 2011 Sep 3.
Patients presenting with suspected pulmonary embolism (PE) may present a challenge, particularly if diagnostic testing is not immediately available or clinically not indicated (iodine allergy, pregnancy, renal dysfunction). These patients have abnormal regional gas exchange that can be recognized by a cardiopulmonary exercise test (CPET), which may become helpful in their evaluation.
A retrospective analysis was performed of outpatients evaluated for subacute exertional dyspnea of 2 to 12 weeks duration with a test for PE and CPET. A total of 108 patients met inclusion criteria. Thirty patients (27.8%) had confirmed PE.
The patients with PE had increased nadir ventilatory equivalent ratio for carbon dioxide (VE/VCO(2)), decreased peak oxygen uptake/predicted, and decreased end exercise saturation (P < .005 for all). All patients but 1 had normal breathing reserve (>15%). A normal nadir VE/VCO(2) excluded PE with 100% sensitivity. By using a "flow chart strategy," the exercise test had 92.8% sensitivity and 92.1% specificity for PE. Eight patients with PE died during follow-up (3.8 ± 4.6 years), 6 of PE-related causes. Peak VO(2)/kg was the best predictor of all-cause mortality and nadir VE/VCO(2) for PE-related mortality. There were no serious complications from any of the exercise tests.
PE may be excluded by a normal nadir VE/VCO(2) in patients presenting with subacute dyspnea. A combination of decreased peak VO(2)/kg, increased nadir VE/VCO(2), normal breathing reserve, and exercise-induced desaturation may be sensitive and specific for PE. CPET may assist in identifying subacute PE in patients with contraindications to use of computed tomography angiography or ventilation perfusion scans.
患有疑似肺栓塞 (PE) 的患者可能会带来挑战，特别是在无法立即进行诊断性检查或临床不适用（碘过敏、妊娠、肾功能不全）的情况下。这些患者存在区域性气体交换异常，可通过心肺运动试验 (CPET) 识别，这可能有助于评估。
对因亚急性运动性呼吸困难就诊、持续 2 至 12 周的门诊患者进行回顾性分析，这些患者接受了 PE 检测和 CPET。共有 108 名患者符合纳入标准。30 名患者（27.8%）被确诊为 PE。
PE 患者的二氧化碳通气当量比（VE/VCO2）最低值增加，峰值摄氧量/预计值降低，运动结束时饱和度降低（所有指标均<0.005）。除 1 名患者外，所有患者的呼吸储备均正常（>15%）。正常的最低 VE/VCO2 可排除 100%的 PE。采用“流程图策略”，CPET 对 PE 的敏感性为 92.8%，特异性为 92.1%。8 名患有 PE 的患者在随访期间死亡（3.8±4.6 年），其中 6 例死于与 PE 相关的原因。峰值 VO2/kg 是全因死亡率的最佳预测指标，最低 VE/VCO2 是与 PE 相关死亡率的最佳预测指标。所有运动试验均无严重并发症。
在出现亚急性呼吸困难的患者中，正常的最低 VE/VCO2 可排除 PE。峰值 VO2/kg 降低、最低 VE/VCO2 增加、呼吸储备正常和运动引起的低氧血症可能对 PE 具有敏感性和特异性。CPET 可辅助确定对 CT 血管造影或通气灌注扫描有禁忌证的亚急性 PE 患者。
