Cardiopulmonary exercise testing (CPET) is a frequently used tool in the differential diagnosis of dyspnoea. Ventilatory inefficiency, defined as high minute ventilation (V'_E) relative to carbon dioxide output (V'_CO2), is a hallmark characteristic of pulmonary vascular diseases, which contributes to exercise intolerance and disability in these patients. The mechanisms of ventilatory inefficiency are multiple and include high physiologic dead space, abnormal chemosensitivity and an altered carbon dioxide (CO₂) set-point. A normal V'_E/V'_CO2 makes a pulmonary vascular disease such as pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH) unlikely. The finding of high V'_E/V'_CO2 without an alternative explanation should prompt further diagnostic testing to exclude PAH or CTEPH, particularly in patients with risk factors, such as prior venous thromboembolism, systemic sclerosis or a family history of PAH. In patients with established PAH or CTEPH, the V'_E/V'_CO2 may improve with interventions and is a prognostic marker. However, further studies are needed to clarify the added value of assessing ventilatory inefficiency in the longitudinal follow-up of patients.

心肺运动试验 (CPET) 是鉴别诊断呼吸困难的常用工具。通气效率低下，定义为相对于二氧化碳输出量 ( V' _{CO 2} ) 的高分钟通气量 ( V' _E ) ，是肺血管疾病的标志性特征，会导致这些患者的运动不耐受和残疾。通气效率低下的机制多种多样，包括高生理死腔、异常的化学敏感性和改变的二氧化碳 (CO ₂ ) 设定点。正常的 V' _E / V' _{CO 2}使肺血管疾病如肺动脉高压（PAH）或慢性血栓栓塞性肺动脉高压（CTEPH）不太可能。在没有其他解释的情况下发现高V' _E /V' _{CO 2}应促使进行进一步的诊断测试以排除 PAH 或 CTEPH，特别是对于具有危险因素（例如既往静脉血栓栓塞、系统性硬化症或 PAH 家族史）的患者。在患有 PAH 或 CTEPH 的患者中，V' _E / V' _{CO 2}可能会随着干预而改善，并且是一个预后指标。然而，需要进一步的研究来阐明评估通气无效率在患者纵向随访中的附加值。