RER: respiratory exchange ratio; VCO2: carbon dioxide output (L/minute); VO2: oxygen output (L/minute); CPET: cardiopulmonary exercise test; FVL: flow volume loop; IC: inspiratory capacity; AT: anaerobic threshold; OUES: oxygen uptake efficiency slope (slope of VO2 versus logVE); ILD: interstitial lung disease; FVC: forced vital capacity; VD/VT: proportion of dead space ventilation per tidal volume breath; BP: blood pressure; HR: heart rate; VE: minute ventilation; ECG: electrocardiogram; SaO2: arterial oxygen saturation; A-a: alveolar-arterial; MVV: maximum voluntary ventilation; VEMAX: maximum minute ventilation at peak exercise (L/minute).
* For use with UpToDate content on cardiopulmonary exercise testing. This algorithm is intended to provide a systematic approach to interpretation of CPET data. The results should be considered in the clinical context. Some patients may have more than one cause of dyspnea, causing a mixed picture.
¶ There can be a discrepancy between these end-points. Maximal metabolic capacity during exercise is assessed by the peak VO2 whereas the maximal functional capacity during exercise is assessed by the peak work.
Δ OUES normally is ≥1.47. It is decreased when exercise is limited by cardiac causes or mitochondrial myopathy.
◊ Evaluation of possible mitochondrial myopathy may include genetic testing and/or muscle biopsy.
§ Breathing reserve is 1 − ([MVV − VEMAX]/MVV) × 100. Normal is 30 to 40%.