Abstract
Rationale: Patients with cancer commonly experience dyspnea originating from ventilatory, circulatory and musculoskeletal sources, and dyspnea is best determined by cardiopulmonary exercise testing (CPET). Objectives: In this retrospective pilot study, we evaluated patients with hematologic and solid malignancies by CPET to determine the primary source of their dyspnea. Methods: Subjects were exercised on a cycle ergometer with increasing workloads. Minute ventilation, heart rate, breathing reserve, oxygen uptake (V’O2), O2-pulse, ventilatory equivalents for carbon dioxide and oxygen (V’E/V’CO2 and V’E/V’O2, respectively) were measured at baseline and peak exercise. The slope and intercept for V’E/V’CO2 was computed for all subjects. Peak V’O2 4% predicted indicated a circulatory or ventilatory limitation. Results: Complete clinical and physiological data were available for 36 patients (M/F 20/16); 32 (89%) exhibited ventilatory or circulatory limitation as shown by a reduced peak V’O2 and 10 subjects with normal physiologic data. The largest cohort comprised the pulmonary vascular group (n = 18) whose mean ± SD peak V’O2 was 61% ± 17% predicted. There were close associations between V’O2 and spirometric values. Peak V’E/V’O2 and V’E/V’CO2 were highest in the circulatory and ventilatory cohorts, consistent with increase in dead space breathing. The intercept of the V’E-V’CO2 relationship was lowest in patients with cardiovascular impairment. Conclusion: Dyspneic patients with malignancies exhibit dead space breathing, many exhibiting a circulatory source for exercise limitation with a prominent pulmonary vascular component. Potential factors include effects of chemo- and radiation therapy on cardiac function and pulmonary vascular endothelium.
Highlights
Patients with cancer commonly experience dyspnea and fatigue [1]
In this retrospective pilot study, we evaluated patients with hematologic and solid malignancies by cardiopulmonary exercise testing (CPET) to determine the primary source of their dyspnea
Dyspneic patients with malignancies exhibit dead space breathing, many exhibiting a circulatory source for exercise limitation with a prominent pulmonary vascular component
Summary
Patients with cancer commonly experience dyspnea and fatigue [1]. These symptoms may originate from ventilatory, cardiovascular, pulmonary vascular, and musculoskeletal causes [2] [3]. Ventilatory limitation can be due to underlying lung and/or pleural disease or from tumor involving the respiratory system itself. Cardiovascular limitation can originate from underlying structural heart disease [4] [5] [6] [7], cardiac involvement by tumor or effects of chemotherapeutic drugs [8]. Pulmonary vascular limitation may represent intrinsic acute or chronic thromboembolic disease, or, again, drug effects [9]. Other contributing factors contributing to functional limitation include anemia [10], muscle wasting, malnutrition, pain, electrolyte disturbances, and depression, all of which may result in a decrease in functional capacity and activities of daily living [1] [11]
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