%0 Journal Article %T Dead Space Breathing in Patients with Malignancies: Determination by Cardiopulmonary Exercise Testing %A Harrison Ngue %A Maranda Ngue %A Ian Lee %A Ching-Fei Chang %A Ahmet Baydur %J Open Journal of Respiratory Diseases %P 15-36 %@ 2163-9418 %D 2022 %I Scientific Research Publishing %R 10.4236/ojrd.2022.121002 %X 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 <84% predicted indicated a circulatory or ventilatory limitation.