Dyspnea Postpulmonary Embolism From Physiological Dead Space Proportion and Stroke Volume Defects During Exercise
Timothy M Fernandes1, Mona Alotaibi1, Danielle M Strozza1
1Division of Pulmonary and Critical Care Medicine, University of California, San Diego, San Diego, CA.
Chest
|November 25, 2019
Summary
Persistent dyspnea after pulmonary embolism (PE) is often linked to increased physiological dead space (VD/VT) and reduced stroke volume reserve. Cardiopulmonary exercise testing can identify these exercise limitations noninvasively.
Area of Science:
- Cardiopulmonary physiology
- Exercise medicine
- Pulmonary vascular disease
Background:
- Dyspnea on exertion is a common sequela for patients treated for pulmonary embolism (PE).
- Distinguishing PE-related limitations from deconditioning or comorbidities is crucial for effective management.
- Increased physiological dead space proportion (VD/VT) and diminished cardiac stroke volume reserve are potential indicators of persistent PE effects.
Purpose of the Study:
- To evaluate persistent dyspnea on exertion in patients with a history of acute pulmonary embolism (PE).
- To assess the utility of cardiopulmonary exercise testing (CPET) in identifying physiological abnormalities post-PE.
- To determine the prevalence of increased VD/VT and decreased stroke volume reserve in this patient cohort.
Main Methods:
- Retrospective analysis of symptom-limited incremental cardiopulmonary exercise tests (CPET).
- Measurement of physiological dead space proportion (VD/VT) at anaerobic threshold using exhaled CO2 and transcutaneous Pco2.
- Estimation of cardiac stroke volume reserve at rest and anaerobic threshold using oxygen consumption and arteriovenous oxygen content difference.
Main Results:
- CPET was performed on 40 patients experiencing post-PE dyspnea.
- Abnormal VD/VT (≥ 0.27) or decreased stroke volume reserve (≤ 128% of resting value) was observed in 65% of patients.
- Elevated VD/VT correlated with perfusion defects on ventilation-perfusion scans (P = .0085).
- Both abnormalities were present in 25% of the study population.
Conclusions:
- Increased VD/VT and reduced stroke volume reserve are common during exercise in patients with post-PE dyspnea.
- These exercise-limiting defects can be identified noninvasively through cardiopulmonary exercise testing.
- CPET provides valuable insights into the pathophysiology of persistent dyspnea after PE.
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