Abstract
Introduction: Indicator-Dilution (ID) is considered as the standard method for the measurement of cardiac output (CO), but is invasive and therefore difficult to use in clinical practice. A non-invasive device reported to work during exercise and based on impedance cardiography (Physioflow, PF) has become available.
Aim: To simultaneously measure CO during exercise with (PF) and (ID) in patients with COPD.
Methods: Ten patients with COPD, (aged 60±7 years, FEV1= 50±6%predicted) were studied.Exercise consisted of four constant-load tests, for (5min at 25% and 50%, 3 min at 75% and 2 min at 100% of their WRpeak). VO2 and CO2 were recorded breath-by-breath, and CO was measured at each exercise level using PF and ID (using indocyanine green) over the last minute of exercise.
Results: CO by PF exceeded that by ID by 2.6±0.3 L/min (Mean±SE) averaged across all exercise levels (p=0.001).
Conclusion: Compared to IT, PF overestimates CO across different levels of exercise but its slope of change relative to VO2 is very similar. Hence PF can accurately estimate changes from resting CO during exercise in COPD.
- © 2011 ERS