Central Vascular Pressure Measurements During Exercise in Copd: How to Handle the Respirophasic Changes?

Introduction: Respirophasic changes are a major confounder when evaluating central hemodynamics during exercise. We studied the accuracy of four different methods to assess mean pulmonary artery pressure (mPAP) and pulmonary capillary wedge pressure (PCWP) in case of heavy respiratory swings. Methods: Central hemodynamics measured simultaneously with esophageal pressure during exercise in 30 COPD-patients. mPAP and PCWP were assessed at end-expiration, averaged over the respiratory cycle and corrected with a from the right atrial pressure (RAP) waveform estimated intrathoracic pressure and compared with the transmural pressures. Results: Bland-Altman analyses showed the best agreement of mPAP averaged over the respiratory cycle (bias: 2.5 mmHg, limits of agreement: -6.0 to 11.8) and when corrected with the nadir of RAP (bias: -3.6 mmHg, limits: -11.2 to 3.9). Measuring mPAP at end-expiration (bias: 10.3mmHg, limits: 0.5 to 20.3) and mPAP corrected with the RAP-swing (bias: -9.3mmHg, limits: -19.8 to 2.1) resulted in lower levels of agreement. Conclusion: Central hemodynamics measured at end-expiration leads to an overestimation of intravascular pressures in exercising COPD-patients. Averaging pressures over the respiratory cycle or using the right atrial pressure waveform to estimate and correct for intrathoracic pressure leads to better estimations of intravascular pressure.