Impact of intrathoracic pressure in the assessment of central pulmonary pressures in COPD and ILD candidates for lung transplantation.

Abstract

Dynamic hyperinflation and low lung compliance may increase intrathoracic pressure swings throughout the respiratory cycle, which is critical in interpreting central pulmonary pressures (CPP) and detecting pulmonary vascular disease. We analyzed the effect of esophageal pressure (PES) as a surrogate of intrathoracic pressure on the assessment of the CPP during the RHC at rest in chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) candidates for lung transplantation (LTx). Ten consecutive COPD and ILD candidates for LTx (2F, 63±6 yrs, 25±4 Kg/m²) underwent simultaneous RHC and PES (Esophageal Catheter, LATITUDE). End expiratory (ee) and mean respiratory cycle (mrc) measurements were obtained, and transmural (tm) pulmonary pressures were estimated (CPPtm = CPP intravascular - PES at ee and mrc conditions). PESee values were positive in COPD and ILD. All ILD had negative PESmrc values and were lower than COPD patients. The lower the FVC (%), the more negative the PESmrc. All intravascular CPPee were higher than CPPmrc (p &lt;0.05). However, transmural CPP ee were similar to CPPmrc values. ILD pts showed higher transmural than intravascular CPPmrc (p &lt;0.05). Intravascular CPP measured at the end-expiration overestimates the mean respiratory cycle pressures in COPD and ILD candidates for LTx. Averaging intravascular measurements over the respiratory cycle would be accurate in COPD but could underestimate transmural values in ILD patients. §<i>P</i>&lt;0.05 COPD vs ILD; *<i>P</i>&lt;0.05 PESee vs PESmrc