B68-01 Physiologic Predictors of Discrepancy Between End-expiratory and Respiratory-averaged Pulmonary Capillary Wedge Pressure in Pulmonary Hypertension

Rationale of study Pulmonary capillary wedge pressure (PCWP) is influenced by thoracic pressure swings and the abdominal compartment, particularly in the supine position. Knowledge gaps remain over whether end expiratory or respiratory average PCWP should be used. Physiologic factors that influence thoracic pressure swings and abdominal load are expected to cause differences between these two methods. We aimed to identify physiologic factors associated with PCWP measurement differences. Methods We included all subjects from the NHLBI-funded Pulmonary Vascular Disease Phenomics (PVDOMICS) study who underwent right heart catheterization. Binary variables were generated using multiple cut-offs for PCWP difference between 2 - 6mmHg. For each binary threshold, Wilcoxon rank test for continuous and chi-square for categorical variables were performed to assess differences across pulmonary mechanics, left sided compliance, and anthropometric variables. Results Anthropometric measures—waist circumference, hip circumference, body fat percentage, weight, body surface area, and BMI—were predictive of PCWP differences among all subjects (figure 1). In sub WSPH group analysis, the finding was only present among the Group III (GIII) patients. Significant PCWP discrepancy was also related to having a diagnosis of obstructive sleep apnea and the apnea-hypopnea index in the GIII population. Left atrial volume index was associated with PCWP discrepancy in the GII population. Spirometric measures were not associated with PCWP discrepancy. Conclusions Anthropometric measures are significantly associated with PCWP difference, particularly for patients with group III disease or risk factors, while spirometric variables are not associated with PCWP discrepancy among any group (figure 1).