Number of attempts and interventions to obtain a valid pulmonary artery wedge pressure.

Background: A valid pulmonary artery wedge pressure (PAWP) is essential for the hemodynamic characterization of pulmonary hypertension (PH). We prospectively investigated the methodology for obtaining a valid PAWP measurement, while assessing the impact of prespecified factors on its determination.

Methods: In this prospective observational cohort study, we included consecutive patients who underwent right heart catheterization (RHC) using fluoroscopy at the Pulmonary Vascular Disease program at Cleveland Clinic, between February and May 2023. Once a valid PAWP was obtained, we recorded the number of attempts, reason for repeating the determination, pulmonary artery location, depth of the pulmonary artery catheter (PAC) from the introducer hub, and inflation volume of the PAC balloon.

Results: We included 195 patients, age: 57.5±15.7 years, 111 (57%) women, 156 (80%) with PH. The PAWP was 16.4±5.9 mmHg, requiring 1, 2 and ≥3 attempts for a valid measurement in 139 (71%), 39 (20%) and 17 (9%) patients, respectively. PAWP was repeated due to abnormal waveform, incomplete wedge and over wedge. A valid PAWP was obtained in the right pulmonary circulation in 168 (86%) patients, and in the lower third in 134 (69%), middle third in 58 (30%), and upper third of the lung in 3 (2%) patients. The pulmonary artery catheter balloon inflation at valid PAWP was 1.0±0.3 mL, at a distance from the introducer hub of 52.6±5.2 cm. Aspiration of blood in PAW position was obtained in 141 (72%) patients with an arterial oxygenation of 97% (95-99%). The number of measurements for a valid PAWP was directly associated with mean pulmonary artery pressure (mPAP) (r=0.18, P=0.01), PAWP (r=0.22, P=0.002), and pulmonary artery diameter on computed tomography (r=0.16, P=0.04).

Conclusions: A valid PAWP was obtained during the first or second attempt in about 90% of patients that undergo RHC. Advanced interventions such as relocating the PAC to a different place of the same lung or contralateral pulmonary circulation are needed in about 10% of patients.