Pulmonary hypertension (PH) is a frequent and clinically significant complication in patients with end-stage kidney disease (ESKD) undergoing maintenance hemodialysis (HD). However, PH assessment in this population is often confounded by volume overload, leading to potential overestimation and misclassification.

This prospective, multicenter observational study aims to evaluate the prevalence, phenotype, and predictors of PH in HD patients under standardized euvolemic conditions. A structured pretrial phase including volume assessment and correction will be performed prior to echocardiographic evaluation, which will be conducted after confirmation of euvolemia, post-hemodialysis or on the following day.

In participants with echocardiographic findings suggestive of PH, right heart catheterization may be performed when clinically indicated and after obtaining specific informed consent.

The study integrates clinical, biological, dialysis-related, and echocardiographic data to provide a comprehensive characterization of PH in a well-defined ESKD population.

Pulmonary hypertension (PH), defined as mean pulmonary arterial pressure (mPAP) >20 mmHg, is increasingly recognized in patients with chronic kidney disease and is particularly prevalent in those with ESKD on maintenance HD.

Despite its prognostic importance, PH remains under-recognized and insufficiently characterized in HD patients. A major limitation of prior studies is the lack of standardized assessment of volume status, which significantly influences pulmonary pressures.

This prospective, multicenter cohort study aims to address this gap by evaluating PH after rigorous volume optimization. The study includes:

• A pretrial volume assessment phase (3 consecutive HD sessions)
• A structured volume correction phase (if needed)
• A main study cohort including only euvolemic patients
• An exploratory subgroup of patients with persistent hypervolemia

Euvolemia is defined using a multimodal approach including clinical examination, bioimpedance spectroscopy, inferior vena cava (IVC) diameter, interdialytic weight gain, blood pressure stability, and lung ultrasound criteria.

The primary objective is to determine the prevalence of PH in euvolemic HD patients. Secondary objectives include characterization of PH phenotypes and identification of clinical, dialysis-related, and echocardiographic predictors.

Right heart catheterization (RHC) is not mandated for all participants. In patients with echocardiographic findings suggestive of PHafter confirmation of euvolemia, RHC may be performed when clinically indicated and separately consented. When available, invasive hemodynamic data will be used to confirm PH and refine phenotype classification.

Inclusion Criteria:

• Age ≥ 18 years.
• End-stage kidney disease on maintenance HD for ≥ 3 months.
• Stable clinical condition (no hospitalization in last 30 days).
• Able and willing to comply with study protocol.
• Provision of written informed consent

Exclusion Criteria:

• Moderate/severe left-sided valvular disease.
• Active pulmonary or cardiac decompensation.
• Persistent hypervolemia after completion of the volume assessment and correction phase
• Inability to undergo echocardiography or bioimpedance assessment.
• Acute infection or inflammatory condition at the time of enrollment.
• Inadequate echocardiographic window preventing reliable assessment

Adult patients with end-stage kidney disease (ESKD) receiving maintenance hemodialysis in two tertiary referral centers. Participants are consecutively enrolled and undergo structured volume assessment and optimization. The primary analysis includes patients who achieve predefined euvolemia criteria.