Lung Ultrasound in PD Patients

Maintaining volume control is crucial in all renal replacement therapy modalities. Fluid overload is associated with increased mortality both in hemodialysis patients and peritoneal dialysis (PD) patients although peritoneal dialysis has the advantage of better preservation of residual renal function compared to hemodialysis. Many methods have been used to fine tune the volume status of patients including physical examination, chest radiography, blood pressure, laboratory parameters, echocardiography, bioelectrical impedance analysis (BIA), ultrasound for lung.

Symptoms of hypervolemia are mainly paroxysmal nocturnal dyspnea, orthopnea, edema, dyspnea on exertion. On physical examination, hypertension or hypotension, third heart sound, jugular venous distension, rales, edema can be seen. Pulmonary venous congestion, cardiomegaly, interstitial edema, alveolar edema, pleural effusion can be seen on chest radiographies.

Level of N-terminal pro-brain natriuretic peptide (NT-proBNP) increases upon stretching of cardiac myocytes. This is accepted as a reflection of volume status. There are a few studies in which NT-proBNP was found as a useful marker for hypervolemia both in hemodialysis and peritoneal dialysis population.

Vascular endothelial growth factor-C (VEGF-C) is an osmosensitive gene product secreted by macrophages through activation of tonicity-responsive enhancer binding protein found in mononuclear phagocyte system cells infiltrating the interstitium. The result is hypertonic sodium accumulation in the skin which is accepted as a buffer mechanism maintaining blood pressure homeostasis. Serum VEGF-C levels had been found as a promising marker of hypervolemia in a hemodialysis patient cohort by a recent study.

Echocardiography has been used extensively in dialysis patients in which a number of parameters have been measured. Bioelectrical impedance analysis (BIA) is another non-invasive bedside method for the evaluation of volume status.

Lung ultrasound (LUS) is a technique that has become popular in nephrology recently. "B lines" or "lung comets" are the reverberation artifacts arising from the pleural line. They are produced due to thickened subpleural interlobular septa by edema.

The gold standard for volume assessment is isotope dilution and neutron activation analysis methods which are only limited to research activities. The best widely accepted, non-invasive, practical, easy to access method has not been decided yet. Moreover evidence is quite scarce for the peritoneal dialysis than hemodialysis or normal renal functioning group. Lung ultrasound is the most recent promising method for volume control.

The investigators aimed to define lung ultrasound findings in our peritoneal dialysis cohort and its relation with other volumetric parameters.