Increasing fill volume reduces cardiac performance in peritoneal dialysis.

Background: It is generally accepted that peritoneal dialysis (PD) affects systemic haemodynamics less than haemodialysis, but little is known about changes in haemodynamics during PD. It is unknown if increasing PD volume causes changes in cardiovascular haemodynamics possibly increasing the demand on the heart even during normal daily activities.

Methods: Fifteen stable PD patients were included in this randomized, controlled, open-label crossover study. After drainage, we measured blood pressure, pulse rate and cardiac output (CO) after 30 min in the supine position. The measurements were repeated 5 min later in an upright position. Subsequently, following fill, the measurements were repeated after 30 min in the supine and 5 min later in the upright position. The two procedures were repeated twice. The fill was either 2 l or 3 l of dialysate. CO was measured with a non-invasive device based on foreign gas rebreathing. Stroke volume (SV) and total peripheral systemic resistance were calculated.

Results: In the supine position, no difference was found between drained and 2 l fill. With 3 l fill both SV and CO decreased and total peripheral systemic resistance increased, while pulse rate and mean arterial blood pressure remained unchanged. In the upright position, SV and CO decreased and total peripheral systemic resistance increased. Pulse rate and mean arterial blood pressure were unchanged independent of fill volume when compared with the drained situation. During postural change, no significant differences were found between drained and 2 l and 3 l fill.

Conclusion: The present study showed that cardiac performance decreased when increasing fill volume from 2 to 3 l in the supine position. The decreased cardiac performance was already present after 2 l fill in the upright position and did not change negatively by increasing fill. It was also shown that cardiovascular response from the supine to upright position was preserved.