An exploratory study of the relationship between systemic microcirculatory function and small solute transport in incident peritoneal dialysis patients

BACKGROUND

The peritoneal capillary endothelium is widely considered to be the most influential structure in dictating the rate of small solute transport (SST) during peritoneal dialysis (PD). PD patients are at significant risk of systemic microcirculatory dysfunction. The relationship between peritoneal and systemic microcirculations in patients new to PD has not been well studied. We hypothesised that for patients on PD for less than 6 months, dysfunction in the systemic microcirculation would be reflected in the rate of SST.

METHODS

We recruited 29 patients to a cross-sectional, observational study. Rate of SST was measured using a standard peritoneal equilibration test. Laser Doppler Flowmetry was used to measure response to physical and pharmacological challenge (post-occlusive hyperaemic response and iontophoretic application of vasodilators) in the cutaneous microcirculation. Sidestream Darkfield imaging was used to assess sublingual microvascular density, flow and endothelial barrier properties.

RESULTS

We found no moderate or strong correlations between any of the measures of systemic microcirculatory function and rate of SST or albumin clearance. There was however a significant correlation between dialysate interleukin-6 concentrations and both SST (r_s = 0.758 p ≤ 0.0001) and albumin clearance (r_s = 0.53, p = 0.01).

CONCLUSIONS

In this study, systemic microvascular dysfunction did not significantly influence the rate of SST even early in patients PD careers. In conclusion, this study demonstrates that intraperitoneal factors particularly inflammation have a far greater impact on rate of SST than systemic factors.

Reduced residual renal function is associated with endothelial dysfunction in patients receiving peritoneal dialysis

BACKGROUND

Endothelial dysfunction, which contributes to atherosclerosis and arteriosclerosis, commonly accompanies end-stage renal disease (ESRD). However, little is known about the role of residual renal function (RRF) in endothelial protection in ESRD patients. This study aimed to investigate the relationship between endothelial function and RRF in patients undergoing peritoneal dialysis (PD).

METHODS

This was a cross-sectional study involving 72 prevalent PD patients. Demographic and clinical data were recorded and residual glomerular filtration rate (GFR), Kt/V urea, and serum concentrations of inflammatory markers were measured. Endothelial function was assessed by brachial artery endothelium-dependent vasodilation [flow-mediated dilation (FMD)] to reactive hyperemia following 5 minutes of forearm ischemia.

RESULTS

In patients with FMD% above the median value (FMD > 2.41%), residual GFR was significantly higher compared to that in patients with FMD% below the median [1.50 (0 - 9.64) vs 0.48 (0 - 3.89) mL/min/1.73 m(2), P = 0.026]. Correlation analyses revealed that residual GFR (ρ = 0.381, P = 0.001) and total Kt/V urea (γ = 0.408, P < 0.001) were positively correlated with FMD%, whereas PD duration (γ = -0.351, P = 0.003), high-sensitivity C-reactive protein (ρ = -0.345, P = 0.003), pulse pressure (γ = -0.341, P = 0.003), and age (γ = -0.403, P < 0.001) were inversely correlated with FMD%. In contrast, there was no correlation between peritoneal Kt/V urea and FMD%. In multivariate linear regression analysis adjusted for these factors, residual GFR was found to be an independent determinant of FMD% (β = 0.317, P = 0.017).

CONCLUSION

This study shows that RRF is independently associated with endothelial dysfunction in ESRD patients on PD, suggesting that RRF may contribute to endothelial protection in these patients.