1Western Renal Services, Westmead, Australia, 2School of Medicine, Western Sydney University, Campbelltown, Australia

Aim: To investigate whether Cardiopulmonary Recirculation (CPR) impacts on the nutrition of haemodialysis (HD) patients due to potential effects on reduced dialysis effectiveness.
Background: Recirculation during HD impacts on dialysis effectiveness by impairing the ability of treated blood to equilibrate with tissue solute stores. Recirculation can occur within arteriovenous access (in the setting of low access flow (Qa)) as well as by CPR (determined by the relationship of Qa to cardiac output (CO)). The impact of CPR on measures of dialysis effectiveness and nutrition is largely unknown.
Methods: Stable patients undergoing maintenance HD in Western Sydney were identified; these patients have six-monthly Qa, recirculation and CPR measures as part of access surveillance using an indicator dilution method. Demographic details were collected in addition to biochemical markers (serum albumin, potassium, bicarbonate and haemoglobin). Albumin was chosen as a surrogate marker of patient nutrition and patient outcome.
Results: 180 patients were included. Low Qa (<500mL/minute) was found in 21 patients (12%), total recirculation >10% in 74 patients (41%) and CPR>30% in 62 patients (34%). There was no significant difference in biochemical markers for patients with low Qa (<500mL/min). Patients with high total recirculation (determined predominantly by CPR) and those with a CPR of >30% had significantly lower serum albumin (34g/L vs 31g/L, p=0.01 and p=0.02 respectively). Potassium, bicarbonate and haemoglobin levels did not differ between different recirculation groups.
Conclusion: Both CPR and total recirculation are potential contributors to patient nutrition and outcome likely due to their impact on dialysis effectiveness. CPR values should be taken into account when interpreting the results of vascular access performance measures and when prescribing maintenance haemodialysis.

A/Prof Lukas Kairaitis is a nephrologist and university academic working in Western Sydney. He has clinical and research interests in haemodialysis and vascular access.

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