Hemodynamic tolerance of hemodialysis in septic patients with acute renal failure: comparison between recirculating and single-pass bicarbonate hemodialysis

Septic patients with acute renal failure (ARF) are especially intolerant to acetate hemodialysis (HD). Hemodynamic tolerance in septic patients is improved by using bicarbonate dialysis and high Na concentration dialysate. The potential improvement of hemodynamic tolerance with recirculating v single-pass bicarbonate HD (BiHD) has not been evaluated in such patients. We then compared the hemodynamic tolerance in a randomized cross-over study, using a pulmonary artery catheter and biologic changes during the two types of HD in eight severe septic patients with ARF. Patients were dialysed for four hours with a 1 m²1 cuprophan dialyzer, alternatively using single-pass and recirculating system. No absorbent cartridge was used in recirculating BiHD. Intravascular volume expansion (IVE) was used as needed to maintain a systolic arterial pressure of at least 80 mm Hg. Similar doses of catecholamines (dopamine essentially) and equal ultrafiltration rate (mean, 1.55 ± 0.61 for four hours) were used during the two types of dialysis in each patient. No hemodynamic parameter was significantly different between the two procedures, but IVE was lower (370 ± 550 mL v 740 ± 590 mL; P < .05) and weight loss higher (1.06 ± 0.88 kg v 0.68 ± 0.99 kg; P < .05) in recirculating BiHD than in single-pass BiHD. No biologic differences were found between recirculating and single-pass BiHD except for a lower decrease of blood urea (Δ, 10.5 ± 3.4 μmol/L v 12.8 ± 4.9 mmol/L; P <.05) and creatinine (Δ, 107 ± 40 μmol/L v 153 ± 69 μmol/L; P < .05) in recirculating BiHD. Recirculating BiHD was better tolerated than single-pass BiHD, requiring less IVE. This lesser IVE during recirculating BiHD with similar decrease in pulmonary wedge pressure suggests a venoconstrictor effect. This venoconstrictor effect is likely due to a lower loss of catecholamines (dopamine) in the dialysate. Recirculating BiHD is better tolerated than single pass, providing higher weight loss. This procedure is particularly interesting in patients with cardiovascular instability, especially after septic shock.