Objectives

The basic materials and structure of a hemoconcentrator incorporated into cardiopulmonary bypass (CPB) circuits are similar to those of hemodialyzers. Gravity drainage hemodiafiltration (GHDF) is an easy-to-use intraoperative renal replacement therapy (RRT) that utilizes a hemoconcentrator. This study aimed to verify whether GHDF can correct electrolyte imbalance and remove uremic toxins in dialysis-dependent patients and to evaluate the clinical outcomes of GHDF by comparing it with a conventional method of dilutional ultrafiltration (DUF).

Methods

This study retrospectively compared perioperative clinical values of 41 dialysis-dependent patients (21 patients with GHDF and 20 patients with DUF) who underwent open-heart surgery. Changes in serum parameters before and after passing through the hemoconcentrator were also compared.

Results

Compared to DUF, GHDF significantly lowered potassium, blood urea nitrogen, and creatinine levels at the outflow of the hemoconcentrator. Less catecholamine was needed to wean CPB in GHDF than in DUF. The P/F ratio (arterial blood oxygen pressure/inhaled oxygen concentration) at the end of surgery was significantly higher in GHDF than in DUF (450.8 ± 149.7 vs. 279.3 ± 153.5; p < 0.001). Postoperative intubation time was shorter in GHDF than in DUF (8.3 ± 5.9 vs. 18.7 ± 16.1 h; p = 0.006). The major morbidity and mortality rates were comparable in both groups.

Conclusions

GHDF removed both potassium and uremic toxins more efficiently than DUF in dialysis-dependent patients. Less catecholamine was needed to wean CPB using GHDF. It improved the immediate postoperative respiratory function and enabled earlier extubation. GHDF is a novel and effective option for intraoperative RRT in dialysis-dependent patients undergoing open-heart surgery.