Monitoring of Intraperitoneal Fluid Volume during Peritoneal Equilibration Testing using Segmental Bioimpedance

Background: Ultrafiltration failure and fluid overload are common in peritoneal dialysis (PD) patients. Knowledge of intraperitoneal volume (IPV) and time to peak IPV during a dwell would permit improved PD prescription. This study aimed to utilize trunk segmental bioimpedance analysis (SBIA) to quasi-continuously monitor IPV (IPV SBIA ) during the peritoneal dwell. Methods: IPV SBIA was measured every minute using lower-trunk SBIA (Hydra 4200; Xitron Technologies Inc., CA, USA) in 10 PD patients during a standard 240-min peritoneal equilibration test (PET). The known dialysate volume (2 L) rendered IPV SBIA calibration and calculation of instantaneous ultrafiltration volume (UFV SBIA ) possible. UFV SBIA was defined as IPV SBIA – 2 L. Results: Based on dialysate-to-plasma creatinine ratio, 2 patients were high, 7 high-average, and 1 low-average transporters. Technically sound IPV SBIA measurements were obtained in 9 patients (age 59.0 ± 8.8 years, 7 females, 5 African Americans). Drained ultrafiltration volume (UFV drain ) was 0.47 ± 0.21 L and correlated (r = 0.74; p < 0.05) with end-dwell UFV SBIA (0.55 ± 0.17 L). Peak UFV SBIA was 1.04 ± 0.32 L, it was reached 177 ± 61 min into the dwell and exceeded end-dwell UFV SBIA by 0.49 ± 0.28 L (95% CI: 0.27–0.7) and UFV drain by 0.52 ± 0.31 L (95% CI: 0.29–0.76), respectively. Conclusion: This pilot study demonstrates the feasibility of trunk segmental bioimpedance to quasi-continuously monitor IPV SBIA and identify the time to peak UFV SBIA during a standard PET. Such new insights into the dynamics of intraperitoneal fluid volume during the dwell may advance our understanding of the underlying transport physiology and eventually assist in improving PD treatment prescriptions.