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

Abstract

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.