Ultrafiltration during intermittent hemodialysis in dogs with acute kidney injury

Background: Ultrafiltration is performed to alleviate fluid overload in dogs with acute kidney injury (AKI) undergoing intermittent hemodialysis (IHD). Objectives: To describe prescription patterns for ultrafiltration in dogs receiving IHD for AKI and risk factors for ultrafiltration-related complications. Animals: Seventy-seven dogs undergoing 144 IHD treatments between 2009 and 2019. Methods: Medical records of dogs receiving IHD for AKI were reviewed. The initial 3 IHD treatments in which ultrafiltration was prescribed were included. Ultrafiltration-related complications were defined as those requiring an intervention such as transient or permanent discontinuation of ultrafiltration. Results: Mean fluid removal rate per treatment was 8.1 ± 4.5 mL/kg/h. Ultrafiltration-related complications occurred in 37/144 (25.7%) of treatments. Hypotension was rare (6/144, 4.2% of treatments). No ultrafiltration-related complications resulted in deaths. The mean prescribed fluid removal rate per treatment was higher in dogs with ultrafiltration-related complications than without (10.8 ± 4.9 mL/kg/h vs 8.8 ± 5.1 mL/kg/h, respectively; P =.03). The mean delivered fluid removal rate per treatment was significantly lower in dogs with UF-related complications compared to those without complications (6.8 ± 4.0 mL/kg/h vs 8.6 ± 4.6 mL/kg/h, respectively; P =.04). Variables associated with ultrafiltration-related complications (P <.05) included central venous oxygen saturation, body temperature before IHD treatment, total extracorporeal circuit volume and BUN at the end of IHD treatment. Conclusions and Clinical Importance: Ultrafiltration during IHD in dogs with AKI is overall safe. Higher prescribed ultrafiltration rates were associated with increased risk of complications. Decrease in central venous oxygen saturation is associated with ultrafiltration-related complications, emphasizing the utility of in-line blood monitoring.