Peritoneal dialysis for acute kidney injury: Equations for dosing in pandemics, disasters, and beyond

Background: Peritoneal dialysis (PD) is a viable option for renal replacement therapy in acute kidney injury (AKI), especially in challenging times during disasters and pandemics when resources are limited. While PD techniques are well described, there is uncertainty about how to determine the amount of PD to be prescribed toward a target dose. The aim of this study is to derive practical equations to assist with the prescription of PD for AKI. Methods: Using established physiological principles behind PD clearance and membrane transport, a primary determinant of dose delivery, equations were mathematically derived to estimate dialysate volume required to achieve a target dose of PD. Results: The main derivative equation is V-D = (1.2 x std-Kt/V x TBW)/(t(dwell) + 4), where V-D is the total dialysate volume per day, std-Kt/V is the desired weekly dose, TBW is the total body water, and t(dwell) is the dwell time. V-D can be expressed in terms of dwell volume, v(dwell), by V-D = (0.3 x std-Kt/V x TBW) - (6 x v(dwell)). Two further equations were derived which directly describe the mathematical relationship between t(dwell) and v(dwell). A calculator is included as an Online Supplementary Material. Conclusions: The equations are intended as a practical tool to estimate solute clearances and guide prescription of continuous PD. The estimated dialysate volume required for any dose target can be calculated from cycle duration or dwell volume. However, the exact target dose of PD is uncertain and should be adjusted according to the clinical circumstances and response to treatment. The equations presented in this article facilitate the adjustment of PD prescription toward the targeted solute clearance.