Dynamic dosing for continuous renal replacement therapy: Service evaluation of the safety and effectiveness of titrating dose to biochemistry.

Introduction: Continuous renal replacement therapy (CRRT) dose is usually fixed and primarily weight-based. Whilst this is safe, theoretically, underdosing or overdosing may occur in those requiring acute versus maintenance CRRT respectively. We have developed a dynamic dosing protocol for CRRT which individualises and updates dosing according to biochemistry. Here we describe the protocol and compare it to a fixed dose protocol to evaluate its safety and effectiveness.

Methods: We conducted a service evaluation of this novel protocol using data from consecutive non-COVID-19 admissions receiving CRRT within Barts Health NHS trust, United Kingdom (UK). Fifty admissions using the dynamic protocol were compared to historically collected data from 108 admissions who used the fixed protocol. Acute and maintenance CRRT subgroups were analysed.

Results: For the dynamic protocol 49 patients were treated with 135 CRRT circuits. One patient had two admissions. Protocol compliance (compared in one ICU) was 76% (dynamic) vs 61% (fixed) ( < 0.05). For the dynamic versus fixed protocol, median CRRT lifespan censored for reasons other than clotting was: 56 h vs 58 h RCA (ns), 27 h versus 20 h heparin (ns) and 79 h versus 22 h no anticoagulation ( < 0.05). The dynamic vs fixed protocol average CRRT dose was: 30 ml/kg/h (14-57) vs 26 ml/kg/h (20-62) ( < 0.05). The dynamic protocol generated a similar rate of increase of bicarbonate in an acute phase (RCA: 0.2 mmol/l/h vs 0.21 mmol/l/h, ns) and maintained a more stable level in a maintenance phase (RCA: -0.01 mmol/l/h vs 0.07 mmol/l/h,  < 0.05).

Discussion: Dynamic dosing for CRRT in this institution was safe and may lead to more tailored maintenance of biochemical homoeostasis.