Automated electronic monitoring of circuit pressures during continuous renal replacement therapy: A technical report

Background: Automated electronic monitoring and analysis of circuit pressures during continuous renal replacement therapy (CRRT) has the potential to predict failure and allow intervention to optimise function. Methods: Current CRRT machines can measure and store pressure readings for downloading into databases and for analysis. We developed a procedure to obtain such data at intervals of 1 minute and analyse them using the Prismaflex CRRT machine, and we present an example of such analysis. Results: We obtained data on pressures obtained at intervals of 1 minute in a patient with acute kidney injury and sepsis treated with continuous haemofiltration at 2L/hour of ultrafiltration and a blood flow of 200mL/minute. Data analysis identified progressive increases in transmembrane pressure (TMP) and prefilter pressure (PFP) from time 0 until 33 hours or clotting. TMP increased from 104mmHg to 313mmHg and PFP increased from from 131mmHg to 185mmHg. Effluent pressure showed a progressive increase in the negative pressure applied to achieve ultrafiltration from 0mmHg to −168 mmHg. The inflection point for such changes was also identified. Blood pathway pressures for access and return remained unchanged throughout. Conclusions: Automated electronic monitoring of circuit pressure during CRRT is possible and provides useful information on the evolution of circuit clotting.