Impact of protocolized fluid management on electrolyte stability in patients undergoing continuous renal replacement therapy

Abstract

ObjectiveContinuous renal replacement therapy (CRRT) is the standard treatment for critically ill patients with acute kidney injury (AKI). Electrolyte disturbance such as hypokalemia or hypophosphatemia occurs paradoxically in patients undergoing CRRT due to high clearance. We developed a fluid management protocol for dialysate and replacement fluid that depends on serum electrolytes and focuses on potassium and phosphate levels to prevent electrolyte disturbance during CRRT. The impact of our new fluid protocol on electrolyte stability was evaluated.MethodsAdult patients who received CRRT between 2013 and 2017 were included. Patients treated 2 years before (2013–2014; pre-protocol group) and 2 years following development of the fluid protocol (2016–2017; protocol group) were compared. The primary outcomes were individual coefficient of variation (CV) and abnormal event rates of serum phosphate and potassium. Secondary outcomes were frequency of electrolyte replacement and incidence of cardiac arrhythmias. Individual CV and abnormal event rates for each electrolyte were analyzed using the Wilcoxon rank-sum test and Chi-square test with Yates’ continuity correction.ResultsA total of 1,448 patients was included. Both serum phosphate and potassium were higher in the protocol group. The CVs of serum phosphate (pre-protocol vs. protocol, 0.275 [0.207–0.358] vs. 0.229 [0.169–0.304], p < 0.01) and potassium (0.104 [0.081–0.135] vs. 0.085 [0.064–0.110], p < 0.01) were significantly lower in the protocol group. The abnormal event rates of serum phosphate (rate [95% CI], 0.410 [0.400–0.415] vs. 0.280 [0.273–0.286], p < 0.01) and potassium (0.205 [0.199–0.211] vs. 0.083 [0.079–0.087], p < 0.01) were also significantly lower in the protocol group.ConclusionThe protocolized management of fluid in CRRT effectively prevented hypophosphatemia and hypokalemia by inducing excellent stability of serum phosphate and potassium levels.

Management for Electrolytes Disturbances during Continuous Renal Replacement Therapy

“…When patients have both hypernatremia and metabolic acidosis, sodium bicarbonate can be considered as an initial choice. When continuous veno-venous hemodiafiltration (CVVHDF) mode is used, this method needs to be applied to both dialysates and replacement fluids 15 20) . Example concentrations after adding different amounts of sodium are presented in Table 2 .…”

“…Example concentrations after adding different amounts of sodium are presented in Table 2 . The recommended sodium concentration for the initial CRRT solution is set to be 5-10 mmol/L lower than that of the patient 15 20) . Serial changes in serum sodium concentration should be frequently monitored.…”

“…In patients with life-threatening hyperkalemia, potassium-free solutions with a higher CRRT dose should be applied initially. Mild hyperkalemia can be corrected by using CRRT solutions with a potassium concentration of 2 mmol/L 18 20 39) . In patients with progressive tissue damage such as rhabdomyolysis, tumor lysis syndrome, or hemolysis, ongoing potassium load should be considered when choosing CRRT solutions based on their serum potassium concentrations 35 39) .…”

“…Most centers do not use a potassium concentration 4 mmol/L solutions for post-filter replacement fluid to avoid potential risk of hyperkalemia. Potassium concentrations should be monitored every 4 to 8 hours depending on the patients’ condition 20 44) .…”

“…However, this method can potentially induce hypomagnesemia since calcium containing compartment B contains magnesium as well. Therefore, frequent monitoring of serum calcium and magnesium concentration is mandatory to avoid hypocalcemia and hypomagnesemia 20) . An example of a detailed algorithm for patients with hypercalcemia in conjunction with serum potassium and phosphate concentrations is presented in Table 5 .…”