When going beyond 0.8 mg/dL over 4–6 h, citrate accumulation must always be considered.
Hypernatremia?
–Cause: high citrate flow relative to UF flow. May occur when UF flow gradually declines at unchanged citrate flow. Metabolic alkalosis is mostly present.
–Treatment: filter change if TMP >250 mm Hg, target normal sodium concentration, buffer-free solution.
Hyponatremia?
–Cause: use of substitution solutions with low sodium content. Since such solutions contain no buffer, metabolic acidosis may arise.
–Treatment: substitution with normal saline, bicarbonate-buffered solution.
Monitoring of Metabolic Variables and Coagulation Efficacy?
–At 4-h interval: measurement of Na+, K+, Cl−, ionized calcium, blood gas, (strong) anion gap calculation,
–Once daily: total calcium (to calculate calcium ratio or calcium gap), magnesium,
–Once or twice daily: creatinine, urea, phosphate,
–Monitoring intervals can be progressively prolonged in stable patients,
–Monitoring efficacy of circuit anticoagulation is necessary at the start of treatment and may be continued at the physician’s discretion thereafter. A post-filter ionized calcium level of 0.25–0.35 mmol/L (0.8–1.3 mg/dL) is targeted.
Conclusions
Vascular access and anticoagulation for CRRT have considerably evolved over the years. Dialysis catheters are preferentially placed in the RIJ vein with the tip positioned in the right atrium. Ultrasound guidance may assist in placing the catheter. Femoral vein catheterization is a valuable alternative. Future improvements in catheter “technology” and performance are awaited, in particular for use in combined extracorporeal techniques (e.g., low flow extracorporeal CO2 removal embedded in a CRRT circuit).
RCA has revolutionized anticoagulation by allowing lower circuit blood flow, causing less bleeding accidents, and creating better filter performance. However, implementing RCA requires careful monitoring, including early detection and anticipation of potential citrate-related metabolic complications. Novel citrate solutions are being developed that will allow more optimal metabolic fine-tuning.
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