Intensive monitoring of post filter ionized calcium concentrations during CVVHD with regional citrate anticoagulation: A retrospective study.

BACKGROUND: The aim of the present study was to assess the predictive value of post-filter ionized calcium (pfCa) levels for filter-clotting during continuous veno-venous hemodialysis (CVVHD) with regional citrate anticoagulation (RCA). METHODS: Retrospective analysis of a database derived from 6 intensive care units (ICU) at a university hospital. During the 3-year period 1070 patients were treated with RCA-CVVHD with a citrate starting dose of 4 mmol/L blood and a target-range for pfCa of 0.25-0.35 mmol/L. RESULTS: The pfCa concentrations at RCA-CVVHD initiation were within the target range in 69.7% of patients. Within 12 h the fraction of patients with pfCa above target-range decreased significantly from 13.1% to 7.8% (p < .001). There was no significant difference in filter survival between patients with a pfCa initially below, within, or above the target-range (83.7%, 89.5% and 90.4%; p = .228) and no significant correlation between the last pfCa and the incidence of filter clotting (rho 0.018, p = .572 and -0.054, p = .104; respectively). CONCLUSIONS: CVVHD with a citrate starting dose of 4 mmol/L blood resulted in a pfCa within target in the majority of patients. The observation that pfCa was not associated with the incidence of circuit clotting suggests that less frequent measurements of pfCA might be safe.

Hyperlactatemia, Lactate Kinetics and Prediction of Citrate Accumulation in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy With Regional Citrate Anticoagulation.

OBJECTIVES: Citrate accumulation is a major complication of regional citrate anticoagulation during continuous renal replacement therapy. We studied the prediction of citrate accumulation during continuous veno-venous hemodialysis with regional citrate anticoagulation by initial lactate concentrations and lactate kinetics. DESIGN: A retrospective follow-up analysis from a cohort of critically ill patients. SETTING: Mixed medical-surgical ICUs at a university hospital. PATIENTS: All adult patients with acute kidney injury and treated with regional citrate anticoagulation-continuous veno-venous hemodialysis during a 3-year period (n = 1,070) were included in this retrospective study and screened for metabolic signs of citrate accumulation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The frequency of citrate accumulation during the first 48 hours of therapy was 2.26%. In patients with initial normal lactate (< 2.2 mmol/L), elevated lactate (≥ 2.2 to < 4 mmol/L), or severe hyperlactatemia (≥ 4 mmol/L), the frequency of citrate accumulation was 0.77%, 2.70%, and 6.33%, respectively. Receiver operating characteristics-area under the curve of initial lactate concentration was 0.789 for the prediction of citrate accumulation. Optimal cutoff from receiver operating characteristics (2.39 mmol/L) showed strong negative prediction (99.28%), but weak positive prediction (5.21%). The slope intercept of lactate kinetics over 48 hours was positive and significantly higher in patients with citrate accumulation compared to those without (+0.2 vs -0.006 mmol/L/hr; p < 0.001). In patients with initial severe hyperlactatemia (≥ 4 mmol/L), the median calculated lactate clearance at 6, 12, and 18 hours was 24.0%, 48.1%, and 59.4% in the nonaccumulation group. These clearance rates were significantly higher at each time-point compared to patients with citrate accumulation (-9.8%, -20.5%, and 2.3%, respectively; p < 0.001 for each time-point). The highest receiver operating characteristics-area under the curve for citrate accumulation was observed for 12-hour values of lactate clearance (area under the curve = 0.839; 95% CI, 0.751-0.927) with an optimal cut-off value of 24.3%. CONCLUSIONS: Risk of citrate accumulation during regional citrate anticoagulation in a well-selected cohort of patients is low even in case of initial severe hyperlactatemia. Lactate kinetics rather than initially elevated lactate concentration should be considered in assessing the risk of citrate accumulation.

Incidence and outcome of metabolic disarrangements consistent with citrate accumulation in critically ill patients undergoing continuous venovenous hemodialysis with regional citrate anticoagulation.

BACKGROUND: Systemic citrate accumulation is a complication of regional citrate anticoagulation (RCA) during continuous renal replacement therapy (CRRT). Our objective was to determine the incidence of clinical signs consistent with citrate accumulation in a large and representative cohort of intensive care unit patients undergoing RCA-CRRT. METHODS: Patients treated with RCA-CRRT during 2008-2010 were retrospectively analyzed. Decreased systemic ionized calcium (iCa), increased demand for calcium substitution, elevated total calcium to iCa ratio, and metabolic acidosis were evaluated as indicators for citrate accumulation. RESULTS: In the 3-year period, 1070 patients were treated with RCA-continuous venovenous hemodialysis. Metabolic signs of citrate accumulation occurred in 32 patients (2.99%, 64.5 ± 14.0 years, 65.6% male, Acute Physiology and Chronic Health Evaluation score 34.2 ± 9.7): systemic iCa decreased to 1.01 ± 0.10 mmol/L with a simultaneous increase of the calcium substitution rate to 129% ± 26%, and the mean total calcium to iCa ratio increased to 2.51 ± 0.54. All 32 patients had therapy-resistant shock with severe lactic acidosis (pH 7.20 ± 0.11, lactate 136 ± 61 mg/dL), indicating severe intracellular hypoxia. None of the patients survived. CONCLUSIONS: The incidence of disarrangements consistent with citrate accumulation in patients undergoing RCA-continuous venovenous hemodialysis was low, taking place exclusively in patients with severe lactic acidosis due to multiorgan failure. This suggests that the appearance of citrate accumulation is secondary to a severe failure of cellular respiration.