Determinants of Total/ionized Calcium in patients undergoing citrate CVVH: A retrospective observational study

• Published in: Journal of critical care Vol. 59; pp. 16 - 22
• Main Authors: Boer, Willem, van Tornout, Mathias, Solmi, Francesca, Willaert, Xavier, Schetz, Miet, Oudemans-van Straaten, Heleen
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2020; Elsevier Limited
• Subjects: Aged; AKI; Anticoagulants - adverse effects; Anticoagulants - blood; APACHE; Calcium - blood; Calcium ratio; Catheters; Citrate accumulation; Citric Acid - adverse effects; Citric Acid - blood; Continuous Renal Replacement Therapy - methods; Critical care; CVVH; Female; Humans; Hydrogen-Ion Concentration; Male; Metabolism; Middle Aged; Observational studies; Patients; Phosphates - blood; Prospective Studies; Regional citrate anticoagulation; Renal replacement therapy; Retrospective Studies; Serum Albumin, Human - analysis; Treatment Outcome; Variables; Citrate accumulation; Calcium ratio; CVVH; T/iCa; Regional citrate anticoagulation; LMM; CRRT; AKI
• ISSN: 0883-9441; 1557-8615
• DOI: 10.1016/j.jcrc.2020.05.005

To identify potential determinants of the Total/ionized Ca ratio (T/iCa), a marker of citrate accumulation. Single-center retrospective observational study evaluating citrate dose, citrate target, albumin, phosphate, pH, lactate, and APACHE II score as potential determinants. Linear mixed models (LMM) using citrate dose and citrate target were developed describing associations with T/iCa. From a dataset of 471 samples in 103 patients, an LMM in 379 complete samples (95 patients) sets revealed that citrate dose, pH, phosphate, albumin and APACHE were interactively related to T/iCa. A rising citrate dose was associated with a higher increase in T/iCa when phosphate was high, and less when phosphate was low. A rising albumin was associated with a higher increase in T/iCa when APACHE was high and phosphate was low and less when APACHE was low and phosphate high. In case of acidosis, a rising lactate was associated with a higher increase in T/iCa. In the LMM using citrate target, citrate target and pH were the main independent predictors of T/iCa with albumin, phosphate and APACHE score as modifiers. Besides citrate dose, a high pH and high phosphate, albumin and APACHE are also associated with a rising T/iCa. •An increased Total/ionized Calcium ratio (T/iCa) in citrate CVVH need not reflect citrate accumulation.•Besides citrate, changes in albumin, phosphate, pH and severity of disease are associated with changes in T/iCa•There is a biochemical explanation for the T/iCa rise with increasing albumin, pH and phosphate, not reflecting accumulation.•higher pH is associated with an increasing T/iCa ratio, while accumulation of citrate my lead to acidosis.•Clinical suspicion for citrate toxicity is paramount. Complex interactions define T/iCa.