University Hospitals Cleveland Medical Center SHAKER HEIGHTS, Ohio, United States
Background/Case Studies: Citrate is a common anticoagulant used in extracorporeal circuits and is an essential component of apheresis procedures. Citrate toxicity is a common adverse event in apheresis procedures, and it is the result of citrate’s chelation of calcium leading to a transient but significant hypocalcemia. Citrate toxicity initially presents with perioral or extremities paresthesia; however, if left uncorrected, it can result in cardiac arrythmias, seizures, and respiratory distress. Citrate toxicity tends to be more commonly encountered in longer procedures as more calcium is removed from the patient. Ionized calcium (iCal) is an important marker to monitor calcium levels with patients undergoing apheresis procedures.
Automated red cell exchanges (RCE), used predominantly to aid in the management of sickle cell disease, make up a large proportion of apheresis procedures. Despite the risk of citrate toxicity, calcium replacement is not routinely given during the procedure. There is currently little data available studying the changes in iCal during RCE procedure and its relationship with citrate toxicity. This study seeks to quantify the changes in iCal and its relationship with citrate toxicity during RCE procedures conducted at a large academic teaching hospital.
Study
Design/Methods: A chart review was conducted within the electronic medical records to identify patients who have received RCE as part of the chronic RCE program at University Hospitals Cleveland Medical Center between 10/01/2023 to 5/15/2025. Pre and post exchange iCal levels were identified from the laboratory reports. The presence of adverse events, especially citrate toxicity, were noted from the post-procedural notes.
Results/Findings: 32 sickle cell disease patients (13 Female and 19 Male) were included in the study ranging from 16 to 56 years of age. Over the study period, the patients received between 4 and 17 RCE totaling to 413 procedures. The duration of individual procedures ranged from 35 minutes to 3 hours and 55 minutes with an average length of 1 hour and 34 minutes. Pre-procedure iCal levels ranged between 0.95 mmol/L to 1.40 mmol/L with an average of 1.21 mmol/L. 96.6% of RCE procedures resulted in a decrease of post-procedure iCal with an average decrease of 0.13 (+ 0.003) mmol/L; however, there can be a maximum decrease of 0.37 mmol/L. No significant relationship was identified between iCal changes and the duration of the RCE procedure (R2 = 0.08). Adverse events occurred in 25 of the procedures of which only 2 were categorized as citrate toxicity reaction. The 2 citrate toxicity adverse reactions occurred in the same patient with a post iCal of 1.09 mmol/L and 1.10 mmol/L.
Conclusions: The decrease in ionized calcium over the course of an RCE procedure does not strongly contribute to the development of citrate toxicity, and confirms that routine calcium supplementation is not required.
