The activated partial thromboplastin time (aPTT) is a common test used to monitor therapeutic heparin anticoagulation. This test employs optical methods but is susceptible to interference from factors like hemolysis, icterus, and lipemia. Intravenous lipid emulsions, particularly at 20% concentration, have been known to disrupt various clinical assays, including aPTT measurements.
This study aimed to investigate how the administration of propofol affects aPTT measurements in patients receiving both propofol and heparin. The researchers conducted an observational cohort study involving 38 intensive care patients. These patients were monitored with aPTT (a total of 531 measurements were taken).
The results showed that among the 21 patients (55%), a total of 109 aPTT measurements (21%) exhibited interference, requiring additional steps like ultracentrifugation for accurate reporting. Moreover, 12 aPTT measurements from 4 patients couldn’t be reported due to the interference. Interestingly, the doses of propofol were similar between patients experiencing interference and those who didn’t. Importantly, the interference wasn’t linked to factors like hemolysis or high bilirubin levels.
Given these findings, anesthesia professionals should be conscious of this interaction. They might want to explore alternative sedation options, consider different coagulation tests for heparin monitoring, or even contemplate using anticoagulation methods that don’t rely on aPTT assessments for management.
