Urinary 11-dehydrothromboxane B2 aspirin efficacy testing is sensitive to perioperative inflammation in pediatric solid-organ transplant patients.

Background: Evidence for aspirin efficacy testing in pediatrics is limited, especially outside of cardiology, yet thrombotic events have high morbidity in other areas such as pediatric transplant surgery. Debates about whether thromboembolic events while on aspirin represent "aspirin resistance" or "high on-treatment platelet reactivity" persist, given the poor intertest agreement between testing platforms.

Procedure: This prospective observational study involved measuring aspirin efficacy using ex vivo testing of platelet aggregation (VerifyNow-Aspirin, VN) and urine 11-dehydrothromboxane B2 (AsprinWorks, UTxB2) contemporaneously at up to three time points after major noncardiac organ transplant surgery.

Determining optimal waste volume from an intravenous catheter.

Waste is blood drawn from an intravenous (IV) catheter to remove saline or heparin before obtaining a blood sample. This study examines the minimum waste volume resulting in an undiluted sample. A repeated-measures design was used.