Comparison of point-of-care testing (POCT): i-STAT(®) international normalized ratio (INR) vs reference laboratory INR in pediatric patients undergoing major surgery.

Background: The aim of the study was to compare international normalized ratio (INR) results obtained by point-of-care testing (i-STAT® device) with the reference laboratory INR in children undergoing major surgery with expected significant blood loss.

Methods:   Pediatric patients undergoing craniofacial, spine, hip, or cancer surgery were included. Blood samples for coagulation testing were tested at several intraoperative time points and generally withdrawn from the arterial catheter, if accessible. A volume of 1.4 ml citrated blood was used for the reference laboratory INR test, and 0.1 ml of blood was taken for the whole blood INR test using the i-STAT® device. Blood samples for both tests were withdrawn at the same time and immediately analyzed with both devices.

Results: A total of 169 paired blood samples were taken intraoperatively from 44 pediatric patients [IQR 0.9-10.7 years (median 3.3)]. Reference laboratory INR ranged from 0.96 to 3.43 (mean 1.40; sd 0.32) and INR of i-STAT® from 0.95 to 2.29 (mean 1.26; sd 0.22). The correlation coefficient was 0.83 (P < 0.001), and the bias values were 0.12 and 0.55 at the medical decision level of ≤2.0 and >2.0, respectively.

Conclusions: In the perioperative setting, point-of-care INR testing in children using the i-STAT® device is a reliable and easy-to-handle method for INR values ≤2.0, while INR values >2.0 might be underestimated.