Purpose: The objective of the study was to compare a bedside whole blood activated partial thromboplastin time (aPTT) performed by a point of care (POC) apparatus (CoaguCheck(R) Pro) in surgical intensive care (SIC) patients with a conventional aPTT obtained from the central laboratory.
Methods: The prospective concomitant measurements of the two aPTT were performed in 233 samples from 46 consecutive patients admitted after cardiovascular or major abdominal surgery.
Results: Inter-operator, inter-instrument and inter-cartridge variability of the new device measured in three healthy volunteers and in nine patients in stable condition (controls) was low (F test: P=0.86). The agreement by Bland and Altman between POC and central laboratory aPTT (-20.2 +/- 18.8 sec) was not satisfactory. The agreement between POC and central laboratory aPTT in patients after surgery was worst (-17 +/- 33.1 sec). Heparin treatment or timing of blood sampling after intensive care admission (<48 hr vs >48 hr) did not influence the agreement. The correlation between POC or central laboratory aPTT and anti-factor Xa activity was poor (r(2) 0.077 and 0.181 respectively). The test which correlated the best to heparin doses was anti-factor Xa activity (r(2) 0.714).
Conclusion: POC aPTT and central laboratory aPTT showed a poor agreement in SIC patients admitted after surgery, although in healthy volunteers or in control patients, this agreement was better. The best test to monitor heparin treatment in this setting was anti-factor Xa activity.