Point of care and central laboratory determinations of the aPTT are not interchangeable in surgical intensive care patients.
OBJECTIVE
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).


CONCLUSIONS
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.
Ferring
M
M
Divisions of Surgical Intensive Care, Department of Anesthesiology, Pharmacology and Surgical Intensive Care and the Hemostasis unit, Division of Angiology and Hemostasis, Department of Medicine, University Hospital of Geneva, Geneva, Switzerland.
Reber
G
G
de Moerloose
P
P
Merlani
P
P
Diby
M
M
Ricou
B
B
D000005:Abdomen / Q000601:surgery; D000368:Aged; D006348:Cardiac Surgical Procedures; D019411:Clinical Laboratory Techniques; D003422:Critical Care; D015951:Factor Xa / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D019095:Point-of-Care Systems; D011446:Prospective Studies; D015203:Reproducibility of Results
D015951:Factor Xa