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TECHNOLOGY, COMPUTING, AND SIMULATION

Changes in Thrombelastograph^TM Variables Associated with Aging

Department of Anaesthesiology, the University of Hong Kong, Hong Kong, China

Address correspondence and reprint requests to Kwok F. J. Ng, FANZCA, Department of Anaesthesiology, the University of Hong Kong, Room 424, Block K, Queen Mary Hospital, Hong Kong, China. Address e-mail to jkfng{at}hkucc.hku.hk

Aging is associated with hypercoagulability. To assess thrombelastography (TEG®) variables associated with aging, 132 adult patients of various ages undergoing orthopedic surgery for fracture repair had venous blood samples withdrawn for testing of recalcified TEG® before the induction of anesthesia. Age was weakly correlated with all TEG® variables: r time (R) (r = –0.45, P < 0.001; R = 19.5 – 0.09 x age), k time (K) (r = –0.49, P < 0.001; K = 6.5 – 0.04 x age), maximum amplitude (MA) (r = 0.25, P < 0.01; MA = 53.3 + 0.07 x age), and (r = 0.52, P < 0.001; = 52.8 + 0.2 x age). The correlation was stronger for men than for women. Only R was significantly correlated with age when the women were separately analyzed. Part of the correlation may be attributable to a concurrent decrease in hemoglobin with aging, but age remained an independent predictor of R, K, and on forward stepwise linear multiple regression analysis. Aging was weakly associated with changes in TEG® variables, which should be allowed for when interpreting TEG® measurements in the elderly.

IMPLICATIONS: Aging is associated with changes in thrombelastography (TEG®) variables. They change by approximately 20%–40% in the hypercoagulable direction in an 80-yr-old compared with a 20-yr-old. These difference may be important when TEG® interpretation involves patients of different ages, such as in clinical trials or when TEG®-based transfusion algorithms are applied.