Perioperative thromboelastography and sonoclot analysis in morbidly obese patients

Abstract

Purpose: To investigate perioperative coagulation in morbidly obese (MO) patients with the thromboelastograph (TEG) and Sonoclot analyzer.

Methods: Twenty-six consecutive morbidly obese and 26 consecutive lean patients presenting for elective surgery were enrolled in this prospective, observational study. Blood was sampled for TEG and Sonoclot analysis immediately after anaesthetic induction and at the end of surgery in the MO group, and immediately after anaesthetic induction in the lean group. The R and K times, alpha angle, maximum amplitude and percentage fibrinolysis at 30 and 60 min were recorded from the TEG. The Sonoclot ACT, initial clot rate, peak amplitude and time to peak amplitude were recorded from the Sonoclot.

Results: The TEG in the MO group demonstrated decreased R and K times (8.6 +/- 4.8 vs 11.7 +/- 3.9 mm, and 2.8 +/- 1.2 vs 3.5 +/- 0.9 mm respectively (P < 0.05)), and increased alpha angle (73.7 +/- 6.0 vs 66.7 +/- 6.0 degrees, P < 0.05) and maximum amplitude (72.0 +/- 5.4 vs 67.9 +/- 4.4 mm, P < 0.05), without change in fibrinolysis. Sonoclot variables in the MO group included increased clot rate (37.5 +/- 11.5 vs 23.9 +/- 7.7%, P < 0.05) and decreased time to peak impedance (11.7 +/- 5.0 vs 17.5 +/- 7.2 min, P < 0.05), without change in Sonoclot ACT or peak signature impedance.

Conclusion: The MO group demonstrated accelerated fibrin formation, fibrinogen-platelet interaction, and platelet function compared with lean controls but no difference in fibrinolysis. Viscoelastic measures of coagulation may be useful in MO patients, who are at increased risk of thromboembolic events.