Effects of 6% tetrastarch or lactated Ringer's solution on blood coagulation in hemorrhaged dogs.

BACKGROUND: Tetrastarch solution (TS) can impair coagulation but the clinical relevance of this impairment is unclear in veterinary medicine.

OBJECTIVE: Compare the effects of volume replacement (VR) with lactated Ringer's solution (LRS) or 6% TS on coagulation in hemorrhaged dogs.

ANIMALS: Six healthy English Pointer dogs (19.7-35.3 kg).

METHODS: Prospective crossover study. Dogs were anesthetized without hemorrhage and VR (control). Two weeks later, dogs were hemorrhaged under anesthesia on 2 occasions (8-week washout intervals) and randomly received VR with LRS or TS at 3:1 or 1:1 of shed blood, respectively, aiming to decrease the hematocrit to 33%. Rotational thromboelastometry and other coagulation variables were determined before 0.5, 2, and 4 hours after VR during anesthesia and 24 hours after VR (conscious dogs).

RESULTS: Buccal mucosal bleeding time did not differ between treatments after VR. Activated partial thromboplastin time increased from controls 4 hours after TS (P = 0.045). Clot formation time (CFT) and alfa-angle increased from controls from 0.5 to 4 hours after LRS (CFT, P ≤ 0.0001-0.02; alpha angle, P = 0.0001-0.02) and from 0.5 to 2 hours after TS (CFT, P = 0.0002-0.01; alpha angle, P = 0.0005-0.02). The maximum clot firmness decreased from controls from 0.5 to 4 hours after LRS (P ≤ 0.0001-0.01) and TS (P ≤ 0.0001-0.04).

CONCLUSIONS AND CLINICAL RELEVANCE: Tetrastarch does not impair primary hemostasis and induces transient dilutional coagulopathy that is similar to LRS because, when compared to a 3 times higher volume of LRS in hemorrhaged dogs, it does not cause greater interference on the viscoelastic properties of the coagulum.