Abstract
Measurements were undertaken in 38 patients to characterize the haemostatic derangement that occurred in a mainly Arab population undergoing cardiopulmonary bypass (CPB) surgery. During heparinization there was significant prolongation of coagulation screening tests, PT, PTT, TT marked reduction of platelet count, fibrinogen, factors VII:C, V, ATIII, plasminogen and alpha-2 antiplasmin. These parameters increased after protamine. Factor VIII:C, vWF:ricofactor and serum FDP exhibited minimum fluctuation. Platelet aggregation responses to ADP, collagen, adrenaline and arachidonic acid showed significant inhibition during CPB and increased after protamine. In contrast, responses to ristocetin especially the lowest concentrations (1.2 and 1.0 mg/ml) were enhanced during and after CPB.
Patients were categorized according to the amount of postoperative chest tube blood drainage. Heavy bleeders (> 1500 ml/24 h) in contrast to light bleeders (blood loss of < 500 ml/24 h) exhibited more prolongation of PT, PTT and RT and more significant reduction of fibrinogen and vWF:ricofactor and FV, aggregation responses to low concentration of ADP, adrenaline, collagen and ristocetin. In most patients responses to ristocetin were enhanced irrespective of the degree of blood loss after surgery. We conclude that: (1) The derangement of haemostasis in Middle Eastern patients is of the same degree as published in Western (Caucasian) patients. (2) Haemostatic tests were predictive of severe haemorrhage only when performed in the immediate postbypass (postprotamine) period rather than preoperatively. (3) There is no evidence for the von Willebrand-like aggregation response to ristocetin, reported by others in severe bleeders.