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Bleeding due to post-bypass haemostatic dysfunction: An investigation of mechanisms, prevention and therapy

Kallis, Panayiotis; (1996) Bleeding due to post-bypass haemostatic dysfunction: An investigation of mechanisms, prevention and therapy. Masters thesis (M.S), UCL (University College London). Green open access

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Abstract

The morbidity and mortality following cardiopulmonary bypass (CPB) is significantly increased by excessive post-operative bleeding. Furthermore excessive bleeding drains our limited financial resources and supply of homologous blood products. In this thesis the mechanisms responsible for excessive bleeding following CPB are investigated and measures to prevent and to treat excessive bleeding are established. The effect of aprotinin on post-operative blood loss was investigated in a prospective, randomised, placebo controlled, double blind clinical trial in 60 patients who bled in excess of 400 ml during the first three hours following CPB and who had not received prophylactic aprotinin in theatre. The principal conclusions of this trial are: Post-operative aprotinin therapy 1) significantly reduced excessive post-operative bleeding, 2) was associated with a significantly higher Hb at the time of hospital discharge, 3) but did not reduce homologous blood transfusion. Aprotinin therapy was associated with a significant 1) increase in surface expression of platelet GPIb adhesive receptors, 3) reduction in plasma tPA level, 4) increase in plasma fibrinogen levels compared to the placebo group. Aprotinin treatment may have been associated with preservation of platelet vWF levels but without any alteration in platelet aggregation and vWF multimeric structure. The consequences of continuation of pre-operative aspirin, in terms of altered haemostasis and increased bleeding, was defined in a prospective, randomised, placebo controlled, double blind clinical trial in 100 patients scheduled to undergo elective CABG. The principal conclusions of this trial are: Pre-operative aspirin significantly increased 1) post-operative bleeding, 2) transfusion requirements of blood products, and 3) the risk of re-exploration for bleeding. The principal effects of aspirin on platelet function were: 1) Reduction in platelet aggregation, 2) increase in bleeding time, but 3) without any significant effect on the components of platelet adhesion. From the work described in this thesis practical conclusions can be drawn which influence clinical practice: 1) Pre-operative aspirin therapy should be discontinued one week prior to elective CABG in order to reduce postoperative bleeding and 2) in patients who bleed excessively in the first few hours following CPB aprotinin therapy is effective in reducing further blood loss.

Type: Thesis (Masters)
Qualification: M.S
Title: Bleeding due to post-bypass haemostatic dysfunction: An investigation of mechanisms, prevention and therapy
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Biological sciences; Cardiopulmonary bypass
URI: https://discovery.ucl.ac.uk/id/eprint/10106021
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