| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© The Board of Management and Trustees of the British Journal of Anaesthesia [2007]. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org
Management of coagulation during cardiopulmonary bypass
SpR Anaesthetics
St George's Hospital London UK
Consultant Anaesthetist
Department of Anaesthetics
St George's Hospital
Blackshaw Road London SW17 0QT UK
Tel: +44 020 8725 3316 Fax: +44 020 8725 3135 E-mail: hanif.meeran@stgeorges.nhs.uk
Key Words: Coagulation and inflammatory pathways are triggered by contact of blood with the cardiopulmonary bypass (CPB) circuit and surgical wound during open heart surgery. • Heparin remains the standard anticoagulant for CPB; despite inconsistent relationships between coagulation tests, thrombin inhibition, and plasma concentrations. • Activated clotting time is the standard test of coagulation during CPB. • Thromboelastography is a point of care coagulation test that gives rapid, qualitative information about coagulation factors, platelets, and fibrinolysis. • Following protamine reversal of heparin, failure to re-establish normal haemostasis can occur and may result in postoperative bleeding.
| The first 150 words of the full text of this article appear below. |
 |
Coagulation in cardiac surgery |
|---|
During normal haemostasis, a platelet plug forms at the site of vessel injury. This is stabilized by fibrin produced from enzymatic reactions of coagulation factors. These reactions can only proceed at a sufficient rate on the phospholipid surface of activated platelets. This requirement for platelet phospholipid, plus a series of inhibitors, and the fibrinolytic system restrict clot production to the site of injury. Historically, coagulation was considered as two separate pathways of factors, denoted by Roman numerals, arranged in cascades. The ‘intrinsic’ (contact activation) and ‘extrinsic’ (tissue factor) pathways join to form a common pathway at factor Xa that activates thrombin, which in turn converts fibrinogen to fibrin. Although not an accurate representation of in vivo coagulation, this scheme remains useful when trying to understand laboratory tests. The prothrombin time (PT) is a test of the extrinsic pathway. The activated partial thromboplastin time (APTT) is a test of the intrinsic
|
Anticoagulation for cardiopulmonary bypass |
|---|
Unfractionated heparin
Heparin resistance
Alternatives to unfractionated heparin
Heparin reversal with protamine
|
Monitoring anticoagulation |
|---|
Activated clotting time
Other measures of anticoagulation
|
Monitoring coagulation to guide haemostatic blood transfusion |
|---|
Laboratory tests of coagulation
Thromboelastography