Anticoagulation During Cardiopulmonary Bypass

Heparin is a naturally occurring polysaccharide secreted by basophils and mast cells, primarily in lung and liver tissues. The main role of heparin is to prevent coagulation of blood in these slow flowing circulatory systems. Its molecular weight varies between 6000 and 22,000 Daltons depending on its source. Bovine lung heparins are thought to be more immunologically active than the porcine gut heparins. Heparin has a negatively charged molecule that is neutralised electrostatically by a...

Section I Normal Haemostasis A Introduction

Haemostasis is a host defence mechanism that protects the integrity of the vascular system after tissue injury. It is responsible for minimising blood loss. It is critical that formation of blood clot in response to a breach in the vascular endothelium occurs rapidly. Systemic activation of the coagulation cascade or extensive local extension of thrombosis resulting in vascular occlusion, however, should not occur. Immediate vasoconstriction of the injured vessel and reflex constriction of...

Postoperative Haematoma

Postoperative complications from intracranial haematoma are uncommon after elective brain surgery and rare after elective spinal surgery (< 3 ). The principles of meticulous haemostasis and avoidance of dead spaces are common to both cranial and spinal surgery in preventing postoperative haematoma.16 The larger the craniotomy flap, the greater is the risk of a haematoma. This risk increases significantly with emergency trauma surgery because of the wider area of damage. The potential space...

Haemostatic Alteration In Cardiopulmonary Bypass Surgery

Open cardiac surgery produces significant activation of coagulation, fibrinolysis, and platelets, despite the use of heparin. This is due to the presence of the cardiopulmonary bypass circuit. The following are well-documented alterations.186 1. Platelet defects during CPB A qualitative platelet abnormality exists in virtually 100 of patients during CPB and usually reverses within an hour or so after completion of CPB. The blood-material surface interaction and shear effects of flow through the...

Preoperative Assessment

A comprehensive medical history is important to identify patients at risk of bleeding.4 Significant factors include a family history or the patient suffering bleeding after previous surgery or dental extractions. One study indicated that a positive medical history is much more likely to predict bleeding than any laboratory test. Other significant symptoms may include epistaxis, menorrhagia and or bruising. However von Willebrand disease may be clinically silent and may only manifest itself in...

Prostate

Nd YAG lasers cause coagulation and have been used for trans-urethral laser ablation of the prostate in both the contact and the non-contact modes. In addition to coagulation of the prostatic tissue, adequate haemostasis is achieved as the coagulation extends into the blood vessels as well. The major disadvantages are, however, postoperative irritative voiding symptoms,49 and delayed unpredictable tissue sloughing. Vaporisation can be carried out with the CO2 or the Holmium laser. The Holmium...

Historical Note

Till the early 20th century, the scope of cardiac surgery was restricted to the repair of cardiac trauma and the closed heart procedures for rheumatic valvular lesions. There was an urgent need to be able to stop the heart without causing damage to the vital organs and to perform surgery for pulmonary embolus and cyanotic heart disease. This had to wait until the discovery of heparin. Heparin was first discovered in its impure form in liver tissues, by the research fellow, Jay McLean and...

Effects Of Immunosuppressants On Coagulation During

An increased risk of thrombosis is associated with some of the immunosuppressant agents. Cyclosporine, for example, has been associated with elevated fibrinogen level, increased platelet aggregation, and von Willebrand factor changes.29 In addition, corticos-teroids have been associated with increased plasminogen activator inhibitor activity.30 Some studies have debated if the use of sirolimus, in combination with cyclosporine or tacrolimus, is associated with an increased risk of hepatic...