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Haemostasis in neurosurgery [Autosaved].pptx
- 2. Outline • Introduction • Surgical importance • Physiology of haemostasis • Preoperative assessment • Intraoperative techniques • Postoperative techniques • Conclusion • References
- 3. Introduction • Haemo and stasis • Refers to the process of terminating blood loss from an injured vessel • In surgery there is a fine balance between bleeding and thrombosis • Although the haemostatic process helps to halt excessive blood loss it might, in a prothrombotic milieu become pathological and lead to thrombosis
- 4. Introduction • In the management of surgical patients, it is essential to minimise the risk of complications from bleeding. • Neurosurgery is unique in that postoperative bleeding can be devastating and result in death or disability. • As a consequence absolute haemostasis is essential
- 5. Introduction • Technical advances such as the operating microscope and bipolar coagulation allow the accurate control of bleeding from fine cortical vessels. • Chemical haemostasis also plays a part in the control of bleeding from capillaries and veins. • However unlike his colleagues in other specialties the neurosurgeon can rarely rely on drains to an operative site or use monopolar coagulation
- 6. Surgical importance • Adequate surgical haemostasis reduces morbidity and mortality in postop patients by; • Minimising blood loss and anemia • Attenuating metabolic response to trauma • Reducing infection • Improving wound healing
- 7. Physiology of haemostasis • Involves three interdependent processes: • Initial vasoconstriction • Platelet plug formation • Coagulation formation and fibrinolysis
- 8. vasoconstriction • Initial vascular response to injury • Dependent on local contraction of smooth muscles • Vasoconstrictors: 5-HT,TXA2, bradykinins, fibrinopeptides
- 9. Platelet plug formation • Platelets become sticky when exposed to sub- endothelial collagen to which they become adherent • VWF is necessary for platelet collagen adherence • The adherent platelets initiate a reaction to recruit other platelets which aggregate to form a loose platelet plug
- 10. Coagulation formation • Aim is to convert prothrombin to thrombin • Thrombin cleaves fibrinogen molecules to insoluble fibrin • Fibrin provides stability to the platelet plug • Involves two pathways; • Extrinsic factors XII,XI,IX,X,II • Intrinsic factors;VII,X,II
- 11. Clotting cascade
- 12. Preoperative assessment • History • Physical examination • Investigation
- 13. History • Easy bruisability • Mucosal bleeds • Epistaxis • Menorrhagia • Bleeding after surgical procedure or dental extractions • History of comorbid conditions such as hypertension, CLD. • Alcohol consumption • Family history of bleeding disorders • Drug history; anticoagulants, antiplatelets and NSAIDS
- 14. Examination • General examination; Pallor, Jaundice Anasarca, asterixis • Skin; Petechae, Ecchymosis • Abdomen: hepatomegaly, splenomegaly
- 15. General Investigations • Liver function tests • Urea electrolytes and creatinine • Abdominal USS
- 16. Specific investigations • Full blood count and differentials • Bleeding time (1-9minutes) • Prothrombin time (9.6-11.8seconds) • Activated partial thromboplastin time (APTT) (20- 36seconds) • Thrombin time (15-19seconds) • INR • Clothing factor assays • Group and crossmatch blood
- 17. Intraoperative techniques • Anaesthetic techniques • Surgical techniques • Pharmacological techniques • Topical agents • Mechanical factors • Blood products
- 18. Anaesthetic techniques • Posture/position • Permissive hypotension • Normothermia • Combined GA + regional anaesthesia e.g with xylocaine and adrenaline
- 19. Surgical techniques • Appropriate dissection • Minimal access surgery • Use of clamps • Intraluminal balloons • Artery ligation • Bipolar diathemy
- 21. Topical agents • Bone wax • Surgicell • Gelfoam • Avitene • Topical thrombin • Fibrin sealants • Platelet sealants
- 22. Pharmacological techniques • Trenexamic acid • Aminocaproic acid • Aprotinin • Recombinant factor VIIa • Vitamin K
- 23. Mechanical factors • Digital pressure • Pressure packing • Sutures • Staples • Local application of gauzes and sponges • Head elevation
- 24. Blood products • Fresh frozen plasma • Platelet concentrates • Factor concentrates
- 25. Post op management • Antbiotics • Wound care • Elevation
- 26. Conclusion • It is the responsibility of the neurosurgeon to preempt surgically important haemorrhage, employ multiple modalities to prevent it and arrest it when it occurs
- 27. References • Koh MB, Hunt BJ. (2003). The management of perioperative bleeding. Blood Rev 17(3): 179-- 185. • Powner DJ, Hartwell EA, Hoots WK. (2005). Counteracting the effects of anticoagulants and antiplatelet agents during neurosurgical emergencies.
- 28. References • Schwartz principles of surgery
Notes de l'éditeur
- Monro-Kellie • Vbrain Vbrain VbrainVbrain+ Vblood VbloodVblood Vblood+ Vcsf Vcsf= Vic Vic = ConstantConstantConstant ConstantConstant Constant
- Antiplatelet-7-10days before surery NSAIDs-at least 2 days before surgery
- -In neurosurgery one cannot pack the brain, and the area of applied pressure should be as small as possible. Adequate visualisation can often be accomplished with patties and two suckers. -Cannulation of the venous sinus may be considered necessary, using a small Foley catheter to occlude the lumen by distending the balloon. Only the proximal third of the sagittal sinus can be sacrificed without risk of cerebral infarction. Balloon occlusion of the distal sinus may be temporary, until a decision can be taken on whether the opening can be approximated directly or requires grafting. -In a craniotomy plastic haemostatic ‘‘Raney’’ clips are first applied to the edge of the scalp. The bone edges are waxed and then the extradural space is closed with hitch sutures. The dura can then be opened and the operative field is kept clear and dry for working under the microscope -Bipolar coagulation is fundamental to neurosurgery because it enables precise coagulation of small vessels without dangerous spread of the current to adjacent neural and vascular structures
- Bone wax-bees wax serve as mechanical bareer to seal the wound Surgicell (an oxidised regenerated cellulose), gel foam (a gelatinous sponge), sponge for which clotting forms avitene (a microfibrillar collagen) may be used. Floseal matrix haemostatic sealant, a gelatine matrix, is expanding its range of use. It has been found to be a reliable if not expensive agent to control bleeding in both cardiac and spinal surgery
- Anti-fibrinolytic drugs include aprotinin and lysine analogues such as tranexamic acid. The haemostatic effects of these agents depend upon inhibition of fibrinolysis as well as, in the case of aprotinin, a protective effect on platelets. Aprotinin is a 58 amino acid polypeptide of bovine origin, which directly inhibits various serine proteases, including plasmin. Adverse effects are rare but hypersensitivity reactions have been reported including anaphylaxis. The use