Surgical Hemostasis and Electrosurgery

Question 1

What are 5 drugs that might affect bleeding times?

Answer 1

• acetylsalicylic acid (aspirin)
• warfarin
• adequan
• heparin
• NSAIDs

Question 2

What are some disease processes a patient might have going into surgery that could affect bleeding times?

Answer 2

liver dz, biliary duct obstruction, neoplasia, any condition leading to DIC

Question 3

What are 3 hereditary conditions that affect a patient’s bleeding times?

Answer 3

• Von Willebrand’s dz - primarily in Dobies
• Hemophilia A & B - male dog, sex-linked
• Canine thrombopathia - platelet disorder affecting mostly Bassett Hounds

Question 4

What 2 tests measure platelet contribution to hemostasis?

Answer 4

platelet count and BMBT

Question 5

What 2 tests measure intrinsic coagulation?

Answer 5

activated partial thromboplastin time (PTT) or activated clotting time (ACT)

Question 6

What test measures extrinsic coagulation?

Answer 6

prothrombin time (PT)

Question 7

What test measures intravascular coagulation?

Answer 7

fibrinogen-fibrin degration products (FDPs)

Question 8

What are the vascular factors that play a role in hemostasis?

Answer 8

reflex vasospasm, vascular retraction, and inversion of the intima of the b.v.; these lead to either a reduced rate or temporary arrest of hemorrhage and facilitate thrombus formation

Question 9

What are the intravascular factors that play a role in hemostasis?

Answer 9

combined effects of circulating platelets and coagulation factors; net result of their interaction is thrombus formation

1. platelet adhesion > platelet plug formation = primary hemostasis
2. conversion of soluble fibrinogen into insoluble fibrin clot = secondary hemostasis

Question 10

What are the extravascular factors involved in hemostasis?

Answer 10

• release of tissue thromboplastin by adjacent traumatized tissue - activates extrinsic clotting pathway
• tissue elasticity - increases pressure surrounding bleeding vessel to help reduce rate of hemorrhage and increases likelihood of effective thrombus formation; least effective in body cavities

Question 11

What are the various surgical methods of hemostasis, and when are they appropriate to use?

Answer 11

• pressure pad (e.g. Gelfoam) - low pressure hemorrhage from small vessels (capillaries < 1mm diameter)
• hemostatic forceps - alone or in combo w/ ligation/cautery when bleeding vessels are to be sacrified rather than repaired; vascular wall is injured sufficiently to activate physiological clotting mechanism
• vascular ligation - most secure method; most vessels
• ligating clips - vessels up to 5 mm diameter
• atraumatic vascular occlusion - temporarly occlude vessels during sx; either vascular clamps or tourniquets
• topical hemostatics - absorbable gelatin sponges (Gelfoam), oxidized cellulose-treated sx gauze (Surgicel), bone wax (for cancellous bone), Epi or norepi (vasoconstrictors)
• primary vascular repair
• tourniquets - provide bloodless field < 3 hrs
• electrosurgery - incr speed and improved visibility by achieving rapid hemostasis

Question 12

T or F: healing of incisions made using electrosurgery is delayed approximately 7 days compared to incisions made by scalpel

Answer 12

T

Question 13

What are the 2 types of electrosurgery and what are advantages and disadvantages of both?

Answer 13

• Electrocautery - thermal cautery
  
  • A: functions in bloody field, inexpensive
  • DA: extensive tissue destruction, effective only on very small vessels
• High frequency electrocoagulation - tx with electrode is NOT HOT, electrical energy passed into tissue in concentrated area, resistance provided by tissue generates heat
  
  • Monopolar - current passes thru plate beneath patient
    
    • A: can be adjusted to cutting mode or coag mode
    • DA: does not function in bloody field, should not be used near spinal cord/heart
  • Bipolar - current passes from one electrode to another (not thru patient)
    
    • A: Functions in bloody field, can be used near spinal cord/heart