Haemostasis

Question 1

How does shock occur?

Answer 1

Reduced O2 Perfusion

Question 2

What are the clinical skills of shock?

Answer 2

• Sinus tachycardia or bradycardia
• Hypotension, poor pulse quality
• Cold extremities (hypothermia)
• Pallor
• Biochemistry changes (renal, lactate?

Question 3

What is the main approach to intra-operative haemorrhage?

Answer 3

Recognise and address blood loss
* Rule out, identify source of bleeding
* Suture malfunction/deficiency
* Occult haemorrhage (unknown/unexplored/distant to surgical field)
* Accidental damage or collateral damage during surgery
* Damage after surgery (post operative haemorrhage)
* Restore haemostasis
* Reverse hypothermia, shock and other complications
* Monitor
* Stability of coagulation
* New or ongoing blood loss
* Complications

Question 4

How do you quantify blood loss?

Answer 4

Blood losses should be estimated or measured during surgery
* Swabs contain standard amounts of fluid dependent upon size (6, 8 or 10 mls)
* Weigh swabs
* Compare dry swab with saturated swab
* Blood essentially water; 1g=1ml
* Loss onto floor, drapes should be estimated
* Suctioned blood should be measured and recorded
* Record volume of flush used and remaining and calculate blood loss

Question 5

What is the function of haemostatic forceps?

Answer 5

• They crush tissue
• Ratchet allows them to be left in position
• Temporarily arrest haemorrhage
• damage the vascular wall to activate the clotting mechanism

Question 6

What is electrocautery?

Answer 6

Where heat is applied to tissue (e.g disbudding)

Question 7

What is Electrosurgery/ Electrocoagulation?

Answer 7

electrical current passes from the metal tip to the blood vessel
* Heat produced in tissue itself and converted into thermal energy to seal vessel
* Can use for incision but care with thermal necrosis delaying healing
* Works best for vessels 2mm or less

Question 8

What is monopolar electrosurgery?

Answer 8

Ground plate lies contact and beneath the patient.
* Current flows through electrode (handpiece) through patient to ground plate
* If contact not good can cause burns
* Cut and coagulate possible
* Requires dry surgical field
* Bipolar more precise

Question 9

What is radiosurgery?

Answer 9

Similar to electrosurgery
* Cut and coagulation
* Uses high-frequency radio waves
* Patient is not part of the circuit
* Plate is not grounding and doesn’t need to be in contact with skin

Question 10

What is a hotblade?

Answer 10

• Bipolar vessel sealer
• No automatic adjustment or cutting
• Adequacy of coagulation determined visually
• Surgeon activates knife
• ‘Individual use’ but can be sterilised by ethylene
  oxide
• Cheaper than the others

Question 11

What are the two types of harmonic scalpel?

Answer 11

• Ultrasonic energy
• Lasers

Question 12

How does adrenaline help seal wounds?

Answer 12

• Small superficial wounds
• Vasoconstriction may reduce blood flow to allow clot formation
• 1:1000 to 1: 10000
• Diffuse bleed – intranasal/intraoral
• Can have systemic effects
• Local ischaemia

Question 13

Name 5 topical haemostatic agents

Answer 13

• Gelfoam-Spongostan (absorbable haemostatic gelatin)
• Lyostypt (collagen sponge)
• Surgicell –surgicell fibrillar (oxidised regenerated cellulose)
• Surgiflo (haemostatic gelatin matrix)-reconstituted with saline
• Bone wax

Question 14

When might bone wax be used?

Answer 14

Used in neuro-surgery, blocks the blood vessels

Question 15

Name 4 active topical haemostatic agents

Answer 15

• Autogenous muscle tissue
• Thrombin
• Topical fibrin haemostatic sealant

Question 16

What is the function of transexamic acid?

Answer 16

• synthetic analogue of lycine
• binds plasminogen and stops the conversion to plasmin and fibrin breakdown
• duration of the thrombus/ clot is prolonged
• Used in grey hounds

Question 17

What is the function of desmopressin?

Answer 17

• Increases expression of von Willebrand’s factor and factor VIII
• Reduces BMBT in vWD- affected Dobermanns
• Does not work in type III vWD
• Dilute and give 30 minutes before surgery

Question 18

What is the function of a tourniquet?

Answer 18

Reduce the amount of arterial blood reaching the distal limb
* Causes ischaemic and anaerobic respiration of tissues lactic acid accumulation can result in pain

Question 19

How long should a tourniquet be applied for?

Answer 19

For most purposes the tourniquet should be applied for less than 2 hours

Question 20

What is an esmarch bandage used for?

Answer 20

For lower limb surgery

Question 21

How would you use an esmarch bandage?

Answer 21

Exsanguination of the limb
* Useful technique for digital amputation in several species as well as lower limb
surgery in the horse.
* A rubber (Esmarch) bandage is tightly applied to the limb working from the
distal towards the proximal limb and blood prevented from reperfusing the
limb by application of a tourniquet

Question 22

How does post-operative haemorrhage occur?

Answer 22

Often result of ineffective haemostasis
* Physiological or surgical
* Slipped ligatures, necrosis, suppuration of ligated or cauterised vessels
* Hypotension during surgery may prevent detection of vascular injury or ineffective
haemostasis resulting in delayed haemorrhage upon restoration of normal BP post op
* Poor secondary haemostatic plug formation common with coagulation deficiencies

Question 23

How can you use pressure to prevent blood flow?

Answer 23

Abdominal wraps/pressure bandage
* Temporary use in haemoabdomen
* Care with impeding ventilation
* Reduce perfusion to abdominal organs
* Limit/restrict movement