21 – Hemostasis Flashcards

1
Q

Why is hemostasis important? What are some patient concerns?

A
  • Medium for bacterial growth: increased risk of post-op infection
  • Inflammation
    o Delayed healing
    o Adhesions
    o Pain
  • Hemorrhage
    o Anemia
    o Shock
    o Death
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2
Q

What is shock?

A
  • Inadequate oxygen delivery
    o Can’t meet cellular metabolic needs
    o O2 delivery IS LESS THAN tissue/cell O2 requirements
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3
Q

What are some types of shock?

A
  • Cardiogenic
  • Hypovolemic
  • Distributive
    o Septic, anaphylactic, neurogenic
  • Hypoxemic
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4
Q

What are some surgeon concerns with hemostasis?

A
  • Visualization
    o Iatrogenic trauma
    o Inaccurate procedures
    o Higher complications
  • Good surgery=good visibility of target tissue
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5
Q

How can you prevent hemorrhage?

A
  • Good history
  • Good physical exam
  • Breed (ex. von Willebrand’s disease)
  • Baseline blood work
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6
Q

What can you do to assess platelet function?

A
  • Buccal mucosal bleeding time (BMBT)
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7
Q

What can you do to assess coagulation factors?

A
  • Prothrombin time (PT)
  • Partial throbmoplastin time (PTT)
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8
Q

When do you check hemostatic factors?

A
  • Liver disease
  • Exposure to toxin
  • Surgery with major bleeding history
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9
Q

What can the surgeon do to prevent hemostasis?

A
  • Careful planning of approaches (KNOW ANATOMY)
  • Ligation or coagulation of vessels before transection
  • Gentle and accurate dissection
    o Don’t grab or cut unless you can visualize structure
    o Minimize primary hemorrhage
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10
Q

Secured ligature on major vessels

A
  • Ligature slips=most COMMON cause of intra and post-op hemorrhage
  • Hypotensive during surgery
    o Normotensive when awake
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11
Q

What do you not do to approach hemostasis?

A
  • DO NOT DO A BLIND OR FRENZIED ATTEMPT
    o further laceration of the vessel
    o increased hemorrhage
    o damage to surround structures
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12
Q

How should you approach hemostasis?

A
  • You have LOTS of time (ex. with a spay you have at least an hour)
  • APPLY PRESSURE!
  • Vasoconstriction
  • Gather thoughts and ideas
    o Assistant to scrub in
  • Instruments
    o Suction
    o Gauze
    o Hemostats
    o Suture
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13
Q

What is key to the success with approaching hemostasis?

A
  • Don’t clamp or ligate if you can’t see
    o Potential irreversible damage
  • Good exposure=good hemostasis
    o Extend incision or retract tissue
  • Pre-op management
    o Clip hair wide and drape wide
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14
Q

How much is too much?

A
  • If <10% of total blood volume lost=generally okay
  • If >15-20% of total blood volume lost=transfusion and support
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15
Q

How can you calculate blood volume?

A
  • 0.08-0.09 x body weight (kg) = estimated volume in liters
    o 80-90mL/kg
  • Ex. 30kg dog=2.5 L of blood, can safely loss 250mL
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16
Q

How do you estimate blood loss in surgery?

A
  • Photo with percent of saturation and the size of the gauze
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17
Q

Pressure: method of hemostasis

A
  • Slows blood flow
    o Clot formation (<5mins)
  • Dab, don’t wipde
    o Wipe will remove established clots
  • Good enough for SMALL vessels
  • Larger vessels require more time (clot formation and vessel constriction)
  • If NOT stopping: more definitive treatment or clamp vessel
18
Q

Clamp vessel: method of hemostasis

A
  • Accurate grip
    o Minimize trauma to other tissue
  • Good exposure is essential
    o Good hemostasis
    o En
  • *can enlarge incision to visualize the vessel
19
Q

What happens when you crush tissue when clamping a vessel?

A
  • Arrest hemorrhage
  • Damage vascular wall TO activate physiological clotting mechanisms
    o Small low-pressure bleeders
    o Normal coagulation factors
  • Larger vessels
    o Temporary hemostasis
    o Facilitating ligation or cauterization of vessel
20
Q

What hemostats do you use for small vessels?

A
  • Halstead mosquito and Kelly forceps
  • *curved hemostats facilitate visulaizaiton
21
Q

What hemostats do you use for tissue bundles and vessels?

A
  • Crile
  • Ochsner
  • Carmalt
  • *curved hemostats facilitates visualization
22
Q

Application of hemostatic foreceps: small superficial bleeders

A
  • Tip
  • Parallel to vessel
  • Concave surface facing down and fall lateral to incision
23
Q

Application of hemostatic forceps: large, deep bleeders

A
  • Jaw
  • Perpendicular to vessel
  • Concave surface facing up or towards proposed line of transection
24
Q

What do you do if you can’t stop the bleeding with the hemostats?

A
  • Cautery
  • Electrosurgery vs. electrocautery
    o Often used interchangeably
25
Electrosurgery
- High-frequency alternating current to cut, coagulate or ablate tissue - More complex, larger electrosurgical units (ESU)
26
Electrocautery
- Heated metal probe to destroy tissue - Uses a direct current to heat a metal probe that is applied to tissue, causing thermal damage - Small, battery-operated devices
27
Electrosurgery: technique
- Pass electrical current through tissue o Ionic agitation in cells and causes frictional heat in the tissues - *results in coagulation (hemostasis) tissue - Small vessels o <1mm artery o <2mm vein - Monopolar and bipolar
28
Monopolar electrosurgery
- Current: handpiece to tissue to patient to ground plate to generator - Ground pad: needs GOOD CONTACT o Hair needs to be shaved o Broad contact: otherwise burns may occur
29
When is monopolar electrosurgery NOT recommended?
- Close to heart - Close to CNS
30
Bipolar electrosurgery
- Forceps type of active electrodes - Current: one tip to tissue between to other tip - NO ground pad required - Minimal trauma to other tissues
31
What do you do if cautery is not working?
- Ligatures and vascular clips
32
Ligature
- GOLD standard o >1mm artery o >2mm vein - Tie end of vessel off o Sacrifice vessel - Absorbable suture: monocryl or PDS
33
Single ligature
- Circumferential ligature - GOLD standard - Square know + 2 o 4 throws total
34
Double ligation
- Larger artery/veins
35
Transfixation ligature
- Prevent slippage - NOT necessary? (preference)
36
Vascular clips: basic principles
- Dissect vessel wall - Vessel diameter: no more than 2/3 and no less than 1/3 of length of clip - Apply several mm from cut end of vessel - Artery and vein pair are clipped separately - *can occlude vessels up to 5mm
37
What are the advantages of vascular clips?
- Quick - Apply in locations inaccessible to ligation
38
What are some disadvantages of vascular clips?
- More frequently dislodged - Persist in wound o Absorbable clips are now available - Irritating to load into applicator o New applicators are easier to use
39
What are some hemostatic agents (2)?
- Gelfoam - Surgical
40
Gelfoam
- Procine gelatin sponge - Forms gel when wet - Matrix for clot to form to - Absorbable: 4-6 weeks - Possible nidus for infection
41
Surgical
- Cellulose - Similar action