Lecture 8: Principles of hemostasis

Question 1

Exsanguination on your pathology report =’s what

Answer 1

Equals pilot error

Question 2

What is hemostasis

Answer 2

A complex process that involves platelet activation & circulating clotting factors

Question 3

Why is hemostasis important

Answer 3

• Allows appropriate visualization of tissue during the procedure
• Prevents life threatening hemorrhage

Question 4

How are low pressure hemorrhages from small vessels controlled

Answer 4

• By applying pressure to the bleeding points w/ gauze sponges
• Once a thrombus has formed the sponge should be gently removed to prevent disrupting clots
• Soaking the sponge w/ saline before removal may also help prevent clot disruption

Question 5

How can hemostatic forceps be used to control bleeding from small vessels

Answer 5

The vessel is grasped & clamped w/ the forceps for several mins until coagulation occurs

Question 6

How do ligatures help with ligation

Answer 6

• Ligate larger vessels
• Double ligatures are recommended for large vessels (especially arteries)
• Transfixation ligatures may be indicated for larger arteries to prevent the ligature from slipping off the end of the vessel
• Use the smallest suture possible for vessel to improve knot security

Question 7

Describe circumferential ligature for vascular ligation

Answer 7

• Less likely to bleed than transfixation ligature
• More likely to slip than a transfixation ligature

Question 8

Describe transfixation ligature for vascular ligation

Answer 8

• Penetrates the lumen of the vessel
• Less likely to slip than a circumferential ligature
• More likely to bleed than a circumferential ligature

Question 9

When double ligating where should the circumferential ligature be placed

Answer 9

Closer to the heart

Question 10

Describe double ligation

Answer 10

• For larger vessels particularly arteries
• Circumferential + Transfixation ligature
• Transfixation is more secure
• Circumferential is less likely to bleed & is closer to the heart

Question 11

Why are ligature(s) placed

Answer 11

To ensure the bleeding is stopped

Question 12

What is the second through in a transfixation ligature for vascular ligation

Answer 12

A square throw (b/c its more secure)

Question 13

Why should a surgeons through not be place in the transfixation ligature

Answer 13

Due to the extra suture material this knot cannot easily be tightened & can withstand only a slight strain on the suture loop

Question 14

List some topical hemostatic agents

Answer 14

• Bone wax
• Gelatin based hemostatic product
• Cellulose based hemostatic products

Question 15

Describe bone wax

Answer 15

• sterile mixture of beeswax, paraffin, & isopropyl palmitate
• Pressed into bleeding channels of bone to control hemorrhage through a tamponade effect
• Used sparingly & w/ caution b/c it is nonabsorbable

Question 16

Why should relating products not be used in closure of skin incisions

Answer 16

May interfere w/ healing

Question 17

Describe gel foam

Answer 17

• Absorbable gelatin sponge that can be used to control hemorrhage
• Provides a physical matrix that initiates clotting through contact activation
• When applied the gel foam swells & exerts pressure on the wound as it absorbs many times its weight in blood
• Absorption occurs in 4 to 6 weeks
• The sponge should not be left in infected sites in areas w/ a high risk of infection or in confined places as it may exert unnecessary pressure on neighboring vital structures

Question 18

Describe a punch biopsy

Answer 18

• Haemostatic foam
• 6 mm minimum

Question 19

What is surgicel

Answer 19

• Absorbable cellulose sponge that is more like a 4x4 gauze in appearance
• Oxidized regenerated cellulose
• Substrate for clot formation
• Can be cut to the desired size & placed on an area of hemorrhage
• Removal is recommended
• Not activated by tissue fluids other than blood

Question 20

Describe electrocautery

Answer 20

• Coagulates small vessels or cuts tissue by using heat generated by direct electric current into a metal wire or probe
• Electrical current doesn’t enter the pxs body

Question 21

Define electrosurgery

Answer 21

• Refers to generating heat inside the tissue using an alternating electric current that passes through the tissue creating a circuit
• Widely used for hemostasis for vessels less than 1.5 to 2 mm diameter ( larger vessels should be addressed by other means)

Question 22

What occurs on the “cut setting” for electrosurgery

Answer 22

• Constant waveform occurs
• Produces less heat & creates a coagulum rather than vaporizing tissue

Question 23

What can be used to perform electrosurgery

Answer 23

Monopolar or bipolar devices

Question 24

What is monopolar electrosurgery

Answer 24

• Most commonly used method of electrosurgery
• Involves the flow of current from an active electrode (handpicece) through the patient to a ground plate
• Concentrates the current density increasing the temperature of the contact tissue & causing coagulation or tissue vaporization
• Larger surface area of the ground plate reduces the current density so that min tissue heating occurs as the circuit is completed

Question 25

What happens if an adequate low impedance ground pad is not present

Answer 25

The circuit will inadvertently use alternate paths to ground & will burn the px

Question 26

How are burns prevent w/ monopolar electrosurgery

Answer 26

• A small ground plate or an alternate path to ground can easily produce a severe burn
• To reduce the risk of a burn use a large pad placed in good contact on a well vascularized area of tissue that is close to the operative site
• Keep electrodes clean & free of eschar will enhance performance by maintaining lower resistance w/in the circuit
• Towels dampened w/ water or conduction gel
• Px return electrodes
• Some models deactivate if the monitor shows impedance levels

Question 27

What is needed for monopolar electrosurgery

Answer 27

• Field must be relatively dry & the electrode kept clean & free of debris
• Direct contact of the electrode w/ the tissue produces lower heat sufficient to coagulate
• Use of the arc btw/ the electrode & tissue produces higher heat & consequently a cutting or vaporization action
• The standard flat tipped electrode is designed to create an eschar or coagulum directly on tissue

Question 28

What does indirect contact of monopolar electrosurgery involve

Answer 28

• Touching the electrode to an instrument (hemostat or forceps) that has been applied to the bleed vessel
• Allows more precise application of energy & effective coagulation

Question 29

Describe bipolar electrosurgery

Answer 29

• Involves forcep like hand piece
• Current passes from one tip of the forceps to the opposite tip through the tissue being held btw/ the tips
• Tips must be held approx 1 mm apart for a current to be generated
• Ground plate or pad is not necessary
• Used when precise coagulation is necessary & to prevent damage to adjacent structures such as in spinal surgery, thyroidectomy, or ophthalmic procedures

Question 30

What is radiosurgery

Answer 30

• Generators & handpieces are similar to standard electrosurgery units except that the energy is generated by a low temp high freq current
• The radio wave passes from an active electrode in the handpiece to a passive electrode beneath or near the px
• Tissue resistance to the radio waves causes an ionic agitation in the cells @ the tip of the active electrode

Question 31

Describe the carbon dioxide laser

Answer 31

• Most widely used laser in small animal surgery
• Wavelength of 10,600 nm (highly & selectively absorbed by water)
• Tissue vaporization occurs as this light energy is absorbed by water into the soft tissues
• Penetration into tissue is shallow & precise w/ little heat dissipated to surrounding tissues

Question 32

What are the proposed advantages of CO2 lasers

Answer 32

• Less bleeding
• Less pain
• Less tissue swelling
• Decreased risk of infection

Question 33

What is vessel sealing used for

Answer 33

Utilized for hemostasis in laparoscopic & thoracoscopic surgery as well as open abdominal procedures & soft palate resection