Lecture 8: Principles of hemostasis (Exam 1) Flashcards
Exsanguination on your pathology report =’s what
Equals pilot error
What is hemostasis
A complex process that involves platelet activation & circulating clotting factors
Why is hemostasis important
- Allows appropriate visualization of tissue during the procedure
- Prevents life threatening hemorrhage
How are low pressure hemorrhages from small vessels controlled
- 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
How can hemostatic forceps be used to control bleeding from small vessels
The vessel is grasped & clamped w/ the forceps for several mins until coagulation occurs
How do ligatures help with ligation
- 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
Describe circumferential ligature for vascular ligation
- Less likely to bleed than transfixation ligature
- More likely to slip than a transfixation ligature
Describe transfixation ligature for vascular ligation
- Penetrates the lumen of the vessel
- Less likely to slip than a circumferential ligature
- More likely to bleed than a circumferential ligature
When double ligating where should the circumferential ligature be placed
Closer to the heart
Describe double ligation
- For larger vessels particularly arteries
- Circumferential + Transfixation ligature
- Transfixation is more secure
- Circumferential is less likely to bleed & is closer to the heart
Why are ligature(s) placed
To ensure the bleeding is stopped
What is the second through in a transfixation ligature for vascular ligation
A square throw (b/c its more secure)
Why should a surgeons throw not be place in the transfixation ligature
Due to the extra suture material this knot cannot easily be tightened & can withstand only a slight strain on the suture loop
List some topical hemostatic agents
- Bone wax
- Gelatin based hemostatic product
- Cellulose based hemostatic products
Describe bone wax
- 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
Why should relating products not be used in closure of skin incisions
May interfere w/ healing
Describe gel foam
- 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
Describe a punch biopsy
- Haemostatic foam
- 6 mm minimum
What is surgicel
- 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
Describe electrocautery
- 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
Define electrosurgery
- 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)
What occurs on the “cut setting” for electrosurgery
- Constant waveform occurs
- Produces less heat & creates a coagulum rather than vaporizing tissue
What can be used to perform electrosurgery
Monopolar or bipolar devices
What is monopolar electrosurgery
- 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