Hemostasis Flashcards
What is hemostasis?
spontaneous physiological defense mechanism to stop hemorrhage
What does hemostasis depend on?
vascular, extravascular and intravascular factors
What is the end product of hemostasis?
an effective thrombus
What is surgical hemostasis used for?
used to augment, faility or bypass physiological clotting
What is the goal of surgical hemostasis?
to reduce blood loss and resultant complications
What are 4 issues with surgical bleeding?
- obscures surgical field, reducing accuracy and efficiency
- blood on field, gloves, drapes, instruments is ideal medium for bacterial growth
- extravated blood has negative effects on body
- severe or prolonged hemorrhage may result in shock, hypoxemia, death
What are the problems caused by extravasated blood in the body?
- irritates tissues
- prevents coaptation of wound edges
- delays healing
- encourages infection
- promotes intraabdominal adhesions
What is primary hemorrhage?
occurs immediately after disruption of blood vessels
occurs during surgical dissection
How do you minimize primary hemorrhage?
know anatomy–ligate vessels
traverse one tissue plane at a time
apply tension in tissue handling?
What is delayed hemorrhage?
(intermediate) within 24 hours of injury
(secondary) >24 hours of injury
What is delayed hemorrhage often caused by?
often caused by ineffective treatment of primary hemorrhage
- slipped ligatures
- necrosis of ligated or cauterised vessels
What is the use of hemostatic forceps?
can be used to clamp vessels that will not be repaired. crushing the vessel stops hemorrhage and damages vessel wall, activating clotting.
only for small vessels
What hemostatic forcep is used for a wound?
- smallest forceps capable of achieving hemostasis
2. curved hemostats improve visibility
How do you apply hemostatic forceps to stop bleeding?
- grip in dominant hand with wide based tripod grip
- small superficial bleeders point the tip towards the vessels
- for deep bleeders, large vessels or pedicles apply hemostasis with convex surface facing end of vessel
How do you apply hemostatic forceps to stop bleeding?
- grip in dominant hand with wide based tripod grip
- small superficial bleeders point the tip towards the vessels
- for deep bleeders, large vessels or pedicles apply hemostasis with convex surface facing end of vessel
- for large vessels use jaw rather than tip
- for large pedicles clamped with a carmalt or similar to minimize slippage
What are the most secure methods for hemostasis?
vascular clips and ligatures
What is an advantage of vascular clips and ligatures?
they are less likely to slip than a clot is to be dislodged
What is a disadvantage of vascular clips and ligatures?
foreign material is left in the wound
How do you apply vascular clips?
- dissect vessel free from the surrounding tissue
- diameter of vessel between 1/3-2/3 the length of the clip
- apply several mm from cut end of vessel
- clip artery and vein separately
What are the advantages of vascular clips?
- can be placed more rapidly than ligatures
2. good for poorly accessible locations
What is a disadvantage of vascular clips?
more likely to be dislodged during surgical manipulation
What is the most commonly used method of hemostasis?
ligatures
What are the advantages of ligatures?
- more secure than hemostatic clips
- better suited for occlusion of multiple vessels and vascular pedicles
- for large vessels the increased security outweighs the application time
What is a disadvantage of ligature?
take longer to apply
What is a disadvantage of ligature?
take longer to apply
What is the advantage of a square knot (ligature)
least likely to loosen (unless half hitch)
What is the advantage of surgeon knot?
used for large pedicles if cannot adequately tighten a square knot (apply square knot over top)
What material should not be used with a surgeon’s knot?
chromic gut because friction causes fraying at the knot
What are two ways you can tie ligatures?
hand or instrument ties
What is recommended for large vessels with regards to applying ligatures?
use double ligatures
What are tansfixation ligatures less prone to?
slippage
What suture size should be used for ligatures?
3-0 for isolated vessels, maximum 0 for pedicles
Why should ligatures be adequately tightened?
because inadequate tightening leads to bulky and less secure knotes
What should be the tail length of ligatures for synthetic sutures?
3-4mm
What is cautery performed on?
arteries up to 1mm and veins up to 2mm
What is used for cautery?
radiofrequency from an electrosurgical unit
How does cautery work?
heat is produced by tissue resistance to current, electrical energy is absorbed and converted to thermal energy
What is a monopolar cautery?
there if flow from handpeice through the patient to a ground plate
the current enters a small volume of tissue and exits a large volume of tissue to avoid burns
What can monpolar cautery do besides cut?
coagulate
What are two ways you can apply monopolar cautery?
- directly onto a vessel
2. indirectly onto forceps holding the vessel (less collateral damage)
What must you remember when usingmonopolar cautery?
- only contact at point of coagulation
- use minimum intensity and time necessary
- dry first
- there is a risk of distant burns if take alternative path to ground plate
- need dry area
What are the featuers of bipolar cautery?
- the current passes between arms when the tips are ~1mm apart
- no need for ground plate
- need electrolyte fluid between tips
- if tips touch the current shorts–no coagulation
What are the advantages of bipolar cautery?
- less current needed
- less risk of injury to surrounding tissue
- no pathway of burns of distant tissues
- works well in wet field
- useful for fine vessels needing precise coagulation
What are the advantages of bipolar cautery?
- less current needed
- less risk of injury to surrounding tissue
- no pathway of burns of distant tissues
- works well in wet field
- useful for fine vessels needing precise coagulation
What is an advantage of cautery?
properly used it provides rapid definitive hemostasis
What is a disadvantage of cautery
less secure ligation
improper use of cautery can cause what?
- secondary hemorrhage
- severe burns
- delayed wound healing
- increased infection rates
- fires and explosions
What is ligasure?
bipolar vessel sealing device
How does ligasure work?
The machine measures the bioimpedence of the current through the tissue and adjusts the current to seal the vessels
proteins denatured and reforms into a sealed end
Where/when can ligasure be used?
- on vessels up to 7mm
2. with laparascopy, thoracoscopy
What is a topical hemostatic agent?
gelfoam
What are topical hemostatic agents (e.g. gelfoam) used for?
diffuse low level bleeding that is not amenable to other methods of hemostasis (cancellous bone, liver biopsy)
What are 4 types of topical hemostatic agents?
- fibrin adhesives
- oxidised cellulose
- microfibrillar collagen sponges
- gelatin sponges
What can topical hemostatic agents be combined with?
thrombin
Why should you use the minimum amount of topical hemostatic agents?
because they can potentiate infection
What is bone wax used for?
- to control bleeding form cancellous bone especially in neurological surgery, mandible
Why must you only use bone wax in clean wounds
because it persists from several years and impedes clearance of bacteria