Hemostasis Flashcards
Patient concerns of hemostasis
-medium for bacterial growth
-inflammation (delayed healing, adhesions, pain)
-hemorrhage (anemia, shock, death)
Shock
Inadequate O2 delivery
-can’t meet cellular metabolic needs
Types of shock
-cardiogenic
-hypovolemic
-distributive (septic, anaphylactic, neurogenic)
-hypoxemic
Surgeon concerns for hemostasis
Visualization (iatrogenic trauma, inaccurate procedures, higher complications)
**good surgery= good visibility of target tissues
How do we prevent hemostasis?
- history - medications, petechia, breeds (Von Villebrand’s disease)
- Baseline bloodwork
How to test for platelet function?
Buccal mucosal bleeding time (BMBT)
How to test coagulation factors?
-prothrombin time (PT)
-Partial thromboplastin time (PTT)
When to check platelet and coagulation factors?
-liver disease
-exposure to toxin
-surgery with major bleeding history
Preventative hemostasis in surgery
-Know anatomy
-ligation or coagulation of vessels before transection
-gentle and accurate dissection= visualize structures first and minimize primary hemorrhage
Ligature slips
Ligature slips off or loosens
*Most common cause of intra and post-op hemorrhage
*worse when awake because increased pressure; hypotensive in surgery
Hemorrhage during surgery
Lots of time- at least 1 hour during spay
*vasoconstriction, ask assistant for help
Instruments for hemorrhage
-suction
-gauze
-hemostats
-suture
Keys to success for surgery hemostasis
-don’t clamp or ligate if you can’t see it = because don’t want to cause irreversible damage
-extend incision/retract tissue
-pre-op management = clip hair and drape wide
How much blood is too much?
<10% total blood volume= ok
> 15-20% of total blood volume = transfusion +support
How to calculate blood volume?
0.08-0.09 x Body weight (kg) = estimated blood volume in litres
How to estimate blood loss?
Applying pressure to stop bleed
-slows blood flow= clot formation <5mins
*dap , don’t wipe
*for small vessels
Clamping vessels to stop bleed
Constrict larger vessel = start clot formation; then need ligation
*ensure accurate grip= minimize trauma to other tissues
*can always enlarge incision to get better visualization
Hemostats
Will crush tissue= sacrifice vessel
-allows body to clot in small low pressure bleeders; also works for larger vessels short term then need ligation/cauterization
**only works if normal coagulation factors
Which hemostats to use?
Small vessels= halsted mosquito and kelly forceps
Large tissues + vessels= crile, Ochsner, carmalt forcepts
Purpose of curved hemostats
Allow for better visualization
Application of hemostats for small superficial bleeders
-use tip
-parallel to vessel
-concave surface facing down and fall lateral to incision
Application of hemostats for large deep bleeders
-use jaw
-perpendicular to vessel
-concave surface facing up or towards proposed line of transection
Electrosurgery vs electrocautery
Electrosurgery: high frequency alternating current to cut, coagulate, or ablate tissue. More complex larger electrosurgical units
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
Electrosurgery
Monopolar electrosurgery
Handpiece >tissue > patient > ground plate >generator
**ground plate needs good contact= hair shaved, broad contact
Burns if poor contact
When not to use monopolar electrosurgery
-close to heart
-close to CNS
Bipolar electrosurgery
one tip of forceps > tissue between forceps> other tip
*no ground pad needed; minimal trauma to other tissues
Electrocautery
Using ligatures
Gold standard: vessels with visible lumens
>1mm artery
>2mm vein
**sacrifice vessel
What sutures to use for ligatures?
Absorbable suture = monocryl or PDS
Types of ligatures
Single ligature= circumferential ligature (2 square knots = 4 throws in total)
Double ligature= large artery/veins
Transfixation ligature= prevents slippage; not needed
Transfixation ligature
Vascular clips
-dissect vessel well first, then apply clip several mm from cut end of vessel
*must clip artery and vein separately
*can be use for vessels up to 5mm
Advantages to vascular clips
-quick
-apply in locations inaccessible to ligation
Disadvantages of vascular clips
-more frequently dislodges
-persist in wounds
-irritating to load into applicator
Hemostatic agents
- Gelfoam
- Surgicel
Gelfoam
Porcine gelatin sponge
-forms gel when wet which results in matrix for clot to form
-absorbable 4-6wks
-possible nidus for infection
Surgicell
Cellulose
-forms gel, allows matrix for clot
-absorbable
