Surgery and Wound Management Flashcards
What affects the assessment and classification of wounds?
Wound factors – classification
Patient factors – comorbidities
Length of time since injury occurred, acute vs chronic
What are the 2 main aspects of wound classification?
By type of damage – abrasion, contusion, incision, laceration, puncture, degloving, burn (less useful)
By extent of contamination
What are the 4 phases of wound healing?
Haemostasis, inflammation, proliferation, remodelling
Overlap in a continuous process
What is key to wound healing?
Cytokine messaging
What is the appearance of granulation tissue?
Looks bright red due to being very vascular. Edges of wound are slightly curved and rounded so shows it is a day or 2 old.
What is the appearance of chronic wounds?
Less red/pale pink and unable to closer.
How are chronic wounds dealt with?
Infection may be present. If unable to close, debridement and surgical closure
How is tissue loss a problem for wound healing?
Not enough tissue to achieve tension-free apposition, wound itself/necessary debridement, may make primary closure difficult/impossible.
How is infection an issue for wound healing?
Heavy initial contamination or delayed treatment, persistent foreign material or necrotic tissue
How is location dependency an issue for wound healing?
Inability to contract
How is movement an issue for wound healing?
Wound keeps pulling apart, dehiscence if primary closure attempted, excessive granulation tissue
How is compromised blood supply an issue for wound healing?
Reduced ability to deal with infection, dead tissue
List the steps of wound management.
- Assess whole animal and stabilise
- Assess wound and explore
- Debride the wound
- Lavage
- Culture and systemic medications
- Decision making – should you close the wound?
- Drains
- Topical medications
- Dressing and bandages
What is done when assessing the animal and stabilisation?
Sedation/muzzle
Triage
Pain relief - opioids
Further diagnostics/imaging if wound has penetrated a body cavity
How is a wound assessed and explored?
- Deep/penetrating wounds under GA
- Extensive clip, check for other wounds, initial clean with saline or dilute hibi.
- Classify severity
How is wound severity classified?
Sterile probe and check for contamination, check for damage to underlying structures, check for contamination and infection
How is wound debridement done?
Remove dead tissue (green, black, grey) and major contamination. Can be done by surgical excision, lavage or dressings soaked in sterile saline and packed into wound.
How is a wound lavaged?
Copious lavage is key. Use sterile saline/Hartmann’s, water if severe contamination, care with antiseptics as these can be toxic to fibroblasts
Describe culture and systemic medications of wounds.
- Take a swab after lavage and debridement to avoid contaminants
- Antibiotic therapy*
- Analgesia
- Tetanus antitoxin in horses if vaccination status is unknown
If a wound has a contamination, should you attempt to close it?
No
What are the 4 types of wound closure?
Primary closure
Delayed primary closure
Secondary closure
Second intention healing
Describe primary closure.
Immediate closure of the wound, fresh (under 6h), clean status, best functional and cosmetic outcome where developed correctly, may dehisce if ongoing infection/tissue necrosis, can still close after 6h but debridement will be needed.
Describe delayed primary closure.
2-3 days, before granulation tissue develops, use for contaminated wounds after initial open wound management.
Describe secondary closure.
5-7 days, after granulation tissue develops, use for heavily contaminated/infected wound after initial open wound management, may need to excise granulation to allow closure.
Describe second intention healing.
If we can’t surgically close, allowed to heal entirely by granulation, contraction and re-epithelialisation.
Why is it essential to avoid tension on your closure?
Risks dehiscence
How can tension be alleviated?
- Skin tension lines – natural way tension is distributed through the skin
- Undermining – more elastic layers beneath skin
- Walking sutures
- Relaxing incisions
- ‘Manipulation of wound geometry’
What are some methods of advanced surgical wound closure and reconstruction?
Advancement flaps
Skin stretching/expansion
Skin grafts
What are the 2 types of skin grafts?
Pedicle grafts (retain a vascular attachment
Free skin grafts – sheets, island grafts
When are drains used?
If large amounts of dead space
What are the functions of a bandage?
- Maintain dressing in place over a wound
- Help with absorption of exudate
- Help to control swelling
- Reduces movement
- Prevent contamination from the environment
What is the primary layer of a typical bandage.
Dressing - this is against the wound itself
What is the secondary layer of a typical bandage?
Absorbent, holds the wound dressing in place, light pressure to provide structure.
What is the tertiary layer of a typical bandage?
Protects the bandage from the animal, the environment and trauma.
When are tie-over dressings used?
Good for flank wounds where it is difficult to wrap bandage all the way around.
List the things of particular concern in horse wounds.
Synovial penetration
Exposed bone
Exuberant granulation tissue
Hoof involvement
Sarcoids
Why is synovial involvement a concern in horses?
- Septic arthritis is poorly tolerated in the horse and leads to non-weight bearing lameness
- Wound near a joint/sheath/bursa
- Arthroscopic lavage - gold standard
Why is exposed bone a concern in horses?
- Particularly with degloving injuries
- Exposed cortical bone will dry out, risk of sequestered
- Must be covered by periosteum (ideally) or bandaging until granulation tissue covers it.
Why is proud flesh/EGT a concern for horses?
- Slow and ineffective inflammatory response
- Associated with movement or contamination at wound site or bandaging
Why do we get EGTs?
The inflammatory phase is prolonged, which means that macrophage cells persist in the wound environment. Their cytokines inhibit fibroblasts differentiation into myofibroblasts. Thus proliferation continues and contraction fails to starts.
Why must bandaging be carefully balanced in horse wounds?
Used to stabilise a wound they are beneficial, to cover exposed bone, they are essential but left on too long they will predispose to excessive granulation.
What is a sarcoid?
Fibrosarcoma tumour caused by bovine papilloma virus at wound sites, including injection sites.
How are sarcoids prevented and treated?
- Keeping wounds covered helps prevent spread – both by flies and humans
- Plenty of fly repellent on existing sarcoids and around (not in) open wounds to prevent transmission
List the 7 Halstead Principles.
- Gentle handling of tissue
- Meticulous haemostasis
- Preservation of blood supply
- Obliteration of dead space
- Minimum tension on tissues
- Accurate tissue apposition
- Strict aseptic technique
What are 5 scalpel blades and their uses?
10 – long straight skin incisions
11 – stab incisions
12 – stitch removal
15 – thinner skin, curved incisions, areas where need to follow a contour, such as paws
20 – like the 10 but larger
What are the 2 ways of holding the scalpel?
Pen grip – steeper angle, allows more precise control. Useful for curves and achieving full thickness depth.
Shallower angle using more of the belly of the blade than the tip – useful for making long, straight incisions.
What is slide cutting?
Place tension on skin with free hand/non-dominant hand. One smooth incision, suing belly/curved bit of the blade
How are stab incisions made?
One clean movement, using point of blade. May need to elevate tissue being incised so that structures underneath are not damaged, such as the linea alba is tented up and stabbed into.
What size scalpel blade is best for excising a 2cm skin mass on the distal limb?
15, 10 would be acceptable but 15 is smaller for more control
What are the 2 types of dissection?
Sharp dissection with extreme care.
Blunt dissection to avoid damaging deeper structures and goes along natural tissue planes or parallel to tissue fibres.
How is dissection done?
Need good visualisation and good anatomical knowledge to avoid damaging delicate structures in the area. Avoid excessive dissection, as this increases dead space and increases risk of infection.
What is haemostasis?
Stopping blood flow
Why is haemostasis important?
- Decreases blood loss
- Increased visibility of surgical field
- Decreases seroma and haematoma formation
- Decreased dead space formation
- Decreased risk for infection
Name the methods of mechanical haemostasis.
Digital pressure
Haemostats
Ligatures
Physical
How is digital pressure used in mechanical haemostasis?
The aim is to stem flow for long enough that platelets form plug. Takes 1-5 minutes
How are haemostats used in mechanical haemostasis?
Place perpendicular to the long axis of the blood vessel and leave in place for at least 5 minutes. Tripod grip
What types of forceps are used for haemostats?
Halsted mosquito forceps. Kelly forceps.
Both have transverse grooves and helps to grasp and secure bleeding vessels through the crushing action of the serrations. Use the haemostats for easily visible, superficial blood vessels, used curved when deeper tissue to aid visibility.
How do ligatures do mechanical haemostasis?
Place haemostat prior to ligation. Absorbable suture material, single ligature for small vessels – circumferential. 2 ligatures for pulsating or large vessels can be circumferential or for very large vessels you can use transfixing.
How is physical haemostasis used?
Soluble, sponge-type materials. Low pressure bleeding. Provides scaffold and promotes clot formation and can delay wound healing and promote infection.
How is thermal haemostasis done?
Electro-coagulation in diathermy and cautery.
How is chemical haemostasis done?
Adrenaline: potent alpha-2 adrenergic agonist causing vasoconstriction.
On bleeding claws – potassium permanganate, silver nitrate and not to be used in surgery.
Whilst making a skin incision, you cut through a small skin vessel which bleeds persistently. What is the best way to stop the bleeding?
Digital pressure
Why is tissue retraction important?
Increase exposure and visibility and therefore decrease tissue trauma and time.
How is tissue retraction done?
- Hand retraction, such as an assistant
- Instrument retraction – hand-held retractors and self-retaining retractors
- Instruments preferred to hands, as it is more gentle
How are incisions made?
- Incision long enough to have good exposure
- Use natural tissue planes
- Avoid excessive undermining or get increased dead space
- Handle tissue with appropriate instruments
- Do not let tissues dry out
What are treves/rat toothed thumb forceps used for?
For dense tissue. Allow good grip without tissue slipping away.
What are adson thumb forceps used for?
Less traumatic than rat-toothed. Mini rat-tooth has a finer tip so can only grasp tiny amount of tissue
What are adson brown tissue thumb forceps used for?
2 longitudinal rows of intermeshing teeth. Broad yet delicate grip without major trauma.
What are debakey thumb forceps used for?
Least traumatic, smooth longitudinal grips, use for delicate tissues.
What are dressing forceps used for?
Transverse serrations
What are allis tissue forceps?
Have saw-toothed edge and crush tissue so should not be used for delicate structures
What are babcock tissue forceps?
Less traumatic, so can be used in more delicate tissue
Why do we lavage?
- Lavage decreases risk of infection by removing surface bacteria and debris
- Moistening of tissues, counteract dehydration from air and lights
- Increased visibility by removing blood.
How do we lavage?
- Nontoxic, iso-osmotic and normothermic (make sure you warm the fluid)
- 0.9% sterile saline
- Traumatic and/or infected wounds: lavage under pressure
Why do we need surgical suction?
If we lavage, we need to remove. Remove blood to increase visibility.
What is a yankauer suction?
Wide diameter tip so used for larger volumes of fluid or thick fluid. One hole so potential for blockage.
What is a poole suction?
Suction tip of choice for abdominal lavage. A narrow diameter, multiple holes so gentler pressure suction. Drain large volumes with minimal chance of blockage.
What are the benefits of surgical drains?
- Facilitate elimination of dead space
- Evacuate existing fluid and gas accumulations
- Prevent anticipated fluid accumulation
What are the complications of surgical drains?
- Foreign body response – remember asepsis lecture
- Ascending infection
- Patient interference
- Decreased rate of healing
What is a passive/open drain?
Drainage by gravity and capillary action. Open so more tissue irritation at exit site for leaking fluid and need to cover exit with sterile dressing.
What is penrose passive draining?
Fluid drains extraluminally along the outer edge of the drain
What is tube passive draining?
Extra and intraluminal flow. Less common and used in abdomen and not wounds.
What is active/closed draining?
Drainage by intermittent or continuous suction, need a vacuum.
What are the benefits of active drains?
- More effective at removing fluid (vs passive)
- Allows monitoring (volume, appearance) of drained fluid
- Decreased risk of ascending infection (vs passive)
What is the risk of active drains?
May cause injury to tissue due to high negative pressure
When should drains be removed?
Fluid production never ceases. Active drains = when drainage decreases. Average 2-4 days.
What is ease of handling determined by?
Pliability
Memory and plasticity
Surface friction
What is catgut made of?
Cow or sheep intestines
What are the properties of natural sutures?
- All natural suture materials are multifilament
- Cause inflammatory reaction with fibrosis
- Less initial strength for given size
- Faster and less predictable loss of tensile strength, absorbed by phagocytosis and proteolysis
What are the properties of synthetic sutures?
- Can be multifilament or monofilament
- Reduced inflammatory reaction
- Higher initial strength for given size
- Slower and more predictable loss of tensile strength, absorbed by hydrolysis
What are the properties of monofilament sutures?
- Provoke less tissue reaction
- Less potential to promote infection
- Less tissue drag
- More difficult to handle and knot – increased memory
- Less knot security
- More irritation from cut ends
What are the properties of multifilament sutures?
- Provoke more tissue reaction
- More potential to promote infection
- More tissue drag
- Less difficult to handle and knot – decreased memory
- More knot security
- Less irritation from cut ends
Clinically, when has a suture lost its tensile strength?
When it has lost a certain percentage of its original strength and so is no longer supporting the wound.
How can a suture material’s tensile strength be reduced?
- Excessive manipulation and use
- Knotting
- Wetting
- Natural absorption in tissues
- Placement in hostile environment - infected wound, gastric acid
- Abuse of the material by grasping it with instruments anywhere other than the end
- Repeated autoclaving
What is the tensile strength of of absorbable suture material?
Loss of TS in 60 days. Short duration retains appreciable TS for 21 days – monocryl and vicryl. Long duration retains appreciable TS for 21-60 days – PDS.
What is the tensile strength of non-absorbable suture material?
Retains TS more over 60 days – nylon, silk, steel.
Which suture is best for intradermal skin sutures?
Absorbable, monofilament
What are the guidelines on the suture material for skin?
Non-absorbable multi, absorbable short duration mono
What are the guidelines on the suture material for subcutis?
Absorbable short duration mono or multi
What are the guidelines for the suture material for fascia?
Absorbable long duration, non-absorbable mono
What are the guidelines for the suture material for muscle?
Absorbable long duration, non-absorbable mono
What are the guidelines on the suture material for viscera?
Absorbable short duration mono
What are the guidelines on the suture material for tendons?
Non-absorbable mono
What are the guidelines on the suture material for vessel ligation?
Absorbable short duration, multi or mono depending on knot
How should you select suture size?
Choose the smallest size that will provide adequate tensile strength.
What does a smaller diameter of suture material allow?
- Greater knot security (can tie tighter)
- Less foreign material (reduces surgical site infection SSI risk)
- Less tissue trauma
What is the rule of thumb for suture size?
3 metric/2-0 dogs. 2 metric/3-0 cats. Reduce by 1 size for delicate tissue or smaller dog. Increase by 1 size for tough tissue or larger dog
What suture material and size is best for closing the muscle of a cat spay?
Absorbable, long duration (muscle takes long to heal than skin), monofilament, 2 metric/3-0
What is the differences between swaged and eyed needles?
Swaged - single-use attached to suture material
Eyed – multi-use so use with suture on reels
What are the advantages to swaged needles?
- Less tissue trauma – always sharp as single use
- Less tissue drag – no knot where suture attaches to needle
- Easier to handle – suture material won’t fall off needle prematurely
What are curved needles good for?
Curved in deeper wounds with restricted access. For example, ½ circle good for thick muscle layer closure
What are straighter needles good for?
Progressively straighter as more superficial. For example, 3/8 circle good for intradermal skin sutures
When are round bodied needle points used?
Less traumatic if delicate tissue. Use in very delicate tissue
When are taperpoint needle points used?
Less traumatic, but the tip is pointed instead of rounded. Delicate fibrous tissue
When are tapercut needle points used?
More traumatic. Use in moderately dense tissue
When are reverse cutting needle points used?
Most traumatic (sharp) but cleaner cut through dense/tough tissue. Use in the most dense tissue
What are the needle point symbols?
Circle = round bodied
Circle with dot in = taper point
Circle with triangle/Y in = tapercut
Triangle, point up = cutting
Triangle, point down = reverse cutting
What type of needle is best for suturing closed the abdominal muscles and the linea alba?
Taper point ½ circle, 3/8 would be okay for a thinnish tissue
What is a square knot?
2 single parallel throws. Standard surgical knot - reverse the direction between each throw.
What is a surgeon’s knot?
1 double throw, then a single throw. Place square knots on top to lock in place. Used for ligatures or areas under light tension.
What is a modified Miller’s knot?
A 2 pass friction knot. Locks in place and doesn’t bind prematurely or loosen, good for ligatures.
What is an Aberdeen knot?
Multiple half hitches. Used to end continuous suture pattern lines. The knot can be buried and results in only 1 tag/cut end instead of 3.
What is a slip knot/granny knot?
Failure to maintain tension evenly on both strands. Bad but can be useful to close under tension and must covert back to square knot and lock with more throws.
Which knots are appropriate for ligating blood vessels?
Surgeons, modified miller’s and transfixing
What does knot security depend on?
- Suture material properties – pliability, memory, surface friction, diameter
- Type of knot used
- Placing the correct number of throws
Which suture material size has better knot security?
A smaller diameter suture can be tied tighter
What are the advantages of interrupted suture pattern?
- Failure of 1 knot does not affect entire suture line
- Allows precise adjustment of tension at each point
What are the disadvantages of interrupted suture patterns?
- Tension not distributed evenly along the entire incision so lower holding power against stress
- Increased surgical time
- Increased suture material
What are the advantages of continuous suture patterns?
- Tension distributed evenly along the entire incision so greater holding power against stress
- Decreased surgical time
- Decreased suture material
What are the disadvantages of continuous suture patterns?
Failure of one knot may cause failure of entire suture line does not allow adjustment of tension at each point
What are appositional suture patterns?
Bring the edges into close approximation, with tissue edges in the same position as prior to the incision. Use for skin, muscle, fascial planes, tendon, viscera.
Name 3 appositional suture patterns.
Intradermal
Cruciate
Ford locking
What is intradermal suture pattern?
Secure skin closure, good cosmetic outcome
What is cruciate suture pattern?
Quicker and less suture material than a simple interrupted, spreads tension locally
What is ford locking suture pattern?
Compared to simple continuous, locking means suture line less likely to be completely disturbed by self-trauma. Uses more suture material and is more time consuming to remove.
What are inverting suture patterns?
Tissue edges turn away from the surgeon. Traditionally used to close hollow viscera – GI tract, bladder and uterus. But now appositional is preferred in small lumens, such as GI tract.
Name 3 inverting suture patterns.
Utrecht
Parker-Kerr oversew
Purse string
What is Utrecht suture pattern used for?
Especially used to close the uterus
What is Parker-Kerr oversew used for?
To close the stump of a hollow viscus, inverts wound edges into the viscus
What is purse-string suture pattern used for?
To close the stump of a hollow viscus, inverts wound edges into the viscus, securing percutaneous tubes, such as gastronomy tubes.
What are everting and tension-relieving suture patterns?
Tissue edges turn up towards the surgeon, away from the lumen. Used to relieve tension
Name 3 everting and tension-relieving suture patterns.
Horizontal mattress
Vertical mattress
Near-far pattern
What are the advantages of using staples to close skin compared to sutures?
Quicker, cheap, does not increase risk of delayed healing, infection or poor wound cosmesis.
What are the disadvantages of using staples to close skin compared to sutures?
Slightly everts skin edges
Tend to rotate in very mobile areas or thin skin
Should not be placed in wound under tension
Which suture is tied tighter?
Ligature
