Reconstructive techniques 1 + 2 Flashcards
Name the two scissors used for sharp and blunt dissection NOT for cutting suture material
Mayo
Metzenbaum
Name the two needle holders
Mayo-Hegar or Olsen-Hegar
Whenever you make a surgical incision or close a wound what are your aims?
- Square skin edges: when cutting skin, hold the scalpel blade at 90degrees to the skin. Angled cuts cause angled skin edges that tend to overlap when sutured.
- Accurate tissue apposition: for optimal healing the dermis on each side of the wound needs to be in contact.
- Slight eversion of the wound edges: this helps to appose the dermis. Take a larger bite of the deep dermis with your suture needle than of the superficial layers of the skin.
What should you do if you cant close a wound without tension using appositional sutures?
Assess the elasticity and mobility of the skin around the wound and use the simplest, quickest and least expensive suitable tension-relieving technique
Describe undermining and advancing skin
Sharp or blunt undermining allows you to stretch skin to close defects
What should you avoid when undermining and advancing skin?
Avoid injury to the subdermal plexus and preserve direct cutaneous arteries by undermining deep to the panniculus muscle (where present) or in the loose areolar fascia deep to the dermis in areas without panniculus.
In which parts of the body is undermining most successful?
neck, trunk and abdomen
What are the advantages of walking sutures?
Can advance undermined skin towards a defect, spread tension evenly and eliminate dead space
Name some tension relieving suture patterns
Vertical mattress
Horizontal mattress
Far-near-near-far
Far-far-near-near
Describe the use of relaxing/releasing incisions
- Allow the intervening skin to close the primary defect
- Useful when the primary defect overlies a vital structure (nerve, tendon, major blood vessel)
Closure of fusiform (one side is straight one is rounded) or elliptical incisions can sometimes form “dog-ears” at the end of the wound if the two sides are different lengths, how can you correct this (2 methods)?
- Suturing the wound while spacing sutures further apart on the longer side
- Suturing the wound by progressively placing sutures halfway along each section of the wound
How should you suture triangular, rectangular or square defects?
For these, start to suture at the corners and proceed to the centre
How should you suture circular defects?
Either convert the defect into a linear or curvilinear closure by making it into a fusiform defect, perform a 3-point closure or create flaps at each end of the circle and advance them to close the defect.
What are skin flaps
Sections of skin with an intact vascular supply that are moved to close wounds
When do skin flaps have the best cosmetic results?
If the hair of the flap has similar density and colour to the recipient site
Describe the steps involved in planning skin flaps
- Suitable donor sites: ample skin and without excessive tension or movement
- Appropriate flap for the wound, initially larger than the defect you wish to cover
- Avoid narrow base to flap
- Undermine below the panniculus
- Use fine suture material with initial tacking sutures to ensure that flap conforms well to the recipient bed with minimal, even tension
- Ensure the recipient bed is either a fresh surgical wound or a healthy granulation tissue bed free of infection, contamination and necrotic tissue
Where do subdermal plexus flaps get their blood supply from?
The subdermal plexus and attenuated branches of distant direct cutaneous arteries
How are subdermal plexus flaps created?
By undermining skin deep to the panniculus muscle layer (or dermis in areas with no panniculus).
Describe the several types of subdermal plexus flap - based on the shape of the recipient wound bed and the available skin
- Rotation flaps: used for closing triangular defects.
- Transposition flaps: rectangular flaps rotated into place over a wound.
- Interpolation flaps: similar to transposition flaps but they do not share a common border with the wound so a section of the flap must cross the skin between the donor and recipient beds, usually achieved by creating a bridging incision.
- Advancement flaps: unipedicle or bipedicle flaps that use the elasticity of the skin to advance tissue over the recipient bed
What are axial pattern skin flaps?
- These are flaps incorporating a specific, large direct cutaneous artery and vein.
- They can include large areas of skin and are similar in cats and dogs.
For what reasons do skin flaps fail?
- Arterial/venous occlusion caused by thrombi, torsion or stretching of direct cutaneous vessels
- Elevated interstitial pressure due to excessive tension causing reduced circulation and necrosis
- Pressure on the flap from underlying haematomas/seromas or tight dressings reducing blood flow
- Infection (especially if blood supply is compromised)
How can skin flap failure be prevented?
Atraumatic surgical technique
Strict asepsis
Meticulous haemostasias
Careful planning
How can you subjectively assess the health of a skin flap?
- Colour: unreliable as successful flaps may go through red and lavender stages
- Temperature: the flap should be approximately the same temperature as the surrounding skin
- Sensation: unreliable
- Hair growth: only occurs if the flap is viable but this is of little use immediately postoperatively as hair hasn’t had time to grow by then
How can you objectively assess the health of a skin flap?
- Various laboratory measurements – no clinical use
- Fluorescein dye fluorescence – non-fluorescent areas often dehisce, although the delineation between healthy and non-viable tissue may not be clear and non-fluorescent areas sometimes survive
By what methods can you try to salvage a failing skin flap?
- Apply ointments to prevent desiccation
- Debride nonviable tissue
- Open wound management followed by secondary closure or development of a second flap to deal with areas of dehiscence
What are free skin grafts?
Segments of skin completely detached from the donor site and transferred to a distant recipient site where a lack of skin mobility precludes local closure or flap construction e.g. on extremities.
How do free skin grafts survive?
By absorbing tissue fluid from the recipient bed during the initial 48hrs after transplantation, then by developing a new blood supply from the recipient bed.
Why are autographs generally used in small animals?
Cause no problems with rejection
Describe the features of full-thickness skin grafts
Durable, have good hair growth and good survival rates if meshed
Prone to failure if not meshed.
Describe the features of split-thickness skin grafts
More viable than full-thickness but they are less durable, hair may be absent or sparse and harvesting them is more difficult and requires special equipment.
Not indicated in cats as their skin is so thin
What is the role of surgical drains?
Remove unwanted fluid from the wound and eliminate dead space
What are the principles of surgical drain use?
- Aseptically prepare the skin before placing a drain
- Drains cause a foreign body reaction that increases the risk of infection
- Cover the drain exit with a sterile absorbent dressing and regularly change it before it is saturated
- Do not place the drain along the length of or exiting from the suture line as this may cause dehiscence.
Penrose drains are an example of?
Passive drains
Describe the features of passive drains
- Rely on gravity and capillary action to draw fluid from the wound
- Their efficiency is proportional to their surface area
Describe the features of active drains
These apply negative pressure using continuous or intermittent suction to evacuate fluid and collapse dead space
Intermittent suction is applied at least every 6 hours.
Constant suction is better than intermittent
When should a drain be removed?
When a consistently small volume of serosanguineous fluid is being produced
