Ch 75 Primary wound closure Flashcards
What are the 3 division of the vascular supply to the skin?
- Superficial/Subpapillary plexus
- Middle/Cutaneous plexus
- Deep/subdermal/subcutaneous plexus
cutaneous angiosome
A given region of skin supplied by a regional artery and vein
What are the main differences regarind the cutaneous angiosomes in dogs and cats?
- Dogs have a greater density of collateral SQ vessels
- Cats have a smaller number and wider distribution of curaneous perforating vessels
These differences apply mainly to the trunk
Cutaneous circulation
The subdermal plexus is formed and supplied by terminal branches of direct cutaneous vessels at the level of the cutaneous trunci muscle in dogs and cats.
- parallel relationship of the direct cutaneous vessels to the overlying skin compared with the perpendicular orientation of musculocutaneous vessels in humans.
Define the following terms in relation to wound closure:
Primary wound closure (First intention healing)
Delayed primary wound closure
Secondary Closure (Third intention healing)
Second intention healing
- Primary wound closure = Sutured wounds
- Delayed primary wound closure = suturing 2-5 days after wound initial, before granulation tissue development
- Secondary Closure = Closure of the would after granulation tissue has formed in the wound bed
- Second intention healing = Heals without suturing - usually va contraction and epithelialisation
What is the rate of epithelialisation in primary wound healing?
1mm/day.
A perfectly apposed wound can therefore be epitheliased within 24-48hr
What is the reported %strength of wounded skin in comparison to normal skin at the following time points:
14 days
3-4 weeks
Several months
14 days - 5-10% strength
3-4 weeks - 25%
Several months/1 year - 70 - 80% strength
“False healing”
- more frequently in cats than dogs
- wound appears to be healed from superficial observation, but dehiscence occurs after suture removal as soon as the stress of normal motion occurs
differences between dogs and cats
CATS
- lower cutaneous perfusion for the first week after surgery (then more rapid second week)
- 2 weeks: no difference in cutaneous perfusion in the two species.
- lower wound breaking strength than dogs at 1 week
- open wounds seem to heal more by contraction along wound edges,
DOGS
- open wounds heal more by central “pull” of fibroblasts and epithelialization.
cats may have more wound healing problems associated with poor vascular supply or tension in the first postoperative week
Subcutaneous Tissues and Healing
- subcutaneous tissues removed under primary closed wounds > cutaneous perfusion was significantly reduced at 7 and 14 days postoperatively in both cats and dogs
- lack of significant effect on healing of primary sutured wounds
List the 5 braod categories which can effect wound healing
Tension
Pressure
Motion
Self-Mutilation
Patient Health
How does tension affect wound healing?
Tension can disrupt cutaneous perfusion and retard wound healing
defects should be created and closed parallel to tension lines
What patient health factors can significantly retard epithelialisation?
Uraemia
Exogenous steroid excess
- Hyperadrenocorticism (wound healing can be delayed and the immune system’s ability to fight infection can be impaired)
- Steroids prolong the inflammatory phase and delay cutaneous wound healing
Geriatric
- Decreased cutaneous perfusion, increased skin fragility, increases risk of infection
Malnutrition
- delayed neovascularisation, decreased collagen synthesis, prolongation of inflammation, decreased leucocyte phagocytosis, B- and T-cell dysfunction, decreased mechanical skin strength
- Methionine, cysteine and arginine all important
- FAs (within cell membranes, vital for cell function)
- VitC (collagen synthesis, cell mitosis and monocyte migration)
- Zinc and iron (enzymatic reactions in production of DNA and RNA and proteins including collagen)
What are the reported benefits of using a scalpel for a skin incision over electrocautery/CO2 laser/radiowaves?
Meticulous intraoperative hemostasis is critical
- Scalpel incision have approximately twice the wound strength at 10-12 days post-op compared to electrocautery
- Produce less drainage with faster and stronger healing
- Skin incised with radiowave, CO2 laser and monopolar, char will penetrate the skin laterally 0.172, 0.215 or 0.255mm respectively
In humans, studies have concluded that incision made with electrocautery were faster and resulted in less post-op pain with no difference in scar formation of post-op infection
primary closure
- Freshly incised
- clean
- clean-contaminated wounds
- traumatic > occurred within 3 to 6 hours
Dehisced wounds
- converted to primary
- secondary closure
- heal by second intention.
What is meant by the ‘golden period’ for wound management?
- bacteria within a minimally contaminated wound can multiply to 10^5 per gram of tissue, at which point the risk for infection increases dramatically.
- also depending on the type of bacteria and host and local environmental factors
How long may it take for the degree of trauma to be fully established after a crushing injury?
3-7 days
Suture Material and Knot Type When Suturing
What is a chain stitch knot?
What are its advantages?
An aberdeen knot!
Greater relative knot security and less volume
What is the recommended suture tag length of buried knots?
3-5 mm
Which suture materials require 3-6 square knots for security (as apposed to 4-6)?
Polyglactin 910
Polyglytone (Caprosyn)
Nylon
Prolene
For size 3-0
How many throws are required when tying to a loop at the end of a continuous pattern?
at least 5
List 2 options of continuous pattern closure of the SQ
Simple continuous (bits perpendicular to incision)
Running horizontal mattress (Bites parallel to incision)
What is recommended for ideal dermal apposition with a continuous horizontal intradermal pattern?
Length of each bite no more than 0.5cm
Alternating bites should be backtracked 1-2mm
List some advantages of the continuous vertical intradermal pattern
Vascular supply to the wound edges is unlikely to be compromised as the suture material within the wound runs parallel to the cutaneous perforating vessels
Surgery time may be decreased
cutnaeous closure patterns
- Cutaneous sutures are left in place for 14 to 21 days when delayed wound healing is expected
List some techniques for correcting dog ears (5)
Although no studies are available in dogs or cats, in humans dog ears smaller than 8 mm in height will regress completely by an average of 132 day
A, Removal of two small triangles.
B, Removal of one large triangle.
C, Extension of the fusiform excision.
D, Removal of an arrowhead-shaped piece of skin.
E, Half-Z correction.
List two sepcialised methods for correcting dog ears in wounds which are 2cm or smaller
- Apex cutaneous suture
- Horizontal oblique dermal suture
List some methods of prevention/correction of dog ear formation in ellipital incisions
A - Fudging - placing sutures further apart on longer side when discrepancy is small
B - Rule of halves
C - Sutures from ends to center with dog ear removal
D - Suturing from one end to the other with dog ear removal
E - Suturing from centre to ends with dog ear removal
F - Lengthening the short side with half of a fusiform
Four methods to correct a step defect.
A, Manipulation of suture knot.
B, Placement of suture at the same depth on both sides of the wound.
C, Half-buried horizontal mattress suture with intradermal portion on the low side of the wound.
D, Placement of a piece of stiff untied suture from superficial on the high side to deep on the low side.
How may NSAIDs theoretically inhibit wound healing?
COX-2 production occurs at wound edges leading to infiltration of inflammatory cells and fibroblast proliferation within the first week
- NSAIDs could theoretically inhibit this process via inhibition of COX-2
Cold Packing
- help reduce incisional swelling, inflammation, and pain
- In dogs, application of a cold gel pack on the skin surface cooled subcutaneous tissues and muscles in the midfemoral region down to the periosteum
What are the purported effects of therapeutic lasers?
- Enhanced leucocyte infiltration
- Increasing growth factors
- Increasing macrophage activity
- Increasing neovascularisation
- Increasing fibroblast and keratinocyte proliferation
- Promoting early epithelialisation
Incidence and severity of short-term incisional
complications after intraoperative local infiltration of
liposomal bupivacaine in dogs
Power 2021
Retrospective study.
Animals: Client-owned dogs (n = 218).
Complications were documented in 43/218 (19.7%)
TPLO study ~ 9% incision complications vs 13.9% in this study
Bupivacaine liposome injectable suspension is currently
labeled for use as a one-time local infusion in dogs undergoing
cranial cruciate ligament (CCL) surgery to provide
72 h of analgesia postoperatively.1
Local anesthetics (namely bupivacaine and
ropivacaine) do not appear to have a clinically significant
impact on wound healing in animals
Regier 2019 – intradermal closure with barbed suture
improved watertightness of closure
- lower mechanical strength vs conventional monofilament
The use of absorbable staples for skin closure after tibial plateau
leveling osteotomy
F. C. Watson 2019
similar inflammation/infection rate to stainless steel staples
- application of stainless steel staples was faster (30s)
Travis 2018 – quilting subcut suture pattern
reduced incidence of seroma and lower pain score
- no difference in incidence of SSI
