wound healing Flashcards
1
Q
wound lavage goals, mechanics and ideal solution
A
Goals: remove debris, reduce bacterial numbers
mechanics:
*Ideal Pressure – 7 psi
*Low Pressure Ineffective
*Avoid High Pressure
ideal lavage solution:
*Nonirritating
*Bacteriocidal
*Cheap
2
Q
types of wound closure
A
primary wound closure:
-surgical incisions
secondary wound closure:
- resolve infection
- achieve debridement
-before granulation tissue
secondary closure:
-after granulation tissue
3
Q
primary wound closure
A
o Advantages:
o Optimal function
o Best cosmetics
o Shortest healing time
wound selection:
-surgical incisions
-lacerations in the golden period
4
Q
wounds NOT suitable for primary closure
A
o Tension
o Motion
o Devitalized tissue
o Heavily contaminated
5
Q
considerations for closure techniques
A
o Anatomic reconstruction
o Tension free coaptation
o Non-surgical wounds: Avoid braided suture
6
Q
reasons for wound closure failure
A
o Tension
o Devitalized tissue
o Infection
7
Q
ways to manage tension when closing wounds
A
o Tension relieving sutures
o Tissue undermining
o Tension relieving incisions
o Plasty procedures
o Pre-suturing
8
Q
tension relieving sutures
A
o Near-Far-Far-Near
o Vertical mattress (Stented)
o Horizontal mattress( Stented)
9
Q
pre-suturing to relieve tension
A
◦ Large Mattress Sutures
◦ 4 – 8 Hours
◦ Stress Relaxes Skin
considerations:
-$$ client, tissue loss, extension of infection
10
Q
delayed primary infection closures
A
-goals:
-resolve infection
-achieve debridement
-before granulation tissue (3-5 days)
success depends on:
-resolution of infection
-tension managed closure
11
Q
secondary closure avg, dis
A
◦ After granulation tissue
◦ Advantages:
◦ Allows resolution of infection
◦ Host debridement
◦ Disadvantage:
◦ Tissue is less manipulative
◦ Tension relieving techniques:
◦ Tissue undermining
◦ Relief incisions
◦ Tension relieving sutures
12
Q
key components of second intention healing
A
-granulation, contraction, epithelialization
-phases of wound healing are identical to sutured wounds, differ in magnitude and duration of cellular phase
13
Q
contraction of the wound rates
A
body: 1mm/day
limbs: 0.2 mm/day
delays in contraction:
Inelasticity of Skin
Vascular Insufficiency
Fewer
Myofibroblasts Cytokines
14
Q
what stops wound contraction
A
Myofibroblast Disappear: large, old wounds
Contact Inhibition
Opposing Tension
15
Q
wound epithelialization
A
-Body
0.2 mm/day
-Limbs
0.09 mm/day
things impacting epithelialization:
Dry wound bed – scab
Infection
Poor blood supply
Necrotic tissue
Presence of foreign bodies
Systemic factors
16
Q
bandage philosophy
A
▪Pressure Early
▪ Minimize Limb Swelling
▪ Effectively Reduces Wound Size
▪ Seme degree of external coaptation
▪After Inflammatory Phase - “Catch 22”
▪ May Need Mechanical Protection
▪ Reduces oxygen
▪ Increase in granulation tissue production
▪ Slow Healing
17
Q
Management of Exuberant Granulation
Tissue
A
▪Surgical Debridement (predictable result, repeat as needed, hemostasis (bandage)
▪Topical Medications: owner friendly, control granulation tissue, impede healing (slow contraction, slow epithelialization)
18
Q
corticosteroids for wound healing
A
▪Inhibit granulation tissue
▪Slow epithelialization
▪Use judiciously
▪Common preparations: Panolog
▪ Green Wound Cream
▪ 0.1 % Dexamethazone Ointment
19
Q
amnion for wound healing
A
wound dressing, inhibits granulation tissue, promotes epitheliazation speeds healing good
20
Q
honey for wound healing
A
-unpasteurized
-osmotic
21
Q
collagen preperations
A
-no negative effects demonatrated, no benifits
22
Q
Split-thickness skin grafts
A
▪Inhibit granulation tissue
▪Promote wound contraction
▪Zenographs
◦ Pig skin
Allografts
Autografts
23
Q
biosystems
A
▪Porcine small intestinal submucosa
◦ Collagen
◦ Proteoglycans
◦ Cytokines
Promoted
◦ Scaffold
◦ Healing modifier
24
Q
suture materials role in wound repair
A
-hemostasis
-support for healing tissue, should disapear at the same time as the tissue heals
Few days – muscle, SQ, skin
* Weeks – fascia
* Months – tendons
- Suture will lose strength at same rate
that tissue gains strength - Absorbed by tissue = no foreign material
in the wound
25
ideal suture material principles
▪ Easy to handle
▪ Reacts minimally in
tissue
▪ Inhibits bacterial
growth
▪ Holds securely when
knotted
▪ Resists shrinking in
tissues
▪ Absorbs - minimal
tissue reaction
▪ Noncapillary
▪ Nonallergenic
▪ Noncarcinogenic
▪ Nonferromagnetic
26
suture size
Smallest diameter that will secure wounded tissue:
▪ Minimize trauma
▪ Reduce amount of foreign material
▪ No advantage to using a suture that is stronger than tissue sutured
▪ United States Pharmacopeia (USP)
▪ 12-0 (smallest) to 7 (largest)
▪ The smaller the suture the less tensile strength it has
27
flexibility of suture
▪ Determined by torsional stiffness and diameter:Influences handling and use
▪ Ligating vessels and continuous suture patterns
▪ Silk = flexible
▪ Nylon and surgical gut = less flexible
▪ Braided polyester = intermediate flexibility
▪ Wire = least flexible
28
capillarity
▪ Multifilament fibers:
▪ Fluid and bacteria get into interstices
▪ WBCs are too large
▪ Infection may persist – non absorbable
▪ Coating can reduce: Don’t use in infected tissues
▪ Braided materials: Polyglycolic acid and silk
▪ Monofilament - noncapillary
29
relative knot security
-if poor knot security may need to go up a size or use a different suture
▪ Holding capacity of a suture expressed as
percentage of its tensile strength
30
classification of suture
-behavior in tissue: absorbable or non absorbable
-structure: monofilament vs multifilament
-origin: synthetic, organic, metallic
31
Behavior in
tissue of suture
▪ Mechanisms of absorption:
▪ Digestion by tissue enzymes and
phagocytosis
▪ Sutures of organic origin – surgical
gut
▪ Hydrolysis:
▪ Synthetic polymers
▪ Encapsulated/wall offed by fibrous tissue:
▪ Non absorbable
32
structure of suture
▪ Monofilament:
▪ Single strand of material
▪ Less tissue drag
▪ Lack interstices for bacteria
and fluid
-don't need to tie knots they will stay with barbs?
▪ Multifilament:
▪ More pliable and flexible
▪ Can be coated – reduce drag
and increases handling
33
absorbable suture material
Tensile strength: 60 days
Loss of strength and complete absorption: * Varies with type of suture material
34
Organic Absorbable Suture
Materials
▪ Short term
▪ Phagocytosis: causes an Inflammatory reaction, so we dont want to use in the skin usually, depends on cercumstance. (colic)
▪ Absorption rate increased by infection or digestive enzymes
35
catgut (surgical gut)
-Submucosa of sheep or serosa of bovine intestine
▪ 90% collagen
▪ Phagocytosis: Rapidly in infected sites
or within digestive enzymes, breaks down very fast pretty unreliable.
▪ Inflammatory reaction
-loses strength rapidly
▪ Tanning slows absorption and reduces
tissue reaction
▪ 33% reduction in tensile strength at 7 days, 50% at 14 days
▪ Poor knot security
▪ High capillary
36
Synthetic Absorbable Suture Materials
▪ dissolve by Hydrolysis soMinimal tissue reaction
▪ Absorption not as influenced by
infection or digestive enzymes
ex. PDS, maxon, biosyn
37
Monofilament - Long Term suture
-Polydioxanone (PDS II), Polyglyconate (Maxon) and Glycomer 631 (Biosyn)
▪ Retain tensile strength longer than
multifilament sutures
▪ Complete absorption at 6 months: PDS and Maxon
▪ Complete absorption 120 days: Biosyn
38
Polydioxanone
(PDS II)
▪ Maintain tensile strength
▪ 75% @ 14 days
▪ 58%% @ 28 days
▪ 14% @ 8 wks
▪ Noncapillary
▪ Good Handling
▪ Secure Knots: 4 Throws
39
Polyglyconate
(Maxon)
▪ Maintain tensile
strength
▪ 75% @ 14 days
▪ 50%% @ 28 days
▪ 14% @ 8wks
▪ Noncapillary
▪ Good handling
▪ Secure knots
40
Glycomer 631 (Biosyn)
▪ Maintain Tensile Strength
▪ 50% @ 21 days
▪ Noncapillary
▪ Good Handling
▪ Secure Knots
41
Monofilament –
Short to Medium Term
▪ Poliglecaprone 25 (Monocryl) and
Polyglytone 6211 (Caprosyn)
▪ Tensile strength
▪ Deteriorates in 2-3 weeks
▪ Rapidly absorbable
▪ Monocryl 60 – 90 days
▪ Caprosyn – 56 days
▪ Pliable, lack stiffness, good handling
characteristics
42
Poliglecaprone 25
(Monocryl)
- Maintain Tensile Strength
▪ 30% @ 14 days
▪ Noncapillary
▪ Good Handling
▪ Secure Knots
43
Polyglytone 6211
(Caprosyn)
▪ Maintain Tensile Strength= 30% @ 14 days
▪ Noncapillary
▪ Good Handling
▪ Secure Knots
44
Multifilament –
Medium Term
▪ Polyglycolic acid (Dexon) and Polyglactin 910 (Vicryl)
▪ Absorption:
▪ Polyglycolic acid (Dexon) – 100 – 120 days
▪ Polyglactic 910 (Vicryl) – 40 – 90 days
▪ Braided:
▪ can Harbor bacteria
▪ Increased capillary, can cause swelling more
45
Polyglycolic Acid
(Dexon)
* Maintain Tensile Strength
* 67% @ 7 days
* 20% @ 14 days
* Good Handling: Saws Tissue
* Secure Knots: Long Tails, since security of knots isnt as good.
46
Polyglactin
910 (Vicryl)
▪ Maintain Tensile
Strength
▪ 50% @ 14 days
▪ 20% @ 21 days
▪ Good Handling
▪ Saws Tissue
▪ Secure Knots
▪ Tails Long
47
Nonabsorbable
Suture
Materials
Organic nonabsorbable materials:
* Braided multifilament, silk
Synthetic nonabsorbable materials
* Polyester or coated caprolactam
* Monofilament
* Polypropylene
* Polybutester
* Polyamide
48
silk
▪ Maintain Tensile Strength
▪ 70% @ 14 days
▪ 50% @ 1 yr
▪ Good Handling
▪ Secure Knots
49
Polymerized Caprolactam
(Supramid)
▪ Maintain Tensile Strength
▪ > Nylon
▪ Good Handling
▪ Secure Knots
▪ 4 Throws
▪ Don’t bury – infections and fistulation
▪ Inner core and outer sheath – breaks and
allows bacteria
**, don't use in horses they don't tolerate. can lead to reactions
50
Polyester
(Ethibond)
▪ Maintain Tensile Strength
▪ > Nylon
▪ Good Handling: Saw Tissue
▪ Secure Knots
▪ 6 Throws
51
Polybutester (Novafil)
Polypropylene (Prolene)
▪ Maintain Tensile Strength
▪ < Nylon
▪ Noncapillary
▪ Good Handling
▪ Slippery
▪ Secure Knots
▪ 4 Throws
-commonly used in the skin
52
Polyamide/Nylon
(Dermalon)
▪ Maintain Tensile Strength
▪ Good Handling
▪ Memory
▪ Secure Knots
▪ 4 Throws
▪ Antibacterial
53
Stainless Steel
▪ Maintain Tensile Strength > Nylon
▪ Noncapillary
▪ Secure Knots
▪ Difficult to handle
54
selection of suture materials different parts of skin, subQ ect.
-skin: Monofilament nonabsorbable, or absorbable and takes a really long time to absorb
-subQ: Synthetic absorbable
-fascia: Monofilament absorbable or
nonabsorbable Fascia
-tendon: Monofilament absorbable or Nylon
55
suture needles
▪ Swaged On Needles:
▪ Less Traumatic as thred is attached to needle
▪ Technically Easier
▪ Eyed Needle:
▪ More Traumatic
▪ Technically Difficult
56
suture needle choice
Tissue:
▪ Skin – Cutting
▪ Bowel, SubQ – Taper
▪ Fascia, Tendon – Taper or Modified Cutting
▪ Depth of Wound
▪ Type of Circle
57
suture type/needle/ ect to use for suturing linea alba
-absorbable
-monofilament
-cutting needle
-long lasting
-ex. PDS, vicryl
58
suture type/needle/ ect to use for suturing subQ tissue
-absorbable
-monofilament or coated multifilament
-taper needle
-quick to absorb
-ex. monocryll
59
suture type/needle/ ect to use for suturing skin
-non absorbable, or absorbable if you will never see patient again
-monofilament
-cutting needle
-ex. prolene, or PDS which is absorbable but lasts along time
60
suture type/needle/ ect to use for suturing parenchymal organs (liver, spleen, kidney)
-absorbable
-monofilament
-taper needle
-quick to absorb
-ex. monocryll
61
suture type/needle/ ect to use for suturing hollow viscous organs (trachea, GI, bladder)
-absorbable
-monofilament
-taper needle
-long lasting or quick to absorb= you need in between
-ex. monocryll, dexon
62
suture type/needle/ ect to use for vessel ligation
-absorbable
-multifilament (better knot security, easier tie)
-use any needle, not passing though tissue with it just going behind vessel
-long lasting
-ex. PDS, vicryl, Maxon
63
suture type/needle/ ect to use for vessel anastomosis
-non-absorbable
-monofilament
-taper needle
-long lasting
-ex. prolene
64
causes of dead space
* Extensive dissection (surgery undermining)
* Injury resulting in tissue loss
* Removal of large masses
* Reconstruction with flaps and grafts
65
fluid accumulation within a wound causes
* Reduces healing, favors infection if bacteria
are present:
* antibody opsonic activity lost
* disrupts phagocyte-bacteria interaction
* substrate for bacterial growth
* compromises blood supply
* interferes with graft acceptance
66
how to avoid creating dead space
* Meticulous, minimalist technique
* Avoid undermining when you make
incisions
-don't remove tissue unless there's a very good reason for it to go.
-mayo dissection: use Metzenbaum scissors to make a tunnel in the tissue, helps avoid vessels and nerves, only insices on area you need to go.
-use tacking/walking sutures: going through skin into body wall to suture together, decreases dead space.
67
how to deal with dead space
-can use pressure wraps (depending on anatomical location if they will stay)
-If you can’t eliminate dead space, you can
try continuous or intermittent fluid (or gas)
removal. This is called drainage.
-passive, active or physiological drains
68
passive drains ex penrose drains
* Work by capillary action and gravity
* Efficacy dependent upon surface area
mech:
* Make the exit point ventral to the wound
* Avoid exiting through the incision itself
* Aseptic post-op care needed
-don't work well, poor drainage, exit point is very prone to infection you need to place aseptic bandage. use other methods.
69
Active Drains (Closed Suction Drains)
* Work by attaching tubing within the
wound to a suction device outside of the
wound
* More efficient than passive suction and
not dependent on gravity
-can lead to ascending infection
ex. jackson-pratt system or for smaller patients rebel suction device with butterfly and vacuum.
70
physiological drainage
-omentalization
-can use when in the abdomen, very good at sticking omentum to anything and can drain abscesses inside the abdomen,
71
Negative pressure wound therapy (NPWT)
(also known as vacuum-assisted closure, or VAC)
* Vacuum applied to wound through open cell foam covered by occlusive layer
* Encourages granulation tissue formation, eases wound care
-can leave in place for 3-4 days so makes wound healing and treatment easier
72
when to use drainage
* If fluid will remain or be produced post-op, and this is likely to be a problem
* If contamination is present and can’t be
completely resolved surgically (if this is the case, your best bet is to leave the wound open) but depends on location of the wound not abdomen, ect.
73
when not to use drainage
-if you do a nice clean surgery and get postoperative seromas and
hematomas (usually around 2 weeks after)
-wait it out and this will gradually be reabsorbed in 2-3 weeks
74
when to remove a drain
* 1-7 days after surgery: case by case decision when its no longer doing any good and is more leading to a source of infection.
* When it stops working – clogs, kinks
* Dependent on fluid quality and quantity:
- Decreased amount (1/4 of original over 24h)
- Serosanguinous rather than cloudy
- If fluid < 0.2 ml/kg/hr
75
how to remove a drain
* Doesn’t usually require sedation
* Remove the sutures and pull!
* Ensure the entire drain has been removed
* Cover the wound for 24-48 hours
76
tension & excessive tension
-a pull on the wound that counteracts closure
excessive tension:
- prevents wound closure, can lead to dehiscence of sutured wounds.
- Can compromise blood flow: slows healing, may cause necrosis
-Can have a tourniquet effect on distal extremities
-Can lead to scarring and strictures
- Can restrict movement
77
what affects tension
-species and breed (horses don't have any extra skin, as small animals do)
-location on the body (tension lines and nearby appendages)
-orientation of the wound
78
lines of tension
* Wounds usually close best if closed along
(parallel to) the lines of tension
* This way the tension pulls the wound together rather than pulling it apart
-can do a pinch check to test tension in all directions
79
managing tension techniques
* Undermining
* Walking sutures
* Skin stretching
* Releasing incisions
* Plasties
* Flap closure
* Free grafting
80
Managing Tension:
Walking/ taking Sutures
* Obliterate dead space
* Distribute tensile forces throughout the wound
* Facilitate progressive advancement of
undermined skin into the wound defect
-acts like a drawstring to pull things together, like taking sutures but with a few extra bites.
81
Tissue Expanders
* Balloon implanted beneath skin next
to where you need skin to go
* Balloon is gradually inflated with
saline over several weeks
* Skin stretches above balloon
* Balloon removed when skin is moved
-Some skin expanders imbibe fluid from the
tissues instead... ex melanoma on horse head.
82
Skin Stretching: Presuturing
* Large mattress or Lembert sutures
* Fold up skin on either side of defect
* 3-5 cm from defect
* 24-72 hours
83
Managing Tension: Releasing Incisions
* Sometimes it is more critical to have intact skin in a certain area than in adjacent areas
* To help you close a primary incision, you can incise adjacent skin...and leave the secondary incision(s) open
* Avoid leaving a narrow strip of skin between the two incisions: it will die
84
Incisional Techniques to Redistribute Tension: ‘Plasties’
* Useful when wounds are adjacent to
structures that will not tolerate tension:
* Anus
* Prepuce
* Eyelids
V-Y Plasty
* Decreases tension in one direction, increases
tension in the perpendicular direction
Y-U Plasty
* Same idea, backwards: good for making narrow things wider
Z-Plasty
* Decreases tension in one direction at the
expense of increased tension in another
direction
* Good for treating contracture due to a
limiting scar
85
flaps
* Maintain connection to the donor site at one end (at least)
* Depend upon blood supply coming from the donor area to survive
* The need to maintain blood supply from the donor site limits length and positioning of flap
86
grafts
* Term usually reserved for tissue removed entirely from the donor site and placed into the recipient
site
* May be either vascularized (this requires microsurgery) or not (more common in veterinary
medicine)
-widley used in horses since they dont have much extra skin
87
subdermal plexus flaps (random pattern flaps)
* Nourished by the subdermal
plexus (so keep cutaneous
trunci with the skin!)
-subdermal plexus flaps should not be
more than twice as long as they are wide.
-The base of a subdermal plexus flap should be wider than the tip
88
rotation flap
* Arc needs to be at least 3x
length of the defect
* Undermine the flap
89
skin fold flaps
* Redundant tissue in inguinal, axillary region
* Transposed to adjacent thoracic or abdominal wall, or limb
-flank fold or axillary flaps
90
Axial Pattern Flaps
* Contain a cutaneous artery from deeper
* Are generally transposition flaps
* Transposed via bridging incisions, or by tubing middle portion
* Can be transposed up to 180 degrees
* Robust closure for high motion/high pressure areas
* uncommonly used in large animals
* Can be dissected as ‘island’ flaps (just an umbilical cord of vessels attached to an otherwise free flap)
* Be careful to avoid kinking or tension on pedicle
* Useful for reconstruction of large wounds of the head, neck and proximal extremities
* Follow angiosomes
91
Caudal Superficial Epigastric
Axial Pattern Flap
* External pudendal artery exits the inguinal ring, branches into C.G.E.
* Extends cranially along mammary chain
* Angiosome includes glands 3,4,5
* Can extend dissection to include gland 2
* Good for closure of medial thigh wounds
92
skin grafts
-Pieces of skin that are completely detached from the donor site
* Vascularized grafts require microsurgery to connect
their main vessels to supply vessels in the recipient site
* Avascular grafts depend on ingrowth of blood vessels from the wound for survival
93
skin flaps vs grafts
Flaps:
* Robust and require little aftercare
* Not easily used on sites at or distal to carpus or tarsus
* Good cosmetic appearance
Grafts:
-more delicate, lots of aftercare
-comestic apperance depends on graft skin thickness and donor site
-useful for wounds of distal extremities.
94
partial (split) thickness grafts
-takes varying levels of the dermis, delicate, poor regrowth of hair at fonor and recipient sites
-can take a large graph and skin will grow back in donor area (painful)
-need special instruments for harvest
-
95
full thickness grafts
- takes the entire dermis, maintain hair follicles, Prettier, easier to harvest, similar graft survival to partial.
96
skin graft most commonly used in SA
* Sheet, pie crust, mesh
(all the same thing)
* All are generally full
thickness grafts
97
pinch and punch grafts, adv. and disagv.
adv:
* Minimal donor site morbidity (just lots of little holes)
* Can be done under local anesthesia
* Motion at recipient site is less likely to dislodge tiny little independent grafts: each graft moves independently
* Commonly used in horses
Disadvantages
* Not very cosmetic
* Majority of coverage is only epithelial—more prone to trauma than full-thickness skin
98
footpad free grafts
* Are punch grafts
* Place around periphery of wound
* Epithelial component will slough and regenerate
99
how skin grafts become incorporated (take)
-initially depends on suturing and bandaging
-fibrin attachment first then blood vessels and collagen.
-graft must be in close contact with wound bed for nutrition/ oxygenation of cells and later ingrowth of BV & collagen
100
nutrition of skin grafts
* Plasmatic imbibition (osmotic and capillary movement of wound fluid and proteins)
* Inosculation (open ends of vessels in wound bed and graft kiss and allow fluid exchange)
* Vessel ingrowth (capillary buds from wound bed invade graft
101
How do I select an appropriate donor site?
* Can I harvest adequate skin and close the donor defect?
* Do hair characteristics match the recipient site?
* Are there any donor site functional or cosmetic concerns?
102
Full Thickness Mesh Grafting: Technique
-trace template of wound-
-use template to mark donor site, pay attention to hair direction at both sites and ability to close donor wound.
-harvest graft: excise from donor site, leaving as much subQ tissue you can in donor bed. dont want to take SQ tissue.
-mark graft so you know hair direction, and suture the donor site.
graft prep: remove all subQ tissue. look for cobblestone appearance of hair follicles. pin graft to sterile foam or cardboard. makes holes with scalpel.
prep recipient site: surgical prep if not gresh wound. excise granulation tissue and epithelialized edges.
-graft insert: staples or sutures. tacking sutures to hold down. want correct orientation. no tension.
-stabilize graft (post operative considerations): bandages, ect.
103
postoperative Considerations of graft
* Stabilize the graft:
* Bandages
* Negative pressure wound therapy
* Splints/ external skeletal fixation in high
motion areas
Graft bandaging:
* First layer must be nonstick and porous, so that fluid can escape.***
* Petrolatum-impregnated gauze good.
* Telfa pad BAD.
-then absorpent layer, and splint if needed.
-use vetrap or elastoplast.
* Try to avoid changing the
bandage for 5 days postop so
you don’t disrupt ingrowth of
blood vessels
