Wounds Flashcards
What is bacterial infection ?
more than 10^5 bacteria per gram of tissue
list the subtypes of surgical site infections
-incisional
-superficial - skin and sub cut
- deep
-organ/space
List the 4 classifications of degree of contamination , describe
-Clean - non-traumatic , non-inflamed , operative wound resp, gastrointestinal, genitourinary and oro-pharyngeal tracts not entered
-Clean-contaminated - operative wound resp, gastrointestinal, genitourinary tract are entered , under controlled conditions without unusual contamination
-Contaminated -open fresh accidental wound , in which gastrointestinal contents or infected urine is spilled or a major break in aseptic technique.
-Dirty -old traumatic wound with purulent discharge , dead tissue ,foreign bodies ,perforated or faecal contamination.
How to reduce infections as well as factors effecting infections ?
-aseptic technique - patient prep, surgeon prep and theatre , sterilisation , disinfect
-age - young animals struggle to have decent immune response , older cell division occurs slower wound take longer to heal
-physical condition - if unwell immune system might not be as responsive
-concurrent metabolic issues - corticosteroids make wound healing harder so longer exposure
-current medication - chemotherapy or corticosteroids make wound healing harder so more prone to infection
In what circumstances would it be appropriate to use antibiotics .
-surgery <90 min
-prosthetic implantation
-pre-existing prosthesis patient undergoing surgical procedure
-severely infected or traumatised wound
prophylactic antibiotics
basically = prevention antibiotics
Prophylactic antibiotic examples and advantages .
-cephalosporin - known as Zinacef - good against gram positive
-Amoxicilin - known as Augmentin good against gram positive and anaerobic
-metronidazole - for anaerobic
What are the 3 phases of wound healing ?
-haemostasis and inflammation
-proliferation
-maturation
Describe the phase of haemostasis.
-injury occurs causing tissue damage
-bv leak
-activates clotting cascade intrinsic and extrinsic
-platelet aggregation and release cytokines
-stabilisation of platelet plug by fibrin formation - stops blood loss
Describe the inflammatory phase of wound healing .
-overlaps with haemostasis
-occurs for the first 72 hours after injury
-vasodilation - need good blood supply for wbc
-cytokines in fibrin clot attract wbc - firstly neutrophills then macrophages
-carry out phagocytosis
Describe the proliferation phase of wound healing .
-can overlap with inflammatory phase
-formation of granulation tissue formed from macrophages, fibroblasts and new bv
-fibroblasts proliferate and produce new extracellular matrix, elastin and collagen ( starts give wound strength )
-then get formation of new epithelial tissue
-myofibroblasts contract cause wound to contract and shrink
-contact inhibition occurs
Define contact inhibition.
when epithelial cells come into contact it inhibits further cell division so end up with smooth layer of epithelial tissue
Describe the maturation phase of wound healing .
-remodelling occurs
-type III (immature ) collagen replaced by type I (mature) collagen
-cross linking of collagen
-change in components of extracellular matrix
-increase tensile strength
- takes weeks to months
State and describe factors effecting wound healing . ( patient , wound , concurrent treatment )
-age - takes longer older rate of cell division and tissue remodelling is slower
-co-morbities e.g cushings , diabetes slow down wound healing
-nutritional status - healing high energy demand
-infection
-location -tension , movement , blood supply
-corticosteroids - delay all stages of wound healing
-radiation cause tissue fibrosis and vascular scarring
Define abrasion
loss of epidermis and some dermis
blunt trauma / shearing
Define evulsion .
-like degloving
-tearing of tissues from attachments
Define incision
created by sharp object
minimal trauma
Define laceration
tearing of wound creating irregular defect
jagged and tears underlying tissue
Define puncture
penetrating wound
iceberg situation
What is the sub dermal plexus?
terminal branches of cutaneous arteries found in hypodermis and subcutis ( sit below dermis
How to assess a wound ? for SA
-type of wound
degree tissue damage
depth
vital struc - bones , joints , tendons ,nerves
tip of the iceberg
-wound age
golden period = 6-8 hrs
contaminated or infected
-level of contamination
foreign material
dead tissue
bacterial innoculum ( bite vs clean glass)
take into account age and nature of wound
-lavage/debridement
gross contamination - tap water
flush hartmanns (35ml/60ml syringe ,18G needle = 7-8 psi )
no added antiseptics
debridement - dressings , surgical
-managment
primary intention
second intention healing
third intention
Define primary intention healing .
close straight away surgically
Define secondary healing
heal on its own via epithelialisation and contraction
Define third intention healing
delayed surgical closure
close over healthy granulation bed once debride
List and describe factors effecting bacterial contamination and infection
-vascular supply - reduced ability to fight infection
-dead tissue - increase bacteria growth
-foreign body -reduced ability to figth infection
-type of contamination - getting bitten more bacteria involved than cut on some glass
-type of bacteria
What are we getting rid of when we debride
- dead contaminated tissue
-chronic granualtion tissue
What causes chronic granulation tissue ?
cells get stuck in the granulation phase and overgrow granulation tissue so the epithelial cells can’t grow over the top . therefore we must remove it to expose a healthy granulation bed.
What measure of syringe,needle ,pressure and solution is used for lavage in SA
-20-35ml
-18G
-7-8psi
-heartmans
Why do we have to be weary of pressure with a lavage ?
push bacteria and contaminates deeper into the wound tissue instead of drain out .
What’s a common overall treatment for unhealthy granulation bed ?
-surgical debridement - scrap off
-lavage
-wet-dry -dressing
how often is a wet-dry dressing changed ?
every 24 hrs
What is topical negative pressure wound therapy ?
-pump that reduces air pressure under dressing - draws off exudate and reduce odema , increase blood flow , stimulate granulation tissue ( promotes healing )
Why is honey a useful debridement agent ?
-low ph - help draw out fluid
-osmotic effect - draws fluid out
why is manuka honey a good antimicrobial agent ?
-antioxidant
-acidic bacteria can’t grow that can’t take the environment
Name types of immobilising bandages and splints
-robert jones bandage
-gutter splint
-plaster of paris on a roll
-fibreglass impregnated with resin
Describe the different layers of a bandage
-primary layer - incontact layer aids healing and protects
-secondary layer - supportive or padding layer(absorbs excessive exudate ) and then conforming ( helps hold in place and absorb exudate )
-tertiary layer -cohesive layer
Splint areas forelimb equine
region 1 = distal metacarpus , align dorsal cortices placed dorsally ( heel wedge )
region 2 = distal radius- mid-metacarpal ,want to align cortices vertically to keep carpus fully extended and stabilise metacrapal-phalangeal joint , placed lateral , caudally with heavier bandage
region 3= proximal -middle radius , prevent abduction of limb , placed laterally and full robert jones
region 4 =anything proximal from region 3 , no stabilisation needed - heavy distal limb bandage will have pendulum effect - destabilise fracture
Splint areas for hindlimb horse
region 4 - lots of muscle so natural stabilisation
region 3 - tbia , placed laterally , stop abduction ( tibial fractures poor prognosis )
region 2 middle and proximal metatarsal - heavy bandage, plantar splint and maybe lateral splint as well
region 1 distal metatarsals /proximal phalanges - plantar splint for vertical alignment
What are the 3 phases of bone healing ?
inflammatory
restorative
remodelling
Describe what occurs in the inflammatory phase of bone healing .
-lysis of dead soft tissue and osteocytes — attract wbc –macrophages clear debri
-blood clot a fracture site -hematoma ( neovascularisation )
Describe the restorative phase of bone healing
-soft callus formation - fibrous tissue and cartilage , new bv , starts to stabilise
-hard callus formation -cartilage undergoes endochondral ossification ( osteoblasts )
Describe the remodelling phase of Bone healing .
-end of bones are enveloped by fusiform mass = callus
-remodelling - oesteoclasts
Briefly describe two types of healing that can occur in the restorative phase ?
-1st intention minimal bone callus formation there’s just direct formation of bone - (when this occurs -good blood supply , immediate stabilisation , absence infection )
-2nd intention - most common - natural type of healing, there is callus formation ( when this occurs - late treatment ,infection , poor blood supply )
State and briefly describe forces applied to bones .
-axial compression - push down along its long axis
-tension - pulled , stretched - by ligaments and muscle insertion
-bending - due to asymmetrical bone loading
-Torsion - twist
- occur to either weight bearing or muscle contraction
Which side is a plate always applied to ? and why
the tension side because it will not be broken by tensile forces but will be by successive compressions
will break if compressed but not break if stretched
What is an IM pin good at stopping ?
bending
What is good at stopping rotational forces ?
interlocking nail, external fixator , plate
What is good at stopping tension forces ?
lag screw
tension band
What sort of management do you use mainly for necrotic and sloughing phase
debride devitalised tissue
What sort of management do you want to use for sloughing , granulating , epitheliaslising phase ?
maintain moist , clean environment
* depends what stage of sloughing as at some points there will be loads of exudate so need something to absorb it instead of making it more moist
What do foam dressings do ? when might you use them ?
-absorb moisture take away but maintain a constant level of moisture ( optimum for healing if change regularly enough - if not can cause maceration )
-in sloughing phase when there’s lots of exudate and subsequent phases to maintain moisture
What do hydrogel dressings do ? when use ?
add moisture
epithelial /granulation
What are silver dressings good for ?
-killign bacteria
Why use manuka honey ?
-antibacterial effects
-osmotic effect - draws fluid from wound
When would you use a tie-over dressing ?
for areas of the body that are awkward to bandage
Name some splints
-PCV drain pipe
-Kimzey leg saver
What does proud flesh mean ?
excess granulation tissue
Why do we use splints ?
to immobilise joints so wound/fracture can heal
TRUE/FALSE = need periosteum bone layer to allow granulation tissue to form
TRUE
What is faraging ?
drill holes in bone to encourage granulation tissue over the bone ( trying to get into bone marrow cavity )
Define sequestrum.
piece of bone broken off from rest, dead piece of bone
