LA Sx Exam #2: Wound Management Flashcards
What are three synovial structures that can be damaged with distal limb injuries?
1) Joints
2) Tendon sheaths = tarsal, carpal, digital
3) Bursas = calcaneus, navicular
What type of distal limb wound is considered an emergency? What is our goal with these types of wounds?
One involving a synovial structure (joint, tendon sheath, bursa) = commonly infected, synovial membrane is a great bacterial medium
GOAL = eliminate the infection before irreversible damage occurs
*Duration of infection and therapy determine prognosis, survival, etc.
Two main/general methods to eliminate wound/synovial infections
1) Systemic antimicrobial tx
2) Local antimicrobial tx = lavage, topical, intra-articular or intra-thecal, regional limb perfusion, antibiotic impregnanted delivery systems
Route, duration, and types of systemic antibiotics for treatment of systemic infection
- Route = IV first, then oral if necessary
- Duration = until after clinical signs resolve (synovial infections often 2-3 weeks past that point)
- Types = penicilin+gentamicin, penicillin+ceftiofur, enrofloaxacin, oral TMS
Four reasons that provide the rationale for using local over systemic treatment
1) Vascular trauma and inflammation don’t always permit delivery of IV antibiotics to areas = allows bacteria to proliferate
2) Infection and cellular debris = low pH = decreases antibiotic activity = allows bacteria to proliferate
3) High systemic doses can be toxic, don’t often need that high of a dose locally
4) Synovial membrane = great bacterial medium
Purpose and options for local lavage treatment
> Purpose = remove foreign debris, reduce bacterial contamination
- Isotonic saline + 0.1-0.2% povidone iodine = doesn’t always work with lots of cellular debris
- Isotonic saline + 0.05% chlorhex
- Isotonic saline + antibiotics
- Use a drip set and 18-gauge needle to get sufficient but not excessive pressure
- Tap water = causes cell swelling (hypotonic), stop after granulation tissue forms
Things used for local topical treatment (most recommended?) and pros/cons
- Antiseptics
- Antbiotics = based on C&S
- Wound aersol sprays
- Herbal therapies
- Surgeon preference = silver sulfadiazine
- Does it promote resistance
- Need to create a clean wound to work, debride and create a bleeding clean wound (scab = too late)
- Furazone = carcinogenic, decreases wound healing
True or false - with intra-articular or intra-thecal treatments, you want to enter your catheter/CRI into a wound that is different than the original wound
True
Methods and antimicrobials used with local intra-articular/thecal treatments
- Methods = direct, catheter, continuous infusion pump
- Amikacin = 500mg - 1 gram (not in cattle)
- Gentamicin = 200mg - 1 gram
- Cefazolin = 250-500mg (IM only)
- Ceftiofur = 150-500mg
- Penicillin = 2-5 million units
What do you have to remember with aminoglycosides and intra-thecal or intra-articular therapy? (2)
1) Needs to be > 500 mg, otherwise it’s ineffective
2) Subtract out local dose from systemic dose in neonates to avoid nephrotoxicity
Goal of regional limb perfusions
> > Treatment that rapidly reaches high concentration of antibiotics in infected tissues (synovium and subchondral bone)
- Promotes rapid bacterial elimination
- Decrease damage to affected synovial structures
- ADJUNCTIVE TX = use with systemic antimicrobials or surgical tx
Commonly used drugs and doses with regional limb perfusions
- Commonly use 1 gram = don’t see the reaction/inflammation we see going synovially, if we go regionally
- Risk = vasculitis, skin sloughing
a) Gentamicin = 500mg - 1 gram
b) Amikacin = 500mg - 1 gram
c) Penicillin = 10-20 million units
d) Enrofloaxacin = 1.5 mg/kg
Pros and cons of regional IV and IO antibiotic infusions
+ IV = technically easier
+ IV = doesn’t require general anesthesia
+ IV = reaches higher levels in tissue than IO
- IV = can form hematomas
- IO = technically more challenging, drilling into medullary bone
- IO = requires general anesthesia
+ IO = easier if there’s more soft tissue swelling present
+ IO = repeated daily treatments w/ minimal adverse effects (less hematoma risk)
+ IO = easier in younger animals
Regional limb perfusion technique
1) SEDATE and standing horse (don’t always have to block, but always sedate) - detomidine+butorphanol
+/- Local block w/ carbocaine at or below the fetlock (low or high 4-pt, ulnar/median and tibial/peroneal nerves)
2) Apply tourniquet for 20-30 min, proximal to affected area
3a) IV = infuse antibiotic via superficial vein (medial lateral plantar/palmar veins, cephalic/saphenous if more proximal)
3b) IO = directly into medullary cavity with special screw (doesn’t require a tourniquet)
4) Infuse 30 mL for neonates, 60 mL for adults (antibiotics diluted with saline) over 1-30 minutes
5) Remove catheter and wrap site - OR - remove/leave screw
Why do we use local repository treatment (4), what are the two types? (2)
> Biodegradable and non-biodegradable
- Achieves sustained high concentrations in tissue w/o toxic effects
- Reduced labor/time with daily intra-articular infusions
- Useful in difficult to handle patients
- Can use expensive antibiotics that would be cost prohibitive systemically
Types of biodegradable and non-biodegradable repositories
> Biodeg = collagen-based membrane or sponge, beads of plaster or Paris or hydroxyapatite, polylactic or polyglycolic acid (like sutures)
Non-biodeg = PMMA beads
True or false - antibiotics beads work better if tissues can be closed
True - allows you to achieve high enough concentrations in the wound
