The test JB's version Flashcards
3 processes by which a skin graft obtains nutrition
Plasmatic imbibition, inosculation and re-vascularization
Cat specifics when it comes to skin
Decreased vascularity vs dogs
Longer healing time - lower rates of granulation (2x’s longer than dogs), epithelialization, contraction
Critical to preserve the Sub Q
Deploarizing neuromuscular blockade
Name 2 and how do they work “briefly”
Succinylcholine, decamethonium
These drugs mimic ACh
Binds acetylycholine receptors, result in persistent depolarization (Na channels left open = Na inactivation). And receptor burn out - reason uncertain
Non-depolarizing neuromuscular blockade
Name 2 and how do they work “briefly”
Atracurium, pancuronium, vecuronium
These drugs block ACh.
Block ACh post synaptic receptors so no ACh stimulation
Clinical highlights of depoloarizing NM blockade?
Deploarizing = Initially get muscle fasciculation. Paralysis due to prolonged depolarization of the motor end plate. Paralysis is not reversed by anti-cholinesterase drugs but rather metabolism by pseudocholinesterase
Clinical highlights of non-depoloarizing NM blockade?
Gradual relaxation (no mm fasiculations) Can be partially reversed by anti cholinesterase drugs: Neo or Pyrido stigmine, edrophonium
Succinylcholine adverse effects
- Sore next day (fasciculation?)
- Hyperkalemia (K from skeletal mm)
- Malignant hyperpyrexia - Fast wicked high rise in temp +/- rigidity. Usually if give with halothane. Tx signs and use bicarb and dantrolene sodium (1-2mg/lb)
- Histamine release
- Tachycardia and hypertension (symp stim). but can sometimes get brady cardia
Decamethonium adverse effect
Same as succinylcholine except -
- no histamine release
- no metabolism (excreted by kidneys [so no usey if bad kidneys])
- longer duration of action (not metabolized by plasma cholinesterase)
Pancuronium (highlights)
non depolarizing
no histamine or catecholamine release
effects enhanced by inhalants
Major portion excreted unchanged in pee
Atracurium
- non depolarizing
- can give as infusion
- Hoffman elimination (chemical run) no liver or kidney involved
Vecuronium
- non depolarizing
- short onset and duration
- potential choice for renal failure (40% eliminated in bile, 15% through kidney)
What affect, if any could temp have on blockade?
hyperthermia
-prolongs depolarizing and antagonizes non-depolarizing
hypothermia
- prolongs non-depolarizing
What affect if any does respiratory acidosis have on blockade
Augments non-depolarizing blockade
Vicious cycle = inadequate reversal causes depressed ventilation which causes reap acidosis
Why would you give atropine with a neuromuscular blockade reversal
Reversals are anti cholinesterase drugs. By blocking AChesterase they increase the amt of ACh to compete with non-deploarizing blockers for the receptor.
Also get muscarinic stimulation (salivation, bradycardia, increased intestinal motility)
Atropine is an anticholinergic and will help decrease those side effects
Can you reverse succinylcholine
No. Paralysis is reversed by metabolism by pseudocholinesterase
How much trachea can be removed in
Adult
Puppy
Adult - 25-50%
Puppy - 20-25%
tobias says experimentally 15-27 rings
What kind of muscle is the trachealis muscle?
Is it dorsal or ventral
Primarily composed of transversely oriented smooth muscle fibers
Dorsal
What is the blood supply to the trachea
Segmental - from the cranial and caudal thyroid attires. Except near the corona - here it shift primarily to the bronchoesophageal arteries.
How are AB’s incorporated into PMMA beads released?
Bimodal manner (rapid phase then slow)
How much of the antibiotic used is released in the rapid phase and how long is this period
5% of total AB used is released in first 24 hours.
What affect does the addition of Metronidazole have on polymerization of PMMA? And what does that mean for you clinically?
The addition of metronidazole even at very low concentrations (100:1) significantly delays polymerization (hardening). Taking up to about 48 hours (apposed to the normal 5-10 minutes)
Local AB tissue concentrations have been reported to reach up to _______x’s greater than when given systemically
200 (per Saygeh Compend 2003)
20 (per Ramos etal vet surg 2003)
It is estimated that the area receiving therapeutic levels of AB’s may reach?
2-3mm
How long does elution of AB’s persist from PMMA?
21 days in a uniform dose dependent manner is commonly reported (probably longer)
How much of the total ab incorporated into the PMMA elutes
2.3-11% has been reported for a variety of AB’s tested
How much of the total cumulative elution occurs in first hour? First 24 hours?
1/3 in first hour, 2/3 in first 24 hours
What does the elution rates of AB’s from PMMA beads depend on?
Bead associated factors - Size of bead, pore size, permeability and type of cement used, exposed surface area Antibiotic factors -diffusion coefficient -concentration -mixing of some AB's Tissue factors -circulation in the area -amount of fluid surrounding bead
Requirements for AB to be used in PMMA beads
Should be bactericidal, effective against expected bact at MIC, and above all = HEAT STABLE
What is the most common concentration (recipe) of antibiotic to PMMA used
1g AB for every 20g of cement
What AB’s cant you use in PMMA beads? And why?
Polymixin B, tetracyclines, chloramphenicol. Not heat stable enough
Thomas LA, Bizikova T, Minihan AC. In vitro elution and antibacterial activity of clindamycin, amikacin, and vancomycin from R-gel polymer. Vet Surg. 2011
- 2 formulations:
- amikacin + clindamycin
- amikacin + clindamycin + vancomycin
- concentrations eluted over breakpoint MIC for 9 days, Staph was inhibited for all 10
- conclusion: R-get is an effective carrier for at least 9-10 days
Watts AE, Nixon AJ, Papich MG, Sparks HD, Schwark WS. In vitro elution of amikacin and ticarcillin from a resorbable, self-setting, fiber reinforced calcium phosphate cement. Vet Surg. 2011 Jul;40(5):563–70
- FRCP beads (“Norian”-Synthes) resorbable
- with amikacin, ticarcillin-clavulinate, or both
- “biphasic pattern of release”
- beads with either Abx were suitable carriers for elution
- beads with combination of Abx were not! Inhibited eachother’s elution.
- Do not use even two types of beads together (discussion)
Baez LA, Langston C, Givaruangsawat S, McLaughlin R. Evaluation of in vitro serial antibiotic elution from meropenem-impregnated polymethylmethacrylate beads after ethylene oxide gas and autoclave sterilization. Vet Comp Orthop Traumatol. 2011;24(1):39–44.
- meropenem is a carbopenem that is resistant to B-lactamase AND cephalosporinase
- in PMMA beads, its elution stayed above “breakpoint sensitivity limit” for 15 days
- ethylene oxide sterilization did not affect elution
- autoclaving destroyed meropenem activity
Atilla A, Boothe HW, Tollett M, Duran S, Diaz DC, Sofge J, et al. In vitro elution of amikacin and vancomycin from impregnated plaster of Paris beads. Vet Surg. 2010 Aug;39(6):715–21
- plaster of paris is absorbable and osteoconductive
- Amikacin does not work!
- left POP beads so quickly that staph grew within 24 hours
- when mixed with vancomycin, it decreased vancomycin’s efficacy
- Vancomycin worked
- steady release for 12 weeks, suppressed staph growth for 8 weeks
Max screw angulation through a DCP longitudinal and sideways
Through an LcDCP
DCP - 25 degrees longitudinal, 7 degrees sideways
LcDCP - 40 degrees and 7 degree respectively
Benefits of an LcDCP vs DCP
Decreased contact with bone = increased periosteal blood supply (less disruption)
Decreased stress concentration at screw holes
Movement of the bone fragment when placing screws load and neutral guide
- 5mm DCP, LcDCP and 3.5 DCP?
- 7 DCP
- 5 and 2.7 LcDCP
- 5mm DCP, LcDCP and 3.5 DCP = 1mm for each screw loaded up to a max of 4mm. 4.5mm = 0.1mm in neutral guide
- 7 DCP = load guide 0.8mm, neutral is 0.08mm
- 5 and 2.7 LcDCP = 0.75mm and 0.075mm respectively
With respect to a plate rod construct with plate in buttress or a buttress plate and a rod 50% of the IM diameter -
How much stress reduction and what increase in fatigue life is obtained?
~2 fold stress reduction and 10 fold increase in fatigue life
Hulse et al VCOT 2000 reported what changes in stiffness and plate strain associated with the addition of an IM pin of 3 various sizes to a 3.5mm DCP
6, 40 and 78% increases in stiffness and 19,44 and 61% decreases in plate strain with pins 30, 40 and 50% the diameter of the bone respectively
What 3 elements in a 316L stainless steel plate provide corrosion resistance?
Chromium 18% - corrosion resistance
Nickel - strength
Molybdenum - resistance to pitting corrosion
Who is stronger? 4.5mm DCP or 3.5mm broad? Why?
3.5mm broad. Smaller and more screw holes per unit length
How much pressure does one screw in compression apply to the fracture?
50-80kp (kilopascal)
Tramadol MOA
Weak action at mu receptor. Analogue of codeine.
Analgesic properties related to serotonin and adrenergic receptor effects centrally.
Cox 2 constitutively expressed in?
And…..
Brain, kidney
mediates a cytoprotective effect in damaged or inflamed GI mucosa
What does MIPO stand for?
Minimally invasive plate osteosynthesis
What is the rate limiting step in prostaglandin and leukotriene synthesis
The release of arachidonic acid from membrane phospholipids by Phospholipase A