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Intro Surgery I Exam


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What is the MBC:MIC for bacteriocidal drugs?
< 4-6
What is the MBC:MIC for bacteriostatic drugs?
Name two classes of concentration dependent antibiotics.
Fluoroquinolones and Aminoglycosides
Name a class of drugs that are time dependent.
B-lactam drugs: penicillins and cephalosporins
What must the plasma concentrations be for bacteriocidal and bacteriostatic drugs?
Bacteriocidal: peak plasma concentration 4-8x the MIC.
Bacteriostatic: plasma concentrations kept at least MIC during dosing period.
What are the "big three" contaminants?
Staph, Strep, E.coli
What are common contaminants in SA orthopedic surgery? What drugs are commonly used?
Staphylococcus intermedius, coag + Staph sp., B-hemolytic Strep sp.
Use first generation cephalosporins.
What are two common contaminants in SA soft tissue surgery?
What drugs are commonly used?
Enteric bacteria - E.coli and Klebsiella
Use second generation cephalosporins.
Name two drugs used commonly in equine surgery.
Potassium Penicillin (loading dose, then IV QID)
What drug has renal and GI toxicity issues, especially in the horse? What can complicate this?
Gentamicin (concurrent NSAID use)
What is a common drug used in foals? Name two problems with this drug.
1. Expensive ($400/day)
2. Renal compromise
What is the timeframe antibiotics should be administered for prophylaxis during surgery? Why?
At lease 30 minutes prior to incision, but not more than 60 minutes. There's a lag between peak plasma and surgical wound fluid conc. - they equilibriate after ~30 minutes, then rapidly decline.
Name two indications for therapeutic animicrobials related to surgery.
1.contaminated or dirty wounds
2.existing infections
What are the five classic signs of infection?
Loss of function
What laboratory data support a diagnosis of infection?
Degenerative left shift
Elevated fibrinogen
Positive cultures
What radiographic findings support a diagnosis of infection?
Bone lysis
Implant failures
Increased fluid density
Soft tissue swelling
Name three "other" common bacteria associated with infections (one anaerobe).
Pasteurella multocida
Pseudomonas aeruginosa
Where are anaerobic infections predominately found?
Areas with mucosal surfaces - oral cavity, urogenital tract, GI tract. Also abscesses and chronic draining tracts. Less commonly: pleural cavity, bones, respiratory tract, abdominal cavity.
Name four common anaerobic bacteria associated with infections.
Bacteroides sp. (70%)
Porphyromonas sp.
What type of treatment should be considered for anaerobic infections?
Anitmicrobial therapy, surgical debridement (inc. O2 levels)
What are five drugs commonly used for anaerobic infections?
Amoxicillin-clavulanic acid
What are the basic components of POMR?
Problem list
SOAP (Subjective, Objective, Assessment, Plan)
What does the database of POMR include?
Signalment and history, PE findings, initial laboratory data.
What is the most important diagnostic tool that veterinarians possess?
Their ability to obtain a complete history and thorough physical examination!
Physical status I
Healthy with no discernable disease. Ex: Patient presented for elective procedure.
Physical status II
Healthy with localized disease or mild systemic disease. Ex: patellar luxation, skin tumor
Physical status III
Severe systemic disease
Ex: pneumonia, fever, dehydration, heart murmur, anemia
Physical status IV
Severe systemic disease that is life threatening.
Ex: heart failure, renal failure, hepatic failure, severe hypovolemia, severe hemorrhage
Physical status V
Moribund; patient not expected to live longer than 24 hours with or without surgery. Ex: endotoxic shock, multiorgan failure, severe trauma
Which patients should receive a CBC, chem and U/A before surgery?
Those over 5 years old, young animals with a higher physical status, animlas with systemic signs, or animals requiring a prolonged surgical procedure.
What paramaters should be monitored on the anesthetized patient?
reflexes, heart rate, color, capillary refill time, respiratory rate and body temperature. Others include ECG, arterial blood pressure, central venous pressure, pulse oximetry, and blood gas analysis.
What parameters should be monitored following recovery from anesthesia?
temperature, pulse, color, CRT and respirations.
What should be monitored for patients suspected of having active hemorrhge?
Serial PCVs and TPs. Also, palpate for a fluid wave - if positive, do abdominocentesis.
When should LRS vs. blood products be given?
A balanced electrolyte solution like LRS can be given in bleeding cases in which hemodilution is not a concern and PCV is >20%. Blood products should be administered when the PCV is <20% or if hemodilution or ongoing hemorrhage is likely to cause the PCV to drop this low.
What can a rapid respiratory rate indicate in a postoperative patient?
Pain, hyperthermia, respiratory problems such as pulmonary congestion, aspiration pnemonia, or upper airway obstruction.
What is normal urine output in the dog and cat?
1-2 ml/kg/hr.
How soon should most patients resume eating postoperatively?
6-24 hours.
What are some signs of pain?
Tacycardia, tachypnea, hypertension, cardiac arrhythmias, dilated pupils, salivation, vocalization, restlessness, behavior changes (aggression or depression) and abnormal body postures.
What are seromas usually associated with? How should they be treated?
Excessive undermining of the skin and failure to close dead space. Apply warm compresses and pressure wraps as needed - do not drain.
Name the three phases of wound healing and how long each lasts.
1. Substrate phase (1-5 days)
2. Repair phase (6-16 days)
3. Remodeling phase (starts 14-16 days after injury and can last 2-3 weeks to several months.
What is the "substrate phase" of wound healing?
Also called the inflammatory or lag phase. Hemostasis takes placeas platelets form a clot and secrete chemoattractive substances. Inflammatory cells then migrate into the wound.
What are the first inflammatory cells to migrate into a wound and when do they peak?
Neutrophils peak at 24 hours.
What are the second group of inflammatory cells to migrate into a wound and what do they do?
Macrophages become the predominant population after neutrophils and play a major role in the regulation of wound healing. They secrete growth factors and phagocytize debris.
How does the wound matrix change during the substrate phase of wound healing?
Fibrin is replaced by mucopolysaccharides typical of wounded tissue.
When does the repair phase begin? Hint: has to do with the cell type appearing...
When fibroblasts appear, 6-16 days.
What three things take place during the repair phase of wound healing?
Connective tissue repair, wound contraction and epithelialization
What is "contact inhibition?"
The migration and proliferation of fibroblasts stops when fribroblasts from different edtes of the wounds come in contact.
When does collagen systhesis start and what type of collagen is initially deposited?
Collagen type III is deposited on the 4th-5th day.
Is wound contraction related to collagen synthesis?
No. It only occurs in full thickness skin wounds.
How does wound contraction take place?
Specialized fibroblasts called myofibroblasts contain actin and can contract.
When does migration of epithelial cells start?
It starts 1-2 days after migration on the granulation bed stops by contact inhibition.
What happens during the remodeling phase of wound healing?
hyperplastic wound tissue begins to resorb, collagen matures by increased cross linking which results in slow gain in tensile strength.
How does repair take place in primary healing?
Repair is mainly by connective tissue deposition with some epithelialization.
How does repair take place in secondary healing?
Repair involves contraction (+++), connective tissue deposition (++) and epithelialization (+).
Describe third intention healing.
Delayed closure (at least 5 days after injury) of a wound. Surgical closure after granulation tissue has formed.
Describe delayed primary healing.
Wound is closed 2-5 days after injury, but before a complete granulation bed has formed.
How may corticosteroid administration affect wound healing?
It may delay wound healing by inhibiting the inflammatory response.
What are some systemic factors that affect wound healing?
Severe Anemia - impairs oxygenation of tissues
Serum protein <2g/dl
Uremia - impairs quality of collagen
Cytotoxic drugs - inhibit proliferation of fibroblasts and epithelial cells
What are some local factors that affect wound healing?
Trauma, hematoma and infection - prolong initial stages of wound healing
Skin tension
Necrotic or neoplastic tissue
What is the difference between passive and active drainage?
Passive drains rely on gravity flow and capillary action - these are more common. Active drains need a source of negative pressure applied to the drain.
What type of drain is used for thoracic drainage?
Single lumen, active drain.
What type of drain would be used for peritoneal drainage?
Multiple lumen "sump drain"
Describe a penrose drain.
Made of flat latex of various diameters. Drainage relies mostly on capillary action and little due to gravity. This is a passive drain that is extra luminal and related to surface area. DO NOT fenestrate - incise longitudinally.
What is a penrose drain commonly used for? What is it not used for?
Commonly used for drainage of cutaneous wounds or localized abdominal drainage. It's not used for active drainage or drainage of entire abdominal cavity.
Describe a tube drain.
Made of polypropylene, silicone, polyethylene, rubber, etc. Action is mainly gravity and intraluminal; drains are more rigid and can withstand the application of negative pressure. Can be fenestrated to increase drainage.
Name some common indications for tube drains.
Most common: closed active suction.
Thoracic drainage, drainage of small wounds using vacutainer tubes, drainage of larger wounds with major dead space.
What are some considerations when placing a drain?
Clip wide, aseptic preparation, limit size/type/number of drains and exit holes, use a separate exit hole (not the surgical incision), anchor to skin, place in a dependent fashion.
Why would an adherent first layer bandage be used? What are some contraindications?
To help debride the wound in the early stages of wound healing. Do not use if large amounts of necrotic tissue and debris - surgically debride! Also, don't use over granulation tissue.
What are two types of adherent bandages? What are some indications of each?
Dry-to-dry: not commonly used-painful to remove! Used with copius amounts of low-viscosity exudate.
Wet-to-dry: sterile gauze is moistened with sterile solution or hydrogel and covered with a dry absorbent layer. Wet dressing helps liquefy thick exudate and then absorbed by the intermediate layer, away from the wound. The most common bandage used for the debridement of full thickness contaminated wounds in small animals.
Name two types of nonadherent bandages and what each are used for.
Semi-occlusive: prevent dessication- used in surgical wounds immediately after primary closure or in open wounds in repair phase with granulation tissue present
Occlusive: barrier for skin protection or incontinence
What materials are used in a semi-occlusive bandage?
Layer of cotton cellulose wadding between two layers of perforated polyester film (Telfa pads) OR layer of rayon wadding between two layers of perforated polyester film (Release pads)
petrolatum impregnated gauze - may slow epithelialization stage
Polyurethane foam dressing
What can be added to primary layers to act as an antimicrobial? Name any special properties/uses for each.
Chlorhexidine-broad spectrum
Silver sulfadiazine-broad spectrum, good action against Pseudomonas spp., enhances re-epithelization, penetrates eschar and necrotic tissue.
What is a biological dressing? What's it made of?
Vet BioSIST is a biocompatible, degradable scaffold for tissue ingrowth. It's made of porcine SI submucosa. It contains collagen (I, III, V) and growth factors.
How is a biological dressing applied?
After sterile treatment of the wound, apply the SI patch, cover with gel and a non-adherent bandage. The patch is left in place permanently.
What are typical uses for biological dressings?
Large wounds, chronic non-healing wounds, chronic ulcers, 3rd degree burns, augmentation of soft tissue repairs, peridontal defects.
How can tension on a bandage be monitored (what can be done while creating the bandage to make it easier to monitor tension)?
Leave the 3rd phalynx of the digits 3 & 4 out of the bandage.
List the timeframe, contamination potential and closure type for the three classes of traumatic wounds.
Class 1: <6 hours; minimal; primary
Class 2: 6-12 hours; significant; delayed primary or excision
Class 3: >12 hours; gross; secondary closure
Name possible components of a wound lavage solution.
Isotonic saline
Chlorhexidine 0.05% solution
Providone-Iodine 0.1-1% solution
What compounds can be used to clean floors and countertops?
chlorine compounds
What can be used to disinfect lenses and delicate instruments?
What is a precaution when using gluteraldehyde as a disinfectant?
Rinse instruments well before using.
What is the mechanism of action of gluteraldehyde?
Protein and nucleic adic denaturation
What is the mechanism of action of isopropyl alcohol?
Protein denaturation
What is the mechanism of action of chlorhexidine?
cell membrane disruption and cellular protein precipitation
What is the mechanism of action of providone-iodine?
metabolic interference
What is the mechanism of action of hexachlorophene?
cell wall disruption
Which compounds are inactivated by organic debris?
Povidone-iodine, chlorine compounds
Which disinfectant is neurotoxic and inactivated by alcohol?
Hexachlorphene (pHisoHex)
Which disinfectant compound is effective against spores?
Gluteraldehyde (if long exposure)
What is susceptible to isopropyl alcohol?
vegetative bacteria only - NO spores, viruses, fungi
What must be done to items sterilized by ethylene oxide?
They must be aerated for a minimum of 32 hours (mechanical).
What concentration povidone-iodine is used for scrub preparation? Wound treatment?
Scrub - 7.5%
Solution - 0.1% - 1.0%
What concentration chlorhexidine is used for scrub? Solution? Disinfection?
Scrub - 2.0% - 4.0%
Solution - 0.05% or less
Disinfection - 0.5% - 2.0%
How long is the residual activity of povidone-iodine?
4 to 6 hours
How long is the residual activity of chlorhexidine?
2 days
What side effects may occur with use of povidone-iodine?
Contact dermatitis in 50% of dogs.
What are possibe side effects of chlorhexidine use?
eye irritation, ototoxicity

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