Therapeutic Agents & the Surgical Patient - Surgical Infection & Antimicrobials Flashcards
Why is surgical infection a serious issue?
- prolongs healing time
- failure of procedure
- dehiscence
- implant rejection
- mortality
When does a surgical infection occur?
when the microorganisms establish themselves in the tissues & begin to multiple, usually 4-6 hrs after contamination
What are the requirements for infection?
- sufficient dose of pathogenic micro-organisms
- suitable microbial nutrient medium
- impairment of natural host defenses
Development of infection is a mixture of…
- nature & degree of microbial contamination
- the microorganism involved
- local & systemic host defenses
- technical factors relating to the Sx
Factors that influence the battle between contaminants & the host’s defenses include:
- microbe-related risk factors
- host-related risk factors
- Sx-related risk factors
Surgical infection often results from a microorganism being introduced into the surgical site at
the time of surery
What are some endogenous sources of micro-organisms?
- Patient’s flora: GI, resp, urogenital, skin
- pre-existing infection at another body site via continuation, blood, lymph
What are some exogenous sources of micro-organisms?
- surgical team
- operating room
- material that makes contact w/ the wound
- post-op environment
What are some host-related, systemic risk factors that could led to surgical site infection?
- age
- weight
- metabolic status
- presence of distant infections
- hypothermia
- impaired immune response
- chemotherapeutics/ corticosteroids
What are some host-related local risk factors that can cause a surgical site infection?
- dermatitis at the site
- propensity to lick & scratch wounds
- lack of compliance w/ dressings
- foreign bodies (implants, soil, hair, wood)
What are some surgery-related risk factors that may predispose to surgical site infection?
- patient and surgeon prep
- surgical technique
- duration of surgery
- length of hospitalization
What is the clinical definition of a surgical site infection (SSI)?
presence of purulent drainage from the incision site
What are more subtle forms of evaluation of a wound infection?
- general clinical exam
- wound observation
- wound palpation
- labs
- imaging
What are some general clinical signs of infection that may be found on a general clinical exam?
fever, anorexia, lethargy
What signs when observing a wound could indicate a SSI?
- colour, presence, character of discharge
- deformity or swelling at the site
- approximation of wound edges
- appearance of skin at & around wound edges
When palpating a wound, what might indicate a SSI?
- heat, pain, swelling
- fluid accumulation
- pitting oedema
- defects in tissue layers (hernia, dehiscence)
- abnormal texture
What labs might you perform to test for SSI?
- WBC & differentiation, fibrinogen, globulins, etc
- wound fluids (cytology, culture and sensitivity, biochemistry)
What imaging techniques can be used to look for SSI?
radiography
ultrasound
scintigraphy
CT scanning
MRI
How do you classify the likelihood of wound infection?
I - clean
II - clean-contaminated
III - contaminated
IV- dirty &/or infected
What wounds are considered clean wounds?
- non traumatic wounds that do not include the resp/oropharyngeal/ GI, or urogenital organs & have no inflammatory processes
- elective, primarily closed & undrained
- non-traumatic, uninfected
- no inflammation encountered
- no break in aseptic technique
What wounds are considered clean-contaminated wounds?
- GI, resp, urogenital tracts under controlled conditions & w/ usual contamination
- minor breaks in aseptic techniques
- clean wounds w/ drains
What wounds are considered contaminated wounds?
- open, fresh, traumatic wound
- gross spillage of the GIT
- entrance into the urogenital or biliary tracts in presence of infected urine or bile
- incisions in which acute, non-purulent inflammation is encountered
- major breaks in aseptic techniques
What wounds are considered dirty &/or infected?
- traumatic wound w/ retained devitalized tissue & foreign bodies, fecal contamination, or delayed treatment, or from a dirty source
- perforated viscous
- acute bacterial inflammation w/ purulent exudates experienced during operation
- gross infection already present
What are some pre-operative ways of improving surgical techniques to prevent SSI’s?
- minimize surgical time w/ pre-op planning
- delay hair removal until just prior to Sx
- perform emergency Sx only as necessary
- Establish good metabolic status & positive nutritional plane
- minimize length of hospitalization
- consider pre-op bathing of patient
What are some intra-operative ways of improving surgical techniques to help prevent SSI’s?
- prep patient & surgeon’s skin w/ antiseptics
- use aseptic technique & barriers (surgical caps, masks, gowns, etc)
- use Sx techniques to minimize tissue trauma, hemorrhage, dead space
- debride infected or devitalized tissue
- minimize use of foreign materials
- use good surgical judgement when closing contaminated or infected wounds
- tension free tissue apposition
What are some post-op methods of improving surgical techniques to help prevent SSI’s?
- minimize length of post-op hospitalization
- cover or bandage wounds
Risk of surgical infection must outweigh the potential adverse side effects to warrant…
the use of prophylactic antibiotics
prophylactic antibiotics should only be used when…
indicated by a likelihood of infection or when occurrence of infection is likely to be catastrophic
When would you need prophylactic antibiotics in clean wounds?
- wounds involving an implant or prosthesis
- situation where development of infection is considered life-threatening
- high risk patients, animals suffering from concurrent dz processes, underweight or malnourished, geriatric patients, possible those receiving corticosteroids
When are prophylactic antibiotics indicated?
- clean-contaminated wounds
- contaminated wounds
Dirty wounds receive…
therapeutic antibiotics based on culture & sensitivity testing
What serum concentrations of antibiotics should be used to fight an infection?
4-8x the MIC for the bacteria being treated
Timing of administration should permit…
absorption & distribution to the target tissue without promoting bacterial resistance
The first dose of surgical prophylactic antibiotics should be given…
IV 30-60 mins before the first skin incision
OR IM 1-2 hrs before first skin incision
How often should prophylactic surgical antibiotics be repeated during surgery?
every 90-120 mins
It is essential to repeat prophylactic surgical antibiotics if a procedure takes longer than
3 hrs
What are the guidelines for therapeutic antibiotics?
- initial selection based on the most likely organism and usual sensitivity pattern
- drug must be able to reach the target tissue
- continuing therapy based on culture and sensitivity testing
- appropriate length of treatment varies w/ tissue, patient, and wound factors
– appropriate wound management is critical
