Robinsons Flashcards
What are the most common causes of infections and from where
- Most frequent cause of infections: Staph aureus, E coli, Group A Strep, Pseudomonas
- Most common source: staph aureus from the patient’s anterior nares (85% of isolates are genetically identical)
What % are nasal carriers
21.6% of US population are nasal carriers - have a 3-9.6 fold increased risk of SSIs
What is a surgical site infection
- Definition: any surgical wound that produces pus within 30 days of the procedure, even in absence of a positive culture
- The exception: suture abscess, which suppurates but resolves when removed
Does a positive swab equate an SSI
A positive culture may just indicate colonisation. If bacteria per gram of tissue >10^5 then this is more likely infection
Define clean, clean contaminated, and dirty wound
- Clean: elective incisions on non-inflamed tissues under aseptic technique, with no entry into GIT, resp or genitourinary
- Clean contaminated: minor break in aseptic technique, or entry into a tract, or inflammation but no frank purulence
- Dirty wound: frank purulent fluid, perforation of a viscus or faecal contamination
Patient factors that increase risk of infection
- Age
- Malnutrition
- Obesity
- Hypothermia
- Immunosuppressants - including alcohol
- Length of procedure
What antiseptic agents are there
Alcohols
Chlorhexidine gluconae
Povidone iodine
PCMX (not used)
60-95% Alcohol as an antiseptic
- Wide spectrum of action - positive and negative, M tb, fungi, enveloped viruses
- Fastest onset
- Drawbacks: flammable, poor cleansing agent
- Must use liberal amount and allow to dry
Chlorhexidine gluconate - onset, spectrum, activity, drawbacks
- Most common formulation is 4% scrub solution
- Binds to the stratum corneum, fast onset
- Spectrum: relatively wide as well, covers M tb, fungi, enveloped viruses, gram pos and negative
- Sustained activity, additive effect with repeated use. Residual activity in excess of 6 hours, even when wiped off
- Caution:
- Ocular toxicity with conjunctivitis and severe corneal ulceration
- Ototoxicity if it reaches the middle ear through a perforated tympanic membrane. Application to pinna and EAM does not pose risk to patients with in tact TM, but you never know the status really so avoid it
- Prolonged exposure to middle ear –> deafness.
Povidone-iodine onset, spectrum, activity, drawbacks
- Better spectrum than Clorhex as covers M TB more
- Fast onset
- Sustained activity is poor if wiped from skin –> need to leave on
- Approved for mucosal surfaces - PI 10% aqueous solution commonly used off label around eyes –> there is a lot of data from bacterial enophthalmitis prophylaxis in cataract surgery
- Caution:
- Potential systemic toxicity with neonates or large body surface area
- Rapidly neutralized by blood, serum proteins or sputum
- Chronic maternal use has been associated with hypothyroidism in newborns
- Scrub form: has a detergent in it, so shouldn’t make contact with the eyes
- Prolonged skin contact: irritant and rarely ACD. Once dried generally not irritating
PCMX
Parachlorometaxylenol - PCMX
- Not as good coverage as the others
- Intermediate onset
- Sustained activity for several hours
- Has very poor pseudomonas coverage –> to address this they add EDTA (chelator)
- We don’t use this
Can you combine anti-septic solutions
- DuraPrep - IP and 74% isopropyl alcohol
- Chloraprep - 2% chlorhex in 70% isopropyl alcohol
Which anti-septic is better
- The jury is still out
- CHG-alcohol reduces bacterial colonies at the end of surgery and reduced SSIs, but not to stat significance
- CHG-alcohol was compared to PI and was found better, but they should have put alcohol in the PI for an appropriate comparison
- CHG and iodophor-alcoholic formulations are likely superior to their aqueous counterparts, and might be preferable for derm surgery in areas with higher rates of infection - like the groin
- Alcohol based - good to clean skin and fingernails but not that good on its own. Also highly flammable, so need to be careful before electrocautery or laser, make sure its dried.
What is the typical protocol for hand washing for derm procedures
- Remove any visible debris with a single 1 minute handwash with soap at the beginning of the day
- Follow this with 2 applications of alcohol solution ~4mL to forearms and hands for every procedure or when changing gloves
- Air dry for 1 minute prior to donning glove
Is there anything that can be done the day before a procedure to reduce infection?
- Night before surgery: preoperative shower with chlorhex or PI has been shown to decrease bacterial colonization and wound infection rates, but meta-analysis does not support this as routine practice –> consider for large surgical fields and those at increased risk of infection (lower legs)
- Obviously if the eyes use PI solution and half strength (5%)
What is the aim of surgical site preparation?
aim is to lower the resident bacterial count as much as possible and limit rebound growth with minimal skin irritation
Tell me about antiseptics and their use around the eye
- Betadine ophthalmic solution: 5% PI, for eye use, cost significantly higher, comes in 30mL single use
Tell me about environmental cleaning of the procedural room and good practices
- Desquamated skin cells disperse and settle on horizontal surfaces, then can be re-aerosolized with movement/breeze
- To reduce this, keep doors shut, and minimize people walking through as much as possible
- Disinfection should be done regularly with a quaternary ammonium sanitiser
- no evidence to thoroughly clean between each patient, but review between patients and make sure is cleaned
- Terminal clean at the end of each day of use: wet vacuum or 2-mop system: first mop applies disinfectant, and the second mops it up
What is the definition of sterilisation
chemical or physical process that completely destroys or removes all forms of viable microorganisms, including spores, from an object
What are the different ways to sterilise?
Autoclave (steam under pressure) Heated chemical vapour Dry heat Gas sterilization Chemical immersion
Tell me about steam under pressure (autoclave) sterilization
most efficient, economical and easy to monitor. Generates pressures of 2 pascals and temp of 121 degs, and maintains that for 15-30 minutes. Good for liquids, glass, metal instruments, paper, cotton. Not good for plastics or oil. Limitation: repeated exposure to high humidity may dull sharp cutting surfaces (particularly high grade carbon steel edges of reusable hair transplant punches)
Tell me about heated chemical vapour sterilization
low-humidity method so better for sharp instruments. Doesn’t require drying, and shorter heat-up time. This method uses alcohol and formaldehyde, so you need protective gear, adequate ventilation and safety monitoring
Tell me about dry heat sterilisation
prolonged exposure to 121-204 degs, and is humidity free. Good for glass, oils and sharp instruments. Risk of burns, so need protective equipment
Tell me about gas sterilisation
With ethylene oxide or formaldehyde, good for heat sensitive and moisture sensitive. These are toxic and known carcinogens. Need really strict monitoring as they’re highly toxic. Rarely done outside of hospital settings.