Sx Skills - Sterilization & Disinfection

drraythe's version from 2016-05-05 10:12

Intro + Sterilization Techniques

Question Answer
What is Sterilization?Elimination of all microbes on an inanimate object
What is Disinfxn?Reduction of microbial load (not all!) on inanimate objects
What is Antisepsis?Reduction of microbial load on animate (living) objects
Is boiling water able to sterilize things?Boiling water is not an effective way to sterilize, but can be used in a pinch if you have nothing else. So boiling is more disinfecting than sterilization
Name the 6 methods of sterilizationSteam
Ethylene oxide (EtO)
Gas plasma (H2O2)
Ionizing radiation
Paracetic acid
Cold chemical sterilization
When is steam sterilization indicated?Heat-& moisture tolerant items
When is Ethylene oxide (EtO) sterilization indicated?Heat & moisture sensitive items
When is Gas plasma (58% H2O2) sterilization indicated?Heat sensitive items (no lumens tho. youd think plasma would burn through a wall but nope. & hottest substance for heat sensitive items) BEST FOR HEAT RESISTANT ITEMS
When is Ionizing radiation sterilization indicated?Most single-use, prepackaged items
When is Paracetic acid sterilization indicated?Medical & surgical instruments such as endoscopes (that endo burns like acid bro)
When is Cold chemical sterilization indicated?Items containing metal, rubber or plastic and/or lensed instruments (endoscopes)
What is the mode of action of steam sterilization?Destroys microbes via protein denaturation
Dry heat → how does this sterilization process work? Problems w/ this process?Works by an oxidative process (burns the bugs). However, most items cannot tolerate the high temperature for the length of time reqd to achieve sterilization
Moist heat (Steam) → how does this sterilization process work? How can this process be made even quicker?Coagulation of critical cellular proteins. Steam under pressure = ↓ sterilization time
*What is the most reliable means of sterilization?The autoclave!
How does an autoclave work & what is it indicated for?Works by steam under pressure. Indicated for surgical instruments & other heat-&-moisture-tolerant instruments
Microbial death in an autoclave depends on what 3 things?(1) Exposure time
(2) Temperature
(3) Pressure
What are the 2 types of autoclave?Gravity displacement (most common!)
Before packing the autoclave, you should...Thoroughly clean & prepare instruments before packing. Surgical & gown packs should be double-wrapped.
Explain the art of packing the autoclave (what should you do)Ensure all surfaces exposed to steam!
No stacking, there should be space btwn packs (1-3”)
Avoid trapped air (bowls) packs should be placed vertically on edge.
Ethylene Oxide (EtO) sterilization → how does this work & what does it efficacy depend on? (4)MOA: destroys all microbes via alkylation
EFFICACY depends on...
(1) Temperature → 49-60⁰C (120-140⁰F)
(2) Gas concentration
(3) Exposure time → 4 hours (minimum)
(4) Humidity → 20~40% ideal
How long must you sterilize something in Ethylene Oxide?4hrs minimum
When do you want to use ethylene oxide?Can use on all items that can be steam sterilized & items that are steam intolerant (including items w/ lumens) (ex: endoscope, camera, plastics, powercables)
If you want to sterilize things like endoscopes, cameras, plastics, powercables & things w/ lumens, what type of sterilization might you wanna do?Ethylene oxide (you put ethanol in your intestinal lumen & ethylene in you surgical lumens)
***Disadvantages of Ethylene Oxide?****THIS IS TOXIC & AERATION IS ESSENTIAL!!! Need natural aeration for 7 days or mechanical for 12-18 hours. This results in the lengthy cycle time. It is also bad that a safe level in the air is 10ppm & you can't detect it by smell until 700ppm. (Toxic effects incld CNS depression; irritation of skin, eyes & mucous membranes; probable carcinogen)
**What is the #1 option for sterilization of heat-sensitive items?Gas plasma sterilization (hilarious bc plasma is like the hottest thing ever)
Explain gas plasma sterilization (temp, speed, emissions)This is a LOW TEMP sterilization (50⁰C) which means it is ideal for heat-sensitive items. It is also RAPID (w/in 1 hour) w/ no aeration is reqd → there are no harmful emissions! (uses 58% H2O2)
Applications/when can you use gas plasma sterilization?All items that can be steam sterilized & those that are steam intolerant
What are the limitations of gas plasma sterilization?Gas cannot penetrate walls of items that have lumens (unless used w/ special adaptor) & it cannot do linen, gauze, wood products, endoscopes, some plastics
What is the chemical gas plasma sterilization uses?58% Hydrogen peroxide (H2O2)
(Was a pic not sure how important) explain the pathogenesis of how gas plasma sterilization kills a microbe58% H2O2 is vaporized by radio waves which czs it to be a gas plasma. This releases free radicals which bombard the microbe & kill it
Ionizing radiation sterilization → how does this work?Low-temperature sterilization which utilizes cobalt 60 gamma rays (High initial $$ therefore restricted to commercial use)
Applications/uses of ionizing radiation sterilizationPre-packaged, single-use items eg. Suture material
Disposable (single-use) items
Which sterilization technique would you want to use for pre-packaged, single-use items like sponges or suture?Ionizing radiation sterilization
If you are going to use ionizing radiation sterilization on an item, what must you know about the item now?Items sterilized by radiation should not be re-sterilized by other methods → item could be damaged or unsafe
Peracetic acid sterilization → MOA? How is this done?Protein denaturation, disrupts cell wall permeability & oxidation of proteins & enzymes. Items are bathed in a diluted peracetic acid solution (0.2%) at 50⁰C inside an automated machine
Applications/uses of peracetic acid sterilization?Medical & surgical instruments including flexible endoscopes (requires special channel connector to ensure appropriate contact of solution w/in lumen)
Cold chemical sterilization works how? How can you either disinfect OR sterilize w/ it?Works via alkylation of microbial proteins. You can, depending on the amount of time, either DISINFECT (10 min) or STERILIZE (10 hours) w/ this method
What are the applications for cold chemical sterilization?Temperature-sensitive items
Lensed equipment (arthroscopic or endoscopic equipment)
Endotracheal tubes
Anesthesia machine hoses
Frequent use items
Which method of sterilization is often used for lensed equipment?Cold chemical sterilization
What are 3 different agents which can be used for the cold chemical sterilization technique?(1) Glutaraldehyde 2%
(2) Ortho-phthalaldehyde (OPA) (Cidex OPA) (aka 0.55% 1, 2-benzenedicarboxaldehyde)
(3) Hydrogen peroxide 7.5% (Sporox II)
If you are going to use glutaraldehyde, what must you keep in mind?It is an irritant! (Related to formaldehyde). So you should wear gloves & rinse w/ distilled water or sterile saline & dry w/ sterile towel before use
Chemical sterility indicators change in response to what?Chemical change occurs in response to heat, pressure or humidity but NOT exposure time
Do chemical sterility indicators confirm sterility?Do not confirm sterility → only that certain conditions (heat/pressure/humidity) for sterility were met
Chemical sterility indicators are appropriate to use w/ which methods of sterilization?Appropriate for steam, gas or plasma sterilization
*What is the only means of ensuring sterility following sterilization?Biological sterilization indicators (use once weekly)
How do biological sterility indicators work?Sterility is assessed using bacteria maintained in a broth or on a strip → Broth or strip is cultured after the sterilization process; broth also undergoes a color change w/ microbial growth
How frequently are biological sterility indicators recommended?Recommended once weekly to assess sterilization process

Antiseptics & Disinfectants

Question Answer
What are disinfectants?Chemical agents that reduce microbial load on inanimate objects
What are antiseptics?Chemical agents that reduce microbial load or inhibit growth of microbes on living tissue
What strength must alcohol be for it to be effective? Is it an antiseptic? Disinfectant? Note about it?70% IPA or EA
Can be both a disinfectant or antiseptic
NOTE: Corrosive
Is Povidone-iodine an antiseptic? Disinfectant? Note about it?Both!
NOTE: it stains
Is Glutaraldehyde an antiseptic? Disinfectant? Note about it?Only a disinfectant
NOTE: Czs a tissue rxn
Are Chlorine compounds [i.e. Hypochlorite (bleach)] an antiseptic? Disinfectant? Note about it?It might be (+/-) an antiseptic
It IS a disinfectant
NOTE: Corrosive, inactivated by organic debris (This is why using bleach for cleaning up blood is actually not that good!)
(Serial Killer Pro-tip: Always clean up blood w/ Muriatic acid where possible!)
Which antiseptic/disinfectant is inactivated by organic debris?Chlorine compounds (like bleach)
How does alcohol (IPA) work on...bacteria? Fungi? Viruses? Spores?Bact: Good
Fungi: Poor
Viruses: Poor
Spores: NOT AT ALL
***Of the antiseptics, which has the broadest spectrum?Povidone iodine
How does povidone iodine (PVI) work on...bacteria? Fungi? Viruses? Spores?Bact: Good (fast)
Fungi: Good
Viruses: Good
Spores: Good
(Broadest spectrum!!)
How does Chlorhexidine (CHG) work on... bacteria? Fungi? Viruses? Spores?Bact: Good (fast)
Fungi: Poor
Viruses: Good
Spores: Not at all
How do alcohol-based solutions (not pure alcohol IPA tho) work on... bacteria? Fungi? Viruses? Spores?Bact: Good
Fungi: +/-
Viruses: +/-
Spores: +/-
Isopropyl alcohol (IPA) → MOA? What is its activity like? Is there residual activity?MOA: Destroys microbes via cell wall destruction & coagulation of intracellular proteins. Its activity is bactericidal (static at lower concentrations) (poor activity against fungi & viruses; not Sporicidal). The residual activity is MINIMAL, as the alcohol will evaporate
What is the MOA of Povidone Iodine? Activity? Is there residual activity?MOA: Free iodine penetrates cell wall & replaces intracellular molecules. Activity: bactericidal, fungicidal, effective against viruses, Sporicidal (15 minute contact time). Residual activity is minimal & effectiveness is ↓ in presence of organic material. Inactivated by sweat & alcohol
How much contact time is needed for Povidone Iodine to be Sporicidal?15 min
**Which disinfectant/antiseptic is inactivated by sweat & alcohol?Povidone iodine
********What concentration would you use of povidone iodine for wound management? Surgical prep?Wound = 0.1-1% solution
Prep = 10% solution
Which 2 are only antiseptics & not disinfectants?Chlorhexidine (CHG) & alcohol based solutions
Chlorhexidine (CHG) → MOA? Activity? Is there residual activity?MOA: affects microbe cell wall permeability → precipitation of intracellular proteins
Activity: bactericidal (rapid); variable activity against viruses & fungi, not Sporicidal
RESIDUAL: ↑ effectiveness w/ repeated use - not inactivated by organic debris, alcohol or soaps
********Concentration of Chlorhex varies according to its use - what is the conc for wound management? Sx prep?WOUND: 0.05% solution
PREP: 4% solution
Why do we combine alcohol w/ other antiseptics?Has superior antimicrobial activity than PVI, CHG or IPA alone & more residual activity than alcohol alone
How do alcohol-based solutions save time?Single step process (“scrubless”; single application & let dry)