Week 4 Principles of Sterilisation and Disinfection Flashcards
Three classifications of medical items
Non-critical items, semi-critical items and critical items
Definition of non-critical item
They come into contact with intact skin. The require regular cleaning and low level disinfection to remove transient infectious agents
Semi-critical items
Come into contact with non intact skin or mucus membranes. They must be disinfected, single use or sterilised prior to use for patient safety
Critical items
Come into contact with sterile tissues and body cavities and must be sterile at the time of use
Cleaning
Removal of organic material that may support the growth and persistence of infectious agents in the healthcare environment. This process is used for non-critical items
Disinfection
The destruction and removal of infectious agents resulting in a reduction in the number of living infectious agents to an acceptable level
Sterilisation
The process of sterilisation results in the complete destruction of ALL living infectious agents
Contact between chemical agent and infectious agent is only effective…
If the surface of the medical item is free from organic material
Exposure time between the chemical agent and infectious agent is important why
The chemical agent must be in contact with the infectious agent long enough to ensure an effective biocides time-course as indicated by the kill-curve
What does adequate concentration mean
There must be an adequate number molecules of the chemical agent to equal the number of infectious cells present.
How is choice of agent determined
By the risk of transmission of infectious agents to susceptible hosts the composition of the item to be treated and the structure of the agent
Physical control methods
Temperature extremes Filtration Pressure (commonly combined with temperature) Filtration Irradiation
Temperature extremes
High (>100°C) and low (<4°C) temperatures can be used to kill and/or control the growth of the infectious agents
Pressure
Autoclaving is the most commonly used sterilisation method .
Filtration
Filtration sifts infectious agents out of solutions that will be administered to people including intravenous fluids and medications
Irradiation
Non-ionising radiation - does not remove electrons, it has low penetrance and is therefore not appropriate for sterilisation of dense materials
Ionising radiation - gamma rays are high energy forms of radiation that effectively sterilise dense materials by removing electrons from atoms and molecules - used on syringes
Chemical control methods
Alcohols Halogens Quaternary ammonium compounds Phenolics Hydrogen peroxide Aldehydes
Alcohols
Ethanol and/or isopropanol at concentrations of 60-90% are highly effective surface disinfectants and antiseptics if allowed to air dry
Halogens
Such as sodium hypochlorite (bleach), iodine and chlorhxidine are broad spectrum and effectively disinfect drinking water, mouth wash, contaminated surfaces and skin
They are inactivated by organic material and are corrosive
Quaternary ammonium compounds
Catatonic agents used for surface disinfection and include hospital grade disinfectants
Phenolics
Are toxic hard surface disinfectants (not very commonly used)
Hydrogen peroxide
is a broad spectrum disinfecting agent that remains active in the presence of high levels of organic contamination
Aldehydes
Broad spectrum disinfectants work in the presence of organic material and are sporicidal
How are chemical control methods impacted
Organic material Temperature Water hardness pH Relative humidity
Biofilms
Can form on any surface iPad the interface between liquid and a solid. Commonly found in healthcare environments. They create a physical barrier between the infectious agents and the chemical agent as well as sheering forces protection
You’re required to re-process a re-usable medical item at the completion of treatment of a non-infectious patient in the clinic.
- medical grade stainless steel
- appears to be contaminated with small amount of flesh blood and tissue
The item must be debunked to reduce interference of organic material with the re-processing procedure
Detergent should be used to remove organic material
The item requires sterilisation prior to re-use
Item can safely be treated with steam under pressure
