Sterility techniques Flashcards
Heat sterilisation can only be done with ________ products. If they are moisture resistant, then __________. If they are moisture sensitive, then __________.
thermostable
moist heat sterilisation
dry heat sterilisation
Moist heat sterilisation is carried out in an instrument called an _______
autoclave
Steam can either be ________ within the steriliser (e.g. portable bench sterilises; in which steam is constantly in contact with ______ - known as ‘___’ steam.)
OR
Steam can be supplied under _____ from a separate boiler (as ‘___’ ______ steam with NO water droplets
generated
water
wet
dry saturated
Which is visible?
Saturated steam or wet steam
wet steam
Which is invisible?
Saturated steam or wet steam
saturdate
Saturated steam is in ________ equilibrium with the water which has produced it
thermal
Saturated steam turns to wet steam once it is released to the _______, where part of it condenses by transferring its ____ to the surrounding air (and clouds of white _____ and tiny droplets of _____ are formed)
atmosphere
heat
vapour
water
Compare killing potential of wet steam and dry saturated steam at the same temperature.
same
Although killing potential of ‘wet’ steam is the same as that of
‘dry’ saturated steam at the same temperature, wet steam is more likely to soak a _____ ____, creating physical difficulties for further steam penetration
porous load
Superheated steam: is an ________ sterilising agent
(created by heating wet or saturated steam beyond the ______ steam point; less efficient, becoming equivalent to ___ heat)
inefficient
saturated
dry
What are the adverse effects of air?
- Air is driven off from water and may be trapped in porous loads (e.g gauze, surgical dressings)
- Air is a poor conductor of heat and inhibits heat flow
- Steam containing air will be at a lower temp than pure steam (and so sterilisation temp will not be achieved)
- Removal of air is important to ensure efficient autoclaving
Autoclaves are ________ steel vessels designed to withstand the steam pressures employed in sterilisation. There are two types:
stainless
portable sterilisers (labs)
large scale sterilisers (hospitals)
What are the three stages for autoclaves?
- Air removal (via downward displacement with steam/ evacuation) and steam admission
- Heating/ sterilising (holding stage)
- Drying/ cooling
What are the two main types of LARGE autoclaves?
- downward displacement autoclaves - a.k.a bottled fluid sterilisers (min temp 121 for 15 mins)
- high pre-vacuum autoclave - for porous loads (min temp 134 for 3 mins)
Whenever possible, aqueous injections are ______ sterilised by autoclaving. The exception is if they are _________ drugs.
terminally
thermolabile
