Sterilisation 5

Question 1

what is downwards displacement

Answer 1

comes in at the top and forces the air out at a drain at the bottom

Question 2

2 types of cooling down?

Answer 2

natural decay- natural cooling down

active: pumping in sterile cold air

Question 3

for moist heat sterilisation there’s __ cycles

Answer 3

4

Question 4

moist heat sterilisation is ______ under pressure

Answer 4

always

Question 5

as the temperature increases the amount of time needed for moist heat sterilisation ______

Answer 5

decreases

Question 6

what are the 4 moist heat sterilisation cycle conditions

Answer 6

115-118 degrees C
30 minutes
10 psi

121-124 degrees C
15 minutes
15psi

126-129 degrees C
10 minutes
20 psi

134-138 degrees C
3 minutes
30psi

Question 7

what is the most common cycle for the autoclave

Answer 7

fluid cycle

Question 8

what materials is the fluid cycle used for

Answer 8

aqueous fluids

can be sold as long as its moisture resistant

Question 9

what materials is the porous load cycle used for ?

Answer 9

fabrics and dressings

Question 10

how long does a porous load cycle take? why

Answer 10

30 minutes

dont take long to heat up

Question 11

on a porous load cycle graph why does it go up and down at the start (think like an ECG)

Answer 11

they hold air- so you need to remove with steam . gradually replace air with steam- red up and down at start of the graph.

Question 12

what is the air ballasted cycle used for?

Answer 12

plastic containers with no screw tops

Question 13

how does the air ballasted cycle work

Answer 13

sealed and sterilised

must get pressure right as its completely sealed unit

Question 14

what is the master temperature record (MTR)

Answer 14

a test load- to ensure it works. They are the real products but wont see a patient.

Question 15

what are thermocouples

Answer 15

these are probes that you put on the product which monitor the temperature

Question 16

what is the temperature record chart (TRC)?

Answer 16

put a probe in the drain
probe in the drain- should in theory be the coldest part of the autoclave. As soon as the drain reaches the correct temperature, this means that the rest of the autoclave should be at the right temperature

Question 17

what is the MTR and TRC apart of?

Answer 17

the moist heat sterilisation cycle validation and monitoring

Question 18

minimum of ___ thermocouples used in a chamber

Answer 18

12

Question 19

is the MRT load specific?

Answer 19

yes need to revalidated if you add or take out any product

Question 20

the F0 concept is specific to?

Answer 20

moist heat sterilisation

Question 21

what is gross overkill

Answer 21

good regarding micro-organisms but can be over processed

problems with product degradation

Question 22

what is compendia lethality

Answer 22

calculating the amount of lethality associated with the kill curve

Question 23

compendial cycles are based on? why can this be an issue when estimating compendia lethality

Answer 23

the green period- holding period.

MOs also die in the heating and cooling down period, not just the holding period. we want the lethality for the whole process- this brings us to the F0 value

Question 24

F0 is an alternative to the ______ ______

Answer 24

compendial cycles

Question 25

what does the F0 value allow?

Answer 25

Allows lethality’s to be compared- previously we only used cycles and took it as fact but don’t know how much we are over processing

Question 26

what is the F0 value defined as?

Answer 26

The lethality expressed in terms of the equivalent time in minutes at a temperature of 121oC delivered by the process to the product in its final container with reference to microorganisms possessing a z-value of 10. 121 degrees is our standard reference So whatever value we calculate for an F0 e.g. 3, it means that for the conditions we've calculated the F0 at, we get the same amount of lethality as if we did it at 121 degrees for 3 minutes

Question 27

if we calculated an F0 value of 3 what does that mean?

Answer 27

it means that for the conditions we've calculated the F0 at, we get the same amount of lethality as if we did it at 121 degrees for 3 minutes

Question 28

the F0 should assure a minimum SAL of?

Answer 28

10-6

Question 29

what is the minimum F0?

Answer 29

8 ( ie equivalent to 8 mins @ 1210C)

Question 30

FOR BIOLOGICAL DATA : cell count, | calculating F0: what is the relationship between F and D values?

Answer 30

F= D (logN0- LogN) Where: D is the D-value at the given temperature N0 is the initial number of microorganisms present (bioburden) N is the number of MO’s surviving the process (actual or expected) expected could be 10^-6 as that’s our SAL

Question 31

why is thermal data more accurate than biological data for calculating F0

Answer 31

not using organisms

Question 32

how do you calculate F0 using thermal data

Answer 32

divide the kill curve into intervals e.g. every minute and calculate the lethality at each minute F0 = F1 + F2 + F3…. + FN

Question 33

thermal data for F0 calculation is a ______ process. meaning?

Answer 33

cumulative | if process is 120 minutes you'll have 120 measurements

Question 34

when calculating F0, what does the cumulative value for thermal data represent

Answer 34

measure of total process lethality for the whole cycle

Question 35

what is the equation for F0 with thermal data

Answer 35

F0= [Log-1 (t-121)/z] x dt 121 degrees is the reference temperature T is the temp of heating Z is 10 degrees C dt is the time of heating

Question 36

if a cycle has a F0 of 7.5 is it acceptable?

Answer 36

no- must be above 8 must ensure its not just for holding time as then if you added in the heating up and cooling down time the F0 value could be above 8

Question 37

if at higher temperatures such as 134-138 degrees, the value of F0 is 60-150, what does this mean

Answer 37

we are massively over processing

Question 38

what can the F0 value allow us to do?

Answer 38

customise the sterilisation cycle

Question 39

the F0 value allows us to compare ______

Answer 39

lethality's

Question 40

similarities between the FH and F0 value?

Answer 40

the equation: FH= [Log-1 (T-170)/Z] x dt 170o is the reference temp. (Bacillus subtilus) T is the temp. of heating Z is 20oC dt is the time of heating

Question 41

differences between the FH and F0 value?

Answer 41

the standards are different for FH: 170 degrees is the reference temperature for F0: 121 if the reference temperature

Question 42

equation of ethylene oxide?

Answer 42

(CH2)20

Question 43

what is ethylene oxide used on? what materials

Answer 43

disposables | medical devices

Question 44

how does ethylene oxide kill MOs?

Answer 44

alkylation of groups on proteins and blockage of MOs active sites shotgun approach

Question 45

what is EtO lethality limited by

Answer 45

concentration temperature and relative humidity

Question 46

how does relative humidity effect EtO

Answer 46

for EtO to be effective you need a moisture content in the chamber of the sterilising unit

Question 47

is EtO easy to get the SAL

Answer 47

no, not as good as other methods as there's so many variables that effect It

Question 48

EtO leaves _____ ______ on the product

Answer 48

toxic products

Question 49

problems with EtO

Answer 49

toxic residues | toxic to humans- blown up

Question 50

what must EtO be mixed with? why?

Answer 50

CO2 or N2- eliminates air explosive aspect

Question 51

temperature needed for EtO

Answer 51

26-65 degrees

Question 52

time needed for EtO

Answer 52

1-24 hours

Question 53

humidity for EtO

Answer 53

40-85%

Question 54

how does high humidity help kill the MOs with EtO

Answer 54

EtO is more lethal in moisture and the bacteria is more susceptible to it in moisture

Question 55

what is used for both validation and moitoring of EtO

Answer 55

B.subtilus