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Medicine- Pharmaceutics > Sterilisation 5 > Flashcards

Sterilisation 5 Flashcards

1
Q

what is downwards displacement

A

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

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2
Q

2 types of cooling down?

A

natural decay- natural cooling down

active: pumping in sterile cold air

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3
Q

for moist heat sterilisation there’s __ cycles

A

4

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4
Q

moist heat sterilisation is ______ under pressure

A

always

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5
Q

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

A

decreases

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6
Q

what are the 4 moist heat sterilisation cycle conditions

A

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

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7
Q

what is the most common cycle for the autoclave

A

fluid cycle

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8
Q

what materials is the fluid cycle used for

A

aqueous fluids

can be sold as long as its moisture resistant

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9
Q

what materials is the porous load cycle used for ?

A

fabrics and dressings

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10
Q

how long does a porous load cycle take? why

A

30 minutes

dont take long to heat up

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11
Q

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

A

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

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12
Q

what is the air ballasted cycle used for?

A

plastic containers with no screw tops

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13
Q

how does the air ballasted cycle work

A

sealed and sterilised

must get pressure right as its completely sealed unit

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14
Q

what is the master temperature record (MTR)

A

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

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15
Q

what are thermocouples

A

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

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16
Q

what is the temperature record chart (TRC)?

A

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

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17
Q

what is the MTR and TRC apart of?

A

the moist heat sterilisation cycle validation and monitoring

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18
Q

minimum of ___ thermocouples used in a chamber

A

12

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19
Q

is the MRT load specific?

A

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

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20
Q

the F0 concept is specific to?

A

moist heat sterilisation

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21
Q

what is gross overkill

A

good regarding micro-organisms but can be over processed

problems with product degradation

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22
Q

what is compendia lethality

A

calculating the amount of lethality associated with the kill curve

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23
Q

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

A

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

24
Q

F0 is an alternative to the ______ ______

A

compendial cycles

25
Q

what does the F0 value allow?

A

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

26
Q

what is the F0 value defined as?

A

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

27
Q

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

A

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

28
Q

the F0 should assure a minimum SAL of?

A

10-6

29
Q

what is the minimum F0?

A

8 ( ie equivalent to 8 mins @ 1210C)

30
Q

FOR BIOLOGICAL DATA : cell count,

calculating F0: what is the relationship between F and D values?

A

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

31
Q

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

A

not using organisms

32
Q

how do you calculate F0 using thermal data

A

divide the kill curve into intervals e.g. every minute and calculate the lethality at each minute

F0 = F1 + F2 + F3…. + FN

33
Q

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

A

cumulative

if process is 120 minutes you’ll have 120 measurements

34
Q

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

A

measure of total process lethality for the whole cycle

35
Q

what is the equation for F0 with thermal data

A

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

36
Q

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

A

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

37
Q

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

A

we are massively over processing

38
Q

what can the F0 value allow us to do?

A

customise the sterilisation cycle

39
Q

the F0 value allows us to compare ______

A

lethality’s

40
Q

similarities between the FH and F0 value?

A

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

41
Q

differences between the FH and F0 value?

A

the standards are different

for FH: 170 degrees is the reference temperature

for F0: 121 if the reference temperature

42
Q

equation of ethylene oxide?

A

(CH2)20

43
Q

what is ethylene oxide used on? what materials

A

disposables

medical devices

44
Q

how does ethylene oxide kill MOs?

A

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

45
Q

what is EtO lethality limited by

A

concentration
temperature
and relative humidity

46
Q

how does relative humidity effect EtO

A

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

47
Q

is EtO easy to get the SAL

A

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

48
Q

EtO leaves _____ ______ on the product

A

toxic products

49
Q

problems with EtO

A

toxic residues

toxic to humans- blown up

50
Q

what must EtO be mixed with? why?

A

CO2 or N2- eliminates air explosive aspect

51
Q

temperature needed for EtO

A

26-65 degrees

52
Q

time needed for EtO

A

1-24 hours

53
Q

humidity for EtO

A

40-85%

54
Q

how does high humidity help kill the MOs with EtO

A

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

55
Q

what is used for both validation and moitoring of EtO

A

B.subtilus

Medicine- Pharmaceutics (6 decks)

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