Breathing Systems Flashcards Preview

Exam Prep MCQs > Breathing Systems > Flashcards

Flashcards in Breathing Systems Deck (43)
Loading flashcards...
1
Q

Which is the most efficient Mapleson system for spontaneously breathing patients?

A

Mapleson A (magill)

2
Q

What % of minute volume does the Mapleson A require of FGF for spontaneous ventilation?

A

It will work with minimal re-breathing at FGF of 70% of minute volume in spontaneous ventilation

3
Q

Is scavenging of exhaled gases easy in the Mapleson A?

A

No.

Scavenging requires an appropriate system to be connected to the APL valve but this is not particularly more or less easy to achieve for the Mapleson A than other systems.

4
Q

What is the coaxial version of the Mapleson A?

A

Lack system

5
Q

Is the Mapleson A efficient for controlled ventilation?

A

No

6
Q

Can the Jackson-Rees modification to Mapleson E (making it mapleson F) be used with a normal reservoir 0.5L bag?

A

The Jackson-Rees modification to the Mapelson E (making it a Mapelson F) includes a specialised reservoir bag with an opening at the end to allow a controlled leak and variable PEEP

7
Q

Do reservoir bags prevent wastage of FGF during the expiratory pause?

A

Yes

8
Q

Can reservoir bags provide a rough visual assessment of the volume of ventilation?

A

Yes

9
Q

Why are reservoir bags required?

A

Because the anaesthetic machine can not provide the peak inspiratory flow required in normal respiration

10
Q

Are the D, E and F systems all T pieces?

A

Yes

11
Q

When is the Magill system most efficient?

A

For spontaneously breathing patient at a FGF of 70% of minute ventilation

12
Q

What FGF does the Bain require to prevent rebreathing?

A

The Bain system (a Mapelson D variant) requires a FGF 2-3x minute ventilation to prevent rebreathing.

13
Q

What does the rate of change of vapour concentration in the circle system depend on?

A

Circle system volume

FGF rate

Net gas uptake

14
Q

Why is the Magill inefficient during controlled ventilation?

A

Because much of the gases are vented via pop-off valve

15
Q

What is the size of soda lime granules?

A

4-8 mesh

16
Q

What does baralyme contain?

A

Calcium hydroxide plus barium hydroxide

17
Q

What will make soda lime produce more compound A?

A

Low FGF

18
Q

Does dry soda lime absorb more CO2?

A

No. Water is generated by the overall reaction of CO2 with soda lime but it’s presence or absence does not influence performance of the compound.

19
Q

What does carbon dioxide react with first in soda lime?

A

Sodium and potassium hydroxide first

20
Q

Can re-breathing be prevented in the Mapleson D during controlled ventilation?

A

Re-breathing can be prevented from occurring in controlled ventilation with the Mapelson D but this is dependent on adequate fresh gas flow

21
Q

Can volatile concentration in the breathing system be higher than the dial setting of the vaporiser at steady state?

A

The delivered volatile concentration is, in practice, rarely the same as the dial setting but it cannot exceed it except in the few moments after the vapouriser is dramatically turned down or switched off and the system is re-equilibrating.

22
Q

In the circle system with a FGF <1L (N2O:O2 = 66:34), what happens to FiO2 in the circle over time?

A

In low flow operation of the circle, particularly where the oxygen volume supplied falls towards or below metabolic requirements, the FiO2 will steadily fall and the circle will empty; N2O rapidly equilibrates and so uptake of N2O will not exceed that of oxygen so increase in oxygen concentration does not result.

23
Q

What FGF does the bain need to prevent re-breathing in spontaneous ventilation?

A

3 x minute volume

24
Q

What happens to dead space gas in the Magill system during spontaneous ventilation?

A

It is preserved

25
Q

What is the MAC of nitrous oxide?

A

105%

So can’t be used at STP as pure nitrous oxide would not have a MAC of 1 nor deliver any O2 to the patient.

26
Q

What is a Quantiflex mixer?

A

Nitrous Oxide can be safely delivered via a Quantiflex mixer which allows a full range oxygen/nitrous oxide mixtures to be administered from 21-100% oxygen so avoiding accidental hypoxic mixtures.

27
Q

Is nitrous oxide an inert gas?

A

Nitrous oxide is not an inert gas and in fact with sufficient heat, dissociates to become an avid oxidant.

28
Q

What is colour and pin index cylinder is nitrous oxide stored in?

A

French blue cylinder with a pin index of 3 and 5

29
Q

Are any of the Mapleson systems non-rebreathing?

A

No, rebreathing can occur with any Mapleson if used incorrectly

30
Q

In the Mapleson A, where is the expiratory valve?

A

The position of the APL relative to the patient is not the critical factor and the Lack system is a Mapelson A where the APL is removed from the patient end of the system

31
Q

What FGF is required by the Mapleson A?

A

Fresh gas flow requirements are determined by the ventilation mode 70% of MV in spontaneous ventilation (efficient)

200-300 ml/kg in controlled ventilation

32
Q

Which will require a higher FGF in manual ventilation, the Mapleson A or D?

A

The Mapleson A will need a higher FGF for controlled ventilation

33
Q

Does nitrous oxide get absorbed by activated charcoal?

A

No

34
Q

What volatiles can activated charcoal absorb?

A

Isoflurane

Sevoflurane

Desflurane

35
Q

Does activated charcoal significantly increase expiratory resistance?

A

No, it’s low resistance

36
Q

How can you remove the absorbed agents from activated charcoal?

A

Heating

37
Q

Does the activated charcoal change when exhausted?

A

Not in colour but will gradually increase in mass as volatiles are absorbed.

38
Q

What is the main ingredient in soda lime?

A

The principal ingredient in soda-lime is calcium hydroxide with others including sodium hydroxide (3%) and water (20%)

39
Q

Does soda lime require water to absorb CO2?

A

Yes

40
Q

Does soda lime absorb N2O?

A

NO

41
Q

When packed, what % of the canister is filled with granules of soda lime?

A

50%

42
Q

What FGF is the minimum in a circle system?

A

Due to the ability to largely recycle gases and a lack of leaks, modern circle systems can sustain very low flows; in a fully closed configuration, total gas flow can be reduced to 100% oxygen at a rate equivalent to the metabolic requirements of the patient (200-300ml/min).

43
Q
A