Ventilators and Breathing circuits

Question 1

What are the 5 tasks of O2 in the anesthesia machine?

Answer 1

1. Powers the ventilator driving gas
2. The flush valve
3. Powers the oxygen pressure failure alarm
4. Powers the oxygen pressure Sensor shut off valve (fail safe valve)
5. Powers O2 to flowmetes

also plays a role in the proportioning system in the hypoxic guard system, maintaining correct proportions of O2:N2O

Question 2

Non-rebreathing Mapleson circuits highly dependent on what? in regards to the amount of rebreathing

Answer 2

Highly dependent on dilution of expirations with high FGF

Question 3

What is the Bain circuit?

Answer 3

A coaxial Mapleson D system–and works by FGF runs coaxially in corrugated tube–ends at the point where FG supply wou

Question 4

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

Answer 4

Mapleson A system

Question 5

What are the 4 types of breathing circuits?

Answer 5

1. Open
2. Semi-open
3. Semi-closed
4. Closed

Question 6

Which breathing circuit is the most common? Subcategories?

Answer 6

Circle system which can be categorized as:
1. Semi open
2. Semi closed
3. Closed

Question 7

In a circle system subcategories, what are the main features in regards to rebreathing?

Answer 7

1. Semi-open: No Rebreathing, Reservoir bag , High FGF with circle system or have non rebreathing system
2. Semi-closed: Yes, Partial Rebreathing, Reservoir bag , low FGF with circle system
3. Closed: Yes, Complete Rebreathing, Reservoir bag, circle system with the APL valve closed

Question 8

Hazards of the Bain system

Answer 8

Detachment of connectors at either end-develops a leak at the machine end, Fresh gas supply becomes kinked or twisted, the system is INCORRECTLY Assembled; defect in the metal head so that fresh gas + exhaled gas mix–increasing dead space

Question 9

Where is there mechanical dead space on the breathing circuits?

Answer 9

1. The mouth to the breathing circuit
2. The elbow on the breathing circuit
3. Any connector used between the end of the tube and the breathing circuit
4. The Y piece at the end of a Y circuit

Question 10

What must occur to overcome mechanical dead space?

Answer 10

The fresh gas flow must be greater than the tidal volume that the patient breathes. Otherwise, there will be CO2 build-up and the difference between tidal volume and fresh gas flow will essentially be additional dead space.

Question 11

Where is the CO2 absorbent best located on the Circle system?

Answer 11

The preferred location for the CO2 absorbent in a circle system is on the inspiratory limb (Quadrant A)
Has two ports—connection to breathing tube and fresh gas inlet

Question 12

Which Mapleson system is most efficient for controlled ventilation?

Answer 12

Mapleson D system

Question 13

What is the Mapleson F (Jackson-Rees or Rees) good for?

Answer 13

Pediatric because it offers slightly less work of breathing ; has low resistance and minimal dead space

Question 14

What are 2 ways CO2 can be eliminated in a breathing circuit?

Answer 14

1. Washout with adequate fresh gas flow
2. Soda lime absorption

Question 15

How are Breathing circuits classified (2)?

Answer 15

1. Presence of a reservoir bag
2. Presence of rebreathing

Question 16

A term for Non-Rebreathing system

Answer 16

Mapleson

Question 17

A term for Rebreathing system

Answer 17

Circle

Question 18

CO2 Absorption

Answer 18

Allows rebreathing of exhaled volume of gas and FGF determines the degree of rebreathing

Question 19

What is compound A?

Answer 19

Soda Lime converts Sevoflurane to CF2=C(CF3)OCH2F, a vinyl ether called “Compound A,

Question 20

Name an alkali-free absorbent used in CO2 absorption

Answer 20

Calcium Hydroxide

Question 21

What does a hardener do in a CO2 Absorption?

Answer 21

A hardener is added to CO2 absorbent b/c some granules within are fine and fragment easily creating dust which can cause system to malfunction

Question 22

What is the ideal granule size of CO2 absorbent?

Answer 22

The ideal size is 2.5 mm or 4-8 mesh

Question 23

What does an indicator do in the CO2 Absorbent?

Answer 23

It will indicate a color change when the soda lime is exhaused..b/c the pH granules change; ethyl violet is an indicator and changes to purple when exhausted

Question 24

Show me the chemistry of Soda Lime

Answer 24

Chemistry of Soda Lime
CO2 + H2O ↔ H2CO3
H2CO3 + NaOH ↔ Na2CO3 + H2O + energy
Na2CO3 + Ca(OH) 2 → CaCO3 + NaOH

Question 25

Explain Bag-Vent Switch

Answer 25

It is a way to rapidly shift b/t manual or spontaneous respiration and automatic ventilation without removing the bag or ventilator

Question 26

Ventilators-What are the 2 types for driving the machine?

Answer 26

1. Double circuit-Driving gas is air, o2 or a mixture
2. Piston -Driving is the electricity to compress a piston to drive gas

Question 27

How many modes on ventilators?

Answer 27

6 modes

Question 28

Name the 6 modes used on ventilators?

Answer 28

1. Spontaneous/manual
2. Volume-controlled (VCV)
3. Pressure-controlled (PCV)
4. Synchronized intermittent mandatory ventilation (SIMV)
5. Pressure Support (PSV)
6. Pressure-Controlled, Volume Guaranteed (PCV-VG)

Question 29

Hanging Bellows vs Standing Bellows? difference between the two and which is safer?

Answer 29

Hanging Bellows descend on expiration vs standing bellows ascend on expiration

Ascending Bellows is safest b/c bellows do not fill and tend to collapse when disconnection occurs.

Question 30

Describe Scavenging system

Answer 30

Collection of waste gases from machine and breathing circuit and removal from the operating room

can be active or passive