The Anesthesia Machine

Question 1

What percent of air is oxygen?

Answer 1

21%

Question 2

T/F: It is ideal to deliver anesthetic gas in air.

Answer 2

False, air is only 21% so it would lead to hypoxemia due to hypoventilation and V/Q mismatch induced by anesthetics themselves.

Question 3

The minimum FiO2 acceptable for people and small animals is ________.

Answer 3

FiO2 = 0.3-0.35 (30-35% O2)

Question 4

The minimum O2 flow required is ________.

Answer 4

5-10ml/kg/min

Question 5

A dog weighs 13kg. Knowing that the minimum O2 flow required is 5-10ml/kg/min, what is the minimum metabolic oxygen requirement for this dog?

Answer 5

65-1300ml/kg/min
(To solve, multiply the weight of the animal by the low and high range of the requirement, so 13x5 = 65 and 13x100 = 1300)

Question 6

Which of the following correctly matches a compressed gas with its tank colour?
A) oxygen = blue, medical air = yellow, nitrous oxide = green
B) oxygen = white, medical air = blue, nitrous oxide = yellow
C) oxygen = green, medical air = yellow, nitrous oxide = blue

Answer 6

C! Oxygen = green, medical air = yellow, nitrous oxide = blue

Question 7

Which of the following is FALSE regarding tank safety?
A) never leave an unsecured tank sitting upright
B) tanks can explode if they are dropped or fall over
C) Clean oils from hands and tank and open the cylinder valves quickly
D) Open and close valves briefly before attaching to machine to remove dust from connecting port

Answer 7

C - you don’t want to open the cylinder valves quickly! The first half of the sentence is true, but you want to open the valves slowly

Question 8

T/F: In regards to pressure gauges, cylinder pressure is usually in cmH2O (centimetres water) and breathing system pressure is in psi (pounds per square inch).

Answer 8

FALSE! Other way around - cylinder pressure is in psi, breathing system pressure is in cmH2O

Question 9

Which of the following is not a high pressure (100-2200+ psi) system?
A) gas cylinder
B) central O2 supply
C) yokes
D) pressure gauges
E) regulators

Answer 9

B - central O2 supply is intermediate pressure (50 psi)

Question 10

Which of the following is not an intermediate pressure (50 psi) system?
A) central O2 supply
B) post-regulator
C) flush valve
D) input to flow meter
E) patient's lungs
F) driving gas for ventilator

Answer 10

E - patients lungs are low pressure (<15 psi)

Question 11

2 places that would have a pressure <15 psi?

Answer 11

1) between flowmeter output and common gas outlet

2) breathing system (= pressure in patient’s lungs)

Question 12

Which is the most common oxygen cylinder used in small animal practice? What is the capacity?

Answer 12

E cylinder, capacity = 660L

Question 13

The capacity of an H oxygen cylinder is _____.

Answer 13

6600 L

Question 14

T/F: both E and H oxygen cylinders are filled to a pressure of 2200 psi.

Answer 14

True

Question 15

What is the Boyle’s law equation that relates volume to pressure?

Answer 15

P1V1=P2V2

Question 16

You want to do surgery on a dog and estimate you will need 1 hour from start of induction to finish. Your E cylinder gauge shows 300 psi. The O2 flow rate will be 2 L/min. Do you have enough O2 in your tank to complete the procedure?

Answer 16

First, 2200psi/660L = 300psi/X
solve for X = (300psi x 660L)/2200psi
X = 90

mins remaining = X liters/(Flow L/min)
= 90L/(2L/min)
mins = 45

Therefore you would not have enough for a one hour procedure!

Question 17

You have an N2O tank and want to calculate how much remaining gas you have. What is your method?
A) P1V1=P2V2 calculation
B) Shake it and see if you can read its mind
C) weigh it

Answer 17

C - weigh the tank

Question 18

This safety system utilizes a non-interchangeable gas specific threaded connection system.
A) Quick connectors
B) Labelling
C) Pin index safety system
D) Diameter index safety system

Answer 18

D - diameter index safety system

Question 19

This safety system involves gas specific pin patterns that only allow connection between the appropriate cylinder yokes and E tanks.
A) Quick connectors
B) Labelling
C) Pin index safety system
D) Diameter index safety system

Answer 19

C - Pin index safety system

Question 20

This safety system facilitates rapid connecting and disconnecting of gas hoses.
A) Quick connectors
B) Labelling
C) Pin index safety system
D) Diameter index safety system

Answer 20

A - quick connectors

Question 21

This part of the anesthesia machine decreases tank pressure to a safe working pressure (~50psi).
A) flowmeter
B) regulator
C) quick flush
D) pressure gauge

Answer 21

B - regulator (also known as pressure reducing valve)

Question 22

Which of the following is TRUE regarding the flowmeter?
A) The flow is read at the top of the ball or the middle of the bobbin
B) Gas exits the top at 50psi
C) O2 should be downstream of other gases if there are multiple flowmeters
D) It increases gas pressure

Answer 22

C is true
A - is the other way around
B - gas enters at 50psi and exits at 15 psi
D - it decreases gas pressure

Question 23

Pressure of the gas that exits the flow meter is _____.

Answer 23

15 psi

Question 24

Which of the following is FALSE regarding the quick flush?
A) it bypasses the vaporizer
B) it delivers gas at a rate between 35-75 L/min directly to the patient circuit
C) patient should be disconnected from circuit before O2 flush valve is utilized
D) it contains concentrated amounts of anesthetic agent

Answer 24

D - it bypasses the vaporizer so it has no anesthetic agent

Question 25

Possible complication of hitting the quick flush without disconnecting patient?

Answer 25

Pneumothorax

Question 26

_____ is the pressure exerted by vaporizer molecules when liquid and vaporizer phases are in equilibrium.

Answer 26

Vapor pressure

Question 27

All modern vaporizers are _______.

Answer 27

Out of circuit (VOC)

Question 28

T/F: modern vaporizers allow us to know the anesthetic % we are administering

Answer 28

True! They are precision vaporizers

Question 29

3 variables that modern vaporizers compensate for are:

Answer 29

1) temperature (between 15-35 C)
2) flow rate (between 0.5 and 10L/min
3) back pressure associated with positive pressure ventilation and use of flush valve

Question 30

What should you do if you fill a vaporizer with the wrong agent?

Answer 30

drain and run 1L/min O2 until completely dry

Question 31

What should you do if you tip the vaporizer?

Answer 31

Run 1L/min through machine with vaporizer off

Question 32

Where does gas exit the vaporizer?

Answer 32

The common gas outlet