Principles of the Anesthesia Machine Part 1

Question 1

What is blood pressure?

Answer 1

the measurement of force applied to artery walls; a practical method for addressing tissue perfusion

Question 2

What is normal blood pressure?

Answer 2

120/80

Question 3

What blood pressure is high and it’s name?

Answer 3

hypertension (HTN) greater than or equal to 140/90

Question 4

What blood pressure is low and it’s name?

Answer 4

hypotension (hTN) less than or equal to 90/60

Question 5

What is mean arterial pressure?

Answer 5

MAP shows diastolic effects MAP twice as much as systolic because it’s twice as long

Question 6

What is the equation for MAP?

Answer 6

MAP=[(2)(Diastolic BP)+Systolic BP]/3

Question 7

What is the MAP for a patient with a BP of 125/85

Answer 7

MAP= 98.3 mmHg

Question 8

What is pulse pressure?

Answer 8

systolic pressure minus diastolic pressure

normal pulse pressure = 30-40mmHg

Question 9

When is pulse pressure narrow?

Answer 9

when it is <25% of systolic BP

Question 10

When is pulse pressure wide?

Answer 10

when it is >50% of systolic BP

Question 11

What is hypertension?

Answer 11

High BP; it may lead to atherosclerosis or heart failure; thickened wall of blood vessel

Question 12

What are the 4 consequences of hypertension?

Answer 12

1- strain to the heart (left ventricle enlargement)
2- increased oxygen demand
3- possible stroke
4- decreased tissue organ perfusion

Question 13

What are the factors that affect BP?

Answer 13

1- blood volume (hypovolemia)
2- vascular tone (vasodilation causes low BP; vasoconstriction causes high BP)
3- medication (vasodilators & vasoconstrictors)

Question 14

Vasodilators

Answer 14

decrease BP by peripheral vasodilation

Question 15

Vasoconstrictors

Answer 15

increase BP by peripheral vasoconstriction thus increasing blood flow to vital organs

Question 16

What does an EKG ( or ECG) measure?

Answer 16

the electrical activity of the heart

Question 17

What are normal, fast and low EKG?

Answer 17

normal= 60-100
fast= greater than 100
slow= less than 60

Question 18

What does the Pulse Oximeter (SpO2) measure?

Answer 18

the % of hemoglobin that is saturated with oxygen

Question 19

What is a normal SpO2?

Answer 19

93-98%

Question 20

What is end tidal CO2 (EtCO2)?

Answer 20

the amount of CO2 in expired air

Question 21

What is normal EtCO2?

Answer 21

35-45mmHg

Question 22

What is a capnograph and its two functions?

Answer 22

EtCO2 monitor
1- reveals EtCO2
2- reveals Respiratory Rate

Question 23

What are normal respiratory rates? Spontaneous? Ventilator?

Answer 23

Spontaneous= 12-20 
Ventilator= 8-12
Pain= increases RR
Narcotic= lower RR

Question 24

What is a normal body temperature?

Answer 24

36-38 degrees celsius

Question 25

Take a moment and sketch the anesthesia machine pathway

Answer 25

check with picture from PPT

Question 26

What are the two purposes of the anesthesia machine?

Answer 26

1- allow positive pressure ventilation (bag or ventilator) | 2- allow us to deliver anesthetic gases to keep patients asleep

Question 27

What are the two types of anesthesia gases?

Answer 27

1- Volatile agents (iso, sevo, des); keep patients asleep, found in vaporizer 2- Fresh gas flow (FGF) gases (air, O2, N2O); come from wall and carry vapors to patients

Question 28

How many volatile agents can be used at once?

Answer 28

1

Question 29

What is atelectasis ?

Answer 29

collapsing of the aveoli/lung

Question 30

What is FiO2?

Answer 30

fraction of inspired oxygen

Question 31

What is apnea?

Answer 31

cessation of breathing

Question 32

Why do we use oxygen as a FGF? (3 Things)

Answer 32

1-the increase in FiO2 compensates for atelectasis 2- some patients (COPD, lung disease) need increased FiO2 to have adequate oxygen saturation (SpO2) 3- in case of apnea at the end of surgery

Question 33

Why use nitrous oxide as a FGF? (2 things)

Answer 33

1- has analgesic properties (ONLY ONE) | 2- allows lower use of volatile agents

Question 34

Why use air as a FGF? (3 things)

Answer 34

has lower FiO2 1- too much oxygen could be toxic (relevant for children) 2-high FiO2 could cause absorption atelectasis 3- An FiO2 above 30% increases the risk of airway fire

Question 35

What is a flowmeter?

Answer 35

Where the FGF gases are held and can be delivered by turning the flow control valves

Question 36

Can multiple FGF gases be delivered at once?

Answer 36

Yes

Question 37

What is the maximum amount in Liters can a flowmeter deliver to the patient in 1 minute?

Answer 37

15Liters

Question 38

What carries the volatile agents to the patient?

Answer 38

Fresh gas flow gases

Question 39

How do you supply the vaporizer the volatile agents?

Answer 39

They are in liquid form and they pour into the vaporizer

Question 40

What are the two sources that supply the FGF gases to the machine?

Answer 40

1- Wall supply (endless); (H cylinders) | 2- E cylinders tanks(limited, for backup)

Question 41

What is the green hose for?

Answer 41

oxygen

Question 42

What is the blue hose for?

Answer 42

nitrous oxide

Question 43

What is the yellow hose for?

Answer 43

air

Question 44

What is the purple hose for?

Answer 44

scavenging

Question 45

What do the wall supply hoses connect?

Answer 45

the wall supply to the machine

Question 46

What is the pressure of FGF gases in the H cylinders?

Answer 46

2,000psi

Question 47

What is the pressure of FGF gases in the wall supply hoses?

Answer 47

50psi

Question 48

What is the pressure of the FGF gases in the machine?

Answer 48

16psi

Question 49

Is the pressure high or low in the E cylinders?

Answer 49

high (up to 2,000psi for oxygen and up to 750psi for nitrous oxide)

Question 50

Are E cylinders a part of the high pressure or low pressure pathway?

Answer 50

High pressure pathway

Question 51

What is the pressure of a FGF gas after it leaves the tank?

Answer 51

~45psi

Question 52

Why does the anesthesia machine use the wall supply over the E cylinders?

Answer 52

The machine preferentially chooses the highest pressure. 50psi (wall).

Question 53

What must the anesthetist do to switch from wall supply to E cylinders?

Answer 53

unplug the wall supply hoses and open up the E cylinders

Question 54

What reduces the FGF gases from 50psi to 16psi?

Answer 54

2nd stage regulator

Question 55

What are the 10 steps in the low pressure pathway?

Answer 55

``` 1- flowmeters 2- common manifold 3- vaporizers 4- common gas outlet 5-inspiratory tubing 6- patient 7- expiratory tubing 8- rebreathing bag or ventilator 9- CO2 absorber and APL valve 10- exhaled gas rejoins the common gas outlet (some goes back to patient and some goes to the scavenging system) ```

Question 56

What are the two things the scavenging system does?

Answer 56

1- removes excess gas from circuit | 2- prevents pressure build up

Question 57

What should the scavenging system be set at?

Answer 57

10-15L/min

Question 58

What valve controls how much gas goes into the scavenging system?

Answer 58

the APL valve

Question 59

What are the 3 things that the APL valve allows adjustment of?

Answer 59

1- amount of FGF going to scavenging 2- amount of gas patient rebreathes 3- amount of pressure in circuit

Question 60

What are the options for delivering positive pressure ventilation (PPV)?

Answer 60

1- bag | 2- ventilator

Question 61

Why do anesthetists want pressure in the system?

Answer 61

to be able to deliver positive pressure ventilation

Question 62

What does opening the APL valve cause?

Answer 62

increase in volume to scavenging | decrease the volume and pressure in circuit

Question 63

What does closing the APL valve cause? (not all the way)

Answer 63

decrease the volume to scavenging | increase the volume and pressure in circuit

Question 64

What happens when the APL valve closes all the way?

Answer 64

patient is rebreathing all of their exhaled gas | the volume and pressure in the circuit can become dangerously high

Question 65

Why would you ever close the APL valve?

Answer 65

difficult time sealing the mask (a leak)

Question 66

True/False The APL valve should normally be partially open?

Answer 66

True; this allows the right amount of pressure to build up in circuit but not too much

Question 67

Why would the APL valve be all the way open?

Answer 67

patient is breathing spontaneously

Question 68

What are the 4 possibilities of a leak?

Answer 68

1- mask leak 2- circuit becoming disconnected from machine or ETT 3- deflated ETT cuff 4- leak in machine

Question 69

What are the two things that the high pressure pathway of oxygen powers?

Answer 69

1- ventilator | 2- oxygen flush valve

Question 70

Does the high pressure oxygen go through the ventilator into the patient?

Answer 70

No, the high pressure oxygen is applied EXTERNAL to the ventilator bellows

Question 71

What does pressing the oxygen flush valve do?

Answer 71

rapid increase the circuit pressure (50psi) | rapid increase in circuit volume (35-75L/min)

Question 72

Why would you use the oxygen flush valve?

Answer 72

When there is a leak in the circuit (beard or difficult mask seal)

Question 73

What will the pressure gauge read when the APL valve is open?

Answer 73

Zero

Question 74

Will the pressure in the system increase or decrease when the anesthetist delivers a positive pressure breath?

Answer 74

Increase

Question 75

What are vascular pressures measured in?

Answer 75

mmHg

Question 76

What are airway pressures measured in?

Answer 76

cmH2O

Question 77

What should the airway pressure be when mask or LMA ventilating?

Answer 77

do not exceed 20cmH2O | *going over could get air in the stomach

Question 78

What should the airway pressure be when ETT ventilating?

Answer 78

do not exceed 40cmH2O | *going over could cause trauma to the lungs

Question 79

What are the 4 ways to get pressure in the system?

Answer 79

1- turn on FGF gases 2- close the APL valve 3- push the oxygen flush button 4- avoid leaks in the system

Question 80

What does the bag do when the patient exhales?

Answer 80

breathing bag expands

Question 81

Is the ventilator a part of the circuit when in bag mode?

Answer 81

No

Question 82

What are the 3 ventilation options in bag mode?

Answer 82

1- spontaneous ventilation (APL valve open) 2- mechanical ventilation (PPV; APL valve partially open) 3- Assisted ventilation (partially close APL valve, squeeze bag when patient is inhaling)

Question 83

Why would a patient cough on a ventilator?

Answer 83

they are trying to breathe spontaneously

Question 84

What are the ways to tolerate the ventilator?

Answer 84

needs to abolish the patients respiratory drive 1- muscle relaxant (long term) 2- narcotic (long term) 3- propofol (short term)

Question 85

What is a Thorpe tube?

Answer 85

the tube found in the flowmeters, wider at the top narrow at the bottom

Question 86

What is considered a low flow?

Answer 86

Less than or equal to 1L/min

Question 87

What is considered a high flow?

Answer 87

up to 15L/min

Question 88

Why is the Oxygen downstream from nitrous oxide in the flowmeter?

Answer 88

it prevents a hypoxic mixture from going to the patient (leaks in the PPT)

Question 89

What is the flowmeters mechanical proportioning system?

Answer 89

built in system that limits the percent of nitrous oxide that can be given to a patient. 3:1 is the max ratio

Question 90

What is the minimum oxygen concentration allowed with nitrous oxide?

Answer 90

25%