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Mar: Sem 3 - Principles I (Full) > Exam 3 Anesthesia Ventilators [7/9/24] > Flashcards

Exam 3 Anesthesia Ventilators [7/9/24] Flashcards

1
Q

Define ventilator.

A
  • An automatic device that will provide/augment:
    • Patient ventilation
    • Patient oxygenation

S2

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2
Q

On the anesthesia workstation, ventilators essentially replace what component?

A
  • The green reservoir bag

S2

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3
Q

What ventilation mode was available from old ventilator models?

A
  • Only controlled mandatory ventilation [CMV]
    • Only offered volume-controlled ventilation
  • No PEEP
  • Couldn’t provide high enough inspiratory pressure (PIP)

S3

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4
Q

Define barotrauma

A
  • Injury resulting from high airway pressures

S4

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5
Q

What is compliance?

A
  • Ratio of a change in volume to a change in pressure
  • C= ΔV/ΔP

S4

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6
Q

Decrease in compliance in the breathing system causes what?

A
  • Decrease in compliance in breathing system causes decrease in Vt as volume is used expand to system (volume controlled)

S4

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7
Q

How do newer vents compensate for system compliance?

A
  • New vents will alter the volume delivered to compensate for system compliance (pressure control)

S4

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8
Q

What is work of breathing?

A

The energy that the patient/ventilator expends to move gas in and out of the lungs.

S4

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9
Q

What is Peak Pressure (PIP) ?

A
  • The maximum pressure during the inspiratory phase time

S4

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10
Q

Define FGF.

A
  • Gas that is coming into the machine that picks up vapor.

S5

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11
Q
  • On older vents, as FGF increases, what happens to tidal volume?
  • In newer vents, if there is excess FGF, what happens?
A
  • Old Vents: as FGF increases, the tidal volume increases
  • New Vents: have excess FGF divereted during inspiration

S5

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12
Q

What is Fresh Gas Compensation?

A
  • This is a way to prevent FGF from affecting tidal volume by measuring tidal volume and adjusting the volume of gas delivered by the ventilator

S5

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13
Q

What is inspiratory pause time?

A

The time during which lungs are held inflated at a fixed volume and pressure. (Inspiratory plateau)

can increase the pause time to keep the alveoli open

  • Google: Inspiratory plateau is measured during the inspiratory pause.

S5

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14
Q

What is the I:E ratio?

A
  • Ratio of the inspiratory phase time to the expiratory phase time

S6

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15
Q
  • Normal I:E Ratio
  • Give an example of when youd want a longer I:E ratio.
A
  • 1:2 (1 sec inspiration : 2 second expiration)
    • We spend more time expiring
  • slow exhalation = keeps pressure in chest for longer period of time —>increases intrathoracic pressure (decreases venous return and CO)
    -obese, CO2 inflation, trendelenburg = increase inspiratory pressure more which we want to limit.
    -Change I:E to 1:1.5 or 1:1 to limit gas in the chest

S6-lecture

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16
Q
  • What is an inverse ratio ventilation?
  • what is an example?
A
  • Inspiratory phase time is longer than the expiratory phase time
  • 2:1 (2 sec inspiration : 1 sec expiration)

S6

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17
Q

The sum of all tidal volumes in one minute

A
  • Minute volume

S6

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18
Q

What is the spill valve?

A
  • The valve in the ventilator that allows excess gases to be sent to scavenging system during exhalation (Outside of the vent bellows)

S7

- gas comes to the ventilator -> fills bellows (exhaled gas fills the bellow) - if there is more volume or pressure, can spill it. - this is on exhalation.
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19
Q

What is the exhaust valve?

A
  • valve that opens to allow driving gas to exit the bellows housing (Inside of the bellows)

If youre EXHAUSTED you are inspiring a lot, therefore the exhaust valve works during inspiration

S8

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20
Q

Factors that affect ventilation

A
  • Compliance
  • Leak

S9

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21
Q

Compliance affects ventilation. What are the 2 types of compliances?

A
  • system compliance: bent tube
  • patient compliance: asthma, COPD, trendelburg, obese

S9

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22
Q
  • Where can a leak occur?
  • How does a leak affect delivered tidal volume?
A
  • around the tracheal tube or supraglottic device
  • Leaks will cause a decrease tidal volume that can’t be compensated by the ventilator

S9

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23
Q

Components of bellow ventilator

Components of bellow ventilators

A
  • Driving gas supply and FGF [double circuit]
    • Either O2, air, or mix
  • Controls
  • Alarms
  • Pressure-limiting mechanism
  • Bellows assembly: accordion-like device
  • Housing

Housing has Driving gas, Bellows have FGF, CAP

S10-11

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24
Q

Components of bellow ventilator

Some ventilators can switch between driving gases, when would they do this?

A

during a loss of pressure

S10

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25
Q

Components of bellow ventilator

  • Driving gas supply is equal to?
  • Total Oxygen Used by anesthesia machine
A
  • Driving gas is equal to minute ventilation
  • Total Oxygen Used by anesthesia machine = Flow control [1-2L/min] + Vm 4-5L/min [breath the pt gets from the bellow] + driving gas 4-5L/min [gas in housing]

S10

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26
Q

Components of bellow ventilator

What do controls do in bellow ventilators?

A
  • regulate flow, volume, timing and pressure

S10

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27
Q

Components of bellow ventilator

What does the driving gas do to the bellows?

A
  • The driving gas is the gas external to the bellows that cause them to collapse.

S10 Andy?

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28
Q

Components of bellow ventilator

  • What kind of alarm does the bellow ventilator have?
  • What are the two standard alarms on the ventilator?
A
  • Alarms: high, medium, and low priorities
  • Must have: low and high pressure alarms

S10

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29
Q

Components of bellow ventilator

What is the most common cause of low-pressure ventilator alarms?

A
  • Disconnection of a circuit

S10 Lecture

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30
Q

Components of bellow ventilator

What are examples of high-pressure ventilator alarms?

A
  • Kinking of the ETT
  • Occlusion of mask

S10 lecture

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31
Q

Components of bellow ventilator

  • What is the pressure limiting mechanism ?
  • What is a good set point/number ?
A
  • limits inspiratory pressure
  • 10 cmH2O above peak pressure with desired Vt

S11

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32
Q

Components of bellow ventilator

What is the housing of the below anesthesia ventilator made of?
What does it allow for?
How do you determine how much Vt is given?

A
  • Clear plastic cylinder
  • Allows movement of bellows to be observed
  • Has scale on side for rough estimation of tidal volume

S11

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33
Q

What are the 2 types of ventilators?

A
  1. Bellow Ventilators
  2. Piston Ventilators

S12/14

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34
Q

Bellows are pneumatically driven, how do they work?

A
  • Driving gas squeezes gas out of bellows into lungs

S12

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35
Q

How/whendo the bellows refill?

A
  • Fill on exhalation
  • Exhalation and FGF in circuit refills bellows

S12

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36
Q

What are the two kinds of bellow arragement?

Which one is safer?

A
  • Ascending Bellows (standing): safer
  • Descending Bellows (hanging)

S12

37
Q

What is the ascending bellows doing on inspiration and expiration?

A
  • ascends on expiration
  • descends on inspiration

S12

38
Q

What is the descending bellows doing on inspiration and expiration?

A
  • descends on expiration
  • rises on inspiration

S12

39
Q

Why are ascending bellows considered safer?

A
  • If there is a disconnection in the circuit, the bellows will fail to rise on exhalation, which will trigger the CRNA to know something is wrong.
  • For descending bellows, they will continue to descend even if there is a disconnection d/t gravity.

S12

40
Q

What are problems that can be encountered bellows?

A
  • improper bellows seating
  • hole in bellows
  • scavenging system closed

S13

41
Q

What is the result of improper bellow seating?

A

inadequate ventilation

S13

42
Q

What is the result of having a hole in the bellows?

A
  • alverolar hyperinflation/barotrauma
  • if driving gas is O2, pts FiO2↑
  • if driving gas is air, pts FiO2 ↓

S13

  1. As bellow collapses the gas goes into the housing instead of pt.
  2. Can also cause barotrauma d/t driving gas pressure pushing in (gas in the housing leaks into the bellow)
43
Q

what is the problem with scavenging sytem being closed?

A

waste gases vented to room/atmosphere

S13

44
Q

Components of piston ventilators

A
  • mechanically driven motor
    • like plunger of syringe
  • no driving gas [single circuit]
  • uses dramatically less gas [O2, air]
  • doesnt alter Vt based on compliance

S14

45
Q

List the qualities of the piston ventilator

A
  • Doesnt alter Vt based on compliance
    • accurate tidal volumes
  • very small piston chamber
  • hidden on machine.. no visual ventilation
  • very quite

4 V qualities: Vt, Very small/quiet, visual ventilation is hidden

S14

46
Q

What are probems encountered with the Piston ventilator?

A
  • refills even with disconnection
    • like descending bellows
  • entrain room air during leaks
    • it dilutes oxygen/volatiles

S15

47
Q

What is the most commonly used mode of ventilation?

A
  • Volume control

S16

48
Q

What is volume control mode of ventilation?
What are the set parameters in volume control?

A
  • Preset tidal volume is delivered (fixed parameter)
  • The machine will give a set tidal volume regardless of the patient’s condition
  • Set parameters: Vt, RR, I:E ratio

S16

49
Q

Volume control mode can cause excessive ____ pressure.

A
  • inspiratory

S16

50
Q

In volume control mode, what happens if pt initiates additional breaths?

A
  • additional breaths at machine preset Vt

S16

VT: 500 and RR 10. If pt initiates an extra breath (RR now 11) the extra breath will get Vt of 500.

51
Q

What conditions would a volume control mode not be beneficial for the patient?

A
  • Conditions with decreased compliance and FRC
  • Obese/Pregnant patients
  • Trendelenburg/Lithotomy procedures
  • Patients with lung pathology
  • Patients that need to be weaned from the vent

S16- Andy

52
Q

How much tidal volume should be delivered to a patient on a ventilator?

A
  • 4-6 mL/kg

S16- Andy

53
Q

Describe pressure control ventilation.
What are the set parameters in pressure control?

A
  • Preset pressure is quickly achieved during inspiration. [fixed parameter]
  • Set: PIP, RR, and I:E Ratio

S17

54
Q

What happens to tidal volume in pressure control ventilation.

A
  • Tidal volume changes with resistance and compliance

S17

55
Q

What will insufflation of the abdomen do to inspiratory pressure?

A
  • Increase inspiratory pressure, which will cause a low tidal volume.

S17-Andy?

56
Q

What is the good thing about pressure control ventilation?

A
  • This vent setting protects lungs from barotrauma of excess pressure

S17-Andy?

57
Q

What is the bad thing about pressure control ventilation?

A
  • can cause atelectasis and hypoventilation
  • The pressure delivered in this mode might not develop enough tidal volume for the patient.

S17

58
Q

What are ways to deliver more tidal volume in pressure control ventilation mode to patients with low lung compliance?

A
  • Increase PIP
  • Use Inverse I:E ratio, longer inspiration than expiratory time. The body will have time to adapt to increased pressure.

S17- Andy

59
Q

Describe Volume Guarantee Pressure-Control.

A
  • Maintains tidal Volume by adjusting PIP over several breaths.
  • Prevent sudden Tidal Volume changes d/t compliance
    • Lost insufflation

S18

60
Q

What is Assist Control Ventilation?

A
  • Predetermined negative pressure will trigger breath
  • Breath is at preset tidal volume

S19

61
Q

What is Intermittent Mandatory Ventilation (IMV)?

A
  • Mandatory ventilator breath is set
  • Additional native breaths at variable tidal volume
  • Allows breath stacking

S19

62
Q

What is SIMV?

A
  • Synchronizes ventilatory-driven breaths with spontaneous breaths
  • Provides backup to weaning ventilator
  • Best for weaning

S20

63
Q

What is Pressure Support?

A
  • PIP and inspiratory time set
  • Vt equates to the native effort
  • Need apnea alarm

S20

64
Q

Why cant standard ventilators be used in MRI?

A
  • Standard machines have variable amounts of ferromagnetic substances

S21

65
Q

What are solutions for using a ventilator during an MRI?

A
  • MRI compatible machines
  • Anesthesia machine kept outside in hallway
  • Machine bolted to wall
  • Aluminum tanks or pipeline gas supply

MAMA what are the solutions for vents for MRI

S21

66
Q

General Hazards: What can cause ventilation failure?

A
  • Fluid in electronic circuitry (excessive humidity)
  • Leaking bellows housing
  • Extremely high FGF
  • Disconnection from power supply

FLED

S22

67
Q

General Hazards: How can there be a loss of breathing system gas?

A
  • Failure to occlude spill valve
  • Leak in the system
  • Pipeline failure (lecture)
  • Empty cylinder (lecture)

S22

Need to do daily anesthesia machine check

68
Q

General Hazards: What can cause incorrect ventilator settings?

A
  • Incorrect settings!!! (easy to turn knobs)
    • Inadvertent bumping
    • Not adjusted for new case (preset at 700 & 10)
    • Not adjusted for position/pressure changes
    • Ventilator turned off for xrays (cholangiogram)

S23

69
Q

Advantages of a ventilator

A
  • Allows anesthesia provider to devote energy to other tasks (free hands)
  • Decreases fatigue
  • Produces more regular rate, rhythm, and Vt

S24

70
Q

Disadvantages of a ventilator

A
  • Loss of “feel” (reservoir bag)
  • Components are hard to clean or fix
  • Lack user-friendliness
  • Older versions may not have all the desired modes
  • Noisy or too quiet
  • Expensive if it requires high-flow driving gases

Lost CLONE

S25

71
Q

What is the trace gas concentration?

A
  • Concentration of a gas far below that needed for anesthesia or detected by smell

S27

72
Q

Trace concentration units

A
  • PPM (parts per million)

S27

73
Q

100% of gas is how many PPM?

A

1,000,000, PPM

S27

74
Q

1% of gas is how many PPM?

A

10,000 ppm

S27

75
Q

Higher levels of trace gas concentration are seen where?

A
  • Pediatric anesthesia
  • Dental surgery
  • Poorly vented PACU’s

S27

76
Q
  • What is the maximum TWA concentration (ppm) for anesthetic agents:
    • halogenated agent alone
    • nitrous oxide
  • What is the maximum TWA concentration (ppm) for combo of halogenated + nitrous oxide: :
    • Halogenated agent:
    • Nitrous oxide?
    • Dental facilities (nitrous oxide alone)
A

⭐️

S28

kane said we need to know this slide!!!

77
Q

What are the 6 common causes of OR waste gas contamination?

A
  • Poorly fitting masks
  • Use of uncuffed ETT
  • Failure to turn off vaporizer
  • Flushing circuit into room
  • Filling vaporizers…spills
  • Scavenging system leaks

PUFFFS

S29

78
Q

For years what did old studies conclude about trace gas exposure/vapor leaks?

A
  • Spontaneous abortions
  • Spontaneous abortion in spouses
  • Infertility
  • Birth defects
  • Impaired performance
  • Cancer/mortality
  • Liver disease
  • Cardiac disease

Cancer Spontaneously Injected Liver/Cardiac Into Births

S30

These negative side effects of gas exposure has been mitigated with the scavenger system

79
Q

Scavenging system function.

A
  • Removes the collection of gases from equipment used to administer anesthesia or exhaled by the patient.
  • Removal of these gases outside the work environment
  • Have active and passive systems

S31

80
Q

Describe the passive scavenging system:
* Location:
* Passage of airflow
* Where is volume exhausted?
* Where is the disposal tubing?

A
  • Attached to room ventilation
  • Air flows through room after being filtered and adjusted for humidity and temperature
  • Entire volume is exhausted to the atmosphere.
  • Disposal tubing from the anesthesia machine is attached to the exhaust grill and removed with room air.
  • very economic; uncommon

S32

81
Q

Describe the active scavenging system:
* Location:
* What must it be able to provide?
* What should be close to the anesthesia machine?

A
  • Attached to central vacuum system
  • Must be able to provide high volume (30L/min)
  • Need plenty of suction outlets and close to anesthesia machine

S33

82
Q

How do we prevent excessive trace gas in the procedural room?

A
  • Mask fit
  • Turn off gas flow (not vaporizer) during intubation
  • 100% wash out at end of case
  • Prevent liquid spills
  • Place anesthesia machine as close to exhaust grill (passive system) as possible

S34

83
Q

What are causes of a hypoxic inspired gas mixture?

A
  • Incorrect gas in the pipeline
  • Incorrectly installed outlets
  • Oxygen tubing or hoses attached to incorrect flow meter
  • Incorrect cylinder attached to yoke
  • Incorrect cylinder…..around world O2 is green, white, blue, and black
  • Flow control malfunction
  • Leak in oxygen flow meter

S36

84
Q

How does Hypoventilation occur on the ventilator?

A
  • Insufficient gas
    -switch from pipeline to cylinder
    -replace cylinder
  • Obstruction
  • Leaks
  • Main machine power off
  • Breathing system leaks (disconnections)
    -absorbent, connectors, gas sampling
       BLO MI if I hypoventilate

S37

85
Q

What are possible reasons why we would have blocked inspiratory/expiratory paths?

A
  • Mask wrapping
  • Absorbent wrapping

S38

86
Q

How can the ventilator cause hypercapnia?

A
  • Hypoventilation
  • Excessive dead space
  • Absorbent failure (increased baseline on etCO2)
  • Defect coaxial system

Head causes hypercapnia

S39

87
Q

How does an anesthetic agent overdose occur with the anesthesia machine?

A
  • Vaporizer accidentally on
  • Overfilled vaporizer
  • Incorrect agent in vaporizer
  • Interlock system failure
  • Tipped vaporizer

Vent Overdoses If It Tips

S40

88
Q

What are ways to prevent inadvertent exposure to volatiles?

A
  • Change breathing system hoses and bag
  • Change fresh gas supply hose
  • Change absorbent
  • Use very high oxygen flows to flush the machine
  • Remove vaporizers
  • Use an auxillary flowmeter for supplemental oxygen

S41

Mar: Sem 3 - Principles I (Full) (29 decks)

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