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Principles I* > E3- Anesthesia Ventilators > Flashcards

E3- Anesthesia Ventilators Flashcards

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1
Q

A ventilator is an automatic device that will provide what two things to the patient?

A
  • Patient ventilation
  • Patient oxygenation
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2
Q

On the anesthesia workstation, ventilators essentially replace what component?

A
  • The green reservoir bag
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3
Q

What ventilation was available from old ventilator models?

A
  • Only offered volume-controlled ventilation
  • No PEEP
  • Couldn’t provide high enough PIP
  • Only controlled mandatory ventilation
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4
Q

Barotrauma is an injury that results from ______

A
  • Injury resulting from high airway pressures
  • Limit PIP to avoid this
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5
Q

Compliance

A
  • Ratio of a change in volume to a change in pressure
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6
Q
  • decrease in compliance causes decrease in ________ bc volume used to expand system (volume controlled)
  • newer vents alter volume delivered to compensate for ____________________ (pressure controlled)
A
  • Vt
  • system compliance
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7
Q

Work of Breathing

A

o Energy expended by the patient/ventilator to move gas in + out of lungs.

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8
Q

Exhaust Valve

A

Valve that opens to allow driving gas to exit the bellows housing during inhalation

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9
Q

What is Fresh Gas Compensation?

A
  • a way to prevent FGF from affecting tidal volume
  • by measuring tidal volume and adjusting the volume of gas delivered by the ventilar.
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10
Q

The time during which lungs are held inflated at a fixed volume and pressure.

A
  • Inspiratory pause time
  • inspiratory platuea

Increase intrathroacic P –> dec preload –> dec CO !!

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11
Q

I:E ratio

A
  • Ratio of the inspiratory phase time to the expiratory phase time
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12
Q

Normal I:E Ratio

A
  • 1:2
  • We spend more time expiring

intrathoracic p > dec preload > dec CO – decrease I:E to 1:1 to help CO

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13
Q

Inverse ratio ventilation

A
  • Inspiratory phase time is longer than the expiratory phase time
  • 2:1
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14
Q

The sum of all tidal volumes in one minute

A
  • Minute volume
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15
Q

Peak Pressure

A
  • The maximum pressure during the inspiratory phase time
  • PIP
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16
Q

Spill Valve

A
  • The valve in the ventilator that allows excess gases to be sent to scavenging system during exhalation
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17
Q

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

A
  • Work of breathing
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18
Q

%%%

Factors that affect delivered tidal volume.

A
  • Fresh gas flow
  • Compliance
  • Leak
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19
Q

On older vents, as FGF increases, what happens to tidal volume?
* what do newer vents do to excess FGF?

A
  • Tidal volume increase
  • diverted during inspiration
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20
Q

How do newer vents compensate for system compliance?

A
  • New vents will alter the volume delivered to compensate for system compliance (pressure control)
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21
Q

2 compliance factors affecting ventilation

A

o System – bent tube, step on circuit
o patient – asthma, COPD, Trendelenburg, supine, laparoscopy CO2 insufflation

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22
Q

How does a leak affect delivered tidal volume?

A
  • Leaks around ETT or LMA
  • will cause a decrease tidal volume that can’t be compensated by the ventilator
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23
Q

Components to the bellows ventilator.

A
  • Driving gas supply + FGF
  • Controls
  • Alarms
  • Pressure-limiting mechanism
  • Bellows (accordion-like device)
  • Housing
  • Exhaust Valve
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24
Q

Components of Bellows Ventilators

What does the driving gas + FGF do to the bellows?
What is another name for this?

A
  • The driving gas is the gas external to the bellows that cause them to collapse.
  • FGF is internal the bellows + delivered to pt
  • Double Circuit
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25
# *Components of Bellows Ventilators* FGF is oxygen, air or mix + in the bellows it is equal to? If oxygen using, what is flow from flowmeters + Vm from FGF?
* Vm * flow control from flowmeters (1-2 L/min) + Vm from FGF (4-5 L/min)
26
# *Components of Bellows Ventilators* What are the two required alarms on the ventilator?
* Low-pressure alarm * High-pressure alarm * high, medium, + low priorities
27
# *Components of Bellows Ventilators* What is the most common cause of low-pressure ventilator alarms?
* Disconnection of a circuit
28
# *Components of Bellows Ventilators* What are examples of high-pressure ventilator alarms?
* Kinking of the ETT * Occlusion of mask
29
# *Components of Bellows Ventilators* What is the pressure limiting mechanism? What is a good set point for the pressure limit of the inspiratory pressure?
* Limits inspiratory pressure * 10 cmH2O above average inspiratory pressure with desired Vt
30
# *Components of Bellows Ventilators* What is the housing of the anesthesia machine?
* Clear plastic cylinder * Allows movement of bellows to be observed * Has scale on side for rough estimation of tidal volume
31
# %%% What is the function of the exhaust valve?
* Communicates with the housing and allows driving gas to be vented to the atmosphere on exhalation
32
The bellows is _______ driven
pneumatically
33
What are the two kinds of bellows? Which one is safer? How are they named?
* Ascending Bellows (standing) **safer** * Descending Bellows (hanging) * named on what they're doing during exhalation
34
Why are ascending bellows considered safer?
* disconnection in circuit, >> bellows will fail to rise on exhalation >> trigger CRNA to know something is wrong. * For descending bellows = continue to descend even if disconnection d/t gravity
35
What are the 3 bellows problems? What do they lead to?
* Improper seating of bellows inside housing >> inadequate ventilation * Hole >> alveolar hyperinflation / barotrauma * Scavenging system closed >> waste gases vented to room
36
Hole in bellows :: if driving gas is O2 vs. air
* if driving gas is O2 - increase FiO2 * if air - dcrease FiO2
37
What are the components of Piston Ventilators?
* mechanically driven motor (plunger of syringe) * no driving gas - **single circuit** * use less gas
38
PIston ventilators don't alter ______ based on compliance.
Vt
39
Piston ventilator 4 extras
o Very small piston chamber o Accurate tidal volumes o Hidden on machine…no visual ventilation o Very quiet
40
What are 2 piston problems
* refills even with disconnection * entrain room air during leaks >> dilutes O2/volatiles
41
3 controlled ventilation modes
* volume control * pressure control * volume guarantee pressure-control
42
What is the most commonly used mode of ventilation?
* Volume control
43
What is volume control mode of ventilation?
* Preset tidal volume is delivered (fixed parameter) * Additional breaths = at machine preset Vt | *any RR is always with set Vt - RR 10 + Vt 500 ,, RR 20 + Vt 500*
44
Volume control mode can cause excessive ________ pressure.
* inspiratory
45
Volume control mode will have set:
* Set Tidal Volume * Set Respiratory Rate * Set I:E Ratio
46
# %%%% What conditions would a volume control mode not be beneficial for the patient?
* 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
47
# %%% How much tidal volume should be delivered to a patient on a ventilator?
* 4-6 mL/kg
48
Describe pressure control ventilation.
* Preset inspiratory pressure is quickly achieved during inspiration. * Set PIP, RR, and I:E Ratio
49
Describe tidal volume with pressure control ventilation.
* Tidal volume varies with resistance and compliance | *Insufflation + Trendelenburg >> cause low Vt *
50
What will insufflation of the abdomen do to inspiratory pressure?
* Increase inspiratory pressure, which will cause a low tidal volume.
51
What is the good thing about pressure control ventilation?
* This vent setting protects lungs from barotrauma of excess pressure
52
What is the bad thing about pressure control ventilation?
* The pressure delivered in this mode might not develop enough tidal volume for the patient. * Increase risk for **atelectasis** * cause **hypoventilation**
53
What are ways to deliver more tidal volume in pressure control ventilation mode to patients with low lung compliance?
* Increase PIP * Use Inverse I:E ratio, longer inspiration than expiratory time. The body will have time to adapt to increased pressure.
54
Describe Volume Guarantee Pressure-Control.
* Maintain Tidal Volume by adjusting PIP over several breaths. * Prevent sudden Tidal Volume changes d/t compliance * **Lost insufflation** - *change in compliance when case finishing up *
55
What is Assist Control Ventilation?
* Predetermined negative pressure will trigger breath * Breath is **preset tidal volume** | set paramter 8 RR + 600 Vt --- pt triggers 10 RR @ 600 ea
56
What is Intermittent Mandatory Ventilation (IMV)?
* Mandatory ventilator breath is set - **RR is set** * **Additional** native breaths at** variable tidal volume** * Allows breath stacking
57
What is SIMV?
* Synchronizes ventilatory-driven breaths with spontaneous breaths * *makes a waiting time before the next breath + pt has to exhale - no stacking* * Provides backup to **weaning** ventilator * Best for weaning
58
What is Pressure Support?
*** PIP + inspiratory time **set * Vt equates to the native effort * Need apnea alarm
59
* standard machines have variable amts of __________ substances What are ways to use a ventilator during an MRI?
FERROMAGNETIC * MRI compatible machines * Anesthesia machine kept outside in hallway * Machine bolted to wall * Aluminum tanks or pipeline gas supply
60
General Hazards: What 4 can cause ventilation failure?
* Disconnection from power supply * Extremely high FGF * Fluid in electronic circuitry * Leaking bellows housing | FIX = Bag the pt
61
General Hazards: How can there be a loss of breathing system gas?
* Failure to occlude spill valve * Leak in the system ## Footnote Need to do daily anesthesia machine check
62
General Hazards: What 4 can cause incorrect ventilator settings?
* Inadvertent bumping * Not adjusted for new case * Not adjusted for position/pressure changes * Ventilator turned off for xrays (cholangiogram)
63
3 Advantages of a ventilator
* Allows anesthesia provider to devote energy to other tasks (free hands) * Decreases fatigue * Produces more regular rate, rhythm, and Vt
64
6 Disadvantages of a ventilator
* Loss of “feel” (reservoir bag) * Older versions may not have all the desired modes * Components are hard to clean or fix * Lack user-friendliness * Noisy or too quiet * May require high-flow driving gases…expensive
65
What is the trace gas concentration?
* Concentration of a gas far below that needed for anesthesia or detected by smell
66
Trace concentration units
* PPM (parts per million)
67
100% of gas is how many PPM?
1,000,000, PPM
68
1% of gas is how many PPM?
10,000 ppm
69
Higher levels of trace gas concentration are seen in... 3
* Pediatric anesthesia * Dental surgery * Poorly vented PACU's
70
Chart from NIOSH 1977 - maximums of how much ppm allowed 1. halogenated agent alone? 1. nitrous oxide? 1. combination - halogenated? 1. combination - nitrou oxide? 1. Dental facilitites (nitrous oxide alone)?
1. 2 2. 25 3. 0.5 4. 25 5. 50
71
6 causes for operating room contamination
* failutre to turn off vaporizer * poor fitting mask * flushing circuit into room * spilling when fill vaporizer * uncuffed ETT * scavenging system leaks
72
For years what did old studies conclude about trace gas exposure?
* Spontaneous abortions * Spontaneous abortion in spouses * Infertility * Birth defects * Impaired performance * Cancer/mortality * Liver disease * Cardiac disease ## Footnote These negative side effects of gas exposure has been mitigated with the scavenger system
73
Scavenging system function.
* Removes the collection of gases from equipment used to administer anesthesia or exhaled by the patient. * removal of these gases outside the work environment
74
Describe the passive scavenging system.
* attached to **room ventilation system** * 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 :(
75
Describe the active scavenging system.
* Attached to central **vacuum** system * Must be able to provide high volume (**30L/min**) * Need plenty of **suction outlets** and close to anesthesia machine | COMMON
76
5 Ways to alter work practices + not contaminate the OR
* mask fit * turn off gas flow durign intubation * 100% wash out at end of case * prevent liquid spills * plase anesthesia machine close to exhaust grill - passive system
77
7 causes of hypoxic inspired gas mixture
1. * Incorrect gas in pipeline 1. * Incorrectly installed outlets 1. * Oxygen tubing or hoses attached to incorrect flow meter 1. * Incorrect cylinder attached to yoke 1. * Incorrect cylinder…..around world O2 is green, white, blue, and black 1. * Flow control malfunction 1. * Leak in oxygen flow meter
78
How can the ventilator cause hypercapnia? 4
* Hypoventilation * Absorbent failure (exhaustion) * Excessive dead space * Defect coaxial system - mapleson D
79
How does an anesthetic agent overdose over with the anesthesia machine? 5
* Tipped vaporizer - lots of liquid * Vaporizer accidentally on * Incorrect agent in vaporizer * Interlock system failure * Overfilled vaporizer
80
How does Hypoventilation occur on the ventilator?
* Insufficient gas : swithc from pipeline to cylinder * Obstruction * Leaks * Main machine power off * Breathing system leaks (disconnections)
81
What are 6 ways to prevent inadvertent exposure to volatiles? | MH , severe nv pts
* 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 axillary flowmeter for supplemental oxygen
82
2 Causes of blocked inspiratory + expiratory paths?
1. mask wrapping 2. absorbent wrapping

Principles I* (20 decks)

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