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Principles I (Summer 2025) > Exam 3- Anesthesia Machine II - Vents (7-11-25) > Flashcards

Exam 3- Anesthesia Machine II - Vents (7-11-25) Flashcards

(73 cards)

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1
Q

A ventilator is an automatic device that provides what 2 things to the patient?

A
  • Ventilation
  • Oxygenation
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2
Q

Ventilators essentially replace what component of anesthesia workstations?

A
  • The reservoir bag
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3
Q

What are disadvantages of old ventilator models? (5)

A
  • Only Volume-Controlled (VC) ventilation (Controlled Mandatory ventilation, CMV)
  • No PEEP
  • No High Inspiratory Pressure
  • Tidal volume affected by FGF & circuit compliance
  • Different bellows required for adults vs pedis
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4
Q

Barotrauma is an injury that results from _____ ________ ____________.

A
  • high airway pressures
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5
Q

Define: Compliance

A
  • Ratio of a change in volume to a change in pressure
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6
Q
  • In volume controlled, ________ is used to expand the breathing system.
  • A decrease in compliance, causes a decrease in _______.
A
  • Tidal volume (Vt)
  • Volume
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7
Q

Pressure controlled compliance

A
  • newer vents are able to alter tidal volume delivered to compensate for system compliance
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8
Q

Define Peak pressure:

A

Max pressure during the inspiratory phase time

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9
Q

Compare Fresh gas flow (FGF) on older vs newer vents:

A
  • Older: Increased FGF caused an increase in tidal volume (Vt)
  • Newer: Excess FGF is diverted during inspiration
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10
Q

What is Fresh Gas Compensation?

A
  • New vents prevent FGF from affecting tidal volume by measuring tidal volume and adjusting the volume of gas delivered by the ventilator (newer models divert excess gas away during inspiration)
  • Altered bellows excursion r/t measured inspiratory FGF → if vent didn’t adjust the gas could falsely expand bellows (barotrauma risk)
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11
Q

Inspiratory Pause time:

A
  • The time during which lungs are held inflated at a fixed volume and pressure
  • Also known as Inspiratory plateau
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12
Q

Sign

Sign:

A

Deliberate increase in tidal volume for one or more breaths

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13
Q

I:E ratio:

A
  • Ratio of the inspiratory phase time to the expiratory phase time
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14
Q

Normal I:E Ratio

A
  • 1:2
  • We spend more time expiring
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15
Q

Define: Inverse ratio ventilation
- Example?

A
  • Inspiratory phase time is longer than the expiratory phase time
  • Example: 2:1
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16
Q

The sum of all tidal volumes in one minute:

A
  • Minute volume (Vm)
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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

Spill Valve

A
  • During exhalation: Valve in the ventilator that allows excess gases to be sent to scavenging system
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19
Q

Exhaust Valve

A
  • During exhalation: Valve that opens to allow driving gas to exit the bellows housing during exhalation
  • During inhalation: Valve closes to help build compressed pressure & drive breath
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20
Q

Factors that affect ventilation (3)

A
  • Fresh gas flow: compensation & decoupling help regulate FGF affects
  • Compliance: New machines alter Vt based on system compliance
  • Leaks: leaks around tracheal tube or subglottic device can not be compensated by vent → decreases tidal volume (Vt)

Newer machines have made alterations to improve

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21
Q

Fresh gas decoupling:

A

Physical diversion of inspiratory FGF through a decoupling valve into a reservoir to prevent barotrauma or inaccurate tidal volumes from high FGF

Newer vents have excess FGF divereted during inspiration

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22
Q

Component of Bellow ventilators: (6)

A
  1. Drives gas supply & FGF (Double circuit) - contains O2, air, or mix
  2. Controls
  3. Alarms: High, medium, low
  4. Pressure-limiting mechanism
  5. Bellows: accordion-like device that expands & compresses
  6. Housing: clear/plastic - able to visualize bellows moving (has scale to estimate Vt)
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23
Q
  • Some vents can switch b/w driving gases during a ________ of pressure.
  • The gas (O2, air, or mix) in the bellows is equal to _______.
A
  • loss
  • minute volume (Vm)
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24
Q

What do the controls regulate?

A
  • Flow, volume, timing & pressure
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25
What alarms are required?
- **Must have a high & low pressure alarm**
26
- What happens if pressure too low? - What happens if pressure too high?
- Too low: insufficient pressure to ventilate - Too high: excessive pressure in airway
27
What is a good set point for the pressure limit of the inspiratory pressure?
* **10 cmH2O above peak inspiratory pressure with desired tidal volume**
28
- What drives the bellows? - What does the driving gas do to the bellows?
* Bellows are pneumatically driven * Driving gas squeezes gas out of bellows into lungs * Inspiration: Driving gas squeezes gas out of bellows into lungs → bellows compress * Expiration: bellows expand ## Footnote **E for E**: Expiration = bellows expand
29
Whhich 2 factors re-fill bellows (expands)?
- **Exhalation** - **FGF**
30
What are the 2 types of bellows? Which one is safer?
* **Ascending Bellows (Standing)** = **safer** -Ascend upward on expiration & descend downward (collapse) on inspiration -Will not rise if disconnected * **Descending Bellows (Hanging upside down)** -Descends downward on expiration & Rises back up (collapse) on inspiration -Will descend if connected d/t gravity ## Footnote Ascending & Descending (gravity related terms)
31
Bellow Complications (3)
1. **Improper bellow seating** = Inadequate ventilation 2. **Hole in bellows** = Alveolar hyperinflation/barotrauma -If driving gas is O2, patient's FiO2 increases -If driving gas is air, pateint's FiO2 decreases (dilutes O2) 3. **Closed Scavenging system** = waste gas vented to room
32
Why are ascending bellows considered safer?
* 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.
33
Piston Vent Characteristics: (4)
- Mechanically driven - No driving gas (single circuit) - Use dramatically less gas - Does not alter Vt based on compliance
34
Other pros of Piston: (4)
- Very small psiton chamber - accurate tidal volumes - Hidden on machine (no visual ventilation) - Very quiet
35
Piston hazards:
- **Refills even with disconnection** (*like descending bellows*) - **Entrain (pull in) room air during leaks** (dilutes gas mixture (O2 & volatiles)
36
Pulmonary Waveform Slide
TK has no notes - Take note of the pressure relationships & when they occur
37
What is the most commonly used mode of ventilation?
* Volume control (Assist Control) - VC/AC
38
What is VC/AC mode of ventilation? - What factors will be fixed on ventilator settings?
* **Preset tidal volume (Vt) is delivered** regardless of the patient's condition (fixed parameter) * Set **Vt, RR, I;E ratio** * Any additional breaths (spontaneous) taken will deliver preset Vt
39
Disadvantage of VC/AC:
- Can cause **excesssive inspiratory pressure** (barotrauma)
40
In VC/AC vent mode, delivered Vt may be terminated if set _________ is reached.
- **peak inspiratory pressure** (PIP)
41
What is Pressure control mode of ventilation? - What factors will be fixed on ventilator settings?
* Preset pressure is quickly achieved **during inspiration & maintained until exhalation begins** * Set **PIP, RR, and I:E Ratio**
42
Describe tidal volume with pressure control ventilation: * Tidal volume __________ with resistance and compliance * Pressure control can improve Vt by increasing _________ _________ ________ or _______ ________.
* Tidal volume **varies** with resistance and compliance * Pressure control can improve Vt by increasing **inspiratory flow rate** or **rise time** (if compliance is good)
43
Disadvantages of pressure control ventilation:
- Pressure control doesn't deliver volume.. if lungs have low compliance, less gas exchange leading to **atelectasis & hypoventilation** ## Footnote PC is a lung protective mode (prevents barotrauma/ excessive pressure)
44
What is Volume Guarantee Pressure-control mode of ventilation? - Advantages
* Maintains Tidal Volume by **adjusting PIP over several breaths** * **Prevents sudden Tidal Volume changes** d/t compliance (ex: lost insufflation)
45
Volume Guarantee Pressure-control mode - What will insufflation do to inspiratory pressure? - What can loss insufflation lead to?
* Insufflation increases inspiratory pressure → decreased tidal volume * Loss of insufflation → increased tidal volume
46
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)
47
- What is Intermittent Mandatory Ventilation (IMV)? - What factors will be fixed on ventilator settings? - What factors are variable? - IMV allows _______. - Often used for _______.
* **Mandatory ventilator breaths are set** * Set/Fixed: **Vt, RR, I:E ratio** * Variable: Additional **spontaneous breaths at variable tidal volume** → * Allows **stacking** of set & spontaneous breaths * Used for **weaning** (slowly decrease RR to increase pt WOB)
48
- What is different in Synchronized Intermittent Mandatory ventilation (SIMV)? - What factors will be fixed on ventilator settings? - Indications for SIMV (2)?
* Synchronizes ventilatory-driven breaths with spontaneous breaths → **prevents stacking by sensing airway pressure changes** * Set **Vt and minimum RR** * Uses: **Weaning during Emergence** & **Pressure Support**
49
- What is Pressure Support? - Triggering sensitivity must be set to what? - Tidal volume equates to _______, ________, & ________. (3 factors) - Required alarm?
* Preset pressure that helps the patient's spontaneous breaths on inspiration * Triggering sensitivity must be set to **5 - 10** cmH2O * Tidal volume (Vt) equates to the **native effort, pressure support, & lung characteristics** * Need **apnea alarm** (no ventilator breaths)
50
Ventilator use during MRI: - Standard vents have varialble amounts of ________ substances. - Safety Solutions (4)
* Ferromagnetic 1. **M**RI compatible machines 2. **A**nesthesia machine kept outside in hallway 3. **M**achine bolted to wall 4. **A**luminum tanks or pipeline gas supply ## Footnote **MAMA** had a safe MRI
51
General Hazards: Ventilation failure (4)
D – Disconnection from power supply E – Extremely high fresh gas flow (FGF) F – Fluid in electronic circuitry L – Leaking bellows housing ## Footnote If ventilation fails, it’s like the system got **DEFL**ated.
52
General Hazards: Loss of breathing system gas (2)
* Failure to occlude spill valve * Leak in the system ## Footnote **Leak in system = gas loss** More common in older machines with compensation
53
General Hazards: Incorrect ventilator settings (4)
* Inadvertent **bumping** (harder with digital settings) * Not adjusted for new case (**must adjust to patient**) * Not adjusted for **position/pressure changes** * Ventilator **turned off for xrays** (may reset to manufacturer when turned back on; standby mode prob prevents this)
54
Advantages of a Ventilator (3)
* Allows anesthesia provider to devote energy to other tasks * Decreases fatigue * Produces more regular rate, rhythm, and tidal volume (Vt)
55
Disadvantages of a Ventilator (6)
* Loss of “feel” (cannot feel negative inspiratory pressure in 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… more expensive
56
What is the trace gas concentration?
* Concentration of a gas far below that needed for anesthesia or detected by smell
57
Trace gas concentration unit:
* PPM (parts per million)
58
- 1% of a gas is how many PPM? - 100% of a gas is how many PPM?
- 10,000 ppm - 1,000,000 ppm
59
**Higher levels of trace gas concentration** are seen in what specialties (3)?
* Pediatric anesthesia * Dental surgery * Poorly-ventilated PACU's ## Footnote **PDP** has High PPM
60
What does NIOSH stand for? What are there recommendations for the following trace gas levels: - Halogenated alone - Halogenated combined - Nitrous alone & combined - Dental Nitrous alone
- NIOSH = National Institute for Occupational Safety and Health (1977) - Halogenated alone: 2 ppm - Halogenated + Nitrous: 0.5 ppm - Nitrous alone & combined: 25 ppm - Dental Nitrous alone: 50 ppm
61
Causes of OR Contanmination
1. **P**oorly fitted masks 2. **U**ncuffed ETT use 3. **F**ailure to turn off vaporizer 4. **F**illing vaporizer excessively (spills) 5. **F**lushing circuit into room 6. **S**cavenging system leaks ## Footnote **PUFFFS** & passes to everyone in the OR
62
How to limit room contamination: (5)
- Proper mask fit - Turn off gas flow during intubation (NOT vaporizer) - Prevent liquid spills - 100% washout at end of case - Place machine as close to exhaust grill as possible (for passive)
63
Old studies that are no longer supported linked trace gas concentrations to what? (long list)
* 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
64
Scavenging system function:
* Removes the collection of gases from equipment used to administer anesthesia or exhaled by the patient to outside the work environment
65
Passive scavenge system:
* Attached to room ventilation * Air flows through room after being filtered & adjusted for humidity & temp * Entire volume is exhausted to the atmosphere. * Disposal tubing from the anesthesia machine is attached to the exhaust grill and removed with room air ## Footnote **Passively through room air** Very economic but uncommon
66
Active scavenge 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 ## Footnote **Active = requires pressurized suction**
67
Hazards of Anesthesia machines and Breathing systems (5)
1. **H**ypoxic inspired gas mixture 2. **H**ypoventilation 3. **H**ypercapnia 4. **B**locked inspiratory/expiratory paths 5. **A**nesthetic agent OD ## Footnote **H**igh **H**igh **H**igh... **B**locked **A**ir!”
68
What can cause Hypoxic inspired gas mixture? (7)
- Incorrect gas in pipeline system - Incorrectly installed outlets - Incorrect tubing/hose connected to flow meter - Incorrect cylinder connected to yoke - Incorrect gas cylinder in use - Incorrect Flow control (malfunction) - Incorrect oxygen flow meter dt leak ## Footnote **Think operator error**
69
How can Hypoventilation occur? (4)
* Insufficient gas (switch from pipeline to cylinder or replace cylinder) * Obstruction * Main machine power off * Breathing system leaks (Absorbent, connectors, gas sampling) ## Footnote Think inadequate gas flow to pt
70
Blocked inspiratory/expiratory paths: Causes (3)
- Mask wrapping - Absorbent wrapping - Occluding elbow connection ## Footnote Think Barriers to ventilation
71
Hypercapnia causes:
* **H**ypoventilation * **E**xcessive dead space * **A**bsorbent failure * **D**efect coaxial system ## Footnote Hypercapnic **HEAD**ache
72
How can an anesthetic agent OD occur on workstation?
V – Vaporizer accidentally ON O – Overfilled vaporizer T – Tipped vaporizer I – Incorrect agent in vaporizer I – Interlock system failure ## Footnote **VOTII**ng for safe anesthetic dosing
73
What do you do if inadvertently exposed to volatiles?
1. Change breathing system hoses and bag 2. Change fresh gas supply hose 3. Change absorbent 4. Use very high oxygen flows to flush the machine 5. Remove vaporizers 6. Use an axillary flowmeter for supplemental oxygen ## Footnote Ex: Malignant Hyperthermia case

Principles I (Summer 2025) (11 decks)

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