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Nurse Anesthesia Summer 19 > ventilators > Flashcards

ventilators Flashcards

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1
Q

Reservoir

A

-how vent gets and delivers gases

  • this is how vents are classified
    1. Bellows
    2. Pistons
    3. Volume
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2
Q

Drive mechanism of reservior

A
  1. pneumatic - bellow

2. mechanical - mechanical

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3
Q

Bellow

A
  • direction of the below on expiration is how its classifies
    1. ascending: bellow rises on expiration *most common
    2. descending: bellow falls on expiration

**bellow separates the driving gas and the pt gas circuit
(double circuit)

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4
Q

Volume control

A

inspiration is terminated when preset TV is delivered

  • 4-5cc usually always lost due to compliance of system
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5
Q

Pressure control

A

inspiration ends and changes to expiratory cycle when airway pressure reaches the preset level

*TV and inspiratory time will vary

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6
Q

Driving force [Drive Gas]

A
  • pressurized gas that flows into the bellows (usually 100% Fi02)
  • on inspiration driving gas enters bellow chamber and increases the pressure
  • when pressure is increased from driving gas
  1. pop off valve close so no gas can escape to scavenge
  2. bellow compressed and gas in bellow (02, N20, anesthetic) is delivered to pt
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7
Q

expiration on a pneumatic (bellow)

A
  1. drive gas exits bellow
  2. pressure in chamber drops to 0, pop-off valve OPENS
  3. pt exhaled gas fills bellows, scavenging ONLY occurs when bellow is completely filled

**pop off only open in EXPIRATION

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8
Q

Issues with Bellows

A
  1. leaks in bellow
    - hyperinflation of lung (bc more driver gas will get into the bellow and when compressed deliver to much pressure)
    - 02 concentration can change (drive gas 100% Fi02 gets in bellow)
  2. Pop off valve (relief valve) problems
    A.-hypo-ventilate (gas goes to scavenger instead of pt)
    ^^disconnection, ruptured valve
    B.-excess suction from scavenging can close valve
    -valve stuck in closed position
    ^^ both cause more pressure (no way for excess gas/ pressure to escape)
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9
Q

Piston vent

A
  • Computer controlled stepper motor
    - no drive gas
    - less gas used
    - single circuit

*bag present and active, fills on inspiration for next breath (acts as reservoir and saves/ recycles gas)

  • Peep relief valve
  • ->prevents higher breathing circuit pressure ( 60-80)

circuit compliance compensation used

**no sound no see (not a very common vent)

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10
Q

circuit compliance mechanism

A

feedback mechanism that delivers more accurate tidal volume (r/t piston movement)

-when pt exhales circuit does some math to make next breath more precise

**piston vent

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11
Q

Piston inspiration

A
  1. PEEP valve closed so nothing escapes
  2. pressure in circuit increases, decoupling valve [separates fresh gas from expired gas] closes, gas flows toward bag and fills it for next expiration and excess gas flows past APL [adjustable pressure limiting] valve –> exhaust check –>scavenger
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12
Q

Piston expiration

A

2 phases

1st phase: pt exhales and gas goes into bag, fresh gas also still flowing into bag
**decoupling valve separates the gases and is closed in the first phase of expiration

2nd phase: vent returns to starting position, brings in gas from bag both fresh and stored (decoupling valve open)
and excess fresh gas back flows into anesthesia bag and vents via exhaust. valve –>scavenger

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13
Q

Issues with Pistons

A
  • nothing to see nothing to hear*
  • compliance and volume correction occurs even with a circuit disconnect
  • leak in circuit, room air will enter and dilute 02 and anesthetic –> hypoxemia
  • problem with peep relief valve will give pt higher pressures
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14
Q

Marquet Flow-i Anesthesia System

A
  • uses volume reflector
  • fresh gas module and reflector. gas module work together in a coordinated manner to control gas flow and pressure in circuit to maintain set ventilation parameters
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15
Q

Exhilation

Marquet Flow-i Anesthesia System

A

-end of exhalation volume reflector is filled at its proximal end (near pt) with the exhaled gas and distally filled with mix of exhaled gas and reflector gas

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16
Q

Inspiration

Marquet Flow-i Anesthesia System

A
  • on inspiration reflector pushes exhaled gas back out of the volume reflector through C02 absorber to pt
  • fresh gas combines with volume reflector outflow to make desired 02 and anesthetic concentration
17
Q

Parameters used to describe Ventilation

A
  1. Time (I:E ratio should be 1:2)
  2. Pressure: impedance to flow, from circuit, pmts lungs/ airway
    - back pressure generated by airway resistance, lung/ thorax complications (PIPs: cmH20, mmHg, kPa)
  3. Volume: how much gas pt receives with each breath (5-7 ml/kg TV)
  4. Flow rate: rate gas volume [TV] is delivered to pt (L/sec or L/min)
18
Q

Tidal Volume

A

5-7ml/kg

19
Q

Flow Rate

A

4-6x the minute ventilation

L/min or L/sec

20
Q

Minute ventilation

A

Tidal Volume x RR

21
Q

Solving for Expiratory time

A

inspiration time :expiration time 1:2
Ti= Tidal volume / Flow Rate

Te: first. figure out total time of each ventilation for 1 min cycle

RR 12 breaths/ min (60sec)
TV 500 mL
Insp. flow 30l/min–> (30,000mL/min)

Ti=500mL÷30,000mL/min. = 0.0167

   0.0167 X 60sec = 1 second

Total = 60 sec ÷ 12b/60 sec= 5 sec

Te= Total - Ti —–> 5-1 = 4

Ti =1 —> Te = 4 ——> I:E 1:4

22
Q

Fi02 equation

A

02 delivery = CO X 02 content

02 content = (hgb x %Sat x 1.34~1.39ml 02) + (Pa02 X .0031 ml 02)

Hgb x %sat x 1.39mL of

P02 x .0031mL

23
Q

How much 02 to give

A

PaO2 = PIO2 – PaCO2/R

R= extraction ratio (0.8)

increase Fi02 by 10% increase Pa02 by 50 mmHg

Pa02 100 Fi02. 21%
150 30%
200 40%
250 50%

24
Q

Vent Alarms

A
  1. Low pressure alarm
    (disconnect alarm): detected by drop in peak circuit pressure
  2. High Peak Pressure alarm: pressure above set parameter (40 cm H20)
  3. Low oxygen supply alarm: can’t silence and WONT prevent hypoxic mixture
  4. Sustained/ continuing pressure alarm: 15 cm H20 more than 10 seconds
  5. Sub-atmospheric pressure alarm: < -10cm H20 (negative pressure occurring)
25
Q

End tidal C02

A

how well is your pt ventilating

End tidal C02 (30-35)
PaC02 will be higher

adjust volume before RR, recruit more alveoli (more gas exchange)

26
Q

Vent Monitors

A
  1. ETC02 ** reveals disconnect. (how well pt is ventilating)
  2. 02 analyzer most important monitor on the machine
    - calibrates @ 21% 02
    - helps prevent hypoxic mixture
27
Q

Vent Monitors

A
  1. ETC02 ** reveals disconnect. (how well pt is ventilating)
  2. 02 analyzer most important monitor on the machine
    - calibrates @ 21% 02
    - helps prevent hypoxic mixture
  3. Respirometer ** vent settings
    - how much pt is breathing
28
Q

Respirometer

A
  1. TV volume sensor
  2. Apnea *respirometer isn’t detecting sufficient breath based on set TV in 30 seconds
  3. Low minute Vent
  4. Gas flow converted to electrical pulses
  5. Exhaled Vt
    = Vt set + Vt fresh flow gas - Vt lost in system
  6. Exhaled volume monitor *activated automatically when breaths are senses and stays active
  7. In expiratory limb *information you get from pt
29
Q

Anesthesia vs ICU vent

A
  1. less powerful, used for shorter duration of time
  2. C02 absorber
  3. driving gas never reaches the pt (in bellows as soon as it hits machine divides into 2 circuits)
30
Q

Controlled Ventilation (CV)

A
  • controlled by vent
  • fixed RR
  • not synched with pt
31
Q

Intermittent mandatory volume (IMV)

A
  • spont breathing by pt, vent delivers preset TV at predetermined interval
  • fixed rate
  • not synched with pt
32
Q

Synchronized Intermittent Mandatory Volume (SIMV)

A
  • bt breaths spontaneously and at predetermined intervals pts breath is assisted
  • pt can trigger breath and vent synchs mechanical breath with set TV at beginning of spont effort (must occur within “trigger window”)
  • fixed RR

**good for pt waking up in OR

33
Q

AC- Intermittent mode of positive pressure ventilation

A

-pts inspiratory effort creates sub-baseline pressure in inspiratory limb of vent circuit
^ this triggers vent to deliver predetermined TV

-if pts RR drops below set rate machine takes over with controlled vent mode
^all breaths will be fully assisted
and can be pressure controlled for volume controlled

34
Q

Pressure Support (PSV)

A
  • aids in normal breathing with set level of positive airway pressure
  • pt spont breathing and vent senses effort and delivers pressure support (giving larger TV than pt would pull on their own)
35
Q

High Frequency (oscillator)

A
  • low tidal volumes
  • high rate

typical settings
100-200. bpm
IT 33%
Drive pressure 15-30psi

**maintain pulmonary gas exchange at lower mean airway pressure

used for Extracorporeal Shock Wave Lithotripsy

36
Q

Pressure Control

A

-pt or time triggered pressure limited, time cycled mode of vent

  • gas flow decreased as airway pressure increased
  • flow stops when pressure = set peak pressure
  • TV varies, keep note of it
  • used in situations where airway pressures can be high (premie)
37
Q

CPAP

A
  • continuous positive pressure
  • positive pressure maintained for both inspiration and expiration
  • can be down the mask
  • useful for one lung anesthesia, very passive and can oxygenate lung being operated on

**pressure >15 cm H20 can cause regurgitation and aspiration (air in stomach)

Nurse Anesthesia Summer 19 (11 decks)

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