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40 Cards in this Set
- Front
- Back
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Double-circuit ventilators have two circuits of gas. Explain..
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1) Bellows CHAMBER which contains the driving gas the moves the bellows.
2) Bellows which internally contain anesthetic gas that is delivered to the patient. |
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Explain what a spill valve does...
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Allows axcess exhaled air to overflow to scavenger.
(During exhalation, once the bellows fill completely a balloon valve collapses, allowing a ball/marble to pop up which opens the spill valve. See pg 50 of the notes.) |
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Double-circuit, pneumatically driven ventilators have two power sources...
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1) Electronic
2) Pneumatic. |
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Driving gas is usually ___% O2 or ____% O2. Explain.
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100% O2 or ~32% O2.
Some ventilators use only O2 as their drive gas. Others use a mix of Air and O2 (totaling ~32% O2). |
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Ascending vs descending bellows. What is the difference? Which are we more likely to see in clinical sites?
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Ascending much more common in US.
Ascending bellows (what we practice on) moves up during exhalation and down during inspiration. Bellows will remain down if patient disconnected. Descending "hanging" bellows. Down during exhalation, up during inspiration. Bellows continue to move even if patient disconnected. |
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What PEEP do ascending bellows add? Does descending add this?
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2.5, No.
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Should you look at the bellows to identify what TV your patient is actually receiving?
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No, Stupid. That will tell you your approximate set TV. Look at digital spirometer for TV patient is receiving.
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What machine brand does not have I:E ratio? How do you then manage this?
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Ohmeda - no I:E ratio.
Manage with flow rate, TV and RR. |
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What are machine ranges for:
RR TV PEEP Insp Flow I:E |
RR 1-99
TV 200-1400 I:E up to 1:4.5 Insp flow: low, med, high PEEP <18 cn H2O |
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What is a sigh option?
What machine features it? |
Every 64th breath is 150% of set TV.
Ohmeda 7800 |
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When the ventilator is on, pipeline O2 enters ventilator gas circuit at ___ psi.
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50 psi
Ventilator will not work if <28 psi. |
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You know tha O2 pipeline must supply psi of 50. Will ventilator work if it is less than this?
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Ventilator will work if O2 pipeline pressure is > 28 psi. 50 is default hospital setting.
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During inhalation, flow through vent circuit is controlled by ______ valve, which is electronically controlled by the ___ and ____ settings you entered.
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SOLENOID valve is electronically controlled by the RR and I:E setting we provide.
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Driving gas in NAD machine is __% ROOM air.
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80% room air.
(20% O2 = for an O2 total of ~32%) |
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When driving gass enters bellows, ______ valve closes and bellows are compressed.
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Spill / ventilatory relief valve
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If pressure in bellows chamber excedes __ psi, gas is released through entrainment port. What is significance of entrainment port and what will it do to the O2 level of your driving gas?
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70 psi is pre-set bellows chamber pressure.
Above this, gas will be release through entrainment port. Entrainment ports MAIN purpose is to bring in (entrain) room air. If, d/t excessive pressure, room air is no longer being entrained then your chamber O2% will increase. |
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Where does bellows chamber gas go during exhalation? Is this a concern?
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Leaves circuit via entrainment port and enters room.
No concern. It's 20% O2 and 80% RA. |
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What opens and closes the solenoid valve? What does it control?
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Computer electronically opens/closes solenoid valve based on I:E & RR we've dialed in. Open solenoid allows O2 pipeline air to enter bellows chamber with entrained RA and force bellows down. Closed solenoid valve drops chamber pressure which allows pt to exhale.
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When does exhaled air enter scavenger?
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Once bellows fill first, then VRV open and allow excess out.
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VRV produces ____ cm H2O PEEP in ascending bellows?
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2.5 cm H2O
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What happens if "ball" in VRV gets stuck?
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Once bellows fill, excess air will not be able to escape to scavenger. PEEP will rise and patient's lungs will explode killing several of your coworkers. Lawsuit.
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How does the PEEP valve work?
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Magnets.
Turning dial will move magnets closer together or farther apart. At start of expiration, out-flow pressure is greater than attraction of magnets. By end expiration, expiratory pressure falls below attraction pressure of magnets. Magnets close together and remaining air is trapped in lungs. |
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If PIP > set pressure limit...
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a spring valve opens and driving gas enters the room. Bellows stop moving and pressure in breathing system no longer increase.
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Scenario: Your patient is undergoing a lung transplant and the surgeon tells you to set your PIP to 24 cm H2O. Your patient's peaks have been close to 30 most of the case and now with the lower pressure setting your bellows won't fully empty. What is happening? How would you ventilate this pt?
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Pressure limit control valve is opening at 24 cm H2O and your pt receives no more TV at that point.
Must increase RR. Given new, smaller TV and fixed pressure limits, RR increase is only way to reach adequate minute ventilation. |
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What are advantages of piston ventilators?
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VERY accurate TV. Nice for peds and pt's with poor compliance.
No mandatory PEEP. Piston vent uses electronic/computer controlled piston. |
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What is fresh gas decoupling vs compensation? What company uses what?
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Drager -- Fresh Gas Decoupling -- Valve diverts FGF into reservoir bag during inhalation. During exhalation valve reopens and allows fresh gas to leave reservoir bag and enter ventilator for delivery during next inhalation.
Datex-Omeda -- Compensation -- D-lite sensors adjust delivered TV to preset TV despite changes in FGF. |
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What is CMV? What are standard TVs and RRs for adults?
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CMV = volume control. Delivers set TV at constant flow and RR. PIP varies.
TV = 8-10 mL/kg RR 8-12 bpm |
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What is pressure control ventilation? What pts is it good for? And what is usual PIP?
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PIP usually 20 cm H2O. Useful in one-lung ventilation and lung trauma, peds, neonates, emphysema.
TV varies in PCV with changes in resistance and compliance. |
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What type of ventilation "can be combined with pressure support ventilation." ?
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SIMV
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Pressure support ventilation increase pt's ___.
(One of the PFT/LFTs) |
Increases FRC.
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For MOST cases, you will want your ventilator set to deliver high ___ and low ___.
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HIGH tidal volume.
LOW resp rate. Prevents atelectasis and keeps airways open. |
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Waste gas enters scavenger system via 2 valves... name them.
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APL valve
Ventilatory Relief Valve |
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Waste gas/ wall evacuation is _______ from regular suction and must be at LEAST ___ L/min.
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SEPARATE from regular suction.
At least 30 L/min. |
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Scavenger hose is _.I.S.S.
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DISS
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OSHA maximum OR contamination:
Halogenated alone ____ N2O alone____ Halogenated agents : N2O____ |
2 ppm
25 ppm 0.5 : 25 ppm. |
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ANSI leak rate < = ___ ml/min resulting in < ___ ppm ambient concentration of N2O.
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<=100 ml/min
<3.7 ppm |
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Close system scavengers: explain what happens when the positive pressure relief valve opens.
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When the waste gas flow surpasses the vacuum capacity ( + reservoir bag) gas is vented into room.
(Better than back pressure on pt's lungs) |
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Closed system scavengers: explain what happens when negative pressure valve opens.
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Negative pressure valve opens and entrains room air when vacuum pressure surpasses waste gas pressure coming from pt
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NAD vs. Ohmeda
Which has two (one main, one back up) negative pressure relief valves? |
NAD
One opens at -0.5 cm H2O, backup opens at -1.8 cm H2O |
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Open system scavengers -- use _____ for reservoirs, not bags.
How does canister work? |
Canisters used instead of bags.
Waste gas enters through tube at top of canister and empties at bottom. Suction tube to vacuum also located at bottom of canister. Negative/Positive relief valves located at top of canister. |
