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95 Cards in this Set
- Front
- Back
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When would one see high levels of CO?
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Prolonged contact between anesthetics and absorbents
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FGF of 5L/min or greater for prolonged periods of time can cause what?
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Critical drying of the absorbent
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Describe the shifts in the oxyhemoglobin curve when excessive dry absorbents react with volatile anesthetics .
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Co reacts with hemoglobin, forming carboxyhemoglobin, shifting the curve to the LEFT
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What does a shift to the left in the oxyhemoglobin curve mean?
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Left shifts in preventing normal uploading of 02 in capillary bed-will suffer tissue hypoxia while blood partial pressure is high
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Is CO produced with hydrated soda lime?
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no
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What is the maximum amt of co2 that be absorbed by soda lime?
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26L of Co2 per 100g of absorbent
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What is the max capacity of calcium hydroxide lime?
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10.2L per 100g of absorbent
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Explain channeling of absorptive granules (what it is and what is reduces).
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Absorbent granules stack up in the absorber canisters, sm passageways form. The passageways channel gases through low-resistance areas. The absorptive capacity of the soda lime/calcium hydroxide is decreased (10-20L of Co2/100g absorbent)
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What is added to both soda lime and calcium hydroxide to assess the functional integrity of the absorbent?
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Ethyl violet
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What does it mean when the absorbent turns from white to violet?
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Ethyl violet changes fr colorless to violet when pH of the absorbent decreases as a result of Co2 production- the change in color indicates that the absorptive capacity of the material has been consumed
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If the absorbent as prolonged exposure to fluorescent light, what considerations should you think about.
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Photodeactivation of the dye occurs and the absorbent will remain white even though the absorptive qualities have been exhausted
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What are five clinical manifestations of hypercarbia?
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1 increase rate and depth of resp.
2 increase in bp 3 ventricular irritability 4 flushing of face, neck, thorax 5 increased icp |
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Gas enters the circle system fr the ____ by way of a gas hose, and exits the circle via _____ to the scavenger.
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CGO, APL
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In the mechanical ventilated pt, gas exits the circle via ______.
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ventilator relief valve
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What prevents accidental detachment of the gas outlet?
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an anti-disconnect device
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Do you typically use higher or lower FGF during emergence/induction?
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higher-the faster the increase of inspired concentration gas
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What is the FGF range for maintenance phase?
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1-3L/min
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What are two things that MAC values will vary with?
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Narcotic usage and relative age of the patient (precedex)
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What is the FGF range for emergence?
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6-15L/min o2
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_____ is the point where the FG hose enters the breathing circuit.
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Fresh gas inlet
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T/F Modern AM have anti-disconnect features.
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T
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What can happen to the valve leaflet(disk) when exposed to moisture or dust?
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It can become damaged, occluded, foreign body contaminated, especially on the expiratory valve
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In general, what do inspiratory/expiratory valves do?
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They enforce a pattern of gas flow by which exhalations are made to pass through the co2 absorbent granules
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What are two reasons for increased inspired co2?
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1. absorbent granules have been exhausted
2. faulty unidirectional valves |
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If there is an incompetent inspiratory/expiratory valve, what happens to the corrugated limb?
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It turns the entire limb into dead space, resulting in increased inspired and expired co2
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T/F It is optional to check valves before use
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False, it is mandatory
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What does the inspirational unidirectional valve do?
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Promotes gas toward the pt in one corrugated limb
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What is the disc in the unidirectional valve held in place by?
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It is held in place by a retainer and keeps disc in proper alignment with the seat...it can only raise a set distance
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What does the expirational unidirectional valve do?
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Exhaled gases lift disc off seat to open
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First portion of gas goes to the _____ and the remaining gas goes to the _____.
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rebreathing bag, APL
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What is the purpose of the breathing hoses?
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Two breathing hoses or currugated limbs carry gases to and from the pt
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Where do the limbs of the breathing hose deliver gas to?
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One limb goes to the inhalational unidirectional valve and the other to the exhalational unidirectional valve
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If one end of the breathing hose goes to the unidirectional valves, where does the opposite end of the limb go?
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It connects to the Y piece to complete the circuit
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How long can the breathing hoses be?
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34-80 in in length and internal diameter is 22mm
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T/F The length of the hose affects dead space and the amount of rebreathing.
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False
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What are some examples of when longer hoses may be required?
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Neurosurgical cases or MRI cases
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Where is the sampling port connection located and what does it do?
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It's located near the Y-piece and is used for gas analysis.
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Can a thermometer be placed in a breathing circuit?
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Yes, it can be placed in a port if headed humidifier is used
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What does the adjustable pressure limiting valve (APL) valve do?
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It creates an adjustable leak during manual ventilation and is usually open during spontaneous ventilation
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If the APL is open, where does the gas go?
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The gas exits to the scavenger, path of least resistance
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If the APL is closed, where does the gas go?
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The gas is rebreathed
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Under what circumstance would the crna be constantly adjusting the APL valve?
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During manual ventilation of the lungs so that a variable resistance sufficient to force gas to inflate the lungs is maintained
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If gas cannot exit through the APL or ventilator relief valve, what will happen?
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Pressure will build within the system...barotrauma may result
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Describe what is happening with the APL valve during spontaneous respiration.
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APL is fully open
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Describe the position of the APL during CPAP.
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The APL is partially closed- negative pressure transmitted from the scavenging system may cause gases to be evacuated from the breathing system
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An obstruction in the scavenging system may result in what?
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The reservoir bag may overdistended become and the patient may be subjected to CPAP
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T/F The APL valve shouldn't be adjusted during assisted ventilation.
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False, it should be adjusted on the basis of chest movements and/or exhaled volume or pressure measurements to achieve the desired level of ventilation and to maintain adequate bag volume
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What is one safety feature of the APL on modern AM?
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APL valve act as true pressur-limiting devices that can never be completely closed (upper limit is usually 70-80cm H20)
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What are two other uses of the APL?
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Chest auscultation (L side first) and assisting with breathing (check sat, watch chest rise, end tidal co2)
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What are the two main classifications of modern ventilators?
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Gas-driven bellows and Piston-driven bellows
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Between Gas-driven and piston-driven vents, which is better for use in offices and why?
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The piston-driven because it uses less gas than gas driven
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Which vent would be better to have in in the case of a pipeline failure.
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The piston-driven because it is electricity driven and can be used without depleting the o2 cylinder
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What are the two types of bellows?
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Standing(ascending) and Hanging(descending)
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Which type of bellow is overall safer to use?
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The standing because they will not fill in an event of a disconnect, whereas hanging bellows may fill with RA even when disconnected to pt
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What determines the classification of the bellows?
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The direction of the bellow movement during expiratory phase (Ascending bellows ascend during expiration, descending descend during expiraiton)
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What is the general purpose of the bellows?
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To deliver ventilation to pt
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If you use descending bellows, what safety device must be present?
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A co2 apnea alarm that cannot be disabled while the vent is in use must be in place
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What is one advantage to using the descending or hanging bellow?
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Provides compactness and ease of sterilization of the entire breathing system
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How to you change vent settings from bag to ventilator?
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Use the bag/vent switch ( it changes the flow of anesthetic gases fr CGO and exhaled gases fr reservoir bag to vent bellows)
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What would the TV be of a pt that is 65kg?
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650ml VT (8-10ml/kg)
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What is a norma I:E ratio?
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1:1.5 or 1:2 (ratio of duration for inspiration to expiration)
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T/F VCV is volume limited, time cycled, and constant flow
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T
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To prevent atelectasis and ETCO2 in the desirable range during VCV mode, what can be adjusted?
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VT can be adjusted to precent atelectasis, and rr can be adjusted to keep ETCO2 at an appropriate level
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What are typical vent settings for VCV?
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VT 10ml/kg, RR 6-12, I:E 1:2
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T/F Volume is controlled for PCV
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F, inspiratory pressure is controlled, not volume
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Describe the basic functions of PCV mode.
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Vent operates as pressure is limited and time cycled, with decelerating flow pattern. Vent generates sufficient flow to maintain target pressures through inspiratory time, high flow is needed at first and then less flow to maintain pressure.
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For what purposes do you make adjustments in PCV mode?
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Target pressure is adjusted to maintain VT, RR is adjusted to maintain ETco2, vt is monitored
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What can happen if pulmonary compliance drops or airway resistance increases (during pcv)?
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Delivered VT may drop substantially, if pulmonary compliance improves, vise versa
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What are some indications for PCV?
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Emphysema, neonates/infants, pregnancy, laparoscopic surgeries, one lung ventilation
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What is the typical setting for PCV?
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Pressure limit 20cm h2o, rr 6-12, I:E 1:2
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If pulmonary function changes during VCV mode, what happens to the volume.
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Nothing...Volume is controlled so alveolar vent and arterial co2 can be maintained
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What must the pt be doing in order for SIMV to be effective?
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The pt must be breathing!
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If a pt has a vent setting of SIMV and has a plan of anesthesia that is too deep, what can happen?
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Resp acidosis can occur
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What is PSV?
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Pressure-support ventilation, similar to PCV, but has rr of 0
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T/F PSV is good for pt's under general anesthesia and paralyzed.
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False, pt must be breathing spontaneously
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What are typical settings for PSV?
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Pressure support of 10cm h2o, apnea block, max inspiratory flow, and trigger window may be set for backup
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What is the purpose of humidifiers?
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Prevents heat loss (ciliary function decreases as air dries)
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What is the purpose of the scavenger system?
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Removes waste anesthetic gases fr the breathing circuit and ventilator and also removes them fr the OR
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T/F THe amt of gas used to anesthetize a pt is usually at or below the amt needed.
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F, usually the amt of anesthetic far exceeds the min amt needed
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What is OSHA's recommendations for exposure to halogenated agents and N2o?
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No worker be exposed to more than 2ppm halogenated agents and no more than 25ppm N20, based on time-weighed 8hr avg concentration
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What are the two main causes of waste gas contamination in the OR?
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1. Anesthetic technique
2. Equipment issues |
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What are examples of equipment issues r/t contamination in the OR?
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High pressure hoses, high/low pressure circuits, the circle system itself, N2o tack mounting
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What are some examples of contamination in the OR r/t anesthetic technique? (6 total)
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1. Failure to turn of gas flow control valves at end of case
2. Poorly fitting masks 3. Flushing the circuit 4.Filling anesthetic vaporizers 5. Use of uncuffed ETT 6. Use of breathing circuits that are difficult to scavenge (Jackson-Rees) |
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What is the most important part of the scavenging system?
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The interface...it protects the pt fr excessive buildup of positive pressure and fr exposure to suction
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What are the 5 main components of the scavenging system?
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1. Gas collection assembly-at APL valve and ventilator valve
2. Transfer tubing-19 or 30mm, can be color coded 3. Interfaces-closed and open 4. Gas disposal tubing 5. Gas disposal assembly-active disposal (common or passive disposal) |
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What active disposal?
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uses central evacuation system to eliminate waste gas
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What is passive disposal?
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The "weight" or pressure of waste gas itself produces flow through passive system
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What is the gas-collection assembly?
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Captures excess anesthetic gas and delivers it to the transfer tubing. Wastes are vented fr the anesthesia system through the APL or ventilator relief valve
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What is transfer means?
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Carries excess gas fr the gas collection assembly to scavenging system
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Why is the tubing in the scavenger system rigid?
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To prevent kinking
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Why is the scavenger tubing short?
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To prevent occlusion
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What is the key difference between open and closed interfaces?
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Open contains no vales and is open to atmosphere, closed communicates to atmosphere via valves
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What is the gas assembly tubing?
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Conducts waste gas fr the scavenging interface to the gas disposal assembly.
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Gas disposal assembly, what is it?
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Eliminates excess waste gas.
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What are the two types of disposal?
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Active and passive
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