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Breathing System

Principles (Test 2)

What is the definition of an anesthesia breathing system/ circuit? path from anesthesia maching --> patient --> back to machine
What is the purpose of the breathing system? links the patient to the anesthesia machine by delivering oxygen and anesthetic gases and eliminating carbon dioxide
Name the 6 major breathing systems and tell whether they are open or closed systems 1)insufflation(open) 2)open-drop(open) 3)draw-over(semi-open) 4)mapleson(semi-open) 5)circle(semi-closed or closed) 6)resuscitation
Name the 5 things that can decrease resistance in a breathing system 1)decreased circuit length 2)increased circuit diameter 3)avoiding sharp bends 4)eliminating valves (if possible) 5)maintaining laminar flow
If you increase fresh gas flow, you (increase or decrease?) rebreathing. decrease
If you increase fresh gas flow, you (increase or decrease?) equilibrium time between "dialed-in" concentration and inspired concentration? decrease
(High or low?) flows are preferred for induction? High (to denitrogenate and get inspired gas concentration up)
(High or low?) flows are preferred for maintenance? Low (to conserve heat, humidity, volatile agent, and minimize OR contamination)
(High or low?) flows are preferred for emergence? High (to "wash out" anesthetic gases)
What does AMBU stand for? Artificial Manual Breathing Unit
What are the advantages to the resuscitation (ambu) breathing system? Simple, portable, can deliver almost 100% O2, self-refilling with O2 source or room air (don't need O2 supply in emergency)
What are the disadvantages to the resuscitation (ambu) breathing system? Needs high flow for high FiO2, difficult to determine mask to face seal (because the bag is self-inflating)
True or False: The resuscitation breathing system has a non-rebreathing valve. True
True or False: The resuscitation breathing system bag is self-filling. True
What is an advantage to rebreathing fresh gas? allows you to use less O2, volatile agents; conserves heat and moisture
What is a disadvantage to rebreathing fresh gas? allows the patient to also rebreathe CO2
Which type of breathing system used ether or chloroform dripped onto a gauze over a mask? Open-drop anesthesia
Open-drop anesthesia uses the rule of latent heat of ___________ to describe the reason the mask gets cold. vaporization (the air passing through vaporizes the liquid on the gauze)
Open-drop anesthesia leads to condensation and (increased or decreased?) vapor pressure. decreased
What type of breathing system uses ambient air inhaled (pulled across) the liquid agent? Draw-over anesthesia
During draw-over anesthesia, valves can be fitted for... oxygen, positive pressure ventilation, and passive scavenging
In draw-over anesthesia, 1L/min flow= ? FiO2 30-40%FiO2
In draw-over anesthesia, 4L/min flow= ? FiO2 60-80% FiO2
What are the advantages to draw-over anesthesia? simple, portable, can be used without compressed gas or ventilators, used in war zones
In draw-over anesthesia, the amount of O2 given over the vaporizer is dependent on what 2 factors? flow and temperature
What breathing system is defined as "blowing gas across the face?" insufflation
List 3 examples of insufflation. 1)Inhalation induction(peds) 2)Under drapes during sedation 3)Apneic techniques
What type of technique is defined as "strictly oxygenation (no ventilation) method to keep a survivable O2 Sat during aiway surgeries"? Apneic techniques
Name the components that make up a Mapleson breathing system. 1)breathing tube 2)fresh gas inlet 3)adjustable pressure-limiting valve(APL) 4)reservoir bag
True or False: Mapleson systems allow for some rebreathing. False: Mapleson systems are absolute, total nonrebreathing (all exhaled gases go straight to scavenging)
True or False: Mapleson systems require CO2 absorbers. False: (due to total nonrebreathing)
True or False: Mapleson systems require high flows. True: (due to total nonrebreathing)
What is the corrugated breathing tube made of? Rubber or disposable synthetic
What size is the breathing tube and why? 22mm: larger diameter=low resistance
Longer breathing tubes = (larger/smaller?) gradient between gas delivery to circuit and gas delivery to patient. larger
High compliance = (larger/smaller?) gradient between gas delivery to circuit and gas delivery to patient. larger
What gases go through the fresh gas inlet (FGI)? volatiles, N2O, O2, air
The location of the ______________ determines the Mapleson class to which a circuit belongs. fresh gas inlet (FGI)
What part of the breathing system controls pressure build-up in the circuit? adjustable pressure-limiting valve (APL)
APL valves vent from the ______________ to the ______________. Circuit to scavenging system.
What are the 2 functions of the reservoir bag? 1)anesthetic gas reservoir 2)positive pressure ventilation
As volume in the reservoir bag increases, compliance _______________. increases (protective: prevents back-up pressure from reaching patient)
In the Mapleson system, with spontaneous ventilation, fresh gas flow must equal ________________. minute ventilation (they can't breathe more than you're giving them)
In the Mapleson system, with controlled (vent or bag) ventilation, fresh gas flow must equal _______________. 3X minute ventilation
Describe the set-up of the Bain Circuit. the fresh gas outlet runs inside the corrugated tubing to help conserve expired heat and moisture
The Bain Circuit is a version of what class of Mapleson system? Mapleson D
What time of cases may still use the Bain Circuit? peds: used for quick induction for short cases
True or False: The Bain Circuit requires an adapter. True: Because it only has 1 limb since the FGI runs inside the corrugated tubing.
List the components of the Circle Breathing System. 1)CO2 absorber 2)FGI 3)unidirectional limbs and valves 4)Y-connector 5)APL valve 6)reservoir bag
What is the purpose of the unidirectional valves? "check valves" that keep flow moving forward
How does forward flow affect the unidirectional valves opening/closing? forward flow pushes valve up
How does reverse flow affect the unidirectional valves opening/closing? reverse flow closes valve
Describe how inhalation affects the movement of the inspiratory and expiratory valves. Inhalation opens inspiratory valve (inhaled fresh and exhaled gas from CO2 absorber). Simultaneously, expiratory valve closes to block rebreathing.
True or False: Rebreathing only happens during mechanical ventilation. False: Rebreathing happens whether you are manually or mechanically ventilating.
List 3 things that can cause unidirectional valve incompetency. 1)Warped disk-->leak 2)"stuck" in the up position 3)condensation
True or False: Only malfunction of the expiratory valve leads to CO2 rebreathing. False: Malfunction of either valve can lead to CO2 rebreathing and hypercapnia
Scenario: You are watching your ETCO2 monitor, and your waveform begins to change and not reach baseline. What are a few things that could be happening? 1)one of your valves isn't working right and patient is rebreathing/inhaling more CO2 2)patient is tachypneic 3)exhausted CO2 absorbent
Describe the components of the best way to set up a circle system. 1)Valves near patient 2)FGI between absorber and inspiratory valve 3)APL between absorber and expiratory valve 4)Reservoir bag in expiratory limb
In the circle system, why do you want the valves near the patient? prevents backflow when circuit leaks
In the circle system, why do you want the FGI between the absorber and inspiratory valve? less wasted fresh gas
In the circle system, why do you want the APL valve between the absorber and expiratory valve? conserves fresh gas
In the circle system, why do you want the reservoir bag in the expiratory limb? decreases resistance to exhalation and conserves absorbent
What is the biggest advantage of the circle system? allows for rebreathing of all gases with CO2 elimination
Define "dead space". tidal volume that does not move into alveoli
Dead space ends where... inspiratory and expiratory flows divide
Because of the unidirectional valves, all dead space is distal to the ___________. y-piece
Breathing system tube (limb) length (does/does not?) affect dead space does not
Breathing system tube (limb) length (does/ does not?) affect circuit compliance. does
What part of the circle breathing system is dead space? ETT
True or False: The circle system's unidirectional valves and CO2 absorber increase resistance. True: But even neonates do well with circle systems.
True or False: CO2 absorbent pulls heat from the system. False: CO2 absorbent adds heat to the system.
What can be used to prevent patient cross-contamination from the breathing system? bacterial filters (filters on the inhalation side protect the patient; filters on the exhalation side protect the machine)
Name some disadvantages to the circle breathing system. less portable, increased risk of malfunction, problems with absorbers, less predictability with low flows
What are the 2 commonly used CO2 absorbents? soda lime/NaOH (most common) and calcium lime/Ca(OH)2
How do CO2 absorbents work? neutralize H2O3 (carbonic acid) to water and energy (heat)
What CO2 absorber is no longer used due to fire hazard? barium lime
What is added to the CO2 absorber to decrease dust and resistance? silica
Describe how the color change takes place in CO2 absorbent. pH indicator turns white absorbent to purple/pink as acid level builds
Absorbent should be replaced at ________% color change. 50-70%
True or False: CO2 absorbent can revert back to original color and absorbency is restored with "rest". False: Absorbent can revert back to original color, but absorbency is NOT restored
Define "mesh" in regards to CO2 absorbent. number of holes per linear inch of a screen (the larger the #, the smaller the particle)
Most CO2 absorbent measures _____ - _____ mesh. 4-8
Very dry/dessicated absorbent = (higher/lower) volatile gas degradation. higher: (w/ a dessicated absorbent gases are broken down into toxic gases)
What happens when volatile agents are degredated? they are broken down into toxic gases
Desflurane degrades into... carbon monoxide (CO)
Sevoflurane degrades into... compound A
What CO2 absorber isn't used much anymore because it has worst degredation of volatile agents? potassium lime (KOH)
How can you prevent the degradation of sevoflurane into compound A? use flows > 2L
What is the brand name of the new CO2 absorbent that results in less degredation of sevoflurane? Amsorb
Compound A is a by-product of which volatile agent? sevoflurane
Compound A is nephrotoxic at what concentration? 25-50 ppm
What is the NIOSH standard of compound A exposure? 2 ppm
What 3 things can increase risk of compound A formation? 1)high-concentration 2)long anesthesia time (> 2 MAC hours) 3)low-flow technique (< 2L/min)
True or False MAC values are additive. True (ex. 0.5 MAC N20 (53%) + 0.5 MAC Sevo (1%) = 1 MAC total
Define a MAC hour. MAC hr= 1 MAC of something for 1 hr (or it's equilivant) (ex. 0.5 MAC of sevo for 2 hrs)
Define "channeling" of CO2 absorbent. absorbent exhaustion in areas where gas enters the absorber and along the canister walls
What technique is used to minimize "channeling" of CO2 absorbent? Baffles in the absorber direct gas flow through the center to minimize channeling.
At what ETCO2 level (explained by exhausted CO2 absorbent) should you change your canister? >3mmHg
CO2 absorbent should be changed on a scheduled basis to prevent dry absorbent from degrading volatile agents. How often should this be done? weekly
What is one way you can attempt to preserve your CO2 absorber as long as possible? use low flows
Increasing your flows (increases/decreases) you CO2 absorbent use. decreases (because more exhaled gas is going to scavenging and less is going to CO2 absorbent)
Fresh gas flow of _______-_______ L/min is almost total rebreathing. 0.3-0.5L/min
Fresh gas flow of _______-_______ L/min is uses little absorbent because most exhaled gas goes to scavenging. 5-8L/min
What are the 9 steps of the fresh gas pathway through the breathing system? 1)enters throughCGO, 2)flows through insp.1way valve, 3)flows through insp.breathing tube, 4)through y-piece to pt, 5)from pt through exp.breathing tube, 6)through exp.1way valve (excess out APL valve), 7)in/out res. bag, 8)CO2 absorber, 9)back toward pt