click below
click below
Normal Size Small Size show me how
Breathing System
Principles (Test 2)
Question | Answer |
---|---|
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 |