Anesthesia Delivery System Flashcards
What is the function of the anesthesia breathing system?
deliver oxygen and anesthetic gases to patient and remove CO2
What 2 ways can CO2 be removed from the breathing circuit?
washout with FGF or by use of CO2 absorber
What are the essential requirements of a breathing system?
deliver the gases from the machine or device to alveoli in the same concentration as set and in the shortest possible time
effectively eliminate CO2
have minimal apparatus dead space
low resistance
What are some desirable requirements of the breathing system?
economy of fresh gas
conservation of heat
adequate humidification of inspired gas
light weight
convenient to use
efficiency during spontaneous and controlled ventilation
adaptability for adults, children & mechanical vents
provision to reduce environmental pollution
You want low resistance in the breathing circuit, what are some ways this can be achieved?
short tubing, large diameter tubing, avoid sharp bends, caution with valves, minimize connections
Rebreathing may be beneficial, why?
cost reduction and adds humidification and heat to gas
What dont you want the patient rebreathing? How can this be prevented?
CO2; higher FGF is associated w/ less rebreathing in ANY type of circuit
What increases the chance of rebreathing CO2?
deadspace
Deadspace ends where the ___________&_____________gas streams diverge?
inspiratory and expiratory
How can apparatus dead space be minimized?
separating the inspiratory and expiratory streams as close to the patient as possible
T/F: The concentration inspired is closest to what is delivered from the common gas outlet when rebreathing is minimal or absent.
true
What are the 4 classifications of anesthesia delivery systems?
- open
- semi-open
- semi-closed
- closed
What are the characteristics of an open system?
no gas reservoir bag; no valves; no rebreathing of exhaled gases
What are the 2 types of open systems?
insufflation/blow by & open drop
What are some examples of insufflation?
blow by; tent; bronchoscopy port; nasal cannula; steal induction
What are some advantages to insufflation?
avoids direct patient contact; no rebreathing of CO2; no reservoir bag or valves
What are some disadvantages to insufflation?
no ability to assist or control ventilation; may have CO2/O2 accumulation under drapes; no control over anesthetic depths/FiO2; environmental pollution
Schimmelbusch mask was considered a true “open” circuit because it consisted of what?
piece of cloth saturated w/ ether, chloroform, or halathane and held over a patient’s face
The Schimmelbusch mask is an example of what type of open circuit?
open drop method
What are some advantages of the open drop method?
simplicity; low cost apparatus; portable
What are some disadvantages of the open drop method?
poor control of inspired concentration of anesthetic; accumulation of CO2 under mask; predisposes hypoxia risk; spontaneous ventilation only; OR pollution/healthcare provider risk
The semi-open system is characterized by what 5 components?
face mask pop valve reservoir tubing FGF inlet reservoir bag
What are some examples of a semi open system?
Mapleson A-F; Bain; circle
How many functional groups are there of the Mapleson systems?
3
Group 1 of mapleson is characterized as:
Mapleson A: pop off valve is located near face mask; FGF at opposite end
Group 2 of mapleson is characterized as:
Mapleson B & C: pop off valve and FGF both located near facemask
Group 3 of mapleson is characterized as:
Mapleson D-F: FGF located near facemask and popoff valve at opposite end opposite of Mapleson A
CO2 rebreathing depends on what 3 things?
- FGF rate
- MV of patient
- type of ventilation (controlled, spontaneous)
T/F: Mapleson D can be used for both spontaneous and controlled ventilation?
True
With the Mapleson D and spontaneous ventilation the FGF should equal what?
FGF=2-3xMV
With the Mapleson D and controlled ventilation, the FGF should equal what?
FGF=1-2xMV
Mapleson E has no __________and _________.
reservoir bag and popoff valve