delivery systems Flashcards
essential elements of breathing system
1 - deliver gases from machine to alveoli in same conc as set, in shortest ant time
2 - elim CO2
3 - min apparatus dead space
4 - low resistance
desirable elements of breathing system
1 - economy of fresh gas 2 - conservation of heat 3 - adequate humidification of inspired gas 4 - light weight 5 - convenience during use 6 - efficiency during spon/controlled breathing 7 - adaptability for children/adults 8 - reduce environmental pollution
low resistance
- short tubing
- large diameter
- avoid sharp bends
- caution with valves
- minimize connections
rebreathing
may be beneficial
- cost reduction
- adds humidification/heat to gases
don’t want to rebreathe CO2
higher FGF associated w less rebreathing in any type of circuit
dead space
increases chance of rebreathing CO2
ends where inspiratory and expiratory gas streams diverge
apparatus dead space can be minimized by separating inspiratory and expiratory streams as close to patient as possible
Open system
- no gas reservoir bag
- no valves
- no rebreathing of exhaled gases
types:
1 - insufflation/blowby
2 - open drop
insufflation
open system
blowby, tent, bronchoscopy port, nasal cannula, steal induction
advantages of insufflation
avoids direct patient contact
no rebreathing of CO2
no reservoir bag or valves
disadvantages of insufflation
no ability to assist or control vent
may have CO2/O2 accumulation under drapes
no control of anesthetic depth/fiO2
environmental pollution
schimmelbusch mask
true open circuit,
consisted of bit of cloth saturated w ether or chloroform or halothane and held over patients face
open drop method
ether mask (schimmelbusch)
advantages of open drop
simplicity
low cost apparatus
portable
disadvantages of open drop
poor control of inspired concentration of anesthetics accumulation of CO2 under max predisposes to hypoxia risk spontaneous vent only/cannot control OR pollution/health care provider risk
semi open 5 characteristics
1 - facemask or ETT 2 - pop off valve 3 - reservoir tubing 4 - fresh gas inlet 5 - reservoir bag
mapleson A-F, Bain, circle
functional group 1
mapleson A
pop off located near face mask
FGF located at opposite end
functional group 2
Mapleson B/C
pop off and FGF located near facemask
functional group 3
Mapleson D, E, F
FGF located near face mask and pop off located at opposite end
opposite landscape of mapleson A
CO2 rebreathing depends on
1 - fresh gas inflow rate
2 - min vent of patient
3 - type of vent (spon vs controlled)