Breathing Systems Flashcards
(53 cards)
7 basic components of breathing systems
- CO2 absorbent
- two unidirectional valves
- fresh gas inlet
- Y connector
- resevoir bag
- adjustable pressure limiting valve
- low resistance tubing
Soda lime
Calcium hydroxide, some sodium hydroxide and potassium hydroxide. silica added to decrease dust
water and heat are produced which adds humidity and heat to breathing circuit
Why does color change occur soda lime
pH sensitive rxn
L/100g absorbent can soda lime absorb
23-26L of CO2 per 100g
size of granules in absorbents
smaller granules have great surface area for absorption but increased resistance to air flow
incompetence of either valve causes ____
rebreathing
where does fresh gas enter in circle system
between absorber and inspiratory valve
what does reservoir bag store
O2 and anesthetic gases
where is APL valve positioned
near exhalation unidrectional valve, gas scavenging systems collect any gas exiting system via relief valve
safety features in anesthesia breathing system that ensure patient receives adequate oxygen sypply
- fail safe valve
- rotameter
- proportioning device
when does fail-safe prevent hypoxic mixture
if decreased oxygen supply at flowmetes level
device present in gas lines except for O2 and is controlled by O2 sypply pressure
how does fail safe device work
interupts supply of other gases if O2 supply is reduced to a certain level, usually below 30 psi
that level is the opening threshold pressure for the other gases
flowmeters/rotameters control what
control gas proprotions and gas flow to common gas outlet
how does rotameter work
adjusts gas flow by means of flow control needle valves and flow tubes
gas flow enters at base of glass flow tube and glass tube is tapered in that its diameter increases with height
small metal bobbin rides the gas jet
variables that affect flowmeters
temp and altitude (higher altitude, increased flow)
oxygen ratio and proportioning devices
links 2 flows to prevent a final inspired O2 conc of less than 25%. 14teeth in gear for nitrous and 29 for O2
gases that ratio and proportioning devices work on
ONLY O2 and N2O
rebreathing effect on patient depends on
FGF and mechanical dead space
relationship between flow and rebreathing
inverse
system with no valves, tubing or reservoir bag, patient has access to atm gases
open
system with resevoir but no rebreathing, mapleson circuit or circle at high gas flow
semi-open
system with resevoir bag and allows for partial rebreathing
semi-closed
system with resevoir bag and allows for complete rebreathing, CO2 absorbed
closed
noncircle systems
insufflation, open-drop, draw-over, unidirectional, mapleson
