Anesthesia delivery systems Flashcards
Open system
No reservoir bag, valves or rebreathing of exhaled gas
2 types:
*insufflation/blow by: NC, blow-by tent
*Open drop: Schimmelbush mask
Insufflation/blow by
NC, simple
disadvantages: *no ability to assist vent
* no control of anechoic depth/FiO2 *environmental pollution
Open drop
Schimmelbush mask–ether mask (cloth saturated with ether)
simple, low cost, portable
Disadvant: poor control of anesthesia, accumulation of CO2, hypoxia risk, can control vent, and OR pollution
Semi-open system 5 components
- Facemask or ETT
- Spring loaded pop off valve (APL)
- Reservoir inlet (tubing)
- Fresh gas inlet
- Reservoir bag
Semi-open group 1
Mapleson A
APL located near face mask
FGF located at opposite end
*most efficient during Spont breathing, only requires 1 x the MV to prevent rebreathing of CO2
*least efficient during controlled vent and can requires FGF 20L/min to prevent rebreathing
Semi-open group 2
Mapleson B C
APL and FGF near face mask
*spont least efficient
*controlled middle efficient
Semi-open group 3
Mapleson D, E, F FGF located near face mask APL at opposite end *opposite of A *spont middle efficient require 2.5xMV of FGF *controlled most efficient
CO2 rebreathing will depend on
1 *FGF 2 *MV 3 *type of vent 4. VT 5. RR 6. I:E 7. duration of expiratory pause 8. peak inspiratory flow rate *in notes others in book
Anesthesia bag vs ambu
anesthesia-can tell resistance compliance and can see expiration
ambu: self inflating can’t tell in exhaling
modified mapleson A..has non-rebreating valve—so only get fresh gas
*can still ventilate if loose gas source because of self refilling
Mapleson D
FGF located near face mask APL at opposite end
- spont middle efficient require FGF2-3xMV
- controlled most efficient FGF1-2xMV
Mapleson E
modification of T piece
No reservoir bag or Pop off valve
spont FGF 2-3xMV
Mapleson F
Jackson-Rees
modification of E with adjustable pop-off valve at end of reservoir bag
popular in peds
Bain circuit
Modification of D FGF is the corrugated tube allows for fresh gas to warm up preserves heat and humidity can bee use for controlled(1-2mv) or spent vent(2-3MV)
Mapleson advantages
*simple *light weight *can provided + press vent *low resistance *portable
if using inhaled anesthetics—more predictable and less room pollution
Mapleson disadvantages
requires FGF calculations: varies for type and mode
control of anesthetic depth is variable–diluted as FGF goes up
if FGF is not maintained possibility of CO2 buildup and rebreathing
minimal rebreathing of other gases
poor conservation of heat and humidity
circle system 7 components
- FGF source
- insp and expi unidirection valves
- insp and expi limbs and corrugated tubing
- Y-piece connector
- Adjustable pressure–APL valve, pop off valve
- Reservoir bag
- CO2 absorber
Circle system
can be used as:
semi-open– with increased FGF
semi-closed–some rebreathing, need CO2 absorber)
closed–rebreathing all, need CO2 absorber, only providing enough O2 for pts needs
*all this depends on APL valve
Unidirectional valves
gas flowing into valve raises disc form its seat and passes through
reversing gas causes disc to contact its seat, stop flow
the guide prevents lateral/vertical displacement of disc
Transparent dome allows for observation of disc—can unscrew and clean if gets sticky
Reservoir bag
neck 22mm
accummulates exhaled gas
visual/tactile to observe spont respiration
APL valve
pressure relief
when pressure gets to where ever APL is set excess pressure (gas) goes to scavenge
*closing valve increased pressure in system
*provides control of pressure in system
*spont- valve open, close some if reservoir bag collapses
*assisted vent (not ventilator mode)- valve partially open–careful and frequent adjustments necessary
*mech vent-valve closed
O2 flush
gas flow through the absorber
circle arrangement rules
- unidirectional valves must be located btwn pt and reservoir bag, on both insp and expo limbs
- FGF cannot enter system btwn expiratory valve and pt
- APL valve cannot be located btwn pt and inspiratory valve
Semi Open circle
not used much, occasionally for sedation–mask placed over face to increase FiO2, ex preO2
- no rebreathing occurs
- high FGF for eliminate rebreathing
- no conservation of wasted gas, APL open all the way
Semi-closed circle
Most commonly used*requires low FGF
- conserves some heat and gases
- some rebreathing except CO2
- APL is partially closed and adjusted as needed
Closed circle
3rd world countries
- FGF exactly matches metabolic needs–O2 flow = 200ml/min
- total re-breathing of gases after absorption of CO2
- APL is closed
- *O2 consumption: VO2= 10xkg^3/4
Circle system advantages
- stability of inspired gas
- conservation of heat and moisture
- prevention of OR pollution
- can be used with fairly low flows and no rebreathing of CO2
- can scavenge waste gases
Circle system disadvantages
complex design has at least 10 connections potential of malfunctioning valves increased resistance to breathing less portable than mapleson
Circle system check
leak test–btwn every case
set flow to zero, occlude Y piece, close APL, pressurize circuit to 30cmH20 using O2 flush, ensure pressure hold for 10 sec, listen of sustained press alarm, open APL to ensure pressure decreased
Flow test
attach breathing bag to Y piece, turn on vent, assess integrity of unidirectional valves
