machine
basic components
gas supply
pressure gauges
pressure reducing valves
flowmeters
vaporizers
common gas outlet
breathing system
ventilator
three levels of pressure… gas supply
cylinders
incompatible with MR why?
dangerous why?
storage
covered, temp controlled, dry/clean/ventilated
full and empty separately
strict rotation
F and larger vertical, concrete bottom
E and smaller horizontal
no smoking, uncovered bulbs
emergency services notification of location/type
oxygen concentrator
separate room O2 from air
chemical method
generally, in Army, low pressure
can run one anesthetic machine ONLY
O2 distribution systems color coded
green = oxygen
nitrous oxide = blue
medical air = black and white
vaporizers
vaporizers
performance depends on many factors
saturated vapor pressure of agent
splitting ratio of agent
through chamber / bypasses chamber
Two types of vaporizer
positive pressure, gas is proximal to vaporizer, high resistance to flow
negative pressure generated by , in-circuit, low resistance to flow
splitting ratio concept flow enters vaporizer inlet… concentration control valve (the dial with numbers on it) regulates amount of flow through bypass and vaporizing chambers = control of amount of agent delivered to patient
circuits with CO2 absorption circle advantages: small deadspace
CO2 removal is efficient
as all gas must pass through absorbent
reduced hyperthermia
risk
heat generated by CO2 is
dissipated by tubes
to-and-fro disadvantages: heavy, bulky weight on
tube
inadequate and
unpredictable absorption of CO2
if used in pt >10kg, sig
portion of alveolar gas may never reach ansorbent rebreathing / circle circuit / y circuit components
absorbent container
closed reservoir bag
pressure relief valve
to prevent/reduce rebreathing
unidirectional valves between pt and reservoir bag
fresh gas flow cannot enter b/w expiratory valve
and PT
adjustable pressure limiting valve
not located b/w PT and inspiratory valve
rebreathing/circle circuit systems without CO2 absorption bain
T-piece
no unidirectional valves
clearance of CO2 is via adequate fresh gas flow
at least 2 x’s minute volume
inspired gas is cold and dry = contributes
to HYPOTHERMIA in small patients
high fresh gas flow = increased cost
don’t alter fresh gas (ie: O2) flow rate unless…
capnography can increase efficiency by
allowing reduction of flow rate until rebreathing is noted….TBC….
bain circuit for <10 kg bain vs ayre’s T-piece
breathing circuit tubing clean regularly
weekly is ideal
disassemble
hot, soapy water
disinfectant
hang dry
scavenging systems
active
passive
absorbent
weigh container daily as there is no color indicator
place BELOW pressure relief valve
no absorbent
suboptimal
subject to atmospheric and weather conditions dead space
anatomic the patient
mechanical space in circuit where
inhalation and exhalation gases share a common path
ET tube extending out of trachea
elbow on circuit
connectors b/w tube and circuit ie: CO2
Y piece at end of a Y circuit
dead space…cont. y circuit
bains
CAPNOMETRY
direct monitor of the inhaled and exhaled
concentration (partial pressure of CO 2)
indirect monitor of the CO2 partial pressure in
the arterial blood
relies on absorption of infrared light by CO2
presented as a graph of expiratory CO 2 plotted
against time
measured in millimeters of mercury, "mmHg”
