Anesthesia Information
▪Anesthesia Gas Machine Check
Verify that backup equipment is available and functioning.
Ambu bag (with mask)
Check flashlight (working?)
Suction on and ready
Portable oxygen tank available and > 1000 psi
Canister absorbent regenerated and locked down
Elastic gum bougie available
LMAs available
Perform leak test of low pressure system:
Machine and all flowmeters off. Attach suction bulb to common gas outlet; squeeze bulb until fully collapsed and hold end of bulb to maintain suction (bulb should remain collapsed for 10 sec).Open each vaporizer one at a time, squeeze bulb until collapsed, and wait 10 sec. (This check creates a vacuum and if there is a leak the bulb fills quickly.)
Turn AGM on:
Pipeline oxygen pressure should read 45-55 psi; unplug at source.
Make sure O2 cylinder > 1000 psi.
Vaporizers in correct placement—D-E-S-I-H—based on vapor pressure and potency.
Check fill level of volatile agents.
Check scavenging system. Proper connections from APL and ventilator?
Test flowmeters—Attempt to create hypoxic mixture with N2O and O2.
Uninstall O2 sensor, calibrate O2 analyzer to 21% (room air).
Reinstall monitor and flush system with O2; monitor should read ≥ 90 (%).
Negative relief valve check—scavenging system:
Open pop-off fully. Olude Y-piece.
With no O2 flow, allow scavenger bag to collapse—ensure the pressure gauge is 0.
If there is a negative number on the gauge, there is too much suction.
Positive relief valve check—scavenging system:
Activate flush valve to fill scavenger bag and verify that the circle gauge reads ≤ 10 cm H2O.
Perform a leak check of the breathing system:
Set flows to zero. Close pop-off and occlude Y-piece; pressurize to 30 cm using the flush valve. Ensure pressure remains fixed for 10 sec.
To test bellows and unidirectional valves:
Place a breathing bag at Y-piece; select appropriate vent settings for patient. With all flowmeters off, turn vent on and fill bellows using O2 flush; check for proper action of valves.While bellows are filling, compress the bag quickly to check high pressure alarms. Remove breathing bag and wait for “apnea” alarm after several vent breaths.
Final position of AGM:
Vaporizers off
All flowmeters set at zero or minimum
APL (pop-off) open
Patient suction adequate
Selector switch to “bag.”
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Pipeline pressure readings: 45-55 psi.
O2 flush—(bypasses flowmeters) flushes 25-75 L/m directly into circuit from pipeline or cylinder.
APL: When the pop-off knob is fully open, it only takes 1 cm H2O pressure expired from patient to lift open the valve and allow exhaled gases to go to scavenger. When the APL is fully closed, the valve will not open until pressures of ≥ 60 cm H2O are reached.
Barometric Changes with Vaporizor
Higher altitudes deliver slightly less agent than what is set.
Hyperbaric chambers deliver slightly more than what is set.
High pressure system: Receives gases from cylinders to primary pressure regulator.
Intermediate system: Receives gases from regulators or pipelines, delivers to flow meter or flush valve.
Low pressure system: Takes gases from flowmeters to common gas outlet.
▪AGM and Tanks
CO2 Canisters
CO2 Absorption
Chemical reaction: Base (hydroxides) neutralizing an acid (carbonic acid).
Acid + base → salt + H2O + heat.
Exposed to critical pH of 10.3, ethyl violet: white → blue/purple.
Granules
Size and shape: 4-8 mesh, spherical, uneven to increase surface area and increase exposure of gas. Void space: -40% to 60% air space.
Sodasorb®
Sodium hydroxide 4% is the most active component.
Calcium hydroxide ˜95%
Potassium hydroxide 1%
100 grams of soda lime will absorb 26 L of CO2
Baralyme®
Barium hydroxide 20% is the most active component.
Calcium hydroxide 80%
Sevoflurane
Carbon Monoxide
Can accumulate if the system has been unused for at least 24 hours.
Occurs: Iso > Enf” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed5941985ba69da7b22d21874486293aed094c4c2b498cc101c038905a98b47fe12526590bc69f55fe8cc8e}/ID(AB1-M53)”>Des > Iso > Enf, with Baralyme instead of soda lime, higher absorbent temps, dry absorbent, or long case.
▪Capnography
Capnography is read by infrared light absorption. While there may be some CO2 in the stomach from swallowed expired air, this should be washed out in a few breaths.
Gradient b/w end-tidal and PaCO2 reflects alveolar dead space (2-5 mm Hg).
Figures 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9 and 1-10 compare different sine waves to a diagnosis.
 A Inspiration ends A-B Dead space B Expiration begins B-C Ascending slope C-D Plateau (must have) alveolar equilibrium D ETCO2 # D-A Inspiration I Steady state—inhalation ends, exhalation begins II Exhalation begins III Alveolar equilibrium IV Inspiration * ETCO2 number |
 Trace above zero Rebreathing Exhausted CO2 absorbent |
 Slanted upstroke Prolonged expiratory time Common finding with bronchospasm, wheezing, and COPD May fuse with the plateau phase |
 Anything that causes CO2 to rise Gradual Hypoventilation Excessive CO2 production—malignant hyperthermia, fever Absorption of CO2 from body cavity Sudden Tourniquet release Bicarbonate administration Re-perfusion during vascular grafting |
 Anything that causes CO2 to fall Sudden (close to zero) IMMINENT DISASTER Complete ETT disconnection ETT obstruction/kinked tube (can decrease slowly) Ventilator malfunction Esophageal intubation Pulmonary embolism: blood clot, air embolus, fat embolus, low perfusion states Capnograph malfunction (consider last) |
 USUALLY A CATASTROPHIC CV EVENT Exponential decrease in wave size (over 2-3 min) • Severe hypotension • Cardiac arrest • Sudden increase in dead space • Pulmonary embolism |
 Sudden (low value—not zero)
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