In 1993, the U.S. FDA developed the latest guidelines for anesthesia machine checkout.
Before starting case, ensure familiarity w/ all equipment.
Perform a complete anesthesia apparatus checkout at the beginning of each day.
Perform an abbreviated checkout before each subsequent use that day.
Summary of FDA recommendations
» Conduct checkout before administration of anesthesia.
» Anesthesia system should conform to current & relevant standards, including ascending bellows ventilator, capnograph, pulse oximeter, oxygen analyzer, respiratory volume monitor (spirometer), & breathing system pressure monitor w/ high- & low-pressure alarms.
» Modify guidelines to accommodate current equipment design & variations in local clinical practice. Local modifications should have appropriate peer review.
» Refer to the operator's manual for the manufacturer's specific procedures & precautions, especially the low-pressure leak test (step #5).
» If anesthesia provider uses same machine in successive cases on the same day, steps marked with an asterisk (*) may be abbreviated or skipped after initial checkout.
Emergency Ventilation Equipment
» *1. Verify backup ventilation equipment is available & functioning.
» *2. Check oxygen cylinder supply.
Open O2 cylinder & verify at least half full (about 1,000 psi).
» *3. Check central pipeline supplies.
Check that hoses are connected & pipeline gauges read about 50 psi.
» *4. Check initial status of low-pressure system.
Close flow control valves & turn vaporizers off.
Check fill level & tighten vaporizers' filler caps.
» *5. Perform leak check of machine low-pressure system.
Verify that the machine master switch & flow control valves are OFF.
Attach "suction bulb" to common fresh gas outlet.
Squeeze bulb repeatedly until fully collapsed.
Verify bulb stays fully collapsed for at least 10 sec.
Open one vaporizer at a time & repeat previous two steps.
Remove suction bulb & reconnect fresh gas hose.
» *6. Turn on machine master switch & all other necessary electrical equipment.
» *7. Test flowmeters
Adjust flow of all gases through their full range, checking for smooth operation of floats & undamaged flowtubes.
Attempt to create a hypoxic O2/N2O mixture & verify correct changes in flow and/or alarm.
» *8. Adjust and check scavenging system.
Ensure proper connections between the scavenging system & both APL (pop-off) valve & ventilator relief valve.
Adjust waste gas vacuum (if possible).
Fully open APL valve & occlude Y-piece.
With minimum O2 flow, allow scavenger reservoir bag to collapse completely & verify that absorber pressure gauge reads about zero.
With the O2 flush activated, allow the scavenger reservoir bag to distend fully, & then verify that absorber pressure gauge reads <10 cm H2O.
» *9. Calibrate O2 monitor.
Ensure monitor reads 21% in room air.
Verify low O2 alarm is enabled & functioning.
Reinstall sensor in circuit & flush breathing system w/ O2.
Verify that monitor now reads 90%.
» 10. Check initial status of breathing system.
Set selector switch to "Bag" mode.
Check that breathing circuit is complete, undamaged, unobstructed.
Verify that CO2 absorbent is adequate.
Install breathing circuit accessory equipment (eg, humidifier, PEEP valve) to be used during the case.
» 11. Perform leak check of the breathing system.
Set all gas flows to zero (or minimum).
Close APL (pop-off) valve & occlude Y-piece.
Pressurize breathing system to about 30 cm H2O with O2 flush.
Ensure that pressure remains fixed for at least 10 sec.
Open APL (pop-off) valve & ensure that pressure decreases.
Manual and Automatic Ventilation Systems
» 12. Test ventilation systems & unidirectional valves.
Place a second breathing bag on Y-piece.
Set appropriate ventilator parameters for next pt.
Switch to automatic ventilation (ventilator) mode.
Fill bellows & breathing bag with O2 flush & then turn ventilator ON.
Set O2 flow to minimum, other gas flows to zero.
Verify that during inspiration bellows delivers appropriate tidal volume & that during expiration bellows fills completely.
Set fresh gas flow to about 5 L/min.
Verify that the ventilator bellows & simulated lungs fill & empty appropriately w/o sustained pressure at end expiration.
Check for proper action of unidirectional valves.
Exercise breathing circuit accessories to ensure proper function.
Turn ventilator OFF & switch to manual ventilation (Bag/APL) mode.
Ventilate manually & ensure inflation & deflation of artificial lungs & appropriate feel of system resistance & compliance.
Remove second breathing bag from Y-piece.
» 13. Check, calibrate and/or set alarm limits of all monitors: capnometer, pulse oximeter, oxygen analyzer, respiratory volume monitor (spirometer), pressure monitor w/ high & low airway alarms.
» 14. Check final status of machine.
AFL valve open.
Selector switch to "Bag".
All flowmeters to zero.
Pt suction level adequate.
Breathing system ready to use.
Machine malfunction is a significant cause of anesthesia accidents. Catastrophic events can include failure to ventilate, oxygenate, or deliver anesthetics.
It is wise to have a backup source of oxygenation & ventilation readily available at all times (eg, an oxygen cylinder w/ a transport delivery system attached).
The four most important checks are
» Oxygen analyzer calibration
The oxygen analyzer is the only machine safety device that detects a malfunction (breakage & low-pressure leaks) downstream from the flowmeters.
» Low-pressure leak test
This test checks the integrity of the anesthesia machine from the flowmeters to the common gas outlet.
» Circle system test
This test verifies the absence of low-pressure leaks in the system & proper function of the inspiratory & expiratory valves.
» Positive-pressure leak test
This quick test will detect one of the most common causes of machine leaks; that is, when the CO2 absorbent is changed & not reseated properly.
Patricia Roth, MD
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