the anesthesia machine

4 basic functions of anesthesia machine

• deliver O2 to pt

• deliver anesthetic gas to pt

• assistance with ventilation

• removal of exhaled CO2

color of O2 cannisters in the US

green

E tank psi and liters

• psi: 2000-2200

• liters: 600-660 L O2

H tank Liters

~ 7000 L O2

recommended to change E tank when pressure is?

< 500 psi

steps to switch out an E tank

1. make sure no O2 is in the system before unscrewing

2. toe underneath the tank

3. unscrew tank from yolk

4. drop tank out of machine

5. grab new tank

6. attach new tank to yolk

7. screw it back to machine

pressure regulator

• reduces psi down to 50psi

• safer pressure for flow of O2 through the machine

oxygen flow meter

• delivers calculated O2 flow in L/min

• should never be less than 500 mls O2/ min

precision vaporizer

precisely control % inhalant anesthetic delivered to pt

unidirectional flutter valves purpose

• to create 1 way flow of gas on a RB anesthetic circuit

  • prevents re breathing of exhaled gas which contains CO2

passive scavenge

uses pressure within anesthesia machine to collect waste anesthetic gas

passive scavenge exhausted after

• 12 hours of use or

• weight gain of 50g

active scavenge

uses suction to draw WAG into scavenge (needs to be turned on)

pressure relief valve/pop off valve

• is open most of the time, when open it:

  • vents excess gas to scavenge

  • prevents pressure buildup in anesthesia circuit and patient

dangers of a closed pop off valve

• pressure build up in system and pt’s airways

  • pressure buildup can cause barotrauma (pneumothorax)

  • can lead to death

pop off occlusion valve

• prevents pop off from being left in the closed position

• push button to close/ventilate pt

CO2 absorber

• only used with rebreathing system

• any gas not exiting scavenge is directed to the CO2 absorber before returning to pt

• gases can then be rebreathed minus the CO2

CO2 absorbing granules

• exhausted after 6-8 hours of use

• granules change from white to periwinkle, become hard and brittle

pressure manometer

measures the pressure of gasses within patient breathing system, and therefore in patients airways and lungs

pressure manometer unit of measure

cmH2O

pressure manometer, when ventilation patients

• measures ventilatory pressure, indicates approx. pressure being exerted on lungs

• not to exceed 15-20 cmH2O

negative pressure relief valve

• on inspiratory side of anesthesia machine

• safety feature, sense change in pressure and allows room air to enter the circuit if oxygen is discontinued

O2 flush valve

• bypasses flow meter and vaporizer

  • delivers 100% O2 to res bag

steps to set up a rebreathing system

1. attach y tubing to inspiratory and expiratory ports

2. attach res bag to res bag port

3. attach scavenge tubing to scavenge port

4. check pop off valve is open!

advantage of F tubing (over Y tubing)

• tube within a tube- exhaled breath keeps incoming warmer

• only 1 tube attached to ET tube (easier for dentals,etc)

parts of a non-rebreathing system

1. fresh gas hose

2. scavenge tubing

3. res bag

4. pop off valve

steps to set up a 3 step NRB

1. fresh gas hose to outlet port of precision vaporizer

2. hook up scavenge tube directly to scavenge system

3. pop off in OPEN position

set up of a 2 step NRB

1. fresh gas hose to outlet port of precision vaporizer

2. hook up scavenge tube directly to scavenge system

NRB advantages/ reasons to use