Anesthesia Machine

Question 1

What are the 3 pressure systems of the anesthesia machine?

Answer 1

High medium low

Question 2

What does FGF refer to? Volatile?

Answer 2

Fresh gas flow: Air, N2O, O2 volatile: anesthetic gases

Question 3

What % FiO2 level is safe at for electrocautery?

Answer 3

30%

Question 4

What organization sets standards for anesthesia machine?

Answer 4

ASTM (American Society for Testing and Materials)

Question 5

How long does the battery back up last for on an anesthesia machine?

Answer 5

30 min.

Question 6

The contemporary components of an anesthesia machine are: (9)

Answer 6

electrical supply, battery back up, alarms, monitors (insp and exp. O2/CO2, O2 supply failure, hypoxic guard system, anesthetic vapor concentration, VS), O2 supply (pipeline, cylinder), flowmeter, O2 flush valve, vaporizers, waste gas system

Question 7

What are components of the high pressure sytem?

Answer 7

auxillary e cylinder, yoke assembly, bourdon gauge, high pressure regulator (drops pressure)

Question 8

Gas cylinders can be made of what materials?

Answer 8

Steel Aluminum - MRI

Question 9

Gas cylinders come in sizes ________. What is most common? What is largest?

Answer 9

A - H, E most common. H largest.

Question 10

What are the colors for: US, international CO2 He Air N2 N2O O2 Vacuum Waste gas

Answer 10

CO2: grey He: brown Air: yellow, black & white N2: black N2O: blue O2: green, white Vacuum: white, yellow Waste gas: purple

Question 11

What does the yoke assembly do? (6)

Answer 11

pin index safety system (PISS) for attaching, orients tanks, makes a tight gas seal, unidirectional flow of gases, filter (dust), check valves (prevents bleeding)

Question 12

Whats the pin index safety system (PISS)?

Answer 12

prevents misconnections of gas tanks to yokes: air: 1, 5 O2: 2, 5 N2O: 3, 5 CO2: 1, 6 Entonox: 7

Question 13

What is the volume and pressure of a full tank of: oxygen air N2O

Answer 13

O2: 660L, 2000 psi air: 625L, 2000 psi N2O: 1590L, 745 psi

Question 14

Describe how a Bourdon gauge works.

Answer 14

Measures pressure in cylinder/pipeline. It is a high pressure gauge. Metal tube inside straightens in proportion to amount of pressure exerted on it. Moves a needle to show pressure reading.

Question 15

Formula for estimating how much gas left in an ecylinder?

Answer 15

Time remaining (hrs) = Pressure (PSIG) / [200 x flow rate (L/min)]

Question 16

How is O2 stored? How is N2O stored? What is the significance?

Answer 16

as a gas. as a liquid. Pressure will read a constant 745 psi until liquid 75% N2O is gone, about 250-400 mL remains. To determine how much is left in tank, weigh tank.

Question 17

Describe two cylinder safety systems. Why are they in place?

Answer 17

Frangible disk - extreme pressure Fusible plug - extreme temperature Prevents tanks from exploding.

Question 18

What does the high pressure regulator on an ecylinder do?

Answer 18

reduces high and varibale pressure of tank to a lower, more constant pressure for the anesthesia machine (prevents damage to it). Lowers the pressure to 40-45 psi.

Question 19

What is the pressure from an ecylinder? Why?

Answer 19

40-45 psi, slightly lower than pipeline so pipeline pressure is preferred to avoid using tank up if the tank is cracked

Question 20

What is the function of the intermediate pressure system and what components are part of it?

Answer 20

receives gases from pressure regulator/pipeline inlet hospital supply (pipeline inlet) O2 flush pneumatic safety/electrical system: O2 supply, O2 failure protection aux O2 flowmeter second stage regulator

Question 21

How is O2 stored for the hospital? What pressure is it delivered at?

Answer 21

as a liquid, -184 C (critical temperature), supplied at 50 psi

Question 22

How is N2O stored?

Answer 22

as a liquid, in H cylinders

Question 23

How does the pipeline supply connect to the anesthesia machine? What features does it have?

Answer 23

diameter index safety system (DISS) - ensures only correct gas connected filter, check valve - unidirectional flow, pressure gauge

Question 24

What is the function of the O2 flush valve?

Answer 24

provides 100% O2 at flow rate 35-75 L/min and bypasses intermediate meters and vaporizers

Question 25

What are some considerations of the O2 flush valve?

Answer 25

barotrauma, awareness - dilution of anesthesia, to prevent accidental activation: recessed and requires you to hold button

Question 26

Describe the electrical power of the anesthesia machine.

Answer 26

Single power cord. 30 min back up battery. When in back up mode no pt monitors. Don’t plug in extra machines or peripherals into anesthesia machine.

Question 27

Describe the pneumatic safety systems of the anesthesia machine.

Answer 27

Prevents hypoxic delivery of gases. O2 influences the flow of all other gases. O2 concentration is maintained at a minimum of room air, 19%. Has an audible alarm that can’t be silenced w/in 5 sec of pressure drop of O2

Question 28

Describe fail-safe devices and their purpose? What are its limits?

Answer 28

designed to prevent hypoxic delivery of gases if O2 supply fails. based on pressure. either shuts proportionally decreases flow of all gases or shuts off flow of non-O2 gases. limits: doesn’t detect the incorrect gas, or hypoxic mixture that results from empty cylinder, wrong proportion of gas dialed in or wrong cylinder

Question 29

Describe the purpose of auxiliary O2 flow meter.

Answer 29

Allows for low flow of O2 w/out using anesthesia circuit (MAC cases) accessible when power off - emergency. uses pipeline/ecylinder can be used for jet vent.

Question 30

Describe the function of the second stage regulator.

Answer 30

downstream from gas supply. supplies constant pressure to flow control and proportioning system. protects from fluctuations in pipeline pressure. lowers pressure to 14-35 psi O2 - 14 psi N2O - 26 psi O2 is last gas flowing

Question 31

What is the last gas flowing in the intermediate system?

Answer 31

O2

Question 32

What does the 2nd stage pressure regulator drop pipeline pressure to in anesthesia machine?

Answer 32

O2 - 14 psi N2O - 26 psi

Question 33

Describe the Low Pressure System and its components.

Answer 33

Between flow control devices and common gas outlet. Pressure is slightly above atmospheric. Pressure is variable. Contains: flow meters, hypoxia prevention devices, unidirectional valves, pressure relief devices, anesthesia vaporizers, pressure relief valve (APL), common gas outlet

Question 34

Describe flowmeters on the anesthesia machine.

Answer 34

Contains: flow tubes, control valves. Regulates flow of gases entering breathing circuit. O2 and N2O flow are linked mechanically to prevent hypoxic mixture.

Question 35

What are some traits of flow tubes?

Answer 35

called variable orifice or Thorpe tube narrow at bottom, widens vertically. calibrated for specific gases. annular space in between float and tube. laminar flow - low flow - viscosity turbulent flow - high flow - density

Question 36

Why is O2 always the most downstream gas? What is special about O2 flow control?

Answer 36

bc leaks in previous machines upstream having O2 be most downstream gas ensures its last in sequence of gases so that adequate O2 delivered even if there is a leak tactile and large dial so provider can tell its O2 w/out taking eyes off pt

Question 37

What are the hypoxia prevention devices of the anesthesia machine?

Answer 37

proportioning system: O2 % doesn’t fall below 21% machine automatically prevents hypoxic mixture of N2O. at less than 19% O2audible alarm after 5 sec. Based on CONCENTRATION.

Question 38

Describe the function of APL valve/pressure relief valve.

Answer 38

downstream of vaporizers. prevents back pressure relieves pressure if it exceeds 35 kPa (if greater can damage flowmeters/vaporizers)

Question 39

What are some features of vaporizer manifold?

Answer 39

controlled/dialed in amount of volatile delivered to pt as a percentage of saturated vapor added to FGF. only one volatile can be on at a time. as one goes on, the other is shut off - called interlock system

Question 40

What does the common gas outlet do?

Answer 40

where anesthesia machine ends. receives all gases and vapors from machine and delivers it to the breathing circuit. 22 mm male 15 mm female connectors - to prevent misconnections

Question 41

What is the safety feature of the vaporizers preventing more than one volatile being on at a time?

Answer 41

interlock system

Question 42

What are 5 pathways of O2?

Answer 42

flow to FGF powers O2 flush valve activates fail safe valve activates O2 supply low pressure alarm compresses bellows of vent

Question 43

What two checks must be done to the machine? And how often?

Answer 43

Machine check - QD Circuit check - Qpt

Question 44

What emergency equipment are needed when doing machine check?

Answer 44

ambu bag w/ mask, back up O2 cylinder at > 500-1000psi, suction w/ yankauer

Question 45

Machine check steps?

Answer 45

Emergency Equipment - ambu, back o2 cylinder at > 500psi, suction w/ yank. High pressure system check - crack e cylinder, check psi, close it, press O2 flush, DC pipeline from wall low pressure system check - check vaporizers, bulb to common gas outlet see if stays deflated for 10 sec, turn on master switch and hear O2 DC alarm, reconnect pipeline, ensure pipeline at 50 psi, test flowmeters, try to make hypoxic mixture O2 sensor - calibrate it: 21% at RA, verify low O2 alarm (set at 30%), re install and flush w/ O2 make sure reads >90%, install breathing circuit scavenging system - proper connections, adjust waste gas vacuum, fully open APL, occlude y piece ensure < 10 cmH2O (neg pressure), still occluded press O2 flush to distend reservoir bag w/ pressure < 10 ventilator - 2nd breathing bag on y piece, set appro. vent settings for next pt, set O2 5L, turn vent on and ensure bellows deliver Tv, check unidirectional valves, squeeze bag check for alarm, set manual vent mode, ensure manual vent, turn off vent and remove bag breathing system check - set gas flow to 0, close APL and occlude Ypiece, pressurize to 30 cmH2O, ensure remains for at least 10 sec, fully open APL and allow bag to deflate monitors - set and audible for next pt final check - vaporizers off, APL open, select switch to bag, flowmeters to 0, suction avail., monitors set appro., circuit on, CO2 sampling connected, correct mask “Every High Person Loves Oxygen So Vehemently Because Mother Fuckers”