Lecture 6 9/5/24

Question 1

What are the general functions of an anesthesia machine?

Answer 1

-deliver anesthetic gas with precision
-provide O2
-support ventilation
-evacuate anesthetic gases safely and properly

Question 2

What are the characteristics of an ideal anesthesia machine?

Answer 2

-offers minimal resp. resistance to breathing
-maintains resp. airway pressure close to 0
-contains minimal dead space
-eliminates CO2 and prevents its re-inspiration
-has a high compliance

Question 3

What are the basic components of the anesthesia machine?

Answer 3

-gas supply
-pressure gauges
-pressure regulators/reducing valve
-safety systems
-flowmeter
-O2 flush valve
-vaporizers
-common gas outlets

Question 4

What are the potential forms of oxygen supply?

Answer 4

-liquid oxygen
-O2 concentrator
-O2 cylinders

Question 5

What are the characteristics of an oxygen concentrator?

Answer 5

-extracts oxygen from air we breathe
-air passes through filters that extract O2
-allows a concentration of approximately 95% O2

Question 6

What are the characteristics of an H cylinder?

Answer 6

-used as main oxygen source
-brass valve with specific outlet to attach to pipeline/hose

Question 7

What are the characteristics of an E cylinder?

Answer 7

-reserve/mobile source
-valve body attaches directly to anesthesia machine at the hanger yokes

Question 8

Why is it important that the pressure of the O2 gas can is proportional to the gas left in the tank?

Answer 8

it allows for the remaining gas to calculated based on the pressure reading

Question 9

What are the colors associated with the different gases?

Answer 9

oxygen: green
nitrous oxide: blue
medical air: yellow

Question 10

How is pressurized gas safely manipulated?

Answer 10

-transported in carts
-stored in dry, separate, well-ventilated rooms
-E tanks stored horizontal in storage cart
-H tanks chained to wall
-valve protected from dust, oil, inflammable substances, and falls
-close flowmeter prior to opening tank
-close tank when not in use
-open slowly

Question 11

What are the characteristics of pressure gauges?

Answer 11

-measure pressure in the pipeline/cylinders in PSI
-color coded, labelled, and calibrated for each gas
-pressure measurement is proportional to tank content for O2

Question 12

When should a new tank be switched to?

Answer 12

when the pressure reading is 500 PSI or less

Question 13

What is the pressure in the high pressure system component of the anesthesia machine?

Answer 13

1900-2200 PSI

Question 14

What is the pressure in the intermediate pressure system component of the anesthesia machine?

Answer 14

50-60 PSI

Question 15

What is the pressure in the low pressure system component of the anesthesia machine?

Answer 15

12-16 PSI

Question 16

What is the main component of the high pressure system?

Answer 16

O2 cylinder supply

Question 17

What is the main component of the intermediate pressure system?

Answer 17

oxygen flush valve

Question 18

What are the main components of the low pressure system?

Answer 18

-flowmeters
-calibrated vaporizers
-machine outlet/common gas outlet

Question 19

What is the function of the regulator/pressure-reducing valve?

Answer 19

-reduces the high/variable storage pressure to a lower/more constant pressure appropriate for the machine
-maintains a constant pressure of 50-60 psi to ensure constant flow to flowmeter even when the cylinder gas content is depleted
-avoids rupture of hoses and barotrauma to patient

Question 20

What happens if the regulator fails?

Answer 20

downstream pressure relief valves open at a pressure of 80-100 psi to allow gas escape

Question 21

What are the safety systems on the different cylinders?

Answer 21

E tank: PIN index safety system
H tank/pipelines: diameter index safety system

Question 22

What is the function of the tank safety system?

Answer 22

prevent accidental connection of another gas to the oxygen port and vice versa

Question 23

What are the characteristics of the PIN safety system?

Answer 23

-holes with specific configuration on the cylinder valve
-matching pins protruding from anesthesia machine hanger-yoke
-configuration specific for each medical gas to prevent fitting of the wrong cylinder

Question 24

What are the characteristics of the diameter safety system?

Answer 24

-flexible hoses that are labeled and color coded terminate in color coded, self-sealing sockets
-unique, non-interchangeable threaded fittings match each gas-specific coded connector

Question 25

What are the characteristics of the flowmeter?

Answer 25

-transparent glass/plastic tubes containing lightweight ball/bobbin that floats when the gas is on
-individually calibrated for each gas
-graduations vary between adult and pediatric flowmeters

Question 26

What is the purpose of the flowmeter?

Answer 26

controls flow rate at which a specific gas passes through it

Question 27

What is the purpose of the needle valve?

Answer 27

-controls the gas flow through the flowmeter
-final stage of pressure reduction

Question 28

How does gas flow reading differ between a ball and a bobbin?

Answer 28

ball: read at center
bobbin: read at top

Question 29

What are the issues associated with flowmeters?

Answer 29

-must be vertical
-affected by dirt, static electricity, magnetic field, humidity, and mechanical impact

Question 30

What is the vaporizer?

Answer 30

device that converts liquid to vapor

Question 31

What are the characteristics of the vaporizer?

Answer 31

-anesthetic gas quantity is expressed in % related to total quantity of gas passing through
-color coded specific to each anesthetic gas
-must be calibrated to be precise
-area of high resistance to breathing

Question 32

Why does anesthetic gas delivery remain stable over a wide range of temperatures and flowrates?

Answer 32

the vaporizer compensates for changes in external temperature and oxygen flow

Question 33

What is a variable bypass vaporizer?

Answer 33

vaporizer with two chambers that allows for O2 to follow two different paths; bypass chamber carries only O2 to patient, while vaporization chamber carries O2 mixed with anesthetic to patient

Question 34

How does oxygen move through the bypass vaporizer based on desired anesthetic depth?

Answer 34

reduced depth: less O2 goes through vaporization chamber, more O2 goes through bypass chamber
increased depth: more O2 goes through vaporization chamber, less O2 goes through bypass chamber

Question 35

What are the consequences of tilting the vaporizer?

Answer 35

-liquid anesthetic enters bypass chamber
-quantity of anesthetic delivered to patient increases

Question 36

What is the solution to a tilted vaporizer?

Answer 36

-maintain high flow rate for 20 minutes
-monitor inspired gas concentration
-possibly perform maintenance

Question 37

How does anesthetic potency affect inhalant concentration reaching the patient?

Answer 37

the more potent the anesthetic, the higher the concentration and efficacy

Question 38

What is the solution to putting the wrong anesthetic in the vaporizer?

Answer 38

-empty the vaporizer and use a high flow rate for 45 minutes with a low gas setting on the dial
-wait two hours before adding correct gas
-possibly perform maintenance

Question 39

What are the characteristics of the O2 flush valve?

Answer 39

-direct communication between high pressure circuit and low pressure circuit
-supplies O2 to the breathing circuit without anesthetic gas
-should not be activated while patient is connected to circuit
-correct set up involves flush valve bypassing vaporizer

Question 40

What are the functions of the O2 flush valve?

Answer 40

-flush anesthetic gas out of breathing circuit
-pressurize circuit to perform leak test

Question 41

What are the characteristics of the common gas outlet?

Answer 41

-attaches to breathing system
-last step for the gas in the anesthesia machine before entering breathing circuit