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Principles of Anesthesia 1 > Terms for anesthesia machine > Flashcards

Terms for anesthesia machine Flashcards

1
Q

High/Low Pressure Gas sources

A

High Pressure gas source= Cylinders
Low Pressure gas source=Pipeline inlet

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2
Q

Cylinders use what safety system?

A

PISS-Pin Index Safety System

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3
Q

Connectors to anesthesia machine use what safety system?

A

DISS-Diameter Index Safety System

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4
Q

How many Liters and Pressure in a full Cylinder of O2?

A

1900-2000 psig and 660 L

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5
Q

How many Liters and Pressure in a full Cylinder of N20?

A

745 psig and 1590 L

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6
Q

True or False: A steady decline in pressure will show a steady decline in weight as gas is discharged.

A

True

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7
Q

Colors of O2, N2O, Air, CO2, He, N2?

A

O2=Green CO2= Gray
N20=Blue He=Brown
Air= Yellow N2=Black

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8
Q

True or False= Is the color of the cylinder the most reliable indicator in a cylinders content?

A

False: Cylinder colors can vary in shades, have two colors (confusing),
The most reliable way to determine a cylinders content is a cylinders Label.

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9
Q

Safety feature of an O2 cylinder with High Pressure requires what?

A

A Pressure Regulator is needed for High Gas Pressure coming out of a cylinder

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10
Q

Name 6 Potential Pitfalls of High Gas pressure systems

A
  1. Incorrect Cylinder installed
  2. Incorrect Cylinder Contents
  3. Incorrect Cylinder Label
  4. Fires
  5. Projectile Damage
  6. Inoperable/damaged Valve
  7. Asphyxia
  8. Contaminated Cylinder Contents
  9. Overfilled Cylinder
  10. Thermal Injury
  11. Incorrect Cylinder valve
  12. Incorrect Cylinder Color
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11
Q

What is a 4 major safety features for a Low gas pressure system?

A

A pipeline system (low gas pressure) 4 safety features are:
1. Shut off valve
2. Alarms for pipeline failure or decreased pressure
3. Knowing where all Pressure gauges are in each hospital and reading them
4. Making sure DISS connections (or Quick connectors) are correct on anesthesia machine

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12
Q

6 Hazards of a Low Pressure system

A
  1. Inadequate Pipeline Pressure
  2. Leaks
  3. Excessive Pressure
  4. Alarm problems
  5. Gas Cross Connection
  6. Gas Contamination
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13
Q

Battery Life in the event lose electrical power to anesthesia machine?

A

30 minutes

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14
Q

Pneumatic Anesthesia machine has divided into 3 parts?

A

High Pressure system
Intermediate and Low pressure system

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15
Q

MOA/function of a High Pressure system?

A

The main function of a High Gas pressure system in the anesthetic delivery system: is to take the gas from a cylinder and reduce the pressures to a lower more suitable constant flow.

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16
Q

Explain Check Valve?

A

Allows gas from a cylinder to enter the machine but prevents gas from exiting the machine; also prevents gas from higher pressure being transferred to another cylinder with lower pressure (transfilling)
Check valve is unidirectional

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17
Q

Regulators MOA/Function? Measure in ?

A

Regulators Function to reduce the high pressure to a lower constant pressure and measures in psi or kPA.

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18
Q

What is the psi from an O2 cylinder at 2200 psig after it goes through the first regulator?

A

The first regulator reduces the O2 pressure of 2200 psig to 50 psi

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19
Q

What are the hazards that can happen with a first pressure or any regulator?

A

Failure of a first regulator will allow a high gas pressure to enter the anesthesia machine, thus if O2 had failure of a regulator then significan t loss of O2 pressure would result in sudden failure of oxygen delivery.

If there were any leaks or ruptures in the cylinder , can hear loud hissing sound of the leak.

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20
Q

What is the most serious mishap that occurs with cylinders and pipelines? What must occur to prevent this?

A

When both cylinders (especially O2) are open and remain open during anesthesia, plus the pipeline, there will depletion of the cylinder supply;
Once the cylinder is depleted, an alarm will alert the provider and NO O2 would be delivered to the patient;
To prevent this occurring, close all cylinders to off after primary check of adequate pressure in tanks.

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21
Q

What is the Oxygen pressure Failure Safety Device?

A

also called the ‘fail-safe’ and is defined as a device that turns OFF when the supply of gases shuts off or proportionally decreases and ultimately interrupts the supply of the other gases if the oxygen supply pressure decreases. Also an audible alarm will sound

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22
Q

Oxygen failure safety valve

A

Works on oxygen pressure to activate or deactivate the flow of gases utilizing a plunger to release or close the valve.

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23
Q

How many psi would the O2 supply failure alarm start to alarm?

A

when O2 falls within 5 secs below 30 psi

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24
Q

If we didn’t have the O2 fail safe, what would happen to the patient?

A

Without the O2 fail safe feature, the patient would continue to receive N20, considered a hypoxic mixture and can lead to death. It only senses O2 pressure in the supply line not other gases; (ex. N20 could be connected to O2 and readings would not be picked up or alarmed because N20 would be present not O2)

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25
Q

What do second stage regulators do? Where are they located in the pneumatic anesthesia machine?

A

Second stage regulators will continue the process of reducing gas pressures of O2 and N20 (respectively, 14 psi and 26 psi ) causing a more constant flow to flowmeters;
Second stage regulators can be found in the intermediate area of the machine, (not all have it).

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26
Q

O2+ is what?

A

Oxygen Flush or oxygen bypass directs O2 at 35 to 75 L/min to the CGO; unmetered , bypasses regulators

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27
Q

Pitfalls about the O2+?

A

Can be negative or positive pressure affect the Vaporizers (diluting the gas, making the patient light or have recall), can cause barotrauma upon inspiratory phase of patient breathing, obstruct the flowmeters,

28
Q

Flowmeters are found in what area of the pneumatic anesthesia machine?

A

Flowmeter found in the Low Pressure system of the anesthesia machine;

29
Q

Function/MOA of flowmeters? Mechanical and Electronic Flowmeters

A

Flowmeter assembly empties into a common manifold that delivers the measured amount of gases into the low pressure system.

Used to measure FGF, can be mechanical or electronic.

Mechanical Flowmeters deliver low or high flows of gases to a manifold, has a flow control needle knob to open the flow control valve to allow gases into the flowmeter;

Electronic Flowmeters have a valve control called a solenoid to allow for FGF to the flowmeter (variable position solenoid);

30
Q

What are the safety features and pitfalls to mechanical flowmeters?

A

Safety: Must be clear, permanently marked with appropriate color of gas, unit of measure, and name or chemical symbol of gas it measures (ex. O2 always green, bigger fluted knob and right side of anesthesia machine vs N20 always blue, smaller knurled dials)

PISS for safety

Pitfalls: NOT INTERCHANGEABLE; Each flowmeter is calibrated for the specific gas based on a standard manufacturer master flowmeter for each gas at 760 mmHg at 20 degrees C. Creates inaccuracy

Prevention of hypoxic mixture, O2 must always be placed on the right side of the flowmeter groups

A leak in flow meter can deliver lower than expected concentration of the gas to the FGF

Electronic flow meters depend on electricity, thus have mechanical flowmeters available

Operator error of delivery of mix (O2 and N2O) with O2 below 21%–Minimum Oxygen ratio device used–If O2 drops below 25%, then the device will lower the N2O to maintain O2 gas at least 25%;

31
Q

What are the 2 types of flowmeters tubes used? What are the main differences between the two?

A

Single taper-opening is gradual in diameter from bottom to top, measures 1L used ; used for different tubes for low and high flows

Dual Taper- opening increases in diameter above the 1L and have 2 different tapers on the inside of the same tube (a lower tape more gradual and fine flows and the higher flow with a lesser gradual tube); used for when only one tube is used for gas

32
Q

Describe a “Float” and best practice to measure? in what units?

A

A indicator uses a float (ball, rotameter, or bobbin) within the flow meter and free flowing in the tube. The ball is superior to the bobbin-less sticking to tube

Accurate measurements are read vertically at the highest and widest diameter of the indicator; it is measured in L/min or ml or decimal fraction in L/min with a zero in front of the decimal point.

33
Q

The flow rate through the tube depends on 3 factors:

A
  1. The pressure drop across the constriction
  2. The size of the annular opening
  3. The physical properties of the gas
34
Q

Flowmeter sequence for normal gas flow

A

From bottom to top then left to right with O2 closest to manifold

35
Q

Name Two gas properties impact the Flow measurement

A
  1. Low flows—Laminar–then gas property affected is viscosity of the gas
  2. High flows–Turbulent—then gas property affected is density of the gas
36
Q

Where is the manifold and what is the function?

A

The manifold on the anesthesia machine is located down stream of the flowmeters and is used to converge into one channel to direct the one gas flow towards the vaporizers and to also direct the waste gas collection

37
Q

What are the main pressures for pipeline O2
Pipeline N20? Which is lesser for safety precautions?

A

The pipeline inlet pressure for O2 is 45 psi and the pipeline inlet for N2O is 50 psi; The O2 is lesser than the N2O because it will alarm if pressures drop below 30% thru the fail safe device; By having the cylinder O2 closed then ensure less hazard of depleting the cylinder when simultaneously using the pipeline

38
Q

What is a pressure safety failure device?

A

Whenever O2 PRESSURE is reduced below 30% or 30 psi and designed to prevent delivery of gas mixtures below 25%; Works in tandem with low Oxygen Pressure Alarm; If falls below pressure, the valve closes and the gas in the limb does not advance to the flow control valve

39
Q

What components are the HIGH pressure circuit?

A
  1. Cylinder
  2. Hanger Yoke
  3. Filter
  4. Check valve
  5. Cylinder pressure gauge
  6. First Pressure Regulator
40
Q

What components are INTERMEDIATE pressure circuit?

A
  1. Pipeline press or Cylinder pressures (37-55 psi)
  2. Pipeline inlets and pressure gauges
  3. Ventilator power inlet
  4. Oxygen pressure-failure device and alarm–Fail-Safe
  5. Flowmeter valves
  6. O2 and N2O second stage pressure regulators
  7. Oxygen flush valve
41
Q

What components are the LOW pressure circuit?

A
  1. Distal to the flow meter
  2. Valves
  3. Flowmeter tubes
  4. Vaporizers
  5. Check valves
  6. CGO-Common Gas Outlet
42
Q

Describe a proportioning system

A

Board terminology for hypoxic guard system; Prevents you from setting a hypoxic mixture with the flow control valves; It automatically intercedes to maintain a minimum 25% concentrations of oxygen with a maximum N20:O2 ratio of 3:1

It is a mechanical, pneumatic or electronic integration of the N2O:O2 flow control valves; PREVENTS OXYGEN CONCENTRATION LESS THAN 0.25 being delivered to the breathing circuit when N2O is in use.

43
Q

The oxygen pressure failure device is fail safe device or proportioning device

A

Fail safe device

44
Q

The Hypoxia Prevention Safety device is fail safe device or proportioning device

A

Proportioning device

45
Q

Limitations of the proportioning system

A

can still deliver a hypoxic mixture:
wrong supply gas, defective pneumatics or mechanics, Leak downstream of O2 flow tube, Inert gas administration;

Low FGF with lower O2 concentration in a carrier gas or either air or NO— The flaw is the patient uses O2 from the breathing circuit faster than it is being replenished in the FGF. The hypoxic guard system works only with O2:N20

46
Q

Define Vaporizers

A

A vaporizer changes a liquid anesthetic agent into its vapor and adds a controlled amount of that vapor to the FGF to the breathing system

47
Q

How many vaporizers can be used at a time on the anesthesia machine?

A

ONE; up to 3 vaporizers can be attached however ONLY ONE can be used at a time

48
Q

Define the term saturated vapor pressure

A

Liquid evaporates into a space above it, the pressure of its vapor increases until equilibrium is reached.

As a liquid at constant temperature, will achieve equilibrium with rate of condensation and the rate of evaporation until the space above it is saturated.

49
Q

Vapor pressure is a dependent or independent characteristic of a volatile liquid?

A

Vapor pressure is an independent of atmospheric pressures; However it is dependent on the physical characteristics of the liquid and its temperature

50
Q

What is the definition of latent heat of vaporization?

A

Latent heat of vaporization is the number of calories needed to convert 1 g of liquid to vapor without temperature change in the remaining liquid

51
Q

How does temperature affect vapor pressure?

A

As temperature increases, vapor pressure increases causing a shift of equilibrium to more molecules in the vapor phase (compared to liquid phase); Vice versa as condensation occurs then vapor pressure decreases with an equilibrium shift more to the liquids than vapor pressure thus vapor pressure reduces.

52
Q

What are the 2 most common ways used to express the concentration of a gas or vapor ?

A

Volumes percent (vol %) and Partial Pressure
Partial pressure/Total pressure = Volumes %

53
Q

Define volumes %?

A

The number of units of volume of a gas in relation to a total of 100 units of volume for the total gas mixture; the concentration of a gas in a mixture expressed as its percentage of the total volume

54
Q

Define Specific Heat

A

Specific Heat is a substance’s quantity of heat required to raise the temperature of 1 g (or 1 ml) of the substance by 1degree C. important in anesthesia to know the sp. of heat because want to maintain a stable temperature for the liquid anesthesia

55
Q

Define Thermal Conductivity

A

Thermal conductivity is a measure of the speed with which heat flows through a substance. The higher the thermal conductivity, the better the substance conducts heat. Thermostabilization is achieved with a vaporizer of a metal with high thermal conductivity so as to minimize temperature changes when vaporizer is in use.

56
Q

Vaporizers in the US are called and where is it located on the anesthesia machine?

A

Concentration calibrated vaporizers controlled with a single dial (vol %) and is located in the low pressure system between the flowmeters and CGO

57
Q

Describe the basics of a variable bypass vaporizer

A

Variable bypass vaporizers are designed to help dilute saturated vapor by splitting the FGF that passes thru the vaporizer. Some of the FGF goes thru a bypass to the outlet and some of FGF comes in contact with the liquid anesthetic agent in the vaporizing chamber.
The concentration dial controls the variable of the ratio of the bypass gas to gas going to vaporizing chamber; also controlled by the temperature compensation valve

58
Q

Safety and Hazard features with the vaporizers

A

Hazards: Overfilling, Tipping, Leaking, Incorrect agent, reliance on breath by breath gas analysis rather than preventive maintenance; electronic failure; failure of temperature compensation device

Safety: Keyed fillers for specific agents color coded, low filling port, Secured on mounts, Interlock system, Concentration dial increases output in all when rotated counterclockwise

59
Q

Vaporization Methods-name 3

A
  1. Flow over
  2. Injectable
  3. Temperature Compensation
60
Q

What is the “pumping” effect? and the causes?

A

The pumping effect is back pressure may either increase (pumping) or decrease (pressurizing) the vaporizer output; affects concentrations delivered when there is less liquid agent in the vaporizing chamber, when the carrier gas flow is too low, when pressures fluctuate high and frequent and when dial setting is low;

61
Q

What are the effects of rebreathing ?

A

Rebreathing causes a difference between the vaporizer setting and the inspired concentration; As the FGF is lowered, exhaled gases contribute a more significant portion of the anesthetic agent to the inspired gases; If minute volume is increased, more rebreathing occurs

Rebreathing does not always associate with CO2

62
Q

What are the 3 factors influencing rebreathing?

A
  1. FGF-rebreathing varies inversely with the total FGF
  2. Mechanical dead space
  3. Breathing systems design
63
Q

What is the Mapleson system, how many types are there?

A

The Mapleson system characterized by no unidirectional valves to direct gases to or from the patient. No CO2 absorption occurs thus FGF must wash CO2 out of the circuit; Rebreathing can occur; It is considered a NON-REBREATHING breathing circuit

There are 5 types A-F

Hazard: A mechanical ventilator that vents excess gases should not be used b/c entire system become dead space–Mapleson A

64
Q

Describe the Mapleson D system? hazards?

A

Mapleson D systems consists of a T piece connector, pt connection port, a fresh gas port and a port for connection to corrugated tubing ;

65
Q

Define the APL valve and how it works

A

The APL valve is also called the pop off valve and it stands for Adjustable Pressure Limiting valve;
Allows gases to exit the breathing system

It is located in the low pressure system

APL OPEN: For spontaneous respirations and excess gases are vented during expiration

APL PARTIALLY CLOSING: Manually controlled or assisted ventilation, squeezing the bag and excess gases are vented during inspiration

APL CLOSED: Mechanically controlled ventilation, excess gases are vented thru the ventilator spill valve

66
Q

Advantages and Disadvantages of Mapleson system

A

Advantages: Simple equipment, no moving parts, easy to disinfect and sterilize, Resistance to breathing is low (easier for pts to breath), can be used in MRI,

Disadvantages: Require High gas flows, resulting in higher costs, increased pollution, , difficulty assessing spontaneous ventilation, the optimal FGF is difficult to determine , High flows lower heat and humidity

67
Q

Circle Breathing Systems Pathway

A

gases flow in a circular pathway through separate inspiratory and expiratory limbs, CO2 is exhaled by patient and is removed by absorbent.

Principles of Anesthesia 1 (1 decks)

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