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Principles of Anesthesia I > E2 > Flashcards

E2 Flashcards

1
Q

How are compressed gases measured?

A

 Psi = pounds per square inch

 Psig = pounds per square inch gauge

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2
Q

What is the relationship of non-liquefied vs liquefied compressed gases.

A

 Relationship btwn pressure and remaining volume and pressure reading on the gauge

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3
Q

What are non-liquefied compressed gases and their properties?

A

Gases that don’t liquefy @ room temp regardless of pressure applied
 O2
 Nitrogen
 MEDICAL Air
 Helium
b/c boiling point is well below ambient temp

Properties:
Will become liquids at very low temp
volume and Pressure
 Non-liquefied gas = pressure ↓ as volume ↓

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4
Q

Describe the relationship between pressure and volume of non-liquefied compressed gases.
What law is this?

A

THERE IS A LINEAR RELATIONSHIP btwn PRESSURE & VOLUME FOR THESE GASES
 SO P1/V1=P2/V2
 Boyles LAW

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5
Q

What is liquefied compressed gas, examples and it’s properties?

A 
Gas that becomes liquid 
@ ambient temp and at pressures from 25-1500 psi
	Liquid at Room temp & Patm
	N2O
	CO2 (insufflation)
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6
Q

How do non-liquefied gases differ from liquefied gases?

A

Liquefied gases do not follow boyles law

They are liquid at ambient room temp and Patm

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7
Q

How is pressure maintained in liquefied compressed gas?

A

WHEN ONE GAS MOLECULE LEAVES TO BE USED then ANOTHER MOLECULE FROM THE LIQUID TAKES ITS PLACE
 WILL MAINTAIN PRESSURE UNTIL BASICALLY EMPTY
 HAS TO BE OVER 95% EMPTY BEFORE PRESSURE CHANGE ON GAUGE

Liquid pressures = gas pressure

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8
Q

When will a pressure change be noted on liquefied compressed gas gauge?

A

 HAS TO BE OVER 95% EMPTY BEFORE PRESSURE CHANGE ON GAUGE

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9
Q

How is the volume of liquid compressed gas measured?

A

Weight

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10
Q

Government regulations of cylinders. FDA, OSHA, DoT

A

 FDA = gas purity
 Dept of Labor/OSHA = employee safety
 DoT = marking, labeling, storing, maintenance, transportation, and disposition

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11
Q

What are specific DoT gas regulations? (8)

A

• -Inspected & tested ONCE every 10 years
• -Test date stamped on cylinder
• -Must pass visual inspection & pressure testing
• -Color coded in the US (green)
• but should not be the primary means to identify a gas
• -Diamond shaped label
• identifying fire danger
 oxidizer, non-flammable, or flammable
• -Signal word identifying hazard level = CAUTION, WARNING, DANGER
• -Name & address manufacturer & Date of expiration
• -Tag for Full, In USE, Empty to notate gas level

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12
Q

Describe the components of medical gas cylinder? (5)

A 
Body
	Steel or steel carbon fiber = 3AA
	Aluminum = 3AL or 3ALM  need in MRI
	Flat or concave base
	Neck with screw threads

Valve
 Bronze or brass screws into neck
 Allows refilling and discharge of gas at stem

Port
 Point of exit for gas
 Take care not to screw retaining screw into port= damage

Conical depression
 Fits the retaining screw on the yoke

Handle
	Opens/closes cylinder
	Turns counterclockwise** to open
	Also called cylinder** wrench
	Must have one for every machine to be readily use
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13
Q

Describe the purpose of the pressure relief device on the cylinder

A

Vents cylinder to atm if pressure within cylinder becomes too high
• PREVENTS EXPLOSION FROM EXCESSIVE PRESSURE

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14
Q

What are pressure relief device types

A

Rupture or FRANGIBLE disk

Fusible plug

SAFETY relief

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15
Q

Describe the rupture/frangible disk pressure relief device on the cylinder

A
  • good for venting in high temp or overfilling
  • BUT BREAKS AT HIGHER PRESSURES ALLOWING GAS TO ESCAPE
  • non reclosing
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16
Q

Describe the fusible plug pressure relief device

A
  • WILL MELT w/ HIGH TEMPS AND ALLOW THE ESCAPE OF GAS

* non reclosing

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17
Q

Describe the safety relief valve in a cylinder

A

• most common
• SPRING-LOADED MECHANISM TO ALLOW VENTING OF GAS
• IF PRESSURE ↑ IT ALLOWS GAS VENTING
 THEN recloses/SEALS after pressure normalized inside cylinder

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18
Q

What is the most common type of pressure relief device on a cylinder?

A
  • SAFETY relief valve
  • most common
  • SPRING-LOADED MECHANISM TO ALLOW VENTING OF GAS (normalize to Patm)
  • IF PRESSURE ↑ IT ALLOWS GAS VENTING
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19
Q

What are the gas cylinder sizes

A

A = smallest
E = most common on gas machines and for pt transport
 Volume and pressure will vary in any given cylinder

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20
Q

Pressure, volume and color of O2, air and N2O full tanks

A

 Full O2 cylinder (GREEN) = 660 L at 1900 psi (some books 625 L @1900 psi)

 Full Air cylinder (YELLOW) = 625 L at 1900 psi

 Full Nitrous oxide (BLUE) = 1590 L at 745 psi

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21
Q

Cylinder safety considerations (8)

A

Valves, regulators, gauges do not come into contact with oil, grease, or lubricants
Temperature regulation
 < 130F (54C) & > 20F (-7C))
Keep connections Tight
No adapters should be used to change the size of connections for use of w/ hoses, regulators, or gauges
No alteration of markings and labels
No dropping, dragging, sliding of cylinders
Valve kept closed at all times
Cylinders should always be Properly secured to prevent fall

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22
Q

Cylinder storage consideration (8)

A

Storage in Designated secure areas (NOT the OR)
Adequate ventilation
Signage= no smoking, no combustibles in area of cylinders
Not exposed to corrosive chemicals/fumes
N2O secured/locked up to prevent access and abuse
Stored upright in bins or chained to wall
Wrapping and drapes undesirable
Recent jcaho guidelines
• require that empty or partially empty tagged cylinders
• stored separately from partially full and full cylinders w/ proper gauges

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23
Q

Considerations for the use of cylinders prior to using it(5)

A

 Visible inspection for defects of PISS system, label, regulator
 Presence of tamper proof seal around valve (NEW)
 must remove prior to attaching to anesthesia machine
 Presence of a sealing washer
 if absent, you could potentially have a leak

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24
Q

Considerations for opening of cylinder (5)

A 
	Open valve slowly and slightly prior to installation to clean out the valve port
	Check pressure
	Open away from patient
	Face valve away from people
	Correct leaks
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25
Q

Describe the Pin index safety system (PISS)

A

Two holes on cylinder valve
 positioned in an arc = receive pins on the yoke/ pressure regulator
THERE ARE 7 DIFFERENT POSSIBLE PIN POSITIONS
 DEPENDING ON THE TYPE OF GAS IN THE CYLINDER
If cylinder valve has no holes = impossible to attach to yoke/regulator with pins
 SPECIFIC CONFIGURATIONS BE AWARE OF THIS SAFETY MECHANISM

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26
Q

Pipeline supply source guidelines

A

Must have 2 days supply “banks”
 1 primary
 1 reserve
 each with 2 days supply so 4 days total for both

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27
Q

Purpose of pipeline system and gases supplied versus cylinder?

A 
Because E- cylinder use is not enough
Used to deliver gases to anesthetizing locations &amp; patient care areas
•	O2
•	N2O
•	MEDICAL Air
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28
Q

What is included in a pipeline supply system?

A

 central supply system
 piping to transport gases to the specific locations
 branches and terminal units

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29
Q

What is the US pipeline pressure?

What is the most frequent pipeline problem?

A

 pipeline pressures are 380 kPa or approx. 55 psi

 Low pressure is the most frequently reported problem in pipeline systems

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30
Q

Purpose and guidelines of reserve gas supply?

A

Reserve supply
 should be used for emergencies or failure of primary supply.
 Ideally in different area with different routing

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31
Q

Guidelines for liquid O2 use

A

Liquid O2 must be in constant use to be cost effective

 Otherwise pressure ↑ as the liquid boils and is then vented in the Patm

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32
Q

N2O supply and storage guidelines and regulations

A

generally supplied by manifold cylinder system
• b/c regulator prone to freezing
Warning signs need to be posted in N2O are warning of asphyxia due to leak

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33
Q

Medical air supply storage requirements

A

use manifolds or compressors
• important for intake locations are free of contaminants
Air systems need to dehumidify to qualify for medical use

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34
Q

N2O and medical air storage guidelines

A

Both systems have a series of valves, pressure regulators, & alarms
 to regulate pressure and signify problems

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35
Q

What are the components and composition of a pipeline system structure

A

Main line
• connect gas source to risers
Risers
• vertical pipes connecting mainline w/ branch lines on each level of facility
Branch
• sections supplying a room or group of rooms on one level of the facility
Composition of piping is Copper

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36
Q

What are labeling regulations for pipeline systems

A

Regulation:
Name, pressure, and flow direction
• must be clearly marked every 20 ft and in each room

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37
Q

What is the difference in O2 pipeline diameter vs other gases and why?

A

 O2 (1/2 in OD) has different outer diameter than other gases (3/8 in OD) safety mechanism

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38
Q

Purpose of pipeline system shut off valve

A

Allow for certain areas in the piping system to be isolated
 for maintenance or problems
 ON-OFF, isolation of section or zone

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39
Q

2 types of pipeline system shut off valves and their differences.

Where are they located?

A

“Manual Shut Offs” = visible & accessible at all times
Mandatory locations:
• Main supply into building= turns everything OFF to building
• One at each riser
• One at each branch
• except if branch is to an anesthetizing area or critical care area-Why?
“Service Shut Offs” = locked box- NOT ACCESSIBLE TO US

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40
Q

What are 2 types of pipeline alarms and their differences?

A

Master Alarm System
 Must be located in 2 different areas
• 1 panel must be in department responsible for maintaining system
Monitors entire pipeline system

Area Alarm System- check daily, test monthly
 In critical care areas- ICUs and ORs
 Alarms if the pressure ↑/↓ at 20% from normal line pressure***
 May trigger master alarm

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41
Q

What are pipeline alarm requirements

A

 Must be audible and visible
 Must be labeled for gas and area
Will alarm with a 20% increase or decrease

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42
Q

What are terminal units of a pipeline system

A

 Point where piped gas is accessed
 by user through hose connections (flow-meter)
 i.e. wall connector-hose-station outlet

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43
Q

Describe pipeline terminal unit connections

A

 Connection into wall uses quick connectors
 Pair of male and female parts
• only connect w/ proper alignment.
 Each gas has a specific shape and spacing  more prone to leaks vs diss system

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44
Q

What is the station outlet of the pipeline terminal unit?

A

Connection into machine

 uses DISS (diameter index safety system) system

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45
Q

Vaporizer definition and additional requirement

A

Vaporizer = device that changes a liquid anesthetic into a vapor for inhalation
 Changes liquid to gas
 Must add a controlled amount of vapor to FGF in a breathing system

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46
Q

How is the vaporizer calibrated?

A

 Calibrated at sea level

 Affected by barometric pressure changes

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47
Q

What are the stages of anesthesia?***

A

 STAGES OF ANESTHESIA

1) ANALGESIA
2) DELIRIUM
3) SURGICAL
4) RESP CESSATION

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48
Q

How is the vaporizer affected by pressure and what should the anesthetist do prior to using it?

A

BMP changes volatile given
READ THE MANUAL FOR THE VAPORIZER AND MACHINE
• PRESSURE MUST BE TAKEN INTO ACCOUNT

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49
Q

When considering vapor administration and pressure changes what are the 3 most important considerations for the anesthetists?

A

 GIVE THE PT WHAT THEY NEED
 LOOK AT WHOLE PICTURE
 MAKE THE CLINICAL DECISION

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50
Q

What is the vapor pressure of a liquid

A

 the equilibrium pressure OF the vapor ABOVE ITS LIQUID

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51
Q

What is pressure of vapor

A

RESULTS FROM EVAPORATION OF THE LIQUID

 ABOVE THE LIQUID IN A CLOSED system at a CONSTANT temp**

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52
Q

How does temperature relate to VP

A

increase temp = increase VP

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53
Q

How is VP affected by barometric pressure

A

It is not

VP is dependent on the liquid and temperature

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54
Q

What is VP dependent on?

A

The liquid and the temperature

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55
Q

What is saturated vapor pressure

A

WHEN THE GAS CONTAINS ALL THE VAPOR IT CAN HOLD AT A GIVEN TEMP

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56
Q

What is saturated vapor concentration and important consideration during administration

A

SVP/atm pressure

 THE SVC MUST BE DILUTED BY A BYPASS GAS FLOW

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57
Q

What is important to note about each gases VP?

A

 Cannot compare gases by VP

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58
Q

What is the best way to compare gas agents

A

Gas concentration in partial pressure or vol % (MAC)

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59
Q

Describe volume percent expression of gas concentration

A

Concentration of a gas in a mixture
• expressed as percentage of 100% @ 1 ATM
• PP/TP X 100% = volumes %
• MAC is described in terms of volume percent

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60
Q

What affects volumes percent and how is it related to anesthetic uptake?

A

Indirectly relates to patient uptake & anesthetic depth

• IS INFLUENCED BY BAROMETRIC PRESSURE

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61
Q

Describe the partial pressure expression of gas concentration and what is it dependent on?

A

Pressure exerted by any one gas in a gas mixture on the total gas mixture
• Total pressure of the mixture is a sum of all the PP

  • Dependent on temperature
  • Not the pressures exerted by total pressure of the gas mixture
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62
Q

What affects partial pressure of a gas and how is PP related to anesthetic uptake?

A

Affected by: temperature
• Not affected by barometric pressure
• SAME POTENCY NO MATTER WHAT THE BAROMETRIC PRESSURE IS

•Directly relates patient uptake and anesthetic depth

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63
Q

What is heat of vaporization

A

 The number of calories necessary to convert 1G (or 1ml) of liquid into vapor**

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64
Q

How does gas flow affect the heat of vaporization?

A

 As carrier gas flows through the vaporizers
 Vapor molecules leave and more liquid is vaporized
 As more molecules enter the gas phase, the liquid begins to cool.

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65
Q

How does heat flow as gas flows pick up vapor? When is equilibrium established?

A

The liquid begins to cool
 Heat will flow from the surrounding VAPORIZER
 To compensate for the loss of heat in the liquid

 Heat lost to vaporization = heat supplied by surrounding VAPORIZER

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66
Q

What happens to the liquid in the gas state in the vaporizer when the temp drops? Why is this significant?

A

IT DECREASES:
• IF MY VAPORIZER IS SET AT 1, BUT ITS COOLING
• THERE IS LESS GAS LEAVING THE VAPORIZER
 EVEN THOUGH NOTHING HAS CHANGED

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67
Q

What happens to the temp as gas leaves the vapor

A

It cools the whole vaporizer

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68
Q

How do manufacturers account for heat of vaporization effects?

A

MANUFACTURERS MUST ACCOUNT FOR THIS PHENOMENA
 INCORPORATE A SYSTEM TO REPLACE AND EQUALIZE LOST HEAT
 FOR ACCURATE GAS ADMINISTRATION
• THEY CHOSE CERTAIN METALS TO ACCOMMODATE HOV
• SO WE GET A CONSISTENT ANESTHETIC

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69
Q

Specific heat definition

A

the quantity of heat required to raise the temp of 1gram of a substance 1degree C

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70
Q

What is the standard measure of specific heat

A

H2O is the standard

• 1cal/gram/1 degree C

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71
Q

Specific heat considerations for vaporizers

A

 SH must be considered for maintaining a constant temperature to the vaporizer

 Higher SH = temp changes more gradually

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72
Q

Thermal conductivity definition

A

the speed at which heat flows through a substance

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73
Q

Thermal conductivity considerations with vaporizers

A

 Higher TC = better conductor of heat

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74
Q

Specific heat and thermal conductivity considerations with vaporizers

A

must be considered in choosing a material/METALS for vaporizer construction
 ↑ SH=THE HARDER IT IS FOR THE TEMP TO CHANGE-
 Higher SH/TC is desirable b/c changes in the the vaporizers are less likely when the gas leaves the vaporizer

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75
Q

Vapor concentration calibration and location

A

 Calibrated by agent concentration
 Single knob calibrated in volumes percent
 Located between flow meter and common gas outlet (PT) - so it isn’t flushed with O2

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76
Q

Where is the vapor concentration calibration and Why is the location of vapor calibration site important.

A

Located between flow meter and common gas outlet (CGO)

 So gas isn’t flushed w/ O2

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77
Q

How does the vaporizer maintain steady state?

A
  • THE TOTAL VOLUME OF GAS LEAVING THE VAPORIZER IS&raquo_space; THE TOTAL VOLUME THAT ENTERED
  • D/T ADDITIONAL VOLUME ATTRIBUTED TO ANESTHETIC VAPOR AT ITS SVC
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78
Q

2 Types of vaporizers**

A

bypass

electronic

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79
Q

How does vapor pressure and partial pressure of a gas at room temp relate to anesthetic depth?

Why is this important?

A

Vapor pressure of an anesthetic gas at room temp is GREATER than the partial pressure necessary to achieve anesthesia

 so the vaporizer dilutes to a useful concentration
 ↓ potency of gas w/ mix of vapor and gas flow

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80
Q

What is a variable bypass vaporizer?

A

Vaporizer splits flow
 some gas flows into vaporizing chamber
 some gas flows into bypass
 THIS IS KNOWN AS THE SPLITTING RATIO
 Gas that passes through the vaporizing chamber will have volatile agent attached
 Both flows are then rejoined before exiting vaporizer

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81
Q

Process of the variable bypass vaporizer

A

 Gas flow is split
 Portion of gas picks up volatile in vaporizing chamber
 Portion of gas bypasses vaporizer chamber
 Both flows are rejoined before exiting vaporizer

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82
Q

What is splitting ratio dependent upon? (4)

A

 the ANESTHETIC AGENT/CONCENTRATION
 size of the adjustable orifice
 total gas flow
 heat of vaporization

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83
Q

How do temperature compensating mechanisms affect variable bypass vaporizers?

A

 THEY DO NOT PRODUCE INSTANTANEOUS RESULTS

 T/F ANTICIPATED CONCENTRATION MAY NOT BE ACCURATE UNTIL COMPENSATION OCCURS

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84
Q

What is a bypass vaporizer

A

 NO VOLATILE ATTACHED TO FLOW THROUGH BYPASS CHAMBER VS VAPORIZING CHAMBER

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85
Q

How is splitting ratio determined for bypass vaporizer

A

Splitting ratio = vaporizing/bypass

Higher ratio means
 MORE GOES INTO VAPORIZING CHAMBER
 t/f MORE GOES TO THE PATIENT

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86
Q

What happens to the splitting ratio if the vaporizer is cooled?
How is the problem fixed?

A

• IT GETS SMALLERSO LESS GOES OUT TO PATIENT

Increase MAC or FGF to increase depth

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87
Q

How does an electronic vaporizer work?

A 
Computer driven 
Calculates either:
	volume of CARRIER gas 
•	to produce the desired concentration 
OR
	amount of liquid agent needed to be injected into carrier flow
To EQUAL desired concentration
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88
Q

2 methods of vaporization delivery

A

Injection

Flow-over

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89
Q

What are the differences between injection and flow-over vapor delivery

A

Injection
 Inject known volume liquid anesthetic into known volume of gas

Flow-over
 Carrier gas passes over surface area of a liquid
 ↑ surface area= ↑ efficiency of vaporization
 Most common

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90
Q

How is temperature accounted for when delivering volatile gas

A

Thermocompensation
must maintain constant ANESTHETIC output
 Can be mechanical or computer driven
 Splitting ratio changes as temp changes

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91
Q

How is the splitting ratio affected by temperature

A

Splitting ratio changes as temp changes
• ↓ TEMP AND ↓ OUTPUT OF GAS/VAPOR
• SPLITTING RATIO WILL ↓ W/O THERMOCOMPENSATION

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92
Q

What will happen to splitting ratio w/o thermocompensation

A

Splitting ratio will decrease

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93
Q

Purpose of regulating intermittent back pressure on vaporizers

A

To limit the change in vaporizer concentration from IBP

To keep a steady state of volatile delivery

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94
Q

Causes of intermittent back pressure

A

O2+ flush

Positive pressure from inspiration during vent use

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95
Q

What can IBP cause during vaporizer use?

Most common reason?

A

Can Cause pumping effect or pressurizing effect on vaporizer outputs

Most common: d/t vent and flush valve use

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96
Q

Problem of having intermittent back pressure occur

A

 Can cause small changes in the amount of gas delivered

 IBP CAN AFFECT WHAT THE PATIENT IS GETTING

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97
Q

How does intermittent back pressure affect delivery of gases

A

By leading to the pumping or pressurizing effect

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98
Q

What is the pumping effect due to and how does it affect volatile delivery?

A

D/t back pressure during inhalation @ LOW FGF
• Causes INC flow into the vaporizing chamber
• MORE than usual vapor picked up

Effect
= ↑ of vapor output
• COMMON WITH OLDER VAPORIZERS

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99
Q

What can lead to pumping effect and how can it be minimized?

A

More common
• @ LOW FGF
• large pressure fluctuations
• low vaporizer settings

Minimize effect
• Presence of the pressurizing valve
• unidirectional valve
• pressure relief valve

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100
Q

How do pressurizing and pumping effect alter gas delivery

A

pressurizing = not enough vapor output

pumping= too much vapor output

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101
Q

What is the pressurizing effect due to and how does it affect volatile delivery?

A

 D/t back pressure at HIGH FGF
• causes INC density into the vaporizing chamber
• LESS than usual vapor picked up

Effect
=↓ of vapor output

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102
Q

What can lead to pressurizing effect and how can it be minimized?

A 
More common 
•	at high gas flows
•	O2 flush valve use
•	large pressure fluctuations
•	low vaporizer settings

Minimize effects
NEWER, CONTEMPORARY VAPORIZERS
 USE VALVES AND OTHER MECHANISMS TO MINIMIZE THESE ISSUES

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103
Q

How does FGF affect vaporizer?

A

It directly affects vaporizer output

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104
Q

Definition and effects of high FGF

A

Flow > pt minute ventilation
 Little gas rebreathed
 Inspired concentration = vaporizer setting
 HIGH FGF&raquo_space; THAN PATIENT’S MIN VOLUME
• Brand new breath w/ brand new volatile
• NO RECYCLING
• Pt is getting closer to exact gas concentration
• Pt gets what is on the dial

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105
Q

Definition and effects of low FGF

A 
Flow < pt minute ventilation
 Significant rebreathing
 Difference btwn vaporizer setting &amp; inspired concentration
•	Difference is in bellows or bag
 Takes longer to achieve equilibration
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106
Q

How can equilibration be reached faster with low FGF

A

increase volatile concentration

Increase flow

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107
Q

Difference in high and low FGF monitoring, effects and use?

A 
Low FGF
 Flow << min ventilation
 There's a difference between setting and inspired concentration
 Need agent analyzer to get true value
 significant rebreathing
 Used during maintenance
High FGF
 Flow >> min ventilation
 inspired concentration = vaporizer setting
 NO rebreathing
 useful during induction
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108
Q

Where is the difference between min volume and flow w/ low FGF use?

A

In the vent bellows or reservoir bag

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109
Q

What is the problem with rebreathing during low FGF use?

A

Recycling present = patient not necessarily getting dialed concentration

Takes longer to reach equilibrium

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110
Q

What are standard regulations for vaporizers? (6)

A

 Average concentration +/- 20% setting
 Gas may not pass through more than 1 vaporizer
- SAFETY=to prevent mixing of gases
 Output of vaporizer <0.05% in OFF
 All control knobs counterclockwise
 Filling levels displayed
 Cannot overfill when in normal operating position

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111
Q

Types of vaporizer mounting systems.

Which is most common

A

Permanent

Detachable = most common

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112
Q

Describe the permanent vaporizer mounting system including advantages and disadvantages

A 
Tool required
Always filled in upright position
Advantage
•	fewer leaks/damage
Disadvantage 
•	limited mounting locations
•	not easily exchanged
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113
Q

Describe the detachable vaporizer mounting system including advantages and disadvantages

A 
	Most common
	Weight of vaporizer &amp; “O” ring create seal
•	O ring damage = can lead to leak
	Locking lever on back
	Control must be OFF before mounting
	Easily removed/replaced  
•	think MH= machine has to be flushed
	Disadvantages:
•	Site for leak from 
•	damaged O ring 
•	unlocked lever
•	Manufacturer compatibility
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114
Q

Purpose of interlock device on vaporizer

A

– prevents more than 1 vaporizer being turned ON at a time
 Allows only ONE gas to be administered at a one time
 Prevents mixture of gases

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115
Q

4 vaporizer hazards

A

Incorrect agent
Tipping
Overfilling
No Vapor output-

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116
Q

How is the vaporizer hazard of incorrect agent prevented and how is it fixed if it occurs.

A

 Filling systems agent specific=not likely
• Must have correct/compatible key to fill system

 If contaminated filling occurs:
• Must be completely drained
• all liquid discarded
• FGF run until no vapor detected

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117
Q

What happens to potency when the incorrect agent is put in the vaporizer?

A
  • Won’t achieve 1 MAC
  • Won’t deliver what the pt needs
  • dec potency
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118
Q

How does the vaporizer hazard of tipping occur, prevented, the effects and how is it fixed if it occurs.

A

Liquid may get into bypass or outlet
 INC concentration of agent
• Bypass carrier flow will pick & deliver more agent

Prevented:
 Should be placed in OFF/ travel mode when moved
 Newer vaporizers prevent

If tipped:
• High FGF run with low concentration of vapor
• until excessive vapor exhausted
• Until agent analyzer reads concentration that is set on dial

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119
Q

How does the vaporizer hazard of overfilling occur, the hazard and what can this lead to

A

 Liquid may enter FG line or cause vaporizer failure
 Potential for lethal dose
 Can occur during tipping or filling on “ON”

Leads to:
•	failure to tighten filler cap
•	fill valve not closed
•	malfunctioning mount/vaporizer
•	pollutes OR can probably smell
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120
Q

Causes of no vapor output

A

 Most common cause = empty
 Incorrect mounting
 Overfilled = no output because of vaporizer failure

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121
Q

What is the anesthesia gas delivery system composed of? (5)

A 
	anesthesia machine
	vaporizers
	ventilator
	breathing circuit,
	scavenging system
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122
Q

Who sets the standards for anesthesia workstations? When were standards published

A

American Society for Testing and Materials (ATSM)
 starting in 2000
 reviewed in 2005

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123
Q

What does the term “workstation” include and the basic operations.

A

include the ventilator & associated monitoring devices used

operations
components have become more technologically advanced (i.e. virtual flowmeters)

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124
Q

What should workstations be able to do? (5)

A 
	Provide:
•	accurate &amp; safe gas delivery
•	a means for ventilating patients
•	electrical outlets
•	a housing for monitoring devices like vaporizers
•	storage/shelving for other equipment
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125
Q

How does gas travel through the entire workstation?

A

 Gas source delivers gas to machine
 gas delivered to flowmeters & vaporizers
 gas mixture goes to common gas outlet (CGO)
 then flows to breathing circuit to the pt
 gas then leaves the pt through breathing circuit
 excess gas exits either via APL valve (spontaneous resp) scavenger or ventilator
(Mech resp)

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126
Q

Disadvantages to older workstations

A

 may lack the safety features of newer machines
 may be considered obsolete
 there are ASA guidelines to consult to determine if this is the case

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127
Q

What are workstation system components (19)

A
  • Master switch
  • Hanger yoke assembly
  • Cylinder pressure indicator/gauges
  • Cylinder pressure regulators
  • Pipeline inlet connections
  • Pipeline pressure indicators/gauges
  • Gas pathways
  • Machine piping
  • Common gas outlet***
  • Unidirectional valves
  • Pressure relief valve
  • Flow adjustment controls
  • Flowmeters
  • O2 flush valve
  • O2 failure protection device
  • Hypoxia prevention devices
  • O2/N2O linkage
  • Auxiliary O2 flowmeter
  • Power backup/battery
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128
Q

Components of the workstation (16)

A 
	Master switch (ON/OFF)
	Hospital backup/electrical outlets
	Hanger yoke assembly
	Cylinder pressure gauges/regulators
	Pipeline pressure gauges
	Gas pathways 
	Pressure relief valves
	Flow controls/flowmeters
	Vaporizers
	Unidirectional valves (outflow check valve)
	Common gas outlet (CGO)
	Oxygen flush valve
	Oxygen failure protection device (OFPD)
	Minimum oxygen flow and ratio
	Axilllary oxygen flowmeter
	Power failure/battery backup
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129
Q

What does the workstation master switch activate?

A
  • Pneumatic fxn
  • Electrical fxn
  • alarms
  • safety features
130
Q

When workstation master switch is off, what still function

A

Electrical components active
• Battery charger
• Electrical outlets
 for additional monitors

Pneumatic functions
• Maintained when off
 O2 flush valve
 auxiliary O2 flowmeter

131
Q

What functions are available when workstation master switch is turned on.

A

the electronics go through a power ing up protocol
 Usually an automated prompt for machine checkout

• The checkout can be overridden in an EMERGENCY***

The pneumatic functions
 Permit the delivery of gas
 To flow from the flowmeters & vaporizers

132
Q

Requirements for workstation machine and hospital electrical outlets

A

MACHINE
 All contemporary machines
 incorporate electrical systems
 require a connection to electrical power
 Electrical outlets on the machine
 intended to power ANESTHESIA monitors only
 It is for our use, not the entire ORs
 If requirements exceed outlet Circuit breaker will activate

HOSPITAL
RED OUTLETS = Back up generator
 Other appliances should be plugged into hospital main!

133
Q

When should a machine checkout occur

A
  1. Before first care of the day
  2. If any changes are made to the system
  3. Abbreviated check btwn cases (pressures etc)
134
Q

If a machine check is conducted primarily internally by a newer machine, what should still be checked by anesthetist

A
  • O2 sensor calibration

* high pressure checks

135
Q

How is an abbreviated check of the system performed and why

A

 includes high pressure check

• To check for pressure problems in the low pressure system

136
Q

How do newer systems perform machine checks

A

 Will display machine checkout results
• On screen upon completion
• May indicate potential problems
• Problem location for correction

137
Q

what is one of the most important steps in a machine checkout that is overlooked

A

Backup equipment and electrical supply

  • O2 cylinder supply
  • Ambu bag
138
Q

What are some workstation machine functions

A

 to receive compressed gases from their source
 create a gas mixture & flow rate at the CGO to deliver to the pt
 Controlling the flow of gases
 To prevent admin of a hypoxic gas mixture

139
Q

What is the relation between pressure and flow?

Which law?

A

Flow = change in pressure/ resistance

Ohm’s law

140
Q

What are the principles of the flow of gases

A

 from high pressure sources (E-Cylinder or Pipeline pressure)
• through the machine
• through the CGO
• at near Patm

141
Q

What is the hanger yoke assembly and it’s purpose

A 
	Orients and supports cylinder 
	provides a gas-tight seal
	Required to have a least 
	1 yoke for O2 
	1 yoke for N2O

Purpose:
 Has check valve assembly to prevent gas from exiting machine when there is no cylinder in yoke
 Prevents gas from being transferred from a cylinder w/ higher pressure to one with lower pressure
• if both are in a yoke & ON
• thus prevents the unnecessary depletion of gas

142
Q

Purpose of the cylinder pressure gauge and how it works

A

Measures pressure of a gas above ambient Patm
 Must be present for each gas supplied by cylinders

How it works:
 Bourdon tubes
	curved hollow tubes
 inc pressure = straightens curve
 Falling pressure = causes curve to redevelop
	Motion is transmitted to gauge
143
Q

What unit does the cylinder pressure gauge measure in and where is it located?

A

Units
 kilopascals (kPa)
 psi

Location
 on the front of the anesthesia machine for reading

144
Q

Purpose of the cylinder pressure regulator

A

 device that converts a high, variable input gas pressure into a constant, lower output pressure
 Reduces high, variable pressure in cylinders
• to lower constant pressure for machine
• also called reducing valves
 Regulator required for EACH gas supplied by cylinder

145
Q

What would occur without the reducing valve (aka pressure regulator)

A

 the anesthetic provider would have to constantly adjust flowmeter to provide constant flow!!!

146
Q

What is the function of the pipeline inlet connection?

Requirements and connections

A

 Entry point for gases from pipelines to the back of the machine

Connector:
DISS-back of machine

Requirements:
 Require O2 & N2O (most have medical air)
 Must contain unidirectional check valve to prevent
• gas returning
• flowing back into the pipeline

147
Q

Pipeline pressure gauge requirements and functionality

A

Requirements:
 Indicator required for EACH gas monitored
 Indicator must be on pipeline side

Functionality:
 Usually found on front of anesthesia machine
 Digital or newer machines have LED display

148
Q

Why is the pipeline pressure gauge location important

A

If gauge is downstream & cylinder valve open
• Getting pressure reading from cylinder
• Not an accurate reading/reflection of pipeline pressure
• Falsely elevated or normal pressure
• adequate pressure reading until cylinder is 0

149
Q

What drives gas flow?

What is the direction of flow through the system?

A

Change in pressure from higher to lower

  • High pressure system
  • First stage regulator
  • Intermediate pressure system
  • low pressure system
150
Q

What is included in the high pressure system gas pathway

A

 Everything upstream of the cylinder
 includes parts upstream of the cylinder pressure regulator
• aka first stage regulator

151
Q

What is included in the first stage regulator gas pathway, pressure range and it’s purpose

A

Includes
• cylinders and pressure regulators with O2 pressures between 45 and 2200 psi
• receives gases from cylinders

Purpose:
	converts high, variable pressures 
from cylinder gases
•	to constant, lower pressure of 45 psi for machine use
•	aka O2 cylinder pressure regulator
152
Q

What is included in the intermediate pressure system gas pathway and purpose

A

includes
• cylinder pressure regulator and pipeline gas inlet to gas flow control valves (flowmeters)
• going toward flowmeters

Purpose:
• can flow & pressurize gas in multiple directions
• To lower pressure as progress through system
• Pressure goes from higher to lower

153
Q

What is included in the low pressure system gas pathway

A 
includes:
•	Flowmeters
•	Hypoxia prevention devices
•	Unidirectional valves
•	Pressure relief valves
•	Common gas outlet (CGO)
-all parts downstream of the gas flow control valves (FLOWMETERS)
•	Extends from flowmeters to CGO
154
Q

What are the pressure gauge ranges for the intermediate pressure system

A 
Pressure range:
0 psi if master switch off
16 - 55 psi
-50-55 psi for pipeline
40-45 for cylinder
155
Q

Describe the deliberate difference in supply pressure of the pipeline vs cylinder O2 and how pressure flows

A 
Difference in supply:
the pipeline (50-55 psi) &amp; cylinder oxygen (40-45 psi)

How pressure flows:
-From the higher pressure system
-the machine will preferentially receive O2 from the pipeline
 d/t higher pressure difference (∆P)
 b/c pipeline pressure > cylinder pressure

156
Q

When will the gas pathway system receive O2 from the cylinder over the pipeline

A

If the pipeline pressure drops below the cylinder pressure

157
Q

After check cylinder pressure what should be done and why

A

it should be turned off
• to prevent
 exhaustion
 leakage of gases from cylinders

158
Q

What are the pressures in a low pressure system and what is this dependent on

A

Pressures normally slightly greater than Patm
 pressure is variable

Depends on
 flow from flowmeters
 and back pressure from breathing circuit

159
Q

3 Requirements for anesthesia machine piping

A

 Connects components inside machine
 Must be able to withstand 4x intended pressure
 Leaks must not exceed 25 ml/min inside machine

160
Q

What is the CGO and guidelines for use

A 
Common Gas Outlet (CGO) 
 Receives all gases from machine 
	delivers mixture to breathing system to deliver to the pt
 Must be difficult to disconnect 
	to ensure uninterrupted gas flow
161
Q

Why shouldn’t the CGO be used for supplemental O2

A

 Should not be used for supplemental oxygen
 Such as during a delay in emergencies
 Potential delivery of inhalational agents

162
Q

What are the unidirectional valves and where are they located?

A

Pipeline inlet
Outlet check valve (before CGO)
Pressure relief valve (before outlet check valve)
Various places throughout the system

163
Q

What is the purpose of unidirectional valves

A

To prevent pipeline backflow

164
Q

Where is and what is the purpose of the outlet check valve do

A

location:
 Located btwn vaporizer & CGO
 UPSTREAM from O2 flush valve

Purpose:
 Prevents/lessens back pressure from O2 flush or breathing circuit 
•	it prevents reverse gas flow
	causing pumping or pressurizing effect
•	to ↓ intermittent back pressure!!
165
Q

What do unidirectional valve in the pipeline prevent

A

back pressure

decreased intermittent back pressure

166
Q

Location and purpose of the pressure relief valve

A

Prevents the buildup of pressure
 Upstream of the outlet check valve
 open to atmosphere to vent gas if the preset pressure is exceeded
 Limits ability of machine to provide adequate pressure for jet ventilation
-can’t get adequate pressures

Location:

  • Upstream of the outlet check valve
  • Near the CGO and open to atmosphere
167
Q

Purpose of the flow adjustment controls

A

To Regulate
 flow of O2
 medical air
 other gases

168
Q

Guidelines for flow adjustment controls

A

Must be only one control for EACH gas
 must be adjacent to its flowmeter
• turn in only one direction
• counterclosckwise

169
Q

Guidelines for O2 flow adjustment control

A 
O2 flow knob (on flowmeter) must be
	fluted 
	larger than other gases 
•	looks &amp; feels different
•	likely larger &amp; projects out more than other gas knobs
170
Q

Flowmeter purpose

A 
Indicates 
	rate that gas is passing through piping (in this order)
•	1st Vaporizer 
•	 into CGO 
•	then to patient
171
Q

Pressures of the O2 supply flowmeter

A

 is regulated to a constant lower pressure by a 2nd stage regulator
• Part of low pressure system

172
Q

Design of flowmeters

A 
Thorpe tube used
	vertical glass tube
	Smallest diameter at bottom
	Free floating indicator
	A stop at top of tube
	A flow scale

Must be marked with
 appropriate color
 chemical symbol of gas

173
Q

How does flowmetered gas flow and the standards

A

Flowmeter sequence purposeful
 allows gas flow from bottom-top & left-right

Standards:
 O2 flowmeter on RIGHT side, closest to CGO

174
Q

Where is O2 flowmeter and why is the location important

A

 O2 flowmeter on RIGHT side, closest to CGO

Importance:
• if a leak occurs with other gases then unlikely to result in a hypoxic mixture
• Safety feature= where flowmeter is located

175
Q

What is the O2 flush valve and how is the flow directed

A

Delivery of high-flow, 100% O2

Receives O2 from
 pipeline inlet or
 cylinder pressure regulator
Sends high flow O2 to CGO

176
Q

Requirements and design of O2 flush valve (5)

A 
MUST be:
	Operable with 1 hand
•	To deliver O2 to desat pt very quickly
•	So you can use it when connected to pt??
	Single purpose
	Self-closing
	Designed to minimize accidental use (innie)
	Have flow Btwn 35-75 L/min
177
Q

When the O2 flush valve is used what can happen at the CGO. How is the problem prevented.

A

the pressure could ↑ the supply pressure at the CGO
• w/o the presence of pressure relief valves
• to appropriately regulate it

178
Q

What are the hazards of the O2 flush valve

A 
	potential sticking of valve
	barotrauma
	anesthetic awareness
•	b/c can dilute or ↓ volatile anesthetic
•	receive less vapor gas
179
Q

What is the purpose of the O2 failure protection device

A 
AKA “Fail Safes” when O2 fails
 Shuts off or proportionally ↓ N2O
•	to maintain a min 19% O2 flow at CGO 
•	prevents hypoxic mixtures
	Shuts off N2O
	May convert to medical air if no O2
180
Q

How does the O2 failure protection device work

A

How it works:
O2 pressurizes when master switch turned on
 holds open a pressure sensor shut-off valve
 These valves interrupt the supply of other gases to flowmeters except medical air
 in the event the O2 supply pressure falls below threshold or to zero

181
Q

Function of the O2 failure alarm

A

When pressure falls below threshold
• approx. 30 psi
• an alarm sounds w/in 5 sec

182
Q

Purpose and function of hypoxia prevention devices

A

• prevent a hypoxic gas mixture by maintaining a minimum O2 concentration delivery w/ N2O

Function:
 Uses mechanical linkage
• with N2O to limit N2O flow when given in tandem w/ O2
• Link engages when O2 concentration &laquo_space;25% to

183
Q

Hypoxia prevention device requirements

A

Requirement of contemporary machines
 to avoid the administration of a hypoxic gas mixture

Mandatory Minimum O2 Flow
 Min of 50-250 ml/min flow
 Activated  when master switch is ON

184
Q

Function of the auxiliary O2 flowmeter

A

Permits O2 flow at 10 L/min (MAX)
 can be used w/ non-machine airway devices
• NC, masks, Ambu bag
 Similar to the O2 flush valve
 the auxiliary O2 flowmeter is active when the master switch is OFF

185
Q

Purpose of the auxiliary O2

A

 Delivers O2 in case of electronic power or system pressure failure by connecting Ambu bag or modified anesthesia circuit in order to ventilate the patient

186
Q

Purpose of workstation power failure/battery

A

1 backup source for power in the event of power outage

187
Q

Power failure function

A

Power failure alarm
 should be visual & audible
Newer machines
 have 1 backup source for all components

188
Q

Backup battery function for workstation.

Battery life dependent on…

A

 If machine stays plugged in battery backup should be at highest level
• until generator takes over
 Duration of backup depends on power usage
 manual ventilation uses much less power than ventilator usage

189
Q

What is the mission of the breathing system (5)

A

 1. receives gas mixture from the machine
 2. delivers gas to the patient
 3. removes CO2
 4. allows spontaneous, assisted, or controlled respiration
 5. provides gas sampling, measures airway pressure, monitors volume

190
Q

What happens to resistance as it travels through a system

A

The more pressure it overcomes the more resistance drops

 When gas passes through a tube
• The pressure at the outlet is less than the pressure @ the inlet……
 The drop in pressure= resistance which was overcome

191
Q

What can alter resistance

A
  • Volume of gas passing through
  • Flow types (passing thru tubes) can change resistance
  • laminar
  • turbulent
192
Q

Describe movement of laminar flow

A

 Flow is smooth and orderly
 Particles move parallel to the tube walls
 Flow is fastest in the center
• where friction is the least

193
Q

Laminar flow equation

A

 change in P = (L x v x V)/r4
• L = length
• v = viscosity of gas
• V = flow rate

194
Q

How does laminar flow relate to length, viscosity, flow rate and tube diameter

A

Directly r/t:
length, viscosity, flow rate

Inversely r/t
tube diameter (to the 4th power!)
195
Q

Describe movement of turbulent flow

A

 Flow lines are not parallel

• ”Eddies”: particles moving across or opposite

196
Q

Types of turbulent flow

A

 Generalized
• When flow exceeds critical rate
 Localized
• Encounters constrictions, curves, valves

197
Q

What is the significance of resistance and breathing

A
  • Parallel changes in work of breathing

* ETT probably causes more resistance than breathing system

198
Q

How do flow rate and location differ between laminar and turbulent flow

A

laminar = faster in the middle, straight path

turbulent= same across diameter of tube, occurs @ turns

199
Q

How much is too much resistance in a breathing system

A
  • How much is too much???
  • Imposes strain where pt is doing spontaneous work
  • No common agreement
  • watch flow-volume loops
200
Q

How does turbulent flow affect breathing

A

It alters work of breathing d/t increased resistance (turbulent?) from tubes

increased resistance = increased WOB

201
Q

Reason flow-volume loop can be altered by increased breathing system resistance?

A

Changes in the loop d/t:
pt assist less often
pt has Less effort/Vt
pt has Less neg inspiratory pressure

appears as hypoventilation on loop

202
Q

What is compliance and it’s significance in respiration

A

 Ratio of ∆ in volume to ∆ in pressure
 Measures distensibility (mL/cm H2O)

significance: helps determine Vt

203
Q

Identify turbulent vs laminar flow on slide 8 of breathing system lecture

A

straight lines are laminar flow
dots are turbulent flow

drawing B = example of turbulent flow exceeding critical rate

204
Q

In regards to breathing systems, what equipment is most distensible

A

breathing circuit

reservoir bag

205
Q

What is rebreathing

A

 “To inhale previously inspired gases from which CO2 may or may not have been removed”

206
Q

What influences rebreathing in the breathing systems

A
  • Fresh gas flow
  • Dead space
  • Breathing system design
207
Q

How does FGF relate to rebreathing and when does it occur

A

Amt of rebreathing varies
 Rebreathing is inversely r/t FGF
 ↑FGF then ↓ rebreathing
 ↓FGF then ↑ rebreathing

208
Q

What are fail-safes in the system to prevent rebreathing

A

insp and exp valve

separation of insp and exp limbs

209
Q

What can be a benefit of rebreathing

A

utilizing remain volatile

210
Q

How do FGF and Vm relate to rebreathing

A

If FGF is =/> Vm rebreathing DOES NOT occur
 as long as exhaled gas is vented

If FGF is < Vm rebreathing DOES occurs to meet required Vm

211
Q

How can FGF rate be utilized in induction, maintenance and emergence

A

FGF rate can help speed or slow induction and emergence

Rebreathing can help with maintenance

212
Q

3 types of dead space

A

mechanical
anatomic
alveolar

213
Q

What is mechanical dead space and how does this effect rebreathing

A

aka apparatus dead space
 ↓ by having INSP and EXP limb separation
• Separation as close to pt as possible

 rebreathed gases in breathing system; gases don’t change in composition

214
Q

What is anatomical dead space and how is affected by breathing systems

A

No gas exchange in pts conducting airways to alveoli
-Adds H2O vapor

Breathing sys effect:
 ↓ by ETT, tracheostomy (smaller diameter)
 ↑ by circuits, masks, humidifiers (on pt side of insp/exp limb split)

215
Q

What is alveolar dead space

A

volume of alveoli ventilated but not perfused (opposite of shunt)

216
Q

Effects of rebreathing

A 
Retain Heat and moisture retention (increase vapor)
Altered gas tensions (inc/dec PP)
	O2 
	Inhaled anesthetic agents
•	Induction
•	Emergence
	CO2
217
Q

6 desirable characteristics of a breathing system

A

 1. low resistance to gas flow
 2. minimal rebreathing
 3. removal of CO2 at rate of production
 4. rapid changes in delivered gas when required
 5. warmed humidification of inspired gas
 6. safe disposal of wastes

218
Q

classifications of breathing systems

A 
Open (face mask, NC)
	No reservoir &amp; no rebreathing
Semi open (mapleson system)
	A reservoir but no rebreathing
Semi closed
	A reservoir and partial rebreathing
Closed 
	A reservoir and complete rebreathing… but depends on FGF
219
Q

Increased volume delivery with breathing systems concerns

A

 volume of patient or leaks in system

 Modern ventilators designed to eliminate

220
Q

Decreased volume delivery by breathing system concerns

A 
	Results from
•	leaks in circuit
•	gas compression 
•	distention of circuit
	Called “wasted ventilation” (increase in container size)
221
Q

What are 4 discrepancies in gas concentration in a breathing system

A

Dilution
Leaks
Uptake by breathing system components
Release by breathing system components

222
Q

How does dilution or leaks in breathing system affect gas concentration

A

Dilution
 FGF < Vt & leaks in system
 Room air entrained
Compensate by increasing dial–pt response more important than ##

Leaks
 Gas forced out of system
• During positive pressure ventilation
-may not even be able to ventilate pt

223
Q

How does uptake by uptake of gas by system components affect gas concentration in breathing system

A

 May adhere to plastics, rubber, absorbent
 Related to time, surface area
 minuscule absorbance over time

224
Q

How does release of gas by breathing system components affect breathing system gas concentration

A

 Low output
• even after vaporizer turned off
 Inadvertent exposure–think MH – flush system w/ FGF or use non-volatile machine
 Can be released next time used

225
Q

What are the 8 components

A 
	1. breathing tubing
	2. respiratory valves
	3. reservoir bag
	4. carbon dioxide absorption canister
	5. a pop-off valve leading to scavenging
	6. a fresh inflow site
	7. a Y-piece with mask/tube connectors 
	8. a facemask, LMA, or ETT
226
Q

Fit and design of face mask

A 
	Must be clear
	Inflatable or inflated cuff
	Pneumatic cushion that seals to face
	Fits between the interpupillary line and in the groove between the mental process and the alveolar ridge
	Connect to the Y-piece or connector 
	with a 22 mm female connection
227
Q

Why are face masks clear

A

to be able to visualize vapor, vomitus, blood

228
Q

Purpose of breathing system connectors/adapters and their benefits

A

 A fitting to joint together 2 or more components

Benefits
 Extend distance btwn patient & breathing system
 Change angle of connection
 Allow more flexibility/less kinking

229
Q

What are the potential negatives to breathing system connectors/adapters

A

Potential negatives…
 ↑ resistance
 ↑ dead space (WHERE?)
 ↑ locations for disconnects

230
Q

Reservoir bag design (shape, volume, pressures, material etc)

A

 Rubber, plastic, or latex free
 Ellipsoidal for 1 hand
 3-L traditional for adults
 0.5-6 L
 Must have 22 mm female connector on neck
 When bag extended 4x its size…Pressure 35-60 cm H2O

231
Q

Breathing system reservoir bag function

A 
1. Allows gas accumulation 
•	reservoir for next breath
2. A means of assisted ventilation
3. Visual/tactile monitor of breathing
4. Distensibility 
•	Protects from excessive airway pressure
232
Q

Why is proper facemask fit important

A

Prevent corneal pressure

Prevent pressure trauma by “E” hand

233
Q

Female and male connector sizes

A

Female = 22 mm

Male =

234
Q

How does adapter/connector angle affect tube

A

can help prevent kinking

235
Q

How are adapters useful during surgery

A

can move circuit away from surgical site

Some can allow for passage of bronchoscope or suction

236
Q

What are sources of anesthetic gas contamination

A 
	APL valve
	High and intermediate pressure systems
	Low pressure systems
	Ventilator
	Anesthetic errors
	Cryosurgery
237
Q

What is the APL purpose

A

 Outlet for anesthetic gases during spontaneous ventilation and assisted ventilation

238
Q

Design and functional design of the APL valve

A

Depending in FGF
• 5L/min can exit through this valve
• >Vm

Is spring loaded
• only requires minimal positive pressure to open and Allow the exit of waste gas from the circuit

239
Q

Where and how do high/intermediate pressure system leaks occur

A 
Location 
	N2O pipeline 
	cylinder supply 
	the machine piping 
•	that feeds the N2O flowmeters 
•	common site of leaks are connections

How
Leaks in this system can increase waste gas in the OR
• May not be able to hear leak

240
Q

Where can leaks of low pressure system occur

A 
Leaks can occur at 
 CO2 absorber
	Due to 
•	loose seals/connections at valves and circuit
•	vaporizer mount,
•	scavenger system
241
Q

What is included in the low pressure system where gas leaks can occur

A 
	N2O flowmeter
	Vaporizers
	fresh gas lines from the machine to the breathing circuit
	CO2 absorber
•	Ensure it’s seated properly
	breathing hoses
	unidirectional valves
	ventilator
	various components of the scavenger system 
•	bad connections 
•	system overload
242
Q

Why can gas leaks occur at the scavenger system?

A

Bad connections

System overload

243
Q

If you suspect a gas leak at the CO2 absorber, what can you do?

A

Ensure the CO2 absorber is seated properly

244
Q

What can cause leaks in the breathing circuit system

A 
High peak pressure
	can cause leaks in this system 
•	even w/ a functioning scavenger system
•	can have a 2L/min leak
	esp if pressure is greater than what system can handle
245
Q

What can be a major source of gas leak

A

Ventilator
Anesthetic errors
 94-99% of waste gas is due to this

246
Q

How can ventilator leak occur, and what’s the biggest problem when it happens?

A

Can leak internally
• causing the mixing of gases
• can’t really determine concentration of delivered gas

247
Q

What issues may occur as a result of ventilator leak

A

Vent will alarm
• Low Vt
• Alteration in RR
• Issues w/ pressures

248
Q

Causes of anesthesia technique errors

A
  • Insufflation errors of system
  • N2O on w/ open circuit
  • Poor airway seal
  • Uncuffed tracheal tubes
  • Post procedure circuit disconnection
  • Overfill and gas spillage around vaporizer
  • Letting active gases exit open circuit
249
Q

Why do leaks occur with cryosurgery

A

 d/t use of liquid N2O as a tool intraop
 to freeze off cells
 Gas evaporates intraop and into the OR

250
Q

Requirements and design for breathing tubing in the breathing systems

A

 Large bore, corrugated, plastic, expandable
 1 meter in length
 400-500 ml/m of length
 Low resistance
 Flow always turbulent due to corrugation
 Somewhat distensible

251
Q

How does breathing tubing affect the dead space. What Type of DS?

A

 Apparatus DS = only from Y piece to patient (after limb split)
• d/t unidirectional gas flow
 ….longer tubes don’t ↑ DS

252
Q

Purpose of and problems with the unidirectional valves in breathing systems

A

Purpose:
 Ensure gases flow toward pt
 In one breathing tube and away in another

Problem:
 Failure to seal
 Causes a large amount of the circuit into mechanical dead space

253
Q

Manufacturing requirements for unidirectional valves.

A 
Requirements:
	Arrows or directional words
	Hydrophobic so it doesn't stick
	Clear dome 
	Must be placed btwn patient &amp; reservoir bag
•	Prevent rebreathing
254
Q

APL open/close direction

A

Clockwise motion = INCREASE pressure (CLOSES valve)
motion ↓↓ pressure

Counterclockwise motion = DECREASE pressure (OPENS valve)

255
Q

Function of the APL in the breathing system

A

 “pop-off” = over pressure pops-off somewhere else
 User-adjustable
 Controls pressure in breathing system
 Releases gases to scavenging system
 An arrow must indicate direction to close valve

256
Q

APL position with inspiration and expiration during
Spontaneous resp
Assisted ventilation
Mechanical ventilation

A

Spontaneous resp:

  • insp = OPEN (CPAP partially closed)
  • exp= OPEN

Assisted ventilation:

  • insp = partially open (excess diverted)
  • exp= partially open

Mechanical ventilation:

  • insp = bypassed
  • exp= bypassed
257
Q

Components of mapleson system

A 
	Reservoir bag
	Corrugated tubing
	APL valve
	Fresh gas inlet
	Patient connection
258
Q

What components are not included in the mapleson system

A

 CO2 absorbers
 No scavenging
 Unidirectional valves (inc rebreathing)
 Separate INSP & EXP limbs (rebreathing/DS increased)

259
Q

Where is the respiratory gas monitoring piece located in the breathing system

A

Between tracheal tube and corrugated tubing

260
Q

Anatomy and problem with Mapleson A system (aka…)

A

 FGF enters opposite of pt end
 APL at pt end

Problem:

  • FGF would be vented prior to reaching the pt if APL open
  • Can waste the FGF
  • Could just use a NC
261
Q

What is Mapleson A most efficient for

A

• Spontaneous, unassisted pts

262
Q

Anatomy, use and problem with mapleson B system

A

 APL and FGF at T piece
 Much of FGF is vented

Problem:
 inefficient, wasteful
 FGF should be double Vm

 USE: Obsolete

263
Q

Anatomy and use of mapleson A system

A
  • Identical to mapelson B EXCEPT corrugated tubing omitted
  • Lost a lot of DS
  • FGF DOUBLE Vm
Use:
Emergency resus (Ambu-bag)
264
Q

Anatomy and benefits of Mapleson D system

A 
Anatomy:
 3 way T- piece
•	pt connection 
•	fresh gas
•	corrugated tubing
	PEEP valves may be added
Benefits
•	Very popular
•	most efficient for assisted
•	controlled ventilation
•	FGF 1.5-3x Vm
265
Q

Mapleson D modification

A

Bain modification

Made FGF coaxial (exhalation tubing on outside of corrugated tubing for warming)

266
Q

What is not included with mapleson E system

A

No reservoir bag or APL valve

along with no CO2 absorber etc

267
Q

Mapleson E system anatomy and use

A

 Corrugated tubing
• attached to the T-piece forms reservoir

Use:
 Used in spontaneously breathing pts to deliver O2
• Not used in anesthesia d/t no reservoir and difficulty scavenging gases

268
Q

Anatomy and differences of Mapleson F system (aka…?)

A

aka Jackson-Rees modification
 Mapleson E system PLUS Reservoir bag added
 Difficult to scavenge
 Excessive pressure less likely to develop
• Occlude vent hole at end of bag
• No APL valve

USE:
Pediatric patients

269
Q

Kane lecture 2:04::14 @ pg 34

A

Other cards still @ pg 20

270
Q

4 miscellaneous sources of gas leakage

A

 Use of volatiles in CPB (card-pulm bypass) & lack of scavenging
 Diffusion of vapor from circuits and from the pt’s surgical wound & skin
 Cross-contamination of fresh air & exhaust ducts
 Failure to scavenge waste gas appropriately

271
Q

What are two types ventilation systems in the OR ?

Which is most common?

A

Nonrecirculating (most common)

Recirculating

272
Q

What is the setup of the nonrecirculating OR ventilation system

A

• pumps in air from outside
• removes stale air w/ a variable number of air exchanges/hour
 >/= 10/hr is recommended

273
Q

What are considerations for the nonrecirculating OR ventilation system

A

 airflow pattern
 workstation location
 generation of airflow

274
Q

Why is the type of flow for OR ventilation systems important? What type of flow?

A 
Laminar flow in nonrecirculating systems 
•	optimal 
	to prevent air mixing 
	reduce hot spots
•	which are heavily contaminated
275
Q

What are the advantages and disadvantages of the recirculating OR ventilation system?

A

Advantages:
More economical

Disadvantage:
Partially recirculates stale air

276
Q

How does air exchange in the recirculating OR ventilation systems?
Where are they most popular and why?

A

Exchange:
Each air exchange has
• part fresh outside air
• part filtered and conditioned stale air
 Not complete removal of gasses/contaminants

Location:
• popular in locations with temp extremes
• more efficient
• air pockets by waste gases

277
Q

What is the recommended air exchange rate for OR ventilation systems.

A

 recommended to have 15-21 air exchanges/hr

• three must have outside air

278
Q

How much do scavenging systems reduce trace concentration of gases?

A

90% reduction of waste gases

279
Q

What are the 4 parts of the waste gas scavenging system

A 
1. Relief valves
•	APL 
•	ventilator pressure relief
2. tubing to the scavenging interface,
3. interface
4. disposal line
280
Q

What is the function of the ventilator pressure relief valve?
How does it work?

A

Purpose=how waste gases leave the ventilator
• during inspiration

How it works:
• valve is closed d/t positive pressure transmitted from ventilator

281
Q

What is the purpose of the conducting tubing

A

It moves waste gas from the APL and ventilator pressure relief valve to the scavenging interface

282
Q

What are safety mechanisms incorporated with the scavenging interface

A

It is equipped w/ relief valves between circuit and vacuum or ventilation system and can have an open or closed reservoir

283
Q

What are two types of scavenging interfaces

A

Closed

Open

284
Q

Describe the closed scavenging interface. How it works, what happens if the system fails

A

How it works:
• includes a bag for waste gas
• then sent to vacuum or ventilation system

Failure:
•	If the vacuum system fails
•	there is excess pressure in the reservoir bag which causes the APL to open 
	vent waste gases into the room
	visual over-distention
285
Q

How does the open scavenging system interface function? What is and isn’t included?

A
  • It is valveless
  • uses continually open relief ports to avoid positive or negative waste gas buildup

Not included:
• NO valves

Includes:
• a flowmeter to show the waste gas being evacuated;
• may incorporate a reservoir bag

286
Q

Pg 21

A

See Q 269

287
Q

2 types of gas disposal routes. Describe each

A

 may be active or passive

active  using a vacuum or evacuation system

passive the OR ventilation system or the wall disposal

288
Q

Newer scavenging systems setup and benefits

A

 consider the use of low flow scavenging systems
• that don’t function when anesthesia is not being given to
• ↓ costs
• ↓ carbon footprint

289
Q

Requirements for active disposal routes

A
  • suction/vacuum systems

* should be able to vent at least 30 L/min of air

290
Q

What is the optimal setup for scavenging vacuum system

A

Separate vacuum systems to vent anesthetic gases

291
Q

Scavenging requirement for anesthesia ventilators

A

 Ventilators have a disposal system

 sends waste gases to the scavenger system

292
Q

Problems with older machine and ventilator scavenging

A

Older machines
 may vent waste gases into the air
 may not have a scavenging connection

Older ventilator
 may have leaks that cause gas mixing
 & ↑ amount of gas that must be vented
• may overwhelm the scavenging system

293
Q

Scavenging hazards (6)

A

 Scavenging of the breathing circuit
 Excessive positive or negative pressure in the scavenger system
 Can cause CV insult or barotrauma
 Can cause abnormal pressure in breathing circuit
 Ventilator drive gas can be wasted
 Large amounts of volatile waste released into atmosphere

294
Q

How can excessive positive and negative pressure in the scavenger system

A

 d/t malfunction

• can be directed into the breathing circuit

295
Q

Page 22

A

Page 22

skipped 2nd half of pg 33

296
Q

What are types of absorbents (4)

A

high-alkali
low-alkali
alkali-free
lithium hydroxide

297
Q

What is the high-alkali absorbent type

A
  • Traditional  ie. Soda lime
  • High amts of K/NaOH
  • When desiccated form CO
  • Form Compound A w/ Sevoflurane
  • Do not change color if dry
298
Q

What is low-alkali absorbent type

A

 ↓decrease amts of K/NaOH

 May produce lesser CO & Compound A

299
Q

What is alkali-free absorbent type

A 
	Contains calcium hydroxide
	No CO formation
	No Compound A formation
	Changes color if dry
	Poorer CO2 absorber
300
Q

What is lithium hydroxide absorbent type

A 
	Reacts w/ CO2 to form carbonate
	Does not react w/ anesthetic agents
	Expensive
	Care with handling
•	burns to skin, eyes, lungs
301
Q

What are the actual absorbents used shape and size. how are they measured.

A 
Pellets or granules
• Smaller granules
•	Greater surface area
•	Decrease gas channeling
•	Increase resistance and caking
	Hardening agent used to decrease dust

 Measured by mesh number
• 4-mesh= 4 openings/sq inch
• 8-mesh= 8 openings/sq inch

302
Q

Absorbent byproducts (3)

A
  1. Haloalkene formation
  2. Compound A formation
  3. CO
303
Q

What is haloalkene formation

A

 Produce during closed circuit anesthesia w/ halothane
 Produces BCDFE
• 2-bromo-2chloro-1,1-difluoroethene
 Nephrotoxic in rats

304
Q

What is compound A formation

A

 2-fluoromethoxy-1,1,3,3,3-pentafluoro-1-propene

 Possibly nephrotoxic in humans

305
Q

When can compound A form

A 
	Occurs with 
•	Low FGF
•	Absorbents containing K or NaOH
•	Higher sevo concentrations
•	Longer anesthetics
•	Dehydrated absorbent
306
Q

What contributes to CO production

A
  • Dry absorbent w/ strong alkali
  • Many Monday1st case
  • Remote locations
307
Q

What type of reaction occurs when CO is formed from the CO2 absorbent

A

 Reaction is exothermic

• note canister

308
Q

What is the problem with the formation of CO from the CO2 absorbent

A

Not detected by pulse ox or RGM

Highest levels seen w/ des

309
Q

What are APSF recommendations for CO2 aborbent use

A

 ALL gas flows turned off after each case
 Vaporizers turned off when not in use
 Absorbent changed at least weekly
 Machines rarely used should have fresh absorbent
 Packaging intact before use or thrown away
 No supplemental O2 through circle system
 Temperature of canister monitored (CO=exothermic)
 Change when CO2 appears

310
Q

What are manual resuscitator components

A 
	Self-expanding Bag
	Non-rebreathing Valve
	Body
	Bag Inlet Valve
	Pressure-limiting Device
	Oxygen-enrichment Device
	Reservoir
311
Q

Describe the manual resuscitator bag

A
  • Inflated in resting state
  • Expands on exhalation
  • If O2 delivery source inadequate
  • difference is made up by room air
  • Rate at which bag reinflates determines Vm
312
Q

How can Vm be estimated when using the manual resuscitator bag

A

• Rate at which bag reinflates determines Vm

313
Q

Describe the non-rebreathing valve of the manual resuscitators

A 
“exhalation valve”
	Gas flows out of bag 
•	into patient on inspiration
	Gas flows out 
•	expiratory port on expiration
314
Q

Describe the body of the manual resuscitator

A

 Connector connects to ETT or mask
 Swivels
 Deflects exhaled gas
 Housing is transparent

315
Q

Describe the pressure limiting device of the manual resuscitator

A

 “pop off”
 Protects against barotrauma
 Helps prevent gas from entering stomach

316
Q

ATSM standards for pressure limiting device of the manual resuscitator

A

•If pressure limited at 60 cm H2O = must have override

  • If override can be locked
  • must be apparent
  • should have an alarm when override operating
317
Q

What are two locations of O2-enrichment devices on manual resuscitator

A

Near bag inlet valve

Directly into bag

318
Q

How do O2-enrichment devices workand concentrate O2 for near bag inlet valve

A
  • O2 concentration d/t air drawn into bag

* The greater the Vmthe lower the O2 concentration

319
Q

How do O2-enrichment devices work and concentrate O2 directly in bag

A
  • High delivered O2 concentrations
  • If flow is less than bag filling rate
  • then inlet valve will admit air
320
Q

What are the disadvantages of small or large reservoir bags

A

Small
• may limit O2 concentration

Large
• Cumbersome

Principles of Anesthesia I (4 decks)

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