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001 Respiratory Therapy > Anesthesia Equipment > Flashcards

Flashcards in Anesthesia Equipment Deck (116)
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1
Q

What does an anesthesia delivery system consist of

A

An anesthesia delivery system consists of the anesthesia workstation (anesthesia machine) and anesthetic breathing system (circuit)

2
Q

What is the function of the Anesthesia Machine

A

Delivers known concentrations of inhaled anesthetics and medical gases to the patient, as well as removes of the patient’s carbon dioxide through a CO2 absorber or a scavenging system

3
Q

Electrical and Pneumatic Power Sources

A
  • On and off switch
  • Inlet of hospital pipeline
    • Oxygen, nitrous oxide, and medical air
  • Inlet of compressed gas cylinders
  • Power failure indicator
    • Visual/audible alarms
    • Reserve power system
4
Q

Pressure Regulators

A

Reduce pipeline and cylinder pressures

5
Q

Oxygen Fail Safe Device

A

Prevent delivery of hypoxic gas mixture in the event of low or failed O2 supply (when O2 supplies drops below 30 psi)

Proportionately decreased (or shuts off) flow of all gases

Oxygen analyzer required and supply failure alarm

6
Q

O2 Flush Control (emergency O2 flush valve)

A

By passes the flow meters and vaporizers

“O2+“

35-85L/min through the circuit to flush out anesthetic gases

Activated by demand, designed to prevent accidental activation

7
Q

Flow Meters

A

Low pressure and precisely controlled gas flow

An oxygen analyzer is still needed in order to confirm the correct delivery of oxygen

8
Q

Flowmeter Sequence

A

The flow meter sequence matters

Oxygen should always be downstream to other gases and closest to the patient

Oxygen delivery is preserved in the event of a leak upstream

9
Q

Common Gas Line

A

Fresh Gas outlet (fresh gas flow)

A mixture of medical gases and volatile anesthetics

Common gas outlet directs anesthetic mixture to be delivered to the patient

10
Q

Breath Limb Components

A

Oxygen Analyzer

Inspiratory and Expiratory one-way valves

Large bore corrugated tubing

The adjustable pressure limiting valve (APL)

Expiratory gas sampling line and spirometer

CO2 Absorber

Reservoir Bag

Mechanical vent

Scavenger system

11
Q

What side should the oxygen analyzer be on

A

inspiratory side

12
Q

Mechanical Ventilator on the Anesthetic Machine

A

There is a bag/vent selector switch

Modern machines will have the same functions as the ICU vent

powered pneumatically or/and electrically

Bellows

Humidity (both passive and active)

13
Q

Scavenging System

A

Collects and removes vented gas from OR

Active or passive

14
Q

Vaporizers

A
  • Volatile anesthetics are liquids at room temperature and atmospheric pressure.
  • A vaporizer will convert a liquid to a vapor and will take place into a closed container known as a vaporizer
15
Q

Precision and Accuracy of vaporizers

A

Must be precise and accurate and is just as important as the delivery of gases

A measured amount of volatile gas is dispensed into the fresh gas mixture

16
Q

Flow Over Method of Vaporization

A

Gas flows over the liquid agent and becomes saturated

17
Q

Vaporizers variable bypass

A

The gas flow passing through the vaporizer is split

The amount passing into the vaporizing chamber is “variable” (based on operator adjusting the settings), and the rest bypasses the vaporizing chamber

18
Q

Agent Specific Vaporizer

A

Each vaporizer is constructed to a specific volatile agent

Receiving port will only fit the filling spout for its particular anesthetic

19
Q

Vaporizer Classification

A

–Agent-specific

–Variable bypass (concentration calibrated)

–Flow-over

–Temperature-compensated

Out-of-circuit

20
Q

Color Coded Vaporizers

A

the vaporizer, spout, and bottle will all be color coded

21
Q

What is the color-coded vaporizer for Isoflurane

A

Purple

22
Q

What is the color-coded vaporizer for Desflurane

A

Blue

23
Q

What is the color-coded vaporizer for Sevoflurane

A

Yellow

24
Q

Anesthesia Machine Safety Feature

Alarms

A

–Analyzer alarms (oxygen concentration)

–Disconnect/power failure/machine alarms

–Low flow

–Ventilator alarms

25
Q

Anesthesia Machine Safety Feature

Oxygen Fail Safe Valve

A

–Prevents hypoxic gas delivery

26
Q

Anesthesia Machine Safety Feature

Oxygen Flowmeter

A

–Control is often different from other gases

–Oxygen Downstream

27
Q

Anesthesia Machine Safety Feature

Cylinders

A

–Built and tested to specified standards, color-coded

–PISS connectors, safety pressure relief

28
Q

Anesthesia Machine Safety Features

Vaporizer Safety Features

A

–Flowmetercontrols for oxygen and nitrous are linked

–Ratio must always be at LEAST 1:3 (oxygen:nitrous)

–Prevents <25% oxygen delivery

29
Q

Anesthesia Machine Safety Features

Minimum O2/N2O Controller

A

–Flowmetercontrols for oxygen and nitrous are linked

–Ratio must always be at LEAST 1:3 (oxygen:nitrous)

–Prevents <25% oxygen delivery

30
Q

Anesthesia Machine Safety Features

Machine Checks and Alarms

A

Daily pre-use machine check

Quick check between cases

31
Q

Anesthesia Machine Safety Features

Back Pressure Check Valve

A

Prevents back pressure from PPV going into the machine

32
Q

Anesthesia Machine - Circuits Components

A

–Gas reservoir bag in circuit

–Rebreathingof exhaled gases

–Chemical neutralization of CO2

–Unidirectional valves

33
Q

Anesthesia Machine - Circuits Classified

A

Open

Semiopen

Semiclosed,

Closed

34
Q

Most common anesthesia machine circuits

A

}Most common are Mapleson F, Bain, and circle system

35
Q

Mapleson Circuit

A

Six different designs

36
Q

Bain Circuit

A

Modification of Mapleson D System

37
Q

Circle Circuit

A

Most popular system in Canada/US

Clsoed or semi closed circuits

38
Q

Components of the Mapleson Circuit

A

–FGF, reservoir tubing, facemask, reservoir bag, expiratory valve (to administer anesthetic)

–Varying arrangements

39
Q

Mapleson Circuit -Semiopen

A

–No valves to direct gas flow

–No CO2 neutralization

Because of no clear separation of inspired and expired gases, rebreathing occurs when inspiratory flow exceeds the fresh gas flow.

40
Q

Mapleson Circuit Optimal Fresh Gas Flow

A

–Difficult to determine optimal FGF

–Amount of rebreathing depends on FGF

–Best way is to monitor EtCO2

  • In order to prevent rebreathing of exhaled gases a fresh gas flow of 2-3 times the patient minute ventilation is recommended
41
Q

Mapleson F (Jackson-Rees)

A
  • Modification of the Mapleson D
  • Has a pressure limiting overflow valve on the reservoir bag
  • Used for pediatric anesthesia or transport because of minimal dead space and resistance
42
Q

Mapleson F (Jackson-Rees) Disadvantages

A

–Requires high FGF to prevent rebreathing

–Potential for high airway pressure, barotrauma (if valve is occluded)

–No humidification system

Pollution of atmosphere with anesthetic gas (can be hooked to scavenging system

43
Q

Bain Circuit

A

Modification of Mapleson D

–Coaxial version

–Still has no CO2 neutralization, or valves to direct flow

44
Q

Bain Circuit Advantages

A

–FGF is warmed by exhaled gases

–Moisture (from partial rebreathing)

–Easy scavenging of waste gases from overflow valve

45
Q

Bain Circuit Disadvantages

A

–Disconnect or kinking of inner FGF tubing

–Requires high FGF

46
Q

What is the most common type of circuit

A

Circle Circuit

47
Q

Circle circuits semiopen, semiclosed, or closed

A
  • –Depends on amount of FGF
  • –Rebreathingof exhaled gases
    • –Conservation of moisture and heat
    • –Decreased pollution of exhaled anesthetic gas
48
Q

Circle Circuits Disadvantages

A

–Increased airway resistance in system

–Bulky, not portable

–Higher risk of problems/malfunction

49
Q

Circle Circuits Components

A

–Insp/Exp unidirectional valves

–Insp/Exp corrugated tubing

–APL valve, reservoir bag

–CO2 Absorbent

–Bag/Vent selector switch, ventilator

50
Q

Closed Circle Circuit

A

Total rebreathing of exhaled gases

51
Q

Closed Circle Circuit Advantages

A

–Max warming and humidification of inhaled gases

–Less pollution of atmospheric exhaled gases

–Economical

52
Q

Closed Circle Circuit Disadvantages

A

–Can not make rapid changes to delivered concentration of anesthetics or O2

Unpredictable concentrations of anesthetic and O2

53
Q

Non-Invasive Types of monitoring

A

–Electrocardiography (ECG)

–Blood Pressure Cuff

–PulseOximetry

–Capnography

–BispectralIndex (BIS Monitor)

–Temperature Monitoring

–Neuromuscular Twitch (NMT Monitor)

54
Q

Invasive Types of Monitoring

A

–Central Venous Pressure (CVP)

–Pulmonary Artery Pressure (PAP)

–Blood Pressure (Arterial Line)

–Minimum Alveolar Concentration (MAC)

55
Q

ECG

A

–Heart rate, rhythm, waveforms

–3-lead, 5-lead, 12-lead

56
Q

Blood Pressure Monitoring

A

–Automatic cuff, appropriately-sized

–Systolic/Diastolic

57
Q

BIS Monitoring

A

–Level of consciousness (EEG activity)

–Usually aim for 40-60 for healthy patient and routine anesthesia

58
Q

Temperature Monitoring

A

–Can be “invasive” (oral or nasal temp probes)

–Normal for temp to drop after induction

–Cold patients can have a lot of other difficulties

59
Q

NMT Monitoring

A

–Train of Four

–Measures patient’s level of paralysis

60
Q
A

Normal capnography

Shows the changes in CO2 throughout breath cycle

61
Q
A

Decrease EtCO2 Levels

Hyperventilation

Decrease in metabolic rate

Decrease in body temp

62
Q
A

Increasing EtCO2 Levels

Hypoventilation

Increased metabolic rate

Rapid rise in body temp- May be MH

63
Q
A

Rebreathing

Malfunction of CO2 absorber (or needs to be changed)

Insufficient inspiratory flow, or expiratory time

Partial rebreathing circuits

Expiratory valve failure

64
Q
A

Airway Obstruction

Obstruction in breathing circuit

Upper airway obstruction (foreign body?)

Kinked or occluded ETT

Bronchospasm

65
Q
A

Muscle Relaxants

  • NMBA wearing off
  • Patient is triggering breaths again
66
Q
A

Esophageal ETT

-May not see ANY CO2, or may only see small, transient waves

67
Q

1.0 MAC

A

–Concentration of anesthetic required to suppress movement in 50% of patients in response to pain

–Measured as the end-tidal concentration of anesthetic gas

–0.8-1.2 MAC

68
Q

MAC Variation

A

Varies with each person

–Age

Medications or Illicit drug use

69
Q

Ventilation Monitors

A
  • Capnography
  • Spirometry
    • –Volume, and flow waveforms
  • Oxygen Analyzer
    • –FIO2 and EtO2
  • Airway Pressures
    • –Low/High Alarms
    • –PEEP
  • Volume
    • –Low/High Alarms
70
Q
A

Mapleson A

71
Q
A

Mapleson D

72
Q
A

Mapleson B

73
Q
A

Mapleson E

74
Q
A

Mapleson C

75
Q
A

Mapleson F

76
Q

Flowrate of the quick flush

A

35-75L/min

77
Q

Should the patient be hooked up to the circuit when using the quick flush?

A

NO- results in dangerous pressure in the breathing circuit which could result in pneumothorax

78
Q

Anesthetic Vaporizers

A

Change liquid anesthetic into vapor
Deliver selected % of vapor to the fresh gas outlet

79
Q

Quick Flush

A

Delivers intermediate pressure O2 bypassing the vaporizer

80
Q

Use for the quick flush

A

Quickly decrease gas percentage in circuit

Emergency or recovery

81
Q

Modern vaporizer compensations

A

Temp: Between 15-35C
Achieved using efficient heat conducting materials

Flow rate- 0.5-10 L/min

Back pressure- associated with positive pressure ventilation and flush valve

82
Q

Variable Bypass System

A

Delivers a specific concentration by flowing fresh gas over a reservoir of liquid anesthetic and mixing it from carrier gas

83
Q

What do you do if vaporizers are filled with the wrong anesthetic?

A

Drain and run 1L/min O2 until dry

84
Q

Common Gas Outlet

A

Where gas exits the vaporizer, connected by a hose to the fresh gas inlet

Universal for rebreathing and non-rebreating units

85
Q

Rebreathing system advantages

A
  1. Lower fresh gas flow rate
  2. Saves money
  3. Decreases pollution
  4. Patient breathes warm humidified air
86
Q

Non-rebreathing tube types

A
  1. Mapleson D
  2. Mapleson F
  3. Bain
87
Q

Rebreathing system disadvantages

A
  1. More components and potential for leaks
  2. Increased resistance for smaller patients
88
Q

Position of the pop-off valve

A

ALWAYS OPEN

Unless checking for leaks or administering positive pressure ventilation

If the pop off valve is closed Increases pressure in breathing system, Results in possible cardiopulmonary injury

89
Q

Breathing system pressure gauge

A

SHOULD ALWAYS BE ZERO

Except: performing leak checks or providing positive pressure ventilation

90
Q

Colour change in soda lime

A

White- fresh
Violet- exhausted

91
Q

Components of the Rebreathing system

A
  1. Fresh gas and O2 flush
  2. Unidirectional valves (inspiratory and expiratory)
  3. Breathing hoses
  4. CO2 absorber
  5. Adjustable pressure limiting valve aka pop-off valve
  6. Reservoir bag
92
Q

Signs of exhaustion

A
  1. Increase in tidal CO2
  2. Increased ventilation, HR/BP (then drop) if light enough
  3. Rebreathing capnograph
  4. Respiratory acidosis
  5. Red mucous membranes due to carbon monoxide production/inhalation
93
Q

Calculation for reservoir bag size

A

Tidal volume = 10-20mL/kg x 6

Round UP if between sizes

94
Q

Reservoir bag function

A

Observe ventilation, inspiratory reserve, administer manual positive pressure ventilation

95
Q

Non-rebreathing system components

A
  1. Fresh gas
  2. Non-rebreathing tubes
  3. APL (mapleson D) or open/close (mapleson F) valve
  4. Reservoir bag
96
Q

Non-rebreathing Advantages

A
  1. Very light with minimal dead space
  2. Minimal resistance to ventilation
97
Q

Non-rebreathing Disadvantages

A
  1. High Gas flow rate
  2. More expensive to run larger patients
  3. Increased environmental pollution
  4. Gas cold and dry
98
Q

Non-rebreathing Oxygen flow rates

A

2-3x tidal volume in most cases

200-300mL/kg/min O2

99
Q

Benefits of intubation

A
  1. Reduced anatomical deadspace
  2. Maintain inhalant anesthesia with minimal environmental contamination (with properly inflated cuff)
100
Q

What type of tube provides the least air resistance

A

Larger radium and shorter length (Poiseuille’s law)

101
Q

Hwo can carbon dioxide be removed from the anesthesia system

A
  • Carbon dioxide can be removed either by washout (delivered gas flow greater than 5 L/min from the anesthesia machine) or by chemical neutralization.
102
Q

Flowmeter Pressure

A
  • Anything prior to the flow meters is called the high pressure side and after is the low pressure side.
  • Gases are regulated to a typical operating pressure of 50 PSI
  • Back pressure compensated (Thorpe tube) type flow meters will then allow mixing of these gases in very accurate amounts.
    • All flow meters are calibrated to their specific gas.
  • Elongated or ‘I’ shaped flow indicators (rotameters) should be read at the upper edge —-ball shaped indicators must be read at the equator (as always).
103
Q

Flow Meters and Speific Gases

A
  • All flow meters are calibrated to their specific gas, because
    • Because few gases have the same density and viscosity, flowmeters are not interchangeable with other gases.
104
Q

Nitrous Oxide Tanks

A
  • Pressure gauges on nitrous oxide tanks do not serve as contents gauges like oxygen.
  • They are measuring only the vapour pressure of the gas above the liquid/gas interface.
  • N2O is stored as a liquid under about 750 PSI.
  • As the liquid phase changes to a gas, it creates a vapour pressure.
  • Therefore pressure gauges will read ‘full’ until all the liquid is converted and only the gas remains.
105
Q

Vapoorizers and Temperature Compensated

A
  • Some variable by-pass vaporizers have a temperature sensitive device that will increase the fraction of gas in the bypass circuit as the temperature falls thus ensuring a constant concentration of anesthetic vapour despite falling temperature.
106
Q

Desflurance and Temperature Compensation

A
  • Desflurane has a vapor pressure near 1 atm atm (664 mm Hg) at 20 C, nd for this reason , a desflurane vaporizer is electrically heated to 23C to 25C and pressurized with a backpressure regulator to 1500 mm Hg to create an environment in which the anesthetic has relatively lower, but predictable volatility.
107
Q

Circle Anesthesia System During Spontanesou and Positive Pressure Ventilation

A
  • During spontaneous ventilation, excess pressure may build during the last part of exhalation, and be allowed to vent at the pt. APL.
  • During positive pressure ventilation, excess pressure may build at the end of inspiration and be allowed to vent at the ventilator APL. (Pressure relief, depending on mode.)
108
Q

Advantages of the Circle System Anesthesia

A
  • Low flow rates are needed from the fresh gas outlet (economy)
  • Warming and humidification are achieved from the reaction sin the CO2 absorber
  • Reduced chance of overflow and therefore reduced pollution of theatre
109
Q

Transcutaneous Nerve Stimulation

A
  • Small hand-held electric devices are used to introduce a low voltage electrical stimulation to peripheral nerves.
  • The muscles’ reaction to these artificial stimulations can be interpreted by the clinician to quantify muscle block.
  • Supra-maximal stimulation (above that which is needed for muscle contraction) of a facial nerve or the ulnar nerve will yield a muscle twitch in a nerve that is not blocked.
  • A blocked nerve/muscle will not move.
110
Q

Transcutaneous Nerve Stimulation Modes

A
  • Single twitch—can identify if a non-depolarizing agent was used.
  • Train of Four—can indicate degree of block.
  • Tetany—can help identify correct dose of anticholinesterase etc. (post tetanic fasciculation).
111
Q

Train of Four Monitoring

A
  • When the last of the four responses in ‘Train of Four’ is absent, this correlates to about a 70% muscle blockade.
  • The last two absent, correlates to a 80% blockade.
  • The last three absent correlates to a 90% blockade
  • If no response is seen there is a complete block.
  • 90% is seen as adequate in most cases.
112
Q

Tetany

A
  • can help identify correct dose of anticholinesterase etc. (post tetanic fasciculation).
  • Three or more twitches present during emergence indicates little risk of problems with reversal agent.
113
Q

PETCO2 and Alveolar Gas

A
  • Very small Vt may cause increased PACO2 but a ↓PETCO2.
  • This may hinder its usefulness in weaning
    • Weaning patient seldom hyperventilate is a patient has their fear/anxiety/pain under control
    • Small Vt may increase PACO2 but decrease PetCO2 by just shuffling deadspace volume
  • Leak around ETT, unchanged PACO2 but ↓PETCO2
  • Leak in sampling system, unchanged PACO2 but ↓PETCO2.
114
Q

Increased PETCO2

A
  • Malignant Hyperthermia (medical emergency)
  • Decreased Alveolar Ventilation (VA)
  • Hypoventilation Decreased minute ventilation (VE)
  • Increased CO2 production: shivering, pain, fever
  • Seizures, sepsis, rebreathing, admin of HCO3
  • Exhausted carbon dioxide scrubber
115
Q

Increase in V/Q -Ventilation in Excess of Perfusion

A
  • Decrease PACO2
  • Examples
    • Pulmonary embolism
    • Decreased CO
      • Hypovolemia
      • Severe hypotension
      • Cardiac arrest
116
Q

Decreased PETCO2

A
  • ↑ VA —-well above metabolic need
  • Very low Vt, approaching dead-space volume
  • Low perfusion / ↓ cardiac output / arrest
  • Pulmonary emboli
  • ↓ CO2 production eg. Hypothermia
  • Accidental disconnection or extubation