ANESTHESIA MACHINE
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ANESTHESIA MACHINE







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ANESTHESIA MACHINE. ผศ.พญ.สมัญญา ทิศาวิภาต ภาควิชาวิสัญญีวิทยา คณะแพทยศาสตร์ มหาวิทยาลัยศรีนครินทรวิโรฒ. วัตถุประสงค์. เมื่อจบการบรรยายแล้ว นิสิตสามารถ อธิบายส่วนประกอบและหลักการทำงานของเครื่องดมยาสลบได้อย่างถูกต้อง จำแนกประเภทและเลือกใช้วงจรดมยาสลบได้อย่างเหมาะสม
ANESTHESIA MACHINE

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Slide 1

ANESTHESIA MACHINE

ผศ.พญ.สมัญญา ทิศาวิภาต

ภาควิชาวิสัญญีวิทยา คณะแพทยศาสตร์

มหาวิทยาลัยศรีนครินทรวิโรฒ

Slide 2

วัตถุประสงค์

เมื่อจบการบรรยายแล้ว นิสิตสามารถ

  • อธิบายส่วนประกอบและหลักการทำงานของเครื่องดมยาสลบได้อย่างถูกต้อง

  • จำแนกประเภทและเลือกใช้วงจรดมยาสลบได้อย่างเหมาะสม

  • บอกวิธีตรวจสอบเครื่องดมยาสลบและอุปกรณ์ต่างๆ ก่อนการใช้งานตามเกณฑ์มาตรฐานได้

Slide 3

Topics

1. Overview of anesthesia machine

2. Components and systems of anesthesia machine

3. Machine checklist

Slide 4

Overview of Anesthesia Machine

Slide 5

Overview of Anesthesia Machine

Slide 6

DEFINITION

A device which delivers a precisely-known but variable gas mixture, including anesthetizing and life sustaining gases.

Slide 7

Overview of Anesthesia Machine

Slide 8

BASIC FUNCTIONS

Slide 9

Overview of Anesthesia Machine

Slide 10

Models

Conventional anesthesia machine

Modern anesthesia workstation

Slide 11

Overview of Anesthesia Machine

Slide 12

Manufacturing Standards

  • 1988; American Society for Testing and Materials (ASTM) F1161-88

  • 1994; ASTM F 1161-94 (discontinued in 2000)

  • 2000; ASTM F 1850-00

    - Backup for 30 min

    - Monitors: breathing system pressure , exhaled VT ,

    ETCO2, Inhaled anesthetics conc.,

    FiO2, O2 supply pressure,

    SaO2, BP, and ECG.

    - Prioritized alarm system; high, medium, low priority

Slide 13

Topics

1. Overview of anesthesia machine

2. Components and systems of anesthesia machine

3. Machine checklist

Slide 14

Components and Systems

Slide 15

Components and Systems

Slide 16

Medical gas: Types

Slide 17

Machine gas inlet

  • Most machines have gas inlets for oxygen, nitrous oxide, and air.

  • Separate inlets are provided for the primary pipeline gas supply that passes through the walls of healthcare facilities and the secondary cylinder gas supply.

Slide 18

Medical Gas: sources

Slide 19

Pipeline system

  • The centralgas pipeline supply system is the primary source of gas supply for the anesthesia machine.

  • Oxygen is produced by fractional distillation of liquid air and stored as a liquid at -150 to -175oC in a large flask. Safety systems and regulators send oxygen to the hospital pipeline at ~50 psi; the "normal working pressure" of the anesthesia machine.

  • Nitrous oxide is stored as a liquid, at ambient temperature, in large tanks (745 psi- H tank) connected to a manifold which regulates the pipeline pressure to ~50 psi.

Slide 20

Pipeline system

Central gas pipeline supply system

Manifold

Multiple gas cylinders

Slide 21

Pipeline system

Central gas pipeline supply system

Cryogenic tank

Slide 22

Pipeline system

Connector at user terminal

A. Quick connector (Quick-coupler)

Slide 23

Pipeline system

Connector at user terminal

B. Diameter Index Safety System (DISS)

Slide 24

Pipeline system

Machine’s pipeline inlet

Diameter-Index Safety System (DISS)

Slide 25

Pipeline system

Machine’s pipeline inlet

  • The tubing is color coded and connects to the pipeline inlet of the machine through a noninterchangeablediameter-indexsafetysystem (DISS) fitting that prevents incorrect hose attachment.

  • The check valve, located down stream from the pipeline inlet, prevents reverse flow of gases (from machine to pipeline, or to atmosphere), which allows use of the gas machine when pipeline gas sources are unavailable.

Slide 26

Cylinder supply

The commonly used sizes are;

  • The H Cylinders

    - Sources of gas for small and infrequently used pipeline systems,

    - Intermediate or long-term sources of gas at the patient’s bedside, and

    - Backup source of oxygen, when stored in bulk, in case the pipeline of oxygen fails or is depleted.

Slide 27

Cylinder supply

The commonly used sizes are;

  • The H Cylinders

    - Sources of gas for small and infrequently used pipeline systems,

    - Intermediate or long-term sources of gas at the patient’s bedside, and

    - Backup source of oxygen, when stored in bulk, in case the pipeline of oxygen fails or is depleted.

Slide 28

Free-standing H Cylinder

Slide 29

Cylinder supply

  • The E cylinders

    - Backup sources of gas supply to the anesthesia machine, attached directly to the anesthesia machine via a yoke.

Hanger- yoke assembly

Slide 30

Cylinder supply

  • The E cylinders

    - Portable oxygen sources

Slide 31

Cylinder supply

Characteristics of gas cylinders

  • Material: Molybdenumsteel

  • Size: B, D,E, M, G, H or K

    Size E H

    Dimension 4.1/4” x 26” 9.1/4” x 51”

    volume 4.8 L 43.6 L

    Oxygen 1900 psig/660 L 2200 psig/ 6900 L

    Nitrous oxide 745 psig/1590 L 745 psig/15800 L

Slide 32

Cylinder supply

Characteristics of gas cylinders (cont.)

  • Color coding : Oxygen / Nitrous oxide /Air

  • Components:Cylinder valveis the most fragile part and consists of

    - body

    - port (where the gasexits)

    - stem (shaft)

    - handle or hand wheel (to open the valve)

    - safety relief device

    - conical depression (opposite the port, it accepts the tip of the screw which secures the cylinder in the yoke)

    - PISS pins (Pin Index Safety System)

Slide 33

Cylinder Valve

A small-cylinder packed valve

A large-cylinder packed valve

Slide 34

Pin-Index Safety System (PISS)

For small cylinder connection

Slide 35

Diameter-Index Safety System (DISS)

For large cylinder connection

Nipple and Nut

from Hose

Body at cylinder

Slide 36

Cylinder supply

Characteristics of gas cylinders (cont.)

  • Cylinder markings: certain codes are stamped near the neck on all medical gas cylinders.

    1.Cylinder specification: DOT, type and material used, service pressure (psi)

    2. Serial number

    3. Commercial designation

    4. Manufacturing data: date of manufacture and original test date, inspector’s official mark, Cylinder qualifies for 110% filling

    5. Manufacturer’s identifying symbol

    6. Retest markings: Data of first 5 year hydrostatic retest, Retester identifying symbol, Cylinder requalifies for 110% filling, Cylinder qualifies for 10-year retest interval.

    7. Neck ring owner’s identification

Slide 37

Cylinder supply

Cylinder markings

Owner’s Identification

Cylinder specification

Manufacturer’s identifying symbol

Cylinder serial No.

Commercial designation

Retest markings

Manufacturing data

Slide 38

Cylinder supply

Slide 39

Cylinder supply

Cylinder safety issues:

  • Standard quality control of cylinder

  • Prevention of wrong gas cylinder connections

  • Securing cylinder against breakage

  • Transfilling

  • Cylinder hazards:

    : improper filling: empty, partially filled, overfilled to near bursting pressures

    : contamination: volatile hydrocarbon

    : unlabeled, painted over (illegible), incorrectly color coded

    : fitted with incorrect valve outlet port, loose/inoperable valve assemblies

Slide 40

Cylinder supply

Machine cylindrical inlet

  • Cylinders attach to the machine via hanger-yoke assemblies that utilize aPISS to prevent errors.

  • Each yoke assembly includes index pins, a washer, a gas filter, and a check valve that prevents retrograde gas flow.

  • The E cylinders attached to the anesthesia machine are a high-pressure source of medical gases.

  • Cylinder pressure is usually measured by a Bourdon pressure gauge. A flexible tube within this gauge straightens when exposed to gas pressure, causing a gear mechanism to move a needle pointer.

Slide 41

Electrical power supply

  • Main electrical power is supplied to the machine through a single power cord which can become dislodged.

  • New gas machines must be equipped with battery backup sufficient for 30 minutes of limited operation. What functions remain powered during this period is device-specific.

  • Convenience receptacles are usually found on the back of the machine so that monitors or other equipment can be plugged in. These convenience receptacles are protected by circuit breakers (usually) or fuses.

Slide 42

Components and Systems

Slide 43

PROCESSING

  • High pressure system

    • Cylinder supply to pressure regulator

  • Intermediate pressure system

    • Pipeline supply to proportioning system

  • Low pressure system

    • Flowmeters to common gas outlet

Slide 44

PROCESSING: Gas Machine Piping

Slide 45

HIGH PRESSURE SYSTEM

Slide 46

INTERMEDIATE PRESSURE SYSTEM

Slide 47

LOW PRESSURE SYSTEM

Slide 48

HIGH PRESSURE SYSTEM

Consist of those parts which receive gas at cylinder pressure

Hanger Yoke (Connecting Yoke) for Cylinders

  • PISS

  • Gasket

  • Check valve

    Cylinder pressure gauge

    Cylinder pressure regulators (1st-stage regulators)

    Oxygen: from up to 1900 psig to 45 psig

    Nitrous oxide:from up to 745 psig to 45 psig

Slide 49

HIGH PRESSURE SYSTEM

Slide 50

HIGH PRESSURE SYSTEM

Hanger-yoke assembly

Slide 51

HIGH PRESSURE SYSTEM

Double hanger-yoke assembly

Slide 52

INTERMEDIATE PRESSURE SYSTEM

Receive gases at low, relatively constant pressures (37-55 psi)

Pipeline Inlet Connectors

  • DISS

  • Check valve

    Pipeline pressure gauge

    Gas power outlet for anesthesia ventilator

    Anesthesia machine piping system

    Master switch

Slide 53

INTERMEDIATE PRESSURE SYSTEM

Slide 54

INTERMEDIATE PRESSURE SYSTEM

Oxygen Fail-Safe Valve (Nitrous Oxide Shutoff Valve)

Oxygen Supply Failure Alarm

Caution : NOT always prevent Hypoxic gas mixture

Oxygen Flush valve

Second stage pressure regulator

Flow control valve

Proportioning system

Link 25 (OhmedaTM) ,

Oxygen Ratio Monitor Control (Draeger)

Slide 55

Oxygen Fail-safe Valve

  • Pressure sensor

  • shut-off valve

B. Oxygen failure

protection

device (OFPD)

Slide 56

Flow Control Valve (Needle Valve)

Slide 57

Proportioning System

Link – 25 system (OhmedaTM)

Oxygen Ratio Monitor Controller (ORMC) (DraegerTM)

Slide 58

Flow pathway of oxygen

1. Oxygen flush

2. Oxygen supply failure alarm system

3. Pneumatically powered anesthesia ventilator

4. Fail-safe valves

5. Flowmeters

Slide 59

LOW PRESSURE SYSTEM

Include components distal to the flow meter needle valves

Flow meter tubes

  • Thorpe tube

  • indicator

    Vaporizers

    Check valve

    Common gas outlet

Slide 60

LOW PRESSURE SYSTEM

Slide 61

Flow meter tubes

Thorpe tube

Indicator

bobbin ball

Slide 62

Flow meter tubes

Sequence of flow meter tubes

Air

Air

Slide 63

ANESTHESIA VAPORIZER

Slide 64

ANESTHESIA VAPORIZER

Function:

-Produce a controlled and predictable concentration of anesthetic vapor in the carrier gas passing through the vaporizing chamber.

Operating principle: Variable bypass vaporizers

- Total FGF enters and splits into carrier gas and bypass gas, then join at the vaporizer outlet.

- Splitting ratio is controlled by

..concentration control dial, and

..automatic temperature compensation

valve

Slide 65

ANESTHESIA VAPORIZER

Factors affecting vaporizer output:

1. FGF (fresh gas flow) rate

-constant output over FGF rate of 250 ml/min to 15 L/min

2. Ambient temperature

-linear output from 20 – 35 degrees C

3. Intermittent back pressure causing pumping effect

-prevention by check valve

smaller vaporizing chamber

tortuous inlet chambers

Slide 66

ANESTHESIA VAPORIZER

Safety features of anesthesia voporizer:

  • Agent specific and concentration-calibrated

  • Vaporizerinterlocks

  • Liquid level indicated, designed to prevent overfilling

  • Keyed fillers

  • No discharge of liquid anesthetic occurs from the vaporizer even at maximum fresh gas flow

Slide 67

ANESTHESIA VAPORIZER

Keyed fillers

Slide 68

Components and Systems

Slide 69

BREATHING SYSTEMS

  • Anesthetic gas exits the anesthesia machine via the common gas outletand enters a breathing circuit.

  • The function of the circuit is to deliver oxygen and anesthetic gases to the patient and to eliminate carbon dioxide.

  • The carbon dioxide may be eliminated by gas inflow or bysodalime absorption.

Slide 70

OUTPUT: BREATHING SYSTEMS

Classification

Slide 71

Circle absorption System

The Circlesystem can be either

  • closed(fresh gas inflow exactly equal to patient uptake, complete rebreathing after carbon dioxide absorbed, and pop-off closed)

  • semi-closed (somerebreathingoccurs, FGFandpop-offsettingsatintermediatevalues), or

  • semi-open(no rebreathing, high fresh gas flow [higher than minute ventilation])

Slide 72

Circle absorption System

  • Advantages

    • low FGF required, low pollution & cost from gases & inhalation agents

    • PaCO2 depends on ventilation only

    • keep heat and moisture

  • Disadvantages

    • complex, difficult to disinfections

    • high resistance due to unidirectional valve

    • more possibility of leakage or disconnections in circuit

Slide 73

Circle absorption System -components

  • fresh gas inflow site

  • inspiratory & expiratory unidirectional valves

  • inspiratory & expiratory corrugated tubing

  • Y connector

  • Pop-off, adjustable pressure-limiting valve, or APL valve)

  • Carbon dioxide canisters and absorbents

  • Reservoir bag

  • Bag/ventilator selector switch

Slide 74

Circle absorption System

Flow of anesthetic gas through circle breathing system

Slide 75

Circle absorption System

  • Carbon dioxide absorbents

  • Function:

  • conserving gases and volatile agents

  • decreasing OR pollution

  • avoiding hazards of carbon dioxide rebreathing.

Slide 76

Circle absorption System

Carbon dioxide absorbents

Type: Soda lime

  • Activator is NaOH or KOH. Silica and kieselguhr added as hardeners.

  • Indicators for SodasorbTM (such as ethyl violet) are colorless when fresh, and purple when exhausted, because of pH changes in the granules.

CO2 + H2O --> H2CO3

H2CO3 + 2 NaOH (or KOH) --> Na2CO3 (or K2CO3) + 2 H2O + Energy

Na2CO3 (or K2CO3) + Ca(OH)2 --> CaCO3 + 2 NaOH (or KOH)

Slide 77

Circle absorption System

Carbon dioxide absorbents

Type: Baralyme

  • Activator Ba(OH)2, octahydrate; no hardeners, slightly less efficient.

  • Colorless or pink changing to blue-gray with exhaustion.

Ba(OH)2-8 H2O + CO2 --> BaCO3 + 9 H2O + Energy

9 H2O + 9 CO2 --> 9 H2CO3 (Then by direct reactions and by NaOH, KOH if present)

9 H2CO3 + 9 Ca(OH)2 --> CaCO3 + 18 H2O + Energy

Slide 78

Circle absorption System

  • Advantages

    • low FGF required, low pollution & cost from gases & inhalation agents

    • PaCO2 depends on ventilation only

    • keep heat and moisture

  • Disadvantages

    • complex, difficult to disinfections

    • high resistance due to unidirectional valve

    • more possibility of leakage or disconnections in circuit

Slide 79

Non-rebreathing Systems

Mapleson breathing system A - F

Slide 80

Non-rebreathing Systems

  • Advantages

    • Simply, light weight, easy to positioning

    • Remote anesthesia

    • Low resistance

  • Disadvantages

    • Require high FGF, more pollution

    • loss more heat and water from airway

    • Carbon dioxide retention

Slide 81

Modified Mapleson breathing system

  • Ayre’s T-piece circuit (Mapleson E)

    • most suitable in oxygen therapy

    • caution : require high flow of humidified oxygen

  • Jackson Rees circuit (Mapleson F)

    • most suitable in pediatric anesthesia (BW < 20 kg.)

    • require high flow 2-3 times of minute ventilation

Slide 82

Components and Systems

Slide 83

SCAVENGING SYSTEM

Definition:

  • The collection and removal of vented anesthetic gases from the OR.

    Scavenger and operating room ventilation efficiency are the two most important factors in reduction of waste anesthetic gases (WAGs).

Slide 84

SCAVENGING SYSTEM

Type:

  • Active

    • Suction applied

    • Require a means to protect patient’s airway from suction or build up of positive pressure

  • Passive

    • waste gases proceed passively down corrugated tubing through the exhaust grill of the OR.

    • Require a means to protect patient’s airway from build up of positive pressure only.

Slide 85

SCAVENGING SYSTEM

Scavenging interface

  • The most important component.

  • Protects breathing system from excess positive or negative pressure.

  • Reservoir is highly desirable with active system.

  • Closed interface communicates with atmosphere only through valves.

Closed scavenging interface

Slide 86

OUTPUT: SCAVENGING SYSTEM

Slide 87

OUTPUT: SCAVENGING SYSTEM

Closed scavenging interface

Slide 88

Topics

1. Overview of anesthesia machine

2. Components and systems of anesthesia machine

3. Machine checklist

Slide 89

Machine Checklist

  • Pre-anesthesia checklist 2008

  • Electronic and automated checklist

  • Local department checklist procedures

  • Minimum test under life-threatening conditions

Slide 90

WHY negative pressure leak test?

A high pressure check of the breathing circuit will not detect leaks upstream of check valves, since the high pressure in the breathing circuit will only be transmitted upstream to the check valve, and no further.

Slide 91

Negative pressure leak test

Slide 92

Negative pressure leak test

Slide 93

Future Anesthesia Machine

Slide 94

Questions from audience


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