Guidance on airway management during laser surgery of upper airway

Intended to help minimize the risk of an airway fire when using a laser. Represents current knowledge at the time of publication and is subject to review. Does not address management of the patient with a tracheotomy. Also intended to assist related groups, such as laser safety committees.

Guide pour assurer la ventilation au cours d'opérations par laser des voies respiratoires supérieures

General Information

Status
Withdrawn
Publication Date
28-Jun-1995
Withdrawal Date
28-Jun-1995
Current Stage
9599 - Withdrawal of International Standard
Start Date
14-Jul-2020
Completion Date
14-Jul-2020
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ISO/TR 11991:1995 - Guidance on airway management during laser surgery of upper airway
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TECHNICAL ISO
REPORT TR 11991
First edition
1995-07-15
Guidance on airway management during
laser surgery of upper airway
Guide pour assurer Ia Ventilation au cours d ’opkations par laser des voies
respiratoires suphieures
Reference number
ISO/TR 11991 :1995(E)
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ISO/TR 11991:1995(E)
Contents
Page

1 Scope ........................................................................................................ 1

2 References ................................................................................................ 1

3 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 Ideal proper-Ges of tracheal tubes for use with lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.2 Design .......................................................................................................

4.3 Packaging and labelling ............................................................................

5 Description of current practices which reduce the risk of airway fire.. .... 4

5.1 Non-intubation techniques ........................................................................

5.2 Intubation techniques ...............................................................................

5.3 Management of airway fires ..................................................................... 10

Tables

1 Combustion properties of conventional tracheal tube materials . . . . . . . . . . . . . . .

2 Primary emergency management following recognition of airway fire . . .
3 Secondary emergency management following recognition of an airway

fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Annex

A Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0 ISO 1995

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or

utilized in any form or by any means, electronie or mechanical, including photocopying and

microfilm, without permission in writing from the publisher.
International Organization for Standardization
Gase Postale 56 l CH-121 1 Geneve 20 l Switzerland
Printed in Switzerland
---------------------- Page: 2 ----------------------
0 ISO ISO/TR 11991:1995(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of

national Standards bodies (ISO member bodies). The work of preparing International

Standards is normally carried out through ISO technical committees. Esch member

body interested in a subject for which a technical committee has been established has

the right to be represented on that committee. International organizations, govem-

mental and non-govemmental, in liaison with ISO, also take part in the work. ISO

collaborates closely with the International Electrotechnical Commission (IEC) on all

matters of electrotechnical standardization.

The main task of technical committees is to prepare International Standards, but in

exceptional circumstances a technical committee may propose the publication of a
Technical Report of one of the following types:
type 1, when the required support cannot be obtained for the publication of an
International Standard, despite repeated efforts;
- type 2, when the subject is still under technical development or where for any

other reason there is the future but not immediate possibility of an agreement on

an International Standard;
- type 3, when a technical committee has collected data of a different kind fiom

that which is normally published as an International Standard ( “state of the art ”,

for example).
Technical Reports of types 1 and 2 are subject to review within three years of

publication, to decide whether they tan be transformed into International Standards.

Technical Reports of type 3 do not necessarily have to be reviewed until the data they

provide are considered to be no longer valid or useful.
ISO/TR 11991, which is a Technical Report of type 3, was prepared by Technical

Committee ISO/TC 12 1, Anuesthetic and respiratory equipment, Subcornmittee SC 2,

Tracheal tubes and other equipment.
This document is being issued as a type 3 Technical Report to summarize current

methods for airway management during laser surgery of the upper airway to minimize

the risk of fne. (See the Introduction.)
. . .
Ill
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ISO/TR 11991:1995(E)
0 ISO
Introduction

This guide provides information for clinicians for appropriate selection of airway

devices for operations on the upper airway, including the larynx, in which a laser

is used. It also provides information for the appropriate selection of intubation

Tracheal tubes are commonly used in patients
and non-intubation techniques.
during general anaesthesia for such operations. These tubes provide effective
control of Ventilation and oxygenation, protect the airway from aspiration (if
cuffed), and allow monitoring of Ventilation through capnography and spirometry.

A laser is a Source of intense light energy which tan provide an ignition Source. so

that a fire is a risk in the operative field. Risk of fire is particularly enhanced in

oxidant (0, or N,O) enriched atmospheres. Tracheal tubes assist Ventilation and
Patient monitoring but may be ignited by the laser in these circumstances.

In these procedures, the clinician must be aware of tlie risk of fire. Fire requires

three elements: an ignition Source, a combustible material, and an Oxygen Source.

These three are sometimes referred to as “the fire triangle ”. During laser surgery

on the upper airway, all three elements are often present. The laser is an intense

light energy which tan provide a Source of ignition. Tracheal tubes when present

are usually made of combustible material. Finally, most patients are treated in an

oxidant-enriched atmosphere. Care to minimize these three elements is essential
to avoid a fire during laser surgery of the upper airway.
Of the numerous methods available for airway management during laser

operations on the upper airway, each has its own risks and advantages. This guide

summarizes the current methods and the applications, advantages, and

disadvantages of each. The guide serves to assist the anaesthetist and surgeon in

their joint cdecision regarding selection of the most appropriate method tob
ovgenate and ventilate the Patient during laser surgery involving the upper
airway.
This guide does not recommend any one method of airway management.
The test datakluded in Table 1 of this guide are based upon continuous beam
CO, Lasers. While this data may not be directly applicable to other wavelengths
or beam modes (such as super pulse), the basic principles still apply. Decisigns
regarding practice methods tan onlv be made by the clinicians caring for the

Patient, having knowledge of the clinical circumstances, available expertise, and

technology, e.g. the properties of the specific laser wavelength planned for the
surgery.
Other complications of laser surgery not involving aiway management may be
found in ANSI 2136.1 (l), and ANSI 2136.3 (2), CAN/CSA 2386 M91 (3).
---------------------- Page: 4 ----------------------
ISO/TR 11991:1995(E)
TECHNICAL REPORT @ ISO
Guidance on airway management during laser surgery of
upper airway
1 Scope
At present there is no way to avoid completely the risk of an airway fire when a

laser is used in the airway. This guide is intended to help minimize this risk by

listing a) those characteristics of a tracheal tube that make it most suitable for

laser airway operations, recognizing that it may not be possible in practice to

produce a device combining such characteristics; b) several Standard practices that

reduce the risk of airway fire during laser operations on the airway; c)
recommendations for emergency management should an airway fire occur.

This guide represents current knowledge at the time of publication and is subject

to review. This guide does not address management of the Patient with a

tracheostomy. This guide is also intended to assist related groups, such as laser

safety committees.
2 References
ISO 5361-1: 1988, Tracheal tubes - Part 1: General requirements.
Part 2: Oro-tracheal and naso-tracheal tubes of Magill type (plain
ISO 5361-2: 1993, Tracheal tubes -
and cuffed).
Part 5: Requirements and methods of test for cuffs and tubes.
ISO 5361-5: 1984, Tracheal tubes -
ISO 7228: 1993, Tracheal tube connectors.
- Part 1: Evaluation and testing.
ISO 10993-l:- l) ) Biological evaluation of medical devices
1) To be published. (Revision of ISO 10993- 1: 1992)
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ISO/TR 11991:1995(E)
0 ISO
3 Terminology
For the purpose of this technical report, the following definitions apply.
3.1 anatomical airway : Natura1 pathways through which respired gases pass in
either direction between the atmosphere and the alveoli.
3.2 combustion : Rapid Oxidation to produce heat and light.
concentration of Oxygen in inspired gas.
33 F,O, : The fractional
bility to sustain combustion.
3.4 flammability : The a’
3.5 ignitability : The ability to initiate combustion.
3.6 intubation : Placement of a tracheal tube into the trachea.
: A surgical handpiece made of a non-combustible material
3.7 laser platform
with a non-reflective surface. The end of the device is placed behind the target
tissue as a backstop for the laser.
3.8 laser plume : Gaseous and particulate by-products of combustion and/or
pyrolysis produced by the effect of laser enerw upon a target.
3.9 oxidant enriched atmosphere : Any atmosphere that contains oxidants (0,,
N,O) in total concentration greater than 25% of volume at ambient pressure.
3.10 Oxygen index of flammability : The minimum concentration of 0, in N,
necessary to support a candle-like flame for a given substance.
3.11 pledget (cottonoid) : A compress, usually of gauze or absorbent cotton.
: The power delivered by a laser beam per unit
3.12 power density (irradiance)

area of irradiated surface (Spot size), expressed as Watts per Square centimetre.

3.13 pyrolysis : Transformation of a compound into one or rnore other substances
by heat alone (without Oxidation).

3.14 specular reflectance : The characteristics of a material to reflect light in such

a way that the angle of reflection is equal to the angle of incidence, such as the

reflectance from a mirror.
3.15 thermal conductivitv : Time rate of heat flow through unit area, per unit
’ 1
temperature gradient, in the direction perpendicular to the area.
3.16 upper anatomical airway (the upper airway) : The airway above the
laryngotracheal junction.
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0 ISO
ISO/TR 11991:1995(E)
4 Ideal properties of tracheal tubes for use with lasen
4.1 Materials
The materials used for the manufacture of the part of the tracheal tube intended
to lie in the upper airway should have the following characteristics:
4.1.1 Ignitability

Materials should be resistant to ignition by a laser beam in the presence of 100 %

4.1.2 Flammability
Materials should not maintain combustion in 100 % 0,.
4.13 Specular reflectance

Materials should have no specular reflectance so as to avoid injury to non-targeted

tissue.
4.1.4 Heat transfer
Materials should minimize heat transfer that may darnage adjacent tissue.
4.1.5 Products of pyrolysis and combustion
The products of pyrolysis and combustion should satisfy appropriate biological
safety test as specified in ISO 10993-1.
4.2 Design
4.2.1 General
Tubes should comply with the requirements specified in ISO 53614, ISO 5361-2,
ISO 5361-5 and ISO 7228.
4.2.2 Integrity
In the event of tube ignition, integrity of the tube and attached components
should be maintained so that they tan be immediately removed intact.
4.23 Transparency

The material used for the manufacture of the tracheal tube should be sufficiently

optically transparent or translucent to enable condensation of airway vapour and
evidente of combustion to be seen within its lumen.
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ISO/TR 11991:1995(E)
0 ISO
4.2.4 Cuff inflation

The tracheal tube cuff should be capable of being inflated with liquid and rapidly

deflated under normal conditions of use.
4.2.5 The cuff and inflation system
The cuff and inflation system, if exposed, should be laser resistant.
43 Packaging and labelling
43.1 The tracheal tube and attached components should be preassembled and
individually packaged.
43.2 The tube should be intended and labelled for Single use.
5 Description of current practices which reduce the risk of aixway fire
At present there is no way to completely avoid the risk of an airway fire when a
laser is used in the airway. The following are descriptions of current practices

that reduce the risk of airway fire. Accompanying each practice is a discussion of

its advantages and disadvantages. No significance should be attributed to the
Order in which these practices are presented.
5.1 Non-intubation techniques
These methods of Ventilation do not use a tracheal tube.
5.1.1 Spontaneous breathing techniques
With the Patient breathing spontaneously, gas with or without supplemental
Oxygen and/or potent inhalation anaesthetic is insufflated into the operating
laryngoscope, bronchoscope, a metal hook, or a catheter (4). The anaesthetic may
be supplemented with intravenous agents and/or regional anaesthesia to the
airway.
Advantages : There is no tracheal tube in the airway so that the risk of fire is
reduced. The method also provides excellent visibility of the surgical field and
avoids potential trauma to the airway that use of a tracheal tube might Cause.
Dkadvantages : Hypoventilation is a risk which may go undetected since
capnography is difficult and inaccurate, and spirometry cannot be used.
Pulmonary aspiration of gastric contents and/or laser plume tan also occur.
Ventilation cannot be assisted or controlled. Depth of anaesthesia may fluctuate
SO that Patient movement tan occur. Insufflation techniques make scavenging

anaesthetic gases difficult. The risk of fire is increased if a flammable catheter is

used as the insufflation device.
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0 ISO
ISO/TR 11991:1995(E)
51.2 Apnoeic techniques
The Patient is ventilated through a mask, tracheal tube, or bronchoscope, using
Oxygen-enriched gas, with or without potent inhalation anaesthetic. During

Ventilation, the laser is not used. Ventilation is then temporarily discontinued and

the mask or tracheal tube is removed. During apnoea, laser resection is
performed. After a period of time, laser resection is stopped and Ventilation is
resumed. Periods of Ventilation altemate with laser resection/apnoea in this
manner.
Advantages : There is no tracheal tube in the airway so that the risk of fire is
reduced. The method also provides excellent visibility of the surgical field and
avoids potential trauma to the airway that use of a tracheal tube might Cause.
Disadvantages : Hypoventilation is a risk which may go undetected since
capnography and spirometxy are not applicable during apnoea. Pulmonary

aspiration of gastric contents and/or laser plume may occur. There is a potential

for airway trauma from repeated instrumentation.
5.1.3 Jet Ventilation technique

A metal needle or similar device is mounted either in the operating laryngoscope or

placed below the site of Operation and attached to a jet injector. A high-velocity jet

of 02, air/O,, N,0/02, or He/O, mixture is directed into the airway lumen either
above or below the glottis by the surgeon.
The lungs are ventilated with jet gas and
entrained room air (5).
Advmuges : There is no tracheal tube in the airway so that the risk of fire is

reduced. The method also provides excellent visibility of the surgical field and avoids

potential trauma to the airway that use of a tracheal tube might Cause.
Disadvantages : Hypoventilation tan be a Problem with this technique due to the
following: obstructive airway lesions, decreased pulmonary compliance (e.g.

bronchospasm, obesity , or chronic obstructive pulmonary disease), and/or inability of

the surgeon to direct the jet optimally. Spirometry is not possible and capnography is

’ difficult and inaccurate with this method so that hypoventilation may be undetected.

The inspired O2 concentration cannot be controlled or monitored. Pulmonary
aspiratio
...

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