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BS EN 50527-2-3:2021

$227.44

Procedure for the assessment of the exposure to electromagnetic fields of workers bearing active implantable medical devices – Specific assessment for workers with implantable neurostimulators

Published By Publication Date Number of Pages
BSI 2021 110
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This document provides the procedure for the specific assessment required in EN 50527‑1:2016, Annex A, for workers with implanted neurostimulator systems (NS), specifically of the type used for spinal cord stimulation (SCS).

It is recognized that implantable neurostimulators have been developed for a wide variety of clinical applications, however the SCS devices within the scope of this document represent the largest segment of the implantable neurostimulator applications thus far.

NOTE 1 If the worker has other Active Implantable Medical Devices (AIMDs) implanted additionally, they are assessed separately according to EN 50527‑1 or other particular standards within the EN 50527 series .

The purpose of the specific assessment is to determine the risk for workers with implanted SCS devices arising from exposure to electromagnetic fields (EMF) at the workplace. The assessment includes the likelihood of clinically significant effects.

NOTE 2 This document does not address risks from contact currents, or the effects upon any associated non-implantable devices (e.g. Patient Programmers).

The techniques described in the different approaches can also be used for the assessment of publicly accessible areas.

The frequency range to be observed is from 0 Hz to 3 GHz. Above 3 GHz no interference with the devices within the scope of this document is expected to occur.

NOTE 3 The rationale for limiting the observation range to 3 GHz can be found in ISO 14708‑3 [1].

NOTE 4 Further information concerning the functions of neurostimulator systems can be found at /2.

This document provides the procedure for the specific assessment required in EN 50527‑1:2016, Annex A, for workers with implanted neurostimulator systems (NS), specifically of the type used for spinal cord stimulation (SCS).

It is recognized that implantable neurostimulators have been developed for a wide variety of clinical applications, however the SCS devices within the scope of this document represent the largest segment of the implantable neurostimulator applications thus far.

NOTE 1 If the worker has other Active Implantable Medical Devices (AIMDs) implanted additionally, they are assessed separately according to EN 50527‑1 or other particular standards within the EN 50527 series .

The purpose of the specific assessment is to determine the risk for workers with implanted SCS devices arising from exposure to electromagnetic fields (EMF) at the workplace. The assessment includes the likelihood of clinically significant effects.

NOTE 2 This document does not address risks from contact currents, or the effects upon any associated non-implantable devices (e.g. Patient Programmers).

The techniques described in the different approaches can also be used for the assessment of publicly accessible areas.

The frequency range to be observed is from 0 Hz to 3 GHz. Above 3 GHz no interference with the devices within the scope of this document is expected to occur.

NOTE 3 The rationale for limiting the observation range to 3 GHz can be found in ISO 14708‑3 [1].

NOTE 4 Further information concerning the functions of neurostimulator systems can be found at /2.

PDF Catalog

PDF Pages PDF Title
2 undefined
9 1 Scope
2 Normative references
3 Terms and definitions
11 4 Specific assessment
4.1 Overview of specific assessments
4.1.1 Relation to OH&S Management Systems
4.1.2 Description of the assessment process
14 4.2 Specific assessment phase 0: Exclusion based on history and physician warnings
15 4.3 Specific assessment phase 1: Consideration of equipment and SCS therapy type
17 4.4 Specific assessment phase 2a – workplace EMF compared to Action Levels
19 4.5 Overview of specific assessment phases 2b and 2c
20 4.6 Methodology for assessment of unintended nerve stimulation and tissue damage risk
4.6.1 General
4.6.2 Overview of the assessment method given in Annexes D and E
21 4.6.3 Selection of device parameters for assessment
4.6.4 Assessment levels for electric and magnetic fields
25 4.6.5 NSR and TDR calculation results for unipolar and bipolar configurations
28 4.6.6 Phase 2a risk assessment summary
29 4.7 Specific Assessment phase 2b – workplace EMF compared to NSR / TDR EMF threshold levels
4.7.1 Phase 2b general approach
4.7.2 EMF threshold zones
31 4.7.3 Conversion of EMF values
4.7.4 Phase 2b assessment procedure
41 4.8 Specific assessment phase 2c – adjustments for known lead characteristics
4.8.1 Phase 2c general approach
43 4.8.2 Phase 2c assessment procedure
44 5 Documentation
45 Annex A (normative)Device specific replacement of EN 505271:2016, Table 1
49 Annex B (informative)Rationale
B.1 Introduction
B.2 Rationale for specific clauses of this document
50 Annex C (informative)Nerve Stimulation for SCS
C.1 Neurostimulation techniques
C.1.1 Types of neurostimulators and their usage
C.2 Spinal Cord Stimulation
C.2.1 The main features of SCS
51 C.2.2 SCS leads and stimulation methods
C.2.2.1 General
C.2.2.2 Unipolar stimulation
52 C.2.2.3 Bipolar stimulation using one lead
C.2.2.4 Bipolar stimulation using two leads
C.2.2.5 When leads are longer than is needed
C.2.2.6 Wire diameters
C.2.3 Electrodes for SCS
C.2.3.1 General
53 C.2.3.2 Cylindrical electrodes
C.2.3.3 Paddle electrodes
C.2.4 Summary of dimensions
C.2.5 Implantation of electrodes
54 C.2.6 Dura to spinal cord distances
55 C.2.7 Connections to the IPG
56 Annex D (informative)Selection of Conductivity Values for SCS Modelling
D.1 The use of conductivity in the standard
D.2 Conductivity literature
D.2.1 1996 data
57 D.2.2 Subsequent developments
D.2.2.1 Overview of subsequent developments
D.2.2.2 Gabriel et al. 2009; frequencies below 1 MHz
58 D.2.2.3 Peyman and Gabriel 2010; Cole-Cole parameters for microwave frequencies
D.2.2.4 Peyman et al. 2007; porcine cerebrospinal tissues at microwave frequencies
61 D.3 Selection of values for tissue Types
D.3.1 General
D.3.2 Fat
63 D.3.3 Cerebrospinal fluid (CSF) and spinal cord (nerve)
D.3.4 Cerebrospinal tissues
D.3.4.1 Physiology
64 D.3.4.2 Combining conductivities for cerebrospinal tissues
65 D.3.4.3 Combined conductivity in region between electrodes and spinal cord
66 D.3.4.4 Conductivity for determining electric field at electrodes from external electric field
67 D.4 Summary
68 Annex E (informative)Modelling Nerve Stimulation for SCS
E.1 Introduction
E.1.1 General
E.1.2 Literature
E.1.3 Elementary representation
70 E.1.4 Detailed model
E.1.4.1 General
72 E.1.4.2 The SENN computer model
73 E.1.5 Application of the SENN Computer Model
74 E.1.6 Effect of altering separation between electrode and nerve
75 E.1.7 Electrode Factor for point-electrodes
E.1.7.1 General
E.1.7.2 For one point-electrode in isotropic tissue
77 E.1.7.3 For one point-electrode in non-isotropic tissue
78 E.1.7.4 Electrode Factor for two point-electrodes in isotropic tissue
79 E.1.7.5 Electrode factor for actual electrodes
E.1.8 Stimulation from internal electric field
82 E.2 Internal electric field threshold for nerve stimulation
E.2.1 General
84 E.2.2 Stimulation at higher levels of in situ electric field
E.2.3 Overview of method for assessing whether nerve stimulation occurs
E.3 Avoiding damage to tissue
E.3.1 General
85 E.3.2 Assessment of localized SAR
E.3.2.1 General
E.3.2.2 At electrode surface
86 E.3.2.3 Allowing for the averaging volume
87 E.3.2.4 Relationship with ICNIRP reference levels for contact current
E.3.3 Overview of method for assessing whether tissue damage might occur
88 E.4 Assessment of voltages and currents induced in leads
E.4.1 Voltages induced by magnetic fields
E.4.1.1 The voltage calculation
E.4.1.2 The current calculation
E.4.1.3 Selection of loop areas A
E.4.1.4 Magnetic field assessment levels, B
E.4.1.5 Magnetic field exposure levels used for assessment
90 E.4.1.6 Calculated voltages
91 E.4.2 Voltages and currents induced by electric fields
E.4.2.1 General
E.4.2.2 Low frequencies (<10 MHz)
92 E.4.2.3 Radio frequencies (thermal effects)
93 E.4.2.4 Selection of electrode separation, L
E.4.2.5 Selection of electric field assessment levels
94 E.4.2.6 Calculated voltages
95 E.5 Assessment of nerve stimulation from external fields
E.5.1 Method for assessing nerve stimulation risk
96 E.5.2 Nerve stimulation from magnetic fields
E.5.2.1 General
97 E.5.2.2 Conclusions on nerve stimulation from magnetic fields
98 E.5.3 Nerve stimulation from electric fields
E.5.3.1 Full nerve stimulation assessment results for electric field induction
99 E.5.3.2 Conclusions on nerve stimulation from electric fields
E.6 Assessment of tissue damage from external fields
E.6.1 Method for assessing tissue damage risk
100 E.6.2 Tissue Damage from magnetic fields
E.6.2.1 General
E.6.2.2 Conclusions on tissue damage from magnetic fields
101 E.6.3 Tissue Damage from electric fields
E.6.3.1 General
E.6.3.2 Conclusions on tissue damage from electric fields
102 E.7 Overall assessment
103 Annex F (informative)Electrode factor for non-isotropic tissue
F.1 Application to isotropic tissue
105 F.2 Application to non-isotropic tissue
BS EN 50527-2-3:2021
$227.44