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IEC 60601-1 patient applied parts for Medical Electrical Equipment-Notes 1-2-3

In this blog, “IEC 60601-1 patient applied parts for Medical Electrical Equipment-Notes 1-2-3,” the author uses many figures to explain critical concepts. 

Note 1: Figures that explain APPLIED PART concepts

In IEC 60601-1, Figures 3 and 4 (shown below) are used to show where different parts of ME EQUIPMENT are located, and to help explain some of the defined terms in a pictorial way.

fig 3 AM IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

 

fig 4 IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

In both figures, the APPLIED PART is intended to come into contact with the PATIENT. Figure 3 shows a CLASS I medical device as per sub-clause 3.13. The device is PROTECTIVELY EARTHED (i.e., grounded), in addition to providing BASIC INSULATION. Figure 4 shows a CLASS II medical device per sub-clause 3.14. The device is not PROTECTIVELY EARTHED. Instead, Figure 4 shows how the design uses two levels of protection, which is a basic tenet of the IEC 60601-1 standard. The two levels of protection used is either DOUBLE or REINFORCED INSULATION.

 

Figures A.1 to A.7 provide examples of the way APPLIED PARTS and PATIENT CONNECTIONS are identified in order to apply the requirements for PATIENT LEAKAGE CURRENT and PATIENT AUXILIARY CURRENT. APPLIED PART circuits can provide isolation to other parts of the circuitry in the medical device, and these figures present several options for compliance with SPACINGS (i.e., CREEPAGE and AIR-CLEARANCE), DIELECTRIC WITHSTAND (i.e., HiPot test) and INSULATION requirements. The following discussion is limited to Figures A.1 and A.2. For additional information about Figures A.3-A.7, purchase a copy of IEC 60601-1, edition 3.0 (http://bit.ly/IEC60601-1) or edition 3.1 (http://bit.ly/IEC60601Consolidated).

a 1 IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

Figures A.1 and A.2 show an ECG monitor that includes the monitor, PATIENT cable, PATIENT leads and ECG electrodes. The key elements of figure A.1 are:

1)     the APPLIED PARTS includes the electrodes and those parts of the PATIENT leads, or PATIENT cable that need to physically contact the PATIENT in NORMAL USE (sub-clause 3.8 definition),

2)     application of RISK MANAGEMENT might id other parts of the PATIENT leads or PATIENT cable that need to treated as APPLIED PARTS because of the probability they will come in contact with the PATIENT, (sub-clause 4.6 requirements), and

3)     the PATIENT CONNECTIONS consist of the ECG electrodes, which are part of the same function of the APPLIED PART.

Figure A.2 below shows the required F-TYPE APPLIED PART insulation incorporated in the medical device itself. The components within the dotted line form the PATIENT circuit.

a 2 IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

Note 2: Parts that are not APPLIED PARTS may need to be treated as an APPLIED PART

Sub-clause 4.6 and Annex A, sub-clause 4.6 provide additional details that apply to the following paragraph below.

Parts of medical devices that are not APPLIED PARTS, but which touch the PATIENT during the NORMAL USE of the device, may need to be treated as APPLIED PARTS. In this case, the part shall not be marked as an APPLIED PART. A RISK ASSESSMENT PROCESS needs to be conducted to determine whether the parts that come in contact with the PATIENT, but aren’t APPLIED PARTS, should meet the requirements of APPLIED PARTS. Figures A.4 through A.7 all have a statement that roughly states: “The application of RISK MANAGEMENT might identify some parts of the device/system as having to be treated as APPLIED PARTS because of the probability they will come in contact with the PATIENT.” If your RISK ASSESSMENT determines that sub-clause 4.6 is applicable, then all applicable requirements and tests for APPLIED PARTS should be applied to the parts identified in the RISK ASSESSMENT—with the exception of sub-clause 7.2.10 for marking of APPLIED PARTS. These requirements apply to this standard and the relevant collateral and particular standards in the 60601 series of standards. An example of the type of parts that could fall under sub-clause 4.6 could be computer system interface cable (I/O).

Note 3: Definition of associated term PATIENT CONNECTION

A PATIENT CONNECTION is part of the APPLIED PART as shown in figure A.1. Sub-clause 3.78 defines a PATIENT CONNECTION as: “Individual point on the APPLIED PART through which current can flow between…PATIENT and ME EQUIPMENT in NORMAL…or SINGLE FAULT CONDITION.” In this example, the conductive part of the ECG electrode is considered the PATIENT CONNECTION.

partial a1 IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

IEC 60601-1 assumes the PATIENT is earthed as a NORMAL CONDITION per sub-clause 8.5.4, 4th dashed item, because there are many opportunities in normal operation of medical electrical devices where the PATIENT can accidentally become grounded. Therefore, some PATIENT LEAKAGE CURRENT tests are configured with the LEAKAGE CURRENT measuring device (see Figure 12) directly connected to earth on one side and passing thru the measuring device to the APPLIED PART circuit that is being tested. The boxed in area in Figure 15 is the portion of the PATIENT LEAKAGE CURRENT test measuring circuit that is connected from the PATIENT CONNECTION (item 4) thru the measuring device to earth (left hand corner of figure—symbol sometimes called “upside down Christmas tree”).

fig 12 IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

 

fig15 IEC 60601 1 patient applied parts for Medical Electrical Equipment Notes 1 2 3

Leo Eisner is the owner and founder of Eisner Safety Consultants (http://bit.ly/LeoEisner). If you need help wth IEC 60601 compliance, email Leo directly at Leo@EisnerSafety.com or call him at +1 (503) 244-6151.  You can also connect on LinkedIn at: http://bit.ly/ConnectwithLeo.

 

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IEC 60601-1 Definition of Patient Applied Parts

iec 60601 1 me IEC 60601 1 Definition of Patient Applied Parts

This article reviews the IEC 60601-1 definition of patient applied parts for medical electrical equipment. It includes examples, as well.

Classification of medical electrical devices was discussed in a previous blog (http://bit.ly/IEC60601-FAQ), while this article focuses on APPLIED PARTS—one portion of the “Protection Against Electric shock” classification in sub-clause 6.2 of IEC 60601-1. ALL CAPITAL LETTERS identifies a defined term for the IEC 60601 series of standards within this blog.

All clause references in this blog are to both IEC 60601-1:2005 (3rd edition) and IEC 60601-1:2005 (3rd edition) + Amendment 1:2012 (http://bit.ly/IEC60601-1am1), or the consolidated version IEC 60601-1:2012 ed. 3.1, but the actual text comes from edition 3.1 (http://bit.ly/IEC60601Consolidated).

Definition

To understand what an APPLIED PART is, we first need to understand its definition. Sub-clause 3.8 states that an APPLIED PART is “part of ME EQUIPMENT that in NORMAL USE necessarily comes into physical contact with the PATIENT for ME EQUIPMENT or an ME SYSTEM to perform its function.”

Examples

An APPLIED PART can be an blood pressure cuff, or an SpO2 sensor of a multi-parameter monitor, the table top of an MRI and many other parts of ME EQUIPMENT that manufacturers intend to come into contact with a PATIENT during NORMAL USE.

iec 60601 1 me 2 IEC 60601 1 Definition of Patient Applied Parts

Electrical-medical devices can have different types of APPLIED PARTS or more than one of the same type (e.g., multi-parameter monitors frequently have temperature sensors and blood pressure monitoring components in the base configuration and other APPLIED PARTS can be added). As discussed in the previous blog (http://bit.ly/IEC60601-FAQ), APPLIED PARTS can have six different classifications: TYPE B, BF, or CF (and each can be DEFIBRILLATION PROOF). Each of these classifications also has an associated symbol.

The requirements for an APPLIED PART are more stringent because it has to be assumed that the PATIENT’s immune system is depressed. So, the probability of HARM is increased for a sick PATIENT, rather than for a healthy OPERATOR. Therefore, the standard aims to reduce the severity of HARM by requiring more stringent limits upon LEAKAGE CURRENTS. The computer equipment standard (IEC 60950-1 Information Technology Equipment Standard) applying to your home or business computer allows for higher limits for LEAKAGE CURRENTS because the computer equipment standard assumes the user is healthy—just like medical equipment operators.

The level of HARM to a PATIENT by an APPLIED PART can be adversely affected if a PATIENT is not conscious (e.g., during general anesthesia), because the PATIENT may be unable to react while they are unconscious. Therefore, understanding a device’s intended use (i.e., what the device is intended to do), and indications for use (i.e., environment of use, part of the anatomy and intended population), is critical when you are conducting RISK ANALYSIS and USABILITY ANALYSIS of a device. 

Three Notes About the IEC 60601-1 Definition of Patient Applied Parts

There are three (3) notes associated with the definition of APPLIED PART:

  1. Sample figures that show APPLIED PARTS in different system configurations
  2. Parts of the device that are not APPLIED PARTS, but in NORMAL USE necessarily come into physical contact with the PATIENT, shall be treated as APPLIED PARTS, but is not allowed to be marked as an APPLIED PART; and
  3. The associated term PATIENT CONNECTION

The sample figures related to the first note, Figures 3 & 4 and figures A.1 to A.7 of Annex A, show APPLIED PARTS in different system configurations. These figures provide guidance and a rationale for why and what is happening. The second note is important because any part that necessarily comes into physical contact with the PATIENT, for the equipment to perform its function, will also need to be tested as if it were an APPLIED PART, but it will not be allowed to be marked as such. The third note regarding PATIENT CONNECTION, in sub-clause 3.78 & Annex A for 3.78, is the part of the APPLIED PART that is intended to contact the PATIENT that current flows through. The next blog will review all three notes in greater detail.

If you need help with the IEC 60601 series of Standards, email Leo Eisner (http://bit.ly/ConnectwithLeo) directly at Leo@EisnerSafety.com, or call Leo at +1-(503)-244-6151. He is the owner and founder of Eisner Safety Consultants (http://bit.ly/LeoEisner).

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IEC 60601 Medical Electrical Equipment Classification: FAQs

IEC 60601 medical electrical equipment classification frequently asked questions are discussed in this blog. 

subclause IEC 60601 Medical Electrical Equipment Classification: FAQs

All clause references in this blog are to both IEC 60601-1:2005 (3rd edition) and IEC 60601-1:2005 (3rd edition) + Amendment 1:2012 (http://bit.ly/IEC60601-1am1), or the consolidated version IEC 60601-1:2012 ed. 3.1, but the actual text comes from edition 3.1 (http://bit.ly/IEC60601Consolidated).

*Note: ALL CAPITAL LETTERS identifies a defined term for the IEC 60601 series of standards within this blog.

What are the various classifications that are used in IEC 60601-1, edition 3.1? – The table at the beginning of this blog posting identifies the five parts of the Classification section. Each classification is described in more detail below.

Why do I need to classify my product for IEC 60601-1, 3rd ed.? – The standard says you have to classify …ME EQUIPMENT, or parts thereof, including applied parts… as noted in sub-clause 6.1. But a more practical reason you would want to classify your products that fall under the scope of IEC 60601-1 (http://bit.ly/60601scope) is it is a helpful tool in identifying the requirements that apply to the device, and helps us in determining the test plan for the product to be tested.

What is an applied part? – The definition of an APPLIED PART is in sub-clause 3.8 of the standard. It states that an APPLIED PART is “part of ME EQUIPMENT that in NORMAL USE necessarily comes into physical contact with the PATIENT for ME EQUIPMENT or an ME SYSTEM to perform its function.” So, it can be a cable, lead, electrode, or many other parts of an ME EQUIPMENT, or an ME SYSTEM that is intended, by the manufacturer, in its NORMAL USE to come in contact with the PATIENT.

What are the classifications for Protection Against Electric Shock? –There are two classifications that fall under sub-clause 6.2 of the standard: 1) the power source, and 2) applied parts. Power sources can be an external power source, and is either classified as a class I or class II ME EQUIPMENT or an internal power source, which is classified as INTERNALLY POWERED MEDICAL EQUIPMENT.

Power Sources – External Class I, External Class II or Internal – Class I provides its protection against electric shock by having an additional safety ground (known as PROTECTIVELY EARTHED) that is connected to the internal and/or external conductive parts (metal) of the power source. Class II provides its protection against electric shock by having an additional layer of insulation beyond that of BASIC INSULATION (a single layer of insulation), and is provided either by DOUBLE INSULATION (two layers of insulation) or by REINFORCED INSULATION (the same as DOUBLE INSULATION, but as one insulation system that is twice as thick, typically). An internal power source is typically a battery.

Applied Parts – B, BF, CF (also defibrillation-proof) – The second classification for protection against electric shock is for APPLIED PARTS. APPLIED PARTS are classified in one of six ways, and a product can have more than one type of APPLIED PARTS. The classifications for applied parts are type B, BF or CF. Each of these 3 classifications can be DEFIBRILLATION-PROOF APPLIED PARTS for a total of 6 classifications. There are 6 separate symbols for these APPLIED PARTS, and they are noted in the table below, which comes from Table D.1 of Annex D of the standard.

symbols IEC 60601 Medical Electrical Equipment Classification: FAQsWhy do we have classifications for protection against electric shock? – Protection against electrical shock is important because electric shock is one of the main areas of concern in most electrical safety standards as the shock hazard can cause harm to the OPERATOR or PATIENT or even death. The main reason is we want to protect the PATIENT who may have a depressed immune system from getting an electric shock that could injure or potentially kill the PATIENT. The depressed immune system makes them more likely to be harmed by an electric shock. We also want to consider the OPERATOR of the device but they should not have a depressed immune system so the worst case to consider is the PATIENT.

What are the classifications for protection against harmful ingress of water or particulate matter? – There are a wide variety of these classifications (per sub-clause 6.3 of IEC 60601-1) and they are based on the standard IEC 60529 (http://bit.ly/IEC60529) titled “Degrees of protection provided by enclosures (IP Code)”. The IP Codes range from IP00 to IP68, which means respectively no protection against contact and ingress of objects along with not being protected against liquid ingress (IP00) to No ingress of dust; complete protection against contact along with protected against the effects of continuous immersion in water (IP68).  Table D.3, 2nd row (copied below), in the IEC 60601-1 standard details all the classifications in a short summary list.

ipnn IEC 60601 Medical Electrical Equipment Classification: FAQsWhy do we have classifications for protection against harmful ingress of water or particulate matter? – The reason we want to protect the ENCLOSURES of the device is to protect against ingress of these items (liquids and particulates) so they reduce the possibility of causing a hazard, such as a short based on bridging the electronics of the device causing potentially a fire hazard, a shock hazard, a thermal hazard, or other potential hazards.

What are the classifications for methods of sterilization? – For any part of the ME EQUIPMENT or its parts intended to be sterilized needs to be classified per the requirements of sub-clause 6.4. Classifications are based on the types of sterilization methods used in the medical device industry currently such as ethylene oxide (EtO), irradiation by gamma radiation, and moist heat by autoclave. The standard also mentions “…other methods validated and described by the MANUFACTURER.” Classification of sterilization methods is critical, because each sterilization method presents unique environmental conditions that can adversely affect ME EQUIPMENT. For example, EtO Sterilization frequently includes a vacuum cycle which may not be suitable for embedded batteries.

Why do we have classification for the suitability in an oxygen rich environment? – The RISK of fire in an OXYGEN RICH ENVIRONMENT is considered to exist when a source of ignition is in contact with ignitable material (i.e., flammable materials) and there is no barrier (i.e., a solid enclosure) to prevent the spread of fire.

What are the classifications for modes of operation? – There are two modes of operation described in IEC 60601-1, edition 3.1: 1) CONTINUOUS OPERATION, and 2) non-CONTINUOUS OPERATIONS. When a device is classified as non-CONTINUOUS OPERATION there is some type of duty cycle involved so the device is rated properly. A duty cycle means the device is rated to be on for a certain period of time and off for a certain period of time. Many times the duty cycle is required so a device may pass the EXCESSIVE temperatures in ME EQUIPMENT test in sub-clauses 11.1.1 & 11.1.2 so not to exceed the limits of the test requirements.

Leo Photo Cropped IEC 60601 Medical Electrical Equipment Classification: FAQsIf you have questions about this topic or need help with compliance to the IEC 60601 series of Standards, you can email Leo Eisner (http://bit.ly/ConnectwithLeo) directly at Leo@EisnerSafety.com or call Leo at +1-(503)-244-6151. He is the owner and founder of Eisner Safety Consultants (http://bit.ly/LeoEisner).

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