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Biocompatibility in Respiratory Products - Help interpreting whitepaper

M

milagre

#1
Hello everyone,

I am currently working towards getting a CE mark for a continuous positive airway pressure (CPAP) device. This device accepts air and oxygen inputs, mixes them into a gas stream, humidifies the gas stream, and then delivers it to the patient through a patient circuit.

My question is about biocompatibility of components of the airstream. I found a whitepaper that covers biocompatiblity for respiratory equipment, and it has been generally helpful. It explained that the common classification of respiratory equipment for 10993-1:2009 is "surface device with mucosal membrane contact". This determinition is because the air, not actual device components, has mucosal membrane contact.

The problem I am having is about which components in the airstream need to be biocompatible. Obviously the patient circuit should be, but what about the metal fittings in the internal pneumatic system of the device? To what extent do these components need to be biocompatible?The whitepaper offers an explanation to this question, but I am having trouble understanding it. I am hoping you all can help. They say that:

The materials used as components in some respiratory devices can inherently lead to some failures in the biocompatibility test battery due to the nature of the materials. Some materials such as brass, copper or natural rubber latex, are commonly found to be cytotoxic if extracted as independent samples resulting in concentrations in excess of those found in the actual clinical exposure.

For this reason, it is suggested that test articles be representative of all gas path materials (either assembled or disassembled). Due to complex material configurations, it is often advantageous to extract based on a weight ratio (4 grams/20 mL) rather than a surface area extraction ratio.​

I don't know what it means when it starts talking about creating the test articles. Do you? Any advice is appreciated.



** If this topic sounds familiar, it could be because my co-worker posted about it previously here --> Where does Contact begin for Biocompatability?
 

somashekar

Staff member
Super Moderator
#2
Re: Biocompatibility in respiratory products (help interpreting whitepaper)

it is suggested that test articles be representative of all gas path materials (either assembled or disassembled).
Decide what constitutes your gas path materials.
Discuss it with your Bio-compatibility testing lab.
They will extract it together in a cell culture medium and this is what they will use further in the tests.
This will represent your test article and the same will be detailed in the report issued to you.
 

Ronen E

Problem Solver
Staff member
Super Moderator
#3
Hello everyone,

I am currently working towards getting a CE mark for a continuous positive airway pressure (CPAP) device. This device accepts air and oxygen inputs, mixes them into a gas stream, humidifies the gas stream, and then delivers it to the patient through a patient circuit.

My question is about biocompatibility of components of the airstream. I found a whitepaper that covers biocompatiblity for respiratory equipment, and it has been generally helpful. It explained that the common classification of respiratory equipment for 10993-1:2009 is "surface device with mucosal membrane contact". This determinition is because the air, not actual device components, has mucosal membrane contact.

The problem I am having is about which components in the airstream need to be biocompatible. Obviously the patient circuit should be, but what about the metal fittings in the internal pneumatic system of the device? To what extent do these components need to be biocompatible?The whitepaper offers an explanation to this question, but I am having trouble understanding it. I am hoping you all can help. They say that:

The materials used as components in some respiratory devices can inherently lead to some failures in the biocompatibility test battery due to the nature of the materials. Some materials such as brass, copper or natural rubber latex, are commonly found to be cytotoxic if extracted as independent samples resulting in concentrations in excess of those found in the actual clinical exposure.

For this reason, it is suggested that test articles be representative of all gas path materials (either assembled or disassembled). Due to complex material configurations, it is often advantageous to extract based on a weight ratio (4 grams/20 mL) rather than a surface area extraction ratio.​

I don't know what it means when it starts talking about creating the test articles. Do you? Any advice is appreciated.



** If this topic sounds familiar, it could be because my co-worker posted about it previously here --> http://elsmar.com/Forums/showthread.php?t=62257
Hi,

1. You already have some good responses in that other thread - read carefully and try to understand them first.

2. That white paper in non-obligatory. It's only a suggestion. There are many approaches to extraction for biocompatibility tests.

3. The clause you apparently couldn't decipher relates to the selection of device components used for extracting the test sample. Obviously only parts that are part of the fluid flow path are relevent; those are sometimes proportioned based on the fluid contact area, which can be tricky to calculate in cases of complex geometry (though today, with 3D CAD it's not such a big deal). The white paper suggests that instead those components are proportioned based on their weight.

What I would do is work together with a reputable test lab, provide them a sample of the finished device as well as all relevant components loose, drawings and technical explanations, so they can help figure out what needs to be extracted and how.

Cheers,
Ronen.
 
#4
Hi all,

Based on this topic, I would like to ask if the biocompatibility requirement applies to parts that contacted by operator, such as control panel.

Both MDD directive and standard 60601-1 do not mention the object clearly (i.e. patient and/or operator). But ISO 10993-1 states that 10993 does not cover testing of materials and devices that do not come into direct or indirect contact with the patient's body.

Please kindly advise it.

Regards,
Roland
 
#5
Roland,

Here is the scope of ISO 10993-1:2009, as defined in section 1:

"This part of ISO 10993 does not cover testing of materials and devices that do not come into direct or indirect contact with the patient's body, nor does it cover biological hazards arising from any mechanical failure."

As a responsible manufacturer you may also want to consider the standard's more general introduction which says "The primary aim of this part of ISO 10993 is the protection of humans from potential biological risks arising from the use of medical devices", and employ ISO 10993-1 to evaluate any biological risks for operators or anybody else who would have contact with the device, e.g. servicing staff.

HTH,

Gerhard
 

Ronen E

Problem Solver
Staff member
Super Moderator
#6
To add on, ISO 10993-1 is harmonized and thus compliance with it satisfies the relevant essential requirements of the MDD as well.

Cheers,
Ronen.
 
#7
Thank you very much Gerhard and Ronen.

But I was told that if the ISO 10993 is required to apply to the operator or servicing staff, all daily necessaries are required to be evaluated according to ISO 10993 considering the probability of contact and duration of contact.

I would like to know that if your notified body requires a biocompatibility evaluation report for operator or someone else other than patient.

Thanks,
Roland
 
D

dwayneq

#8
I am reading this thread with great interest as I was just about to post this same question or get clarification on what contact areas are required to be tested for biocompatibility. I have worked at companies that take the safe route and besides the actual patient contact surfaces will test anything that the user or operator will come in contact with. The issue here is the tremendous cost associated with this testing. I currently have a device that will be used in the clinic, is handheld with a cord leading back to a machine. It has a disposable multi-use module that is attached and will contact the patient's skin. All contact surfaces of the module are tested for biocompatibility and for ability to disinfect. However, I get conflicting answers about the operator held device shell and the control buttons as well as the cord. The materials are used in every day consumer products but do they really need to go through the full triparte testing? If not, then how should this be documented?
 
#9
dwayneq,

for specific advise one would have to know the specific device, and what specific pre-clinical and clinical data is already available to propose a biocompatibility evaluation route.

But generally speaking, I would suggest re-wording your comment from "testing" to "...what contact areas are required to be _evaluated_ for biocompatibility." The key concept of ISO 10993-1:2009 is that you have to consider the biological risks of your device within a risk management process and evaluate for which risks you have enough data to justify test omission and for which risks you do not know enough and thus, justify testing.

Now from an operator perspective, the device is usually in intact-skin contact, whether short-term, prolonged or permanent depends on the cumulative "operation time". Compared to the patient contact, this is usually a low risk contact, right? Thus, you might gather enough material characterization data, by inquiring your suppliers about material composition/purity, helpful certificates like MSDS, RoHS II compliance, colour additives and their chemical nature and quantity, USP VI material testing, ...

Provided you also achieve to gather relevant information about how these materials are processed and gather information about the injection molding process, welding processes, cleaning processes, .... you actually may have gathered enough material characterization data to conclude in you biocompatibility evaluation, that you can justify test omission for the operators' low-risk intact-skin contact.

Reference to everyday consumer products will not help you a lot in justifying test omission - they are no medical devices and thus, usually less strictly regulated. And usually, you would not have access to detailed information what these consumer goods are really made of.

HTH,

Gerhard
 
#10
Gerhard,

The point is not to test or evaluate the compatibility of material. The argument is if biocompatibility for parts that contacted by operator only should be considered. Even evaluation route will lead to some degree of workload.

Roland
 
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