EC.710 | Spring 2010 | Undergraduate

D-Lab: Medical Technologies for the Developing World

Projects

Swiss Army Electrocautery

A combination scalpel and extendable electrocautery tip for rural surgical procedures

Team: Sonya Makhni, Victoria Lee, and anonymous MIT students [AK] and [SG]

This content is presented courtesy of the students and used with permission.

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Post 1

Our project will address some of the problems the rehab center in Nicaragua faces with their electrosurgery machine. Right now, the machine runs a huge risk of burning the patients because there is a faulty circuit between the return pad and the machine’s generator. They used to have a means for checking that the circuit is functioning properly, but this no longer works. As a result, several patients experience severe burns during surgical procedures.

Our first idea was to develop a low cost, easy to use electrocautery device that would have rechargeable batteries. The electrocautery machine would be able to function when plugged in to a power source and if it were simply using the batteries. Another idea we had was to develop a censor-based system that would be used with their existing electrosurgery machine itself. This system would contain an auto-shutoff mechanism that would detect if the circuit between the pad and generator was broken. In addition, this system would contain a series of indicators that would alert the user as to which portion of the circuit was not functioning properly (probably via series of on/off lights).

After a couple weeks of discussions, meetings, and research, our team has decided to shift our project’s focus. We first learned that chargeable electrocautery pens could be purchased for $15, a very inexpensive price. This made us rethink our first idea of creating a cheap pen, as they already exist. We also decided to not focus on the electrosurgery idea, for this would involve hacking a system we do not have access to. We are on the road to coming up with a more innovative solution…

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Pricing for Electrocautery

by [AK]

The cheap ($30-45) electrocautery pens were just the pen unit (no tips or one complementary tip included); typically this can be autoclaved for a certain number of times (40 times was what the representative said). On these, a box of tips (blade or needle type) can be bought for about $50 dollars as Sonya said. The tips must be disposed after each surgery because they cannot be autoclaved (we need to find out why).

The expensive pens (around $80-$125) are actually a box of ten Sterile pens with the pen attached to the tip. Each of these is disposed completely after thesurgery because it cannot be autoclaved. The low temp (which Sonya found out can only coagulate not cut) is a bit cheaper than the high temp (which apparently can cut as well, we need to confirm this).

To do some math:

For 10 surgeries: 1 autoclavable pen + 10 disposable tips = approx $90-$100 (after 40 surgeries a new pen must be bought because it can only be autoclaved 40 times)

For 10 surgeries: 10 nonautoclavable (Sterile) pen+tip units = approx $100

Basically, tips cannot be autoclaved, ever….?

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Company Contacts for Electrosurgery

Response from Future Health Concepts 
Rob Gorgas 
List of Contacts 
Production Engineering - Medical Equipment Division 
6035 E. 38th Avenue, Denver, Colorado 80207 USA (303) 393-7800 FAX (303) 393-1482

Valleylab - Covidien 
Tel: 1-800-722-8772

Conmed Electrosurgery 
Telephone: 800.448.6506 
5088135544 Erica McLaughlin 
Denver

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Talk with Ailis…

by Sonya Makhni

Hey Guys,

I just got off the phone with Ailis (pronounced like alyse–whoops, I totally mispronounced her name when I called her). But I got a lot of good info, so here is a recap of the conversation:

  • She really likes our idea (the autoclavable tip + way to modify cheap cautery pens to cut AND coagulate)…She had actually been thinking about something like this before, so she is really excited about this!

Electrocautery vs. Electrosurgery

Both electrosurgery (they call it a bipolar machine) and electrocautery are used. Electrocautery is used more often. They use elctrosurgery for procedures that involve really important structures that they don’t want to damage (i.e. big vessels). It’s used for a more focused area and you can dial up the intensity. Electrocautery is more general and used for a broader number of surgeries. Because its more general, you run the risk of injuring neighboring structures because you essentially have less control than with a bipolar device.

Cutting and Coagulating: Settings

The electrocautery pens have two buttons–blue for coagulate, yellow for cut (or something like that). The surgeon presses the desired button and can immediately perform either function. Sometimes the surgeon uses a foot pedal instead of a button so that he doesn’t have to touch it.

Cut vs. Coagulate

We know that they operate off of different temperatures, but we (before) were wondering why you can’t coagulate with the higher temperature setting typically used for cutting. This is because cutting causes much more damage to neighboring tissue and coagulating uses the minimum temperature needed to get that job done. In other words, the high temperature used for cutting is excessive for the purposes of coagulation and would cause unnecessary damage to neighboring structures/ tissues.

What MGH Does

From what it sounds like, the elctrocautery MGH uses is the kind that runs off of AC current that is attached to a giant machine. She was interested in knowing more about the fancy cautery pens that run off of batteries and can do cutting/coagulation, but I forget exactly where I saw this. Help if you know what I’m talking about on this one please.

They throw away the entire pen. Because it is normal for the tips to get a little bit charred during a surgical procedure (from the vaporized tissue), it seems useful to have replaceable tips. The surgeons have a scratching pad to remove the char, but if it gets to be too much they’ll just replace the tip altogether.

After a surgery they get rid of the whole pen.

The pen they use is from ConMed Corp.

What She Will Do:

She will also get in touch with Yaffe to see if we can visit his OR

She’ll try to get in touch with a medical device representative (the people who come and give demos of their products).

She knows another surgeon that is really into technology for the developing world and will try to help us meet him.

And, she said she could probably get her hands on an electrocautery pen/ tips for us.

What WE Need to Do:

  1. She said she sees no reason why we can’t make these tips out of stainless steel. But, we still need to talk to somebody to make sure there is no reason behind not doing this. This should be our first task to complete.
  2. Find out the mechanism behind how one cautery pen can immediately switch temperature settings. We need to find out how to achieve this same duality on a cheaper, single-purpose coagulation cautery pen.
  3. We also need to let her know of our availability to come in and meet her/ see a surgery. She isn’t free this week, but she will be next week.
  4. Continue to talk to the engineers at these companies to prod them for information.

K, that’s all I think. Let me know if you have any questions, and please respond with comments about your ideas.

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Focusing on Tips

by [AK]

  1. URLs of products of interest:

Electrocautery pens and pencils (corded - cutting)

Cordless low and high temp

Tips of interest:

  1. Possible Materials:

From customer service rep -

silicone and rubber (?)

stainless steel

tungsten

copper

stainless steel

  1. Company contact - Bovie Medical

Vice President of Regulatory Affairs

I just emailed him. If he does not respond in a couple of days, I will call customer service again and other companies.

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Questions that Need to be Answered…

by Sonya Makhni

Hey guys, these are the big questions that we need to get answered (we’ve discussed these all before, but I just thought I would post as complete list as I have on our blog)

  1. Are cordless cautery pens that can switch between high and low temperatures used? Can cordless pens cut and coagulate?
  2. Or, is it more common to use the cautery pens that are attached to a generator that runs off of AC current? Why?
  3. What are the tips most commonly made of?
  4. Can they be made of stainless steel? According to one company, stainless steel tips are not used because they aren’t “approved” in hospitals…
  5. How does a cautery pen switch instantaneously between high and low temp with the push of a button (mechanistically)? Is there different wiring for the two settings or does the same system accommodate both temperatures?
  6. We understand that it is common practice to use a cautery tip once…is it possible to autoclave them? Or is there something inherent in the material that does not make this ideal? We cannot figure out if they are disposed of out of convenience, cost (for hospitals), or because the company says they should be…
  7. How exactly are the tips heated? (Does a current pass directly through them, or is heat conducted from the base of the tip?)

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Questions for Anna…

by Sonya Makhni

Hey Anna, here are a couple questions on the materials side that we said we would post. Please let us know if you have any suggestions/ ideas/ answers! Also, I don’t know if the picture will go through via this email, but I’m also attaching the picture and link of a sample cordless electrocautery pen. This particular one is only high temp, another one is low temp. The company hasn’t gotten back to me about the questions I asked them, but they said they would tomorrow or so.

http://www.medexsupply.com/products/pid-32662/AaronMedicalFineCauteryHighTem.htm?zmam=34602484&zmas=1&zmac=22&zmap=32662

  1. What are some autoclavable materials?
  2. Heat conductivity of stainless steel vs. other materials
  3. Why coat tips with silicon? Does this affect how tips can be autoclaved?

Thanks!

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Material Science Contact

I will be speaking with Professor Kimerling and Anu Agarwal (Principal Research Scientist in the medical area) about some of our materials. I’m planning on asking

  1. What are some materials that can 

    a) withstand temperatures up to 2000 F 

    b) heat up/cool down quickly (from 1000 F to 2000 F) 

    c) be autoclaved

  2. Why coat tips with silicon?

From the initial conversation I had with Professor Kimerling, he said:

“My guess, at this point, is that silicon is i) stable at the temperatures you mention, ii) has a low thermal expansion coefficient, iii) and grows a surface oxide during sterilization that is hard, protective and relatively chemically inert.”

I have to clarify why the last 2 are desirable qualities, but if there are any other questions you think I should ask, let me know.

Answers from Ailis (Correspondence 2)

by Sonya Makhni

Hey, these are some Q&A’s we were wondering about from Ailis.

  1. MGH does use a grounding pad for their electrocautery machine…they place it on the patient’s thigh.
  2. She’s never seen anyone with a cordless Bovie/ an autoclavable tip…we should still continue to look into this, though.
  3. She can give us the exact model of the instrument when we meet with her

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Bovie Electrocautery Tip Material

Just got a response from Bovie Medical, the manufacturers of the Change-A-Tip electrocautery pens.

I asked about the tip material:

“For Bovie’s cautery replacement tips, the body material is ABS with brass post.”

ABS is a plastic (Acrylonitrile Butadiene Styrene) that is a common thermoplastic. It is good for impact resistance, it is tough, light, and a good electrical insulator"

I also asked about the two different temperature settings:

“When referring to the H100 (low temperature) and H101 (high temperature) there are no design differences. This was placed into Bovie’s catalog as quick references for the end user using low/high temp cauteries.”

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