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Sunday, July 28, 2013

Liquid Nitrogen - Gotta Keep It Cold!

If you have ever attempted to order liquid nitrogen online, then I’m sure you are aware that it’s not quite as easy as it would seem. Not only is liquid nitrogen a volatile substance that requires expensive transportation and careful use, but few online retailers will take the risk to deliver it to individuals not affiliated with a large university, medical facility, or specialized industry. Although some online retailers will let you order liquid nitrogen online if they are located in your vicinity and have the capacity to allow their established customers to request a delivery online, they will only arrive at your location and offer to fill up a vessel that has already been purchased. This means that, regardless of the location, if you don’t work in a career that regularly uses and documents purchase of liquid nitrogen, no retailer will offer to sell you and deliver a full tank of liquid nitrogen.

This would explain why on  the "Big Bang Theory", Leslie Winkle, Ph.D., an experimental physicist who was one of Leonard Hofstadter's love interests, was able to flash freeze and shatter a banana for her cereal (she was unable to find a knife to cut it up).  The character works at the labs at the California Institute of Technology along with the other scientists on that popular show.  She also heats up a cup of instant soup with a helium-neon laser.  Needless to say, these are not a normal kitchen's food prep accessories, but normal at a lab at Caltech.  If you want to see an example of a Dewar, as described below, watch the Season 1, Episode 5 show, entitled "The Hamburger Postulate", or catch this "Best of Leslie Winkle" video on YouTube.

So now that we’ve addressed the general difficulty of ordering liquid nitrogen online, especially for the layman, let’s talk about the specialized vessels required for storage of liquid nitrogen. The most common storage container is know as a Dewar, and it is a vacuum sealed and insulated vessel specifically designed to slow evaporation of the liquid nitrogen and prolong the life of the liquid. If that is a bit hard to wrap your head around, a common example of the Dewar that sees everyday use in kitchens around the planet is a thermos. Basically, much like how a thermos keeps warm drinks warm and cold drinks cold, a Dewar keeps liquid nitrogen nice and cold. One example of a Dewar is the Brymill Liquid Nitrogen LN2 Storage Tank.

The reason that liquid nitrogen is so often used commercially and medically is its extremely low boiling point and ability to rapidly freeze and cool machinery, food, and even living tissue. That’s why many medical devices rely on it, such as Brymill and Premier liquid nitrogen sprayers, and also why it is commonly used in food preparation and transportation. However, along with the obvious benefits of liquid nitrogen come many risks.

For instance, one should never place liquid nitrogen in a tightly sealed vessel due to the risk of the container exploding—not in the spectacular, Hollywood sense of the word, but improper storage can certainly result in a major safety hazard. Due to its rapid vaporization, liquid nitrogen can quickly vent off huge amounts of pressure. And if that’s not enough reason to be wary around liquid nitrogen, it can also cause very serious burns. Known as ‘cold burns’, contact of human skin with liquid nitrogen can result in an injury much like severe frostbite, and in the worst of cases, result in amputation of fingers, toes, or even require skin grafts on larger areas of the body. Liquid nitrogen also has many helpful medical uses, however, such as in the removal of skin cancers, warts and skin tags. So in conclusion, while liquid nitrogen has many helpful uses, care must be taken in its transport and storage.

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Friday, July 26, 2013

Why the ConMed ESU is Dominant in Its Field

Despite the daunting implications of a term like ‘electrosurgery’, it’s fascinating to think that the technology behind it has existed for nearly 90 years. Much like cauterization, in which electrical current is used to heat up a probe during a medical procedure, electrosurgery utilizes electrical current to cut, destroy, or coagulate tissues without the use of a traditional cutting tool like a scalpel. For instance, electrosurgery would likely be employed in procedures where bleeding is a serious risk to the patient. The two most important elements of any device used to perform electrosurgery are the generator and a handheld device known as the RF knife, which is popularly referred to as a ‘Bovie’. It should be no surprise that this nickname originates from the creator of the first electrosurgical device, William T. Bovie.

Almost 20 years after the first electrosurgical procedure was performed at Brigham Hospital, a lower-powered and more affordable device was created known as the hyfrecator. This remains a generic term used to denote any device utilized on conscious patients for electrosurgical procedures, although only devices made by the ConMed Company have patent over the term. The most commonly used hyfrecator is a model named the ConMed Hyfrecator 2000 Electrosurgical Generator (sometimes abbreviated as ConMed ESU), which, at the time of this post, remains the highest-selling brand in the nation. The ConMed ESU also provides the added benefit of variable power settings. As one might imagine, this is a useful feature due to the number of different medical procedures that might call for more sensitive and precise manipulation of the device, such as removal of warts, electrocauterization of small arteries, or destruction of skin cancers.

A low-powered hyfrecator like the ConMed ESU owes much of its dominance in the field to its widespread utility across many different avenues of medicine. These would include fields as diverse as dentistry, gynecology, and even veterinary medicine. However, the one caveat that we haven’t discussed yet is the fact that, to perform electrosurgical procedures, the device has to literally pass pulses of AC electrical current into your skin through an electrode, at which point the tissue is either cauterized or destroyed. Apparently, due to the high-frequency of the current utilized by devices such as the ConMed ESU, the patient undergoing the procedure doesn’t feel pain from the electricity—instead, it is often the heat generated from the burning of tissue that causes discomfort to the patient! Amazingly enough, the pain is usually so slight during the more common procedures (like skin tag removal or wart removal) that the patient often requires no anesthesia.

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Wednesday, July 24, 2013

Shine A Light!

Remember the last time you or your significant other had to fix a catastrophic leak under the kitchen sink? Laying on your back, with a pair of ten pound slip-joint pliers in one hand, some plumber’s putty in the other, and absolutely no way to hold a flashlight. Well, you’re not the only one. Much like plumbing, in the world of medicine, the job gets a lot harder if you can’t see what you’re trying to fix!

By this point, we’re all familiar with the many joys of a visit to the dentist. Besides the anticipation and anxiety, the one thing most people remember vividly is the large, bright light hanging above their head and shining almost directly in their eyes. This may be universally unpleasant, but rest at ease knowing that without this light, the dentist would likely need a third arm to get his job done. That light, along with many others located in physician’s offices around the nation, is known as a medical lamp. Medical lamps usually come as either a hand-held light, which is generally portable, or a stationary, hands-free lamp. Typically, the hands-free variety come pre-mounted to a pair of rotating, metal arms for easy manipulation.

One of the most popular medical lamps among medical professionals would be the Waldmann magnifying lamp, which combines the typical high-powered medical lamp with a magnifying lens. This would see practical use in any medical setting where careful observation is a necessity, largely due to the greater visual fidelity provided by the magnifying lens. A good example of such practice would be a dermatological clinic, a dentist’s office, or even the local family doctor. Often, these lamps are very high- powered, typically loaded with LED bulbs rated for 50,000 or more hours of life, and complete with plastic guards to shield both the patient and the doctor from the heat of the lamp.

Additionally, there are far more models of medical lamp available than just the Waldmann magnifying lamp, such as lights with multiple levels of magnification, optical output for use with monitors, or bulbs that emit light of varying wavelengths for specialized procedures. An example these more specialized products would be the mounted line of Waldmann ISIS surgery lights and the Waldmann Tevisio series of LED lights, which feature all multiple points of articulation. So, from plumber to dentist, I think we can all agree that sometimes it’s nice to have a second set of hands!

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