Monthly Archives: April 2012
Understanding Cold Lasers
The term “cold lasers” might sound like an oxymoron. After all, all the lightsabers in Star Wars are capable of cutting through metal, right? And the laser beams used in Star Trek can slice a hole right through a person. And let’s not even think about James Bond villains and their lasers that can end life as we know it! So, how can a laser be any good and be cold at the same time?
The word “cold” when applied to lasers actually means that it’s a low-level laser. The light emissions from cold laser equipment are not as strong, or on as high a frequency, as those in “hot” lasers. Lasers are classed by their ability to damage the retina, and by the amount of wattage needed to produce the light emissions. Let’s break them down by class, with some examples:
- Class I – These lasers use the least amount of power to produce light. They are considered inherently safe. They can be found in CD and DVD players and burners, for example.
- Class II – These lasers use a little more power, typically, but the light emitted can be easily blocked by the eye’s natural blinking process. Your laser pointer is most likely a Class II low level laser.
- Class III – Class III laser equipment is separated into two sub-classes. Class IIIa can only cause slight vision damage if stared into for several seconds. Class IIIb can cause immediate sight damage. These lasers are typically used in machining and other industrial applications.
- Class IV lasers are the most dangerous. They are powerful enough to burn skin as well as damage the eye. Most scientific laser equipment falls into Class IV.
Medical laser equipment is typically somewhere in the Class II to Class III range, depending on its use and application. Most gas-powered surgical lasers require 30-100 watts of power, and fall in the Class III range. Medical science has produced pulsing laser equipment, capable of using high levels of power (up to 50 watts or so) without the risk of heat or burning, so even though a laser has higher power requirements, it may be classed lower than, as its risk of danger is not so great. These are your “cold lasers” used in medical therapies such as body sculpting cosmetic treatments, pain and inflammation therapy, wound healing therapy, and long-term effective pain relief. Cold lasers may not be able to slice a path through evil Sith Lords or bring down satellites, but they have a great and growing future in health care.
How Do Pulse Oximeters Work?
They clip onto our fingers. They slip around our arms. They stick onto our chests. They even belt around our rather large bellies while we’re in childbirth.They appear in doctors’ offices and clinics, on board ambulances and in the waiting area of the pharmacy. Some even find their way into our homes. They are an essential piece of medical equipment in San Diego, New York, Stockholm, London, Tokyo, and all other corners of the globe, too. Clinics in Africa pray for them, even in the form of used medical equipment. Patient monitoring devices are a staple of modern medicine, from the little pulse oximeter to the much larger fetal band; from the fairly straightforward blood pressure monitor to the much more complex Welch Allyn Atlas Monitor, which monitors several vital systems at once. Let’s take a look at one very common type of medical monitor, the pulse oximeter.
Pulse oximeters measure the amount of oxygen being carried in the blood stream. A normal, healthy individual will have a blood oxygen saturation level between 95% and 99%. Levels lower than this can indicate problems or difficulties in breathing. Pulse oximeters use a bit of high-tech magic and some good old-fashioned anatomy to do their work.
Hemoglobin carries oxygen from the lungs throughout the body. The oximeter can measure the amount of oxygen in the blood by monitoring the amount of hemoglobin and comparing it with the maximum level possible. It does this by sending red and infrared light through the body. Oxygenated blood absorbs infrared light while it allows red light to pass through. The amount of infrared light absorbed tells the oximeter how much oxygen is present in the blood stream. The trick is to place the oximeter in a place where it can be assured of an accurate reading. The best placements for adults are the fingers, toes or earlobes. The light has to be able to pass through the body to the photoreceptor in the other half of the oximeter. It can only do this through a thin part of the body. (Oh, and it’s a myth that fingernail polish can trigger a false reading. Surgeons request clean fingernails for visual testing of circulation through the nail bed, not because of the pulse oximeter.)
A pulse oximeter can give the first indication that something is wrong, even before respiratory rate or blood pressure are effected. This is because it can a take the body a few minutes to show visible signs of distress, while the body chemistry at work inside has already begun to change.
Pulse oximeters may seem like nuisances when we’re in need of them, pinching our fingers and making it hard to use our hand, but their all-important service just could save our lives!