Pulse Oximeter
Anyone who has been to hospital for an operation will probably have seen a strange plastic clamp on the end of their finger at some point. The pulse oximeter helps doctors and nurses to see how well the blood stream is absorbing oxygen from the lungs. It is also used by athletes to check their performance during training. Those who are into extreme sports, like mountain climbing and free diving, use a pulse oximeter just to stay alive. There are a range of models available but only the ones approved by health authorities can be used for medical applications.
Oximetry is a non-invasive technique that allows the oxygen content of the blood to be measured, without having to use a needle to draw blood. It is widely used to monitor patients during an operation, but it has also found applications outside of medicine. A pulse oximeter focuses red and infrared light on a small patch of skin, usually the tip of the middle finger. Most of the light is reflected but some is absorbed by the skin and the blood stream. By measuring the difference in absorption between the two light sources, it is possible to work out the oxygen level.
The pulse oximeter is basically a large plastic clip that is designed to fit over the tip of the middle finger. On the jaws of the clip, there are tiny globes that shine light onto the skin, and sensors which measure the amount of light reflecting off the skin. Some models are just a clip attached to a cable, but they cannot be used on their own and need to be connected to a monitor. Other models are missing a cable because they already have a monitor built into the clip. Although most models can only be used by adults, there are some that are designed for children.
There is a perception that only doctors and nurses are allowed to use a pulse oximeter but that is not true. It is not a restricted device and you can easily buy one from a department store or off the internet. Even the professional models used in hospitals are available, although they cost a lot more than the basic models. Mountaineers often use a pulse oximeter during ascents of high mountains, like Everest. Similarly, free divers may use one to make sure they have enough oxygen in their blood to make a long dive. Patients who are sent home to recover are often provided with one so they can keep their doctor inform of their progress.
The grip of a pulse oximeter needs to be very tight around the finger. A false reading will be given if any external light leaks in from the sides. Some models even have an alarm that warns if the grip is not tight enough. Most models are free of latex and rubber which is good news for people with those allergies. The update rate is an important feature to look at when comparing different models, as some models are too slow to give a constant update. Another good feature is an alarm that sounds when the oxygen content drops too low. The advanced models have a large OLED display that is easier to read and shows a waveform chart next to the numbers.
The human body is so incredibly complex that a number of different tests are required for a proper diagnosis of most conditions. The pulse oximeter is just one of a range of test equipment used to monitor patients. It alone will not give a complete picture of the health of the respiration and circulation systems. Unfortunately, too many people think they can diagnose themselves with a pulse oximeter they bought off the internet. Doctors and nurses face this problem all the time, with people coming into their offices thinking they are about to drop dead from some condition or another. It is important to understand the significance of the values that a pulse oximeter gives, but that requires many years of professional medical training.
