The Functioning Of Overnight Pulse Oximeters

By Lela Perkins


Overnight pulse oximeters are medical devices used to noninvasively monitor oxygen saturation in the body of a patient. This equipment is used in a medical method called pulse oximetry. The equipment was invented by a German physician in the year 1935. Since that first invention, there have been many other physicians who have added components to the device with a bid to make it more effective.

Oximetry makes use of two small LEDs, light emitting diodes, which face a photodiode through a translucent part of the body. A fingertip, an earlobe, or a foot in case of an infant can be used. One of the LEDs is red and has a wavelength of about 660 nm. The other LED is normally infrared with a wavelength of either 905, 910, or 940 nm. The rate of absorption of the various wavelengths varies significantly between oxyhaemoglobin and its deoxygenated counterpart.

Due to the disparities in the absorption of infrared and red wave-lengths, ratio of oxyhemoglobin and deoxyhemoglobin could be estimated. At wave-lengths of between 805 nm and 590 nm, absorption of deoxyhemoglobin and oxyhaemoglobin remains similar. Earlier gadgets made use of these range of wave-lengths to rectify hemoglobin concentration.

The monitored signal varies over time with the heart beat since the arterial blood vessels contract and expand with every heartbeat. By analyzing the varying section of the absorption spectrum only, a monitor is able to leave out nail polish or other tissues. By ignoring polish on nails and other tissues, the monitor can discern only absorption that is caused by arterial blood. It is therefore an important requirement to detect a pulse in this exercise, otherwise the oximetry will not work.

The monitors that check the levels of oxygen in blood display the composition of hemoglobin in arterial vessels in oxyhemoglobin configuration. In individuals who do not experience hypoxic drive problems and COPD, the ordinary acceptance range is between 95 to 99 percent. Individuals with hypoxic problems observe values between 89 to 94 percent. Values of a hundred percent are an indication of carbon (II) oxide poisoning.

Oximetry is different from other methods of monitoring the level of oxygen in blood because it is an indirect approach. The equipment can be integrated into multi-parameter patient monitoring systems. Most of them also indicate the pulse rate of an individual under monitoring. Overnight pulse oximeters are normally portable so that they can be carried into homes for home-based medication. They are small and operate on batteries.

These devices can be used in a wide range of applications and environments. They are used in hospital wards, emergency units, urgent care facilities, unpressurized aircrafts, and intensive care units among many others. They are used to assess the need and efficiency of supplemental oxygen to people. The device however cannot determine the rate of metabolism of oxygen in the body. For this reason, it should be used with carbon dioxide monitoring devices complimentarily.

Overnight pulse oximeters are significant for people in critical medical state. They alert health workers of abnormalities in amounts of oxygen in sick people. Technological improvement has rendered it possible to remotely control them for purposes of efficiency and convenience.




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