Fundamentals Of CMS Pulse Oximeters

By Madeline Pittman


CMS pulse oximeters are pieces of equipment used to perform pulse oximetry. This kind of oximetry is a non-invasive technique for monitoring the level of saturation of Oxygen gas in the body. This equipment was first invented by a physician called Glenn Allan Millikan in 1940s. This first device operated on two wavelengths and was placed on the ear. The two wavelengths were red and green filters.

This original product was improved later on in 1949 by a physician named Wood. Wood added a capsule for compressing blood out of ears to obtain nil setting in the attempt to obtain absolute O2 saturation levels. The current makes function on similar principals like the initial one. However, the functioning principal was hard to implement in first makes because of unstable photocells and/or light sources.

Oximetry itself was first developed in 1972 by two bioengineers, Kishi and Aoyagi at Nihon Kohden. These two used the ratio of red to infrared light absorption of pulsating parts at measuring spots. Commercial distribution of the oximeter happened in 1981 through a company called Biox. At that time, the device was mostly used in operating rooms and companies that produced it focused most of their marketing in the same direction.

Oximetry is a very crucial noninvasive way of determining the level of oxygen in the human body. It uses a pair of tiny light emitting diodes that face a photodiode through a translucent part of the body. Such translucent parts include fingertips, toe tips, and earlobes. One LED is red while the other one is infrared. The infrared LED is normally 940, 910, or 905 nm while the red one is usually 660 nm.

The rate of absorption of the two wavelengths differs between the oxygenated and deoxygenated forms of oxygen within the body. This difference in absorption speed can be utilized to estimate the ratio between deoxygenated and oxygenated blood O2. The observed signal changes over some period with every heartbeat because arterial blood veins contract and expand with each heartbeat. The monitor is capable of ignoring other tissues or nail make-ups by monitoring the changing portion of the absorption spectrum only.

By observing the varying absorption section alone, the blood oxygen monitor only displays the percentage of arterial hemoglobin in oxyhemoglobin configuration. Patients without COPD but with hypoxic drive issues have a reading that ranges between 95 and 99 percent. Those with hypoxic drive issues normally have values that range between 88 and 94 percent. Usually figures of 100 percent may suggest carbon monoxide poisoning.

An oximeter is useful in a number of applications and environments where the oxygenation of a patient is unstable. Some of the major environments of application include intensive care units, surgical rooms, hospital and ward settings, recovery units, and cockpits in unpressurized aircrafts. The limitation of these gadget is that it only determines the saturation of hemoglobin and not ventilation. It is therefore not a complete measure of respiratory adequacy.

CMS pulse oximeters are made in several varieties. Some are inexpensive costing a few dollars whereas others are very sophisticated and expensive. They may be purchased from any shop that stocks such pieces of equipment.




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