Alternative Methods of Monitoring Blood Oxygenation
Did you notice how things tend to balance each other in the universe? As the surrounding pollution increases and our health worsens as a result of leading incorrect lifestyles, technology tends to counteract these negative effects by inventing new means of keeping track of the oxygen levels in our blood, in the surrounding air, in the water we drink or certain mechanisms we use (such as the internal combustion engine).
Yes, we are all aware that oxygen monitoring cannot restore the ecological balance of our planet or the frail health of an asthmatic patient. But it can certainly save lives in critical situations! That’s why it’s important to be familiar with the main types of oxygen monitors and to know how to use them in order to cope with various environmental and medical problems.
The blood oxygen monitor (or the pulse oximeter) is not the only way of measuring the oxygen saturation in our blood. Before the apparition of pulse oximetry, specialists used other means (mostly invasive blood tests) to determine the oxygen levels in a patient’s blood. Nowadays, even if pulse oximeters provide fast and reliable readings non-invasively, there are still cases when medical experts need more detailed information about a patient’s condition – information that can be obtained through other oxygen monitoring means.
Here are a few other methods (besides pulse oximetry) of measuring the blood oxygen saturation:
Arterial blood gas test. By using a blood sample extracted from the artery, this analysis provides complex information about the patient’s condition. Besides the oxygen levels, the specialists can also measure the pH level of the blood, the bicarbonate (carbon dioxide) level, hemoglobin concentrations etc. By using these results, they can objectively assess the gas exchange levels in blood which are related to pulmonary functions.
Carbon monoxide monitor. Also called a CO-oximeter, this device is similar to the pulse oximeter, only having an opposite function: instead of detecting the oxygen levels in the blood, it detects the presence of the toxic carbon monoxide.
Important note: don’t confuse carbon monoxide with carbon dioxide! Carbon dioxide (CO2) is occurring naturally during the respiratory process as a gaseous waste product from metabolism. Whenever we exhale, this gas is eliminated from our lungs. Carbon monoxide (CO), on the other hand, is a toxic gas that can form stable compounds with hemoglobin, preventing a normal oxygen supply and causing hypoxia. In high concentrations, it can kill a person in just a few minutes.
The CO-oximeter, consequently, can be very useful for detecting hypoxia in time. Its functioning principles are similar to those of an oxygen monitor: by measuring the difference between the absorption levels of two different light frequencies, this device measures the carboxyhemoglobin and oxyhemoglobin concentrations, being especially useful in situations when specialists suspect a carbon monoxide poisoning (in such cases, a pulse oximeter may be ineffective because it can display normal oxygen saturation levels even if the patient is suffering from carbon monoxide poisoning).
Capnometry is a breathing monitoring procedure that measures carbon dioxide concentrations in expired gases. The device used during this procedure is called capnometer. It also determines the adequacy of ventilation and the breathing rate of the patient. It works by using infrared frequencies and measuring the amount of light that has been absorbed by CO2 molecules during the breathing process. Capnometry is used in intensive care (for example, for monitoring mechanical ventilation), in patients under anesthesia, as well as in studies of pulmonary functions.
T-stat oximeter. This oxygen monitor is a relatively recent invention. Intended for clinical care, it was developed by the Stanford professor David Benaron. By reading the oxygen saturation even in the smallest capillaries, the T-stat oximeter can determine the oxygen levels even in patients with no pulse. Since the functioning principles of this revolutionary device are extremely interesting, I plan to write an entire article dedicated to this new type of oxygen monitor. Read my next post to find out how specialists save lives by determining the oxygenation in situations when simple pulse oximeters cannot function.
