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Did you know how a pulse oximeter cleverly eliminates the influence of skin and bone to obtain accurate readings?
In medical diagnosis, pulse oximeter, as a non-invasive monitoring tool, has become an important device for assessing patients' oxygen saturation. This device uses two different wavelengths of light to detect the oxygen content in the blood and calculate the patient's blood oxygen saturation (SpO2). So, how does a pulse oximeter exclude the influence of other tissues such as skin and bones to ensure the accuracy of measurements?
Basic principles of pulse oximeter
Pulse oximeter mainly uses the different absorption characteristics of red light (660nm) and infrared light (940nm) to determine the ratio of oxyhemoglobin and deoxygenated hemoglobin. When these two types of light penetrate the skin and tissue, oxyhemoglobin absorbs less infrared light and more red light; conversely, deoxygenated hemoglobin absorbs red light and lets in more infrared light. Light passes through.
When the front-end probe is applied to the skin, the oximeter can instantly measure changes in blood flow and send out different pulses with each beat of the heart to provide data for the reading.
How to exclude the influence of other organizations
Due to the design considerations of the pulse oximeter, the device utilizes the characteristics of pulsatile blood flow (i.e., only monitors changes in arterial blood), thereby ignoring the influence of venous blood, skin, muscle, fat and other tissues. When used, it passes light through a thin body part, usually a fingertip or an earlobe, and transmits it to a photodetector on the opposite side for analysis.
Clinical application of pulse oximeter
Pulse oximeter has a wide range of applications, including emergency rooms, operating rooms, intensive care units and other environments. Medical staff can obtain the patient's blood oxygen saturation in a short time, which is crucial for judging the patient's oxygenation status. During the COVID-19 epidemic, pulse oximeters have played an important role in self-testing at home, helping to detect potential hypoxemia early.
In unstable patients, continuous monitoring can more effectively determine the need for immediate supplemental oxygen.
Advantages, Disadvantages and Limitations
Although a pulse oximeter provides a quick and non-invasive measurement, it does have certain limitations. First, a pulse oximeter can only measure hemoglobin saturation and cannot directly detect ventilation. Additionally, inaccuracies may occur in certain disease states, such as anemia or carbon monoxide poisoning. Therefore, in clinical practice, blood gas analysis is still needed for a more comprehensive assessment.
Factors affecting measurement accuracy
Several factors can affect the accuracy of pulse oximeter measurements, including:
- Poor blood flow: For example, if the fingers or earlobes used are affected by cold, the blood flow will become unstable.
- Skin color: Studies have shown that people with darker skin tones may cause deviations in measurements because the absorption of light by people of different skin colors affects the accuracy of the data.
- Exercise: Pulse oximeters do not provide accurate readings if the measurement is taken while the patient is exercising.
The future of pulse oximeters
In the face of changing medical needs, pulse oximeters are also undergoing technological upgrades. For example, with the development of wearable technology, more and more smart bracelets and smart watches are beginning to integrate well-functioning blood oxygen monitoring equipment, which will make daily health monitoring more convenient. However, for clinical accuracy requirements, traditional medical equipment is still indispensable. Therefore, it is crucial to ensure data accuracy and reliability when adopting new detection technologies.
In this era of continuous technological advancement, we might as well think about how future diagnosis and treatment methods will continue to evolve to better serve the health needs of patients.
