A pulse oximeter is a simple device plugged into your finger to measure your oxygen saturation. Values above 95% to 100% are considered normal. Values in between 90 to 95% are considered mild hypoxia and values below 90% are considered significant hypoxia requiring supplemental oxygen therapy. In this pan-demic pulse oximeter has become an essential medical device for almost all families.
Which finger is ideally used in adults to estimate oxygen saturation?
Our hands and fingers have a dual blood supply. This is from the radial and ulnar arteries. The middle finger has a dual blood supply from both the arteries. The middle finger of the right hand is most ideally suited. Make sure that there is no nail polish, the finger is steady during measurements and the patient is not shivering. The ringer can be made warm by rubbing and any sweat needs to be wiped for better accuracy.
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What Ise basis of pulse The pulse oximeter functions by positioning a pulsat• ing arterial vascular bed between two wavelength light-emitting diode and a detector photodiode. Oxygenated hemoglobin will absorb more of the infrared wavelength than reduced hemoglobin. Reduced hemoglobin absorbs more of the red than the infrared wavelengths. The percent saturation reading results from a ratio of oxygenated hemoglobin to the total hemoglobin content.
What are the factors that can adversely affect the readings?
Low blood pressure, can possibly reduce the signal. Reduced blood supply due to vasoconstriction is common due to vasopressor drugs used in critical care. Shivering or muscle twitching may give inaccurate results. Carboxyhemoglobin in carbon monoxide poisoning may give false high Sp02 readings. Methemoglobinemia can give false low Sp02 read-ings blood pressure cuff on the monitored arm may give lower Sp02 read-ings. What about lipids and High blood lipid Concentra-t ions, hyperalimentation, and jaundice can give erroneous readings. The pulse oximeter is designed to measure two specific wave-lengths, other elements of the blood can interfere with the overall transmission of light, including those two wavelengths.
What are the clinical limitations of the pulse oximeter?
Pulse oximeter informs you about the percentage of hemoglobin saturated with oxygen. It does not inform you about the Carbon dioxide in the blood. In presence of COPD and in the late stages of Covid pneumonia, the saturation may be low to normal but the patient remains drowsy or unconscious due to high carbon dioxide levels. It does not reveal the pH of the blood.
What is the other information on the pulse oximeter?
Besides the oxygen saturation, the oximeter gives you the digital display of your peripheral pulse rate per minute. This is equivalent to bpm, which is beats per minute. A rate between 60 to 100 is considered normal. Values beyond this range at the resting stage should be considered abnormal and medical attention should be sought. This is mentioned as PR or bpm. This means pulse rate or beats per minute.
What is the PI value seen on some oximebars?
This is known as the perfusion index. The perfusion index is the ratio of the pulsatile blood flow to the non-pulsatile static blood flow. PI is the pulse strength at the sensor site. The PI values
range from 0.02% for a very weak pulse to 20% for an extremely strong pulse. Higher the PI value, better the pertbsion, and more accurate the oxygen saturation reading. The PI vanes depending on the patient’s physiological conditions and monitoring sites. It can give an early indication of anesthesia failure-The waveform can depict irregular heartbeat, a weak waveform can depict incorrect placement of oximeter or a dirty LED sensor. PI% can depict an irregular heartbeat, Pls can indicate the strength of the pulse and indicate effects of anesthesia m the operation theatre. What is the exact of pulse o This small device relies on the differences of oxygenated and deoxygenated red cells in the absorption of red and infrared light wave-lengths. Oxyhemoglobin and deoxyhemoglobin absorb these wavelengths in different amounts. The pulse oximeter senses these minute color changes in pulsating blood and calculates how many oxygen molecules are bound to haemo-globin or oxygen saturation. A strong regular pulse is required to obtain a good signal and accurate reading.
Who developed the first pulse oximeter?
In 1935 a German physician Karl Matthew developed the first two wavelengths ear oxygen saturation meter The first pulse oximeter was developed in 1972, by Japanese bioengineers Takuo Aoyagi and Michigan Kishi. Smartwatches are being used to assess our oxygen saturation. They are yet to be tlilly validated by health authorities so far However, they may find an important place in our assessment of oxygen saturation. The Pulse oximeter has become a very important tool in assessing individuals with respiratory ailments and in particular Covid infection in this pandemic. It decides about the need for hospitalization and the requirements of oxygen. The oxygen saturation readings may help to decide about the need for nasal oxygen or by re-breathing mask or non-inva-sive or invasive ventilatory support. Unquestionably a very important small inexpensive device if used correctly can help us to monitor a sick patient at home or in the hospital.