How to Choose the Right Oximeter?

Planning to buy an oximeter, are we? Need some help in making the right purchase? Well then, keep reading! In this write-up, we are going to talk about oximeters. We think it’s very important that before you hit that ‘Add to Cart’ button, you know exactly what you are going for. What exactly is an oximeter? What is it used for? What kind of oximeter would be the best for you? All these questions need to be answered so that you go for the oximeter that is really good value for money. Let’s begin, shall we?

What is an Oximeter?

If you are someone like me who loves to watch Grey’s Anatomy but has actually never been inside a hospital as sophisticated as the Grey-Sloan Memorial, you could probably relate to this. The clothespin-like device pinned onto the patients’ index finger had always got me curious. What is this thing? What does it do? And then I googled about it and so I came to know it was an oximeter. I dug really deeper and was amazed how important the role of pulse oximetry in medicine is.

An oximeter is a medical device that is used to measure the concentration of oxygen in the blood. Patients with conditions like Chronic Obstructive Pulmonary Disease (COPD), asthma, congestive heart failure, lung cancer, anemia etc may need a spot or continuous monitoring of blood oxygen level. Pulse oximetry is a non-invasive, quick and very accurate method of doing so.

How Does an Oximeter Work?

An oximeter has a probe which is pinned onto the patient’s index finger, toe or ear lobe, depending on the suitability. There are two light emitting diodes and a photo-detector on the inner side of the probe. When the oximeter is pinned onto the patient and turned on, the two light emitting diodes emit two kinds of lights. One diode emits light in the red spectrum at the wavelength of 660 nm and the other diode emits light in the infrared light at the wavelength of 940 nm.

The working of the oximeter is based on the fact that the oxyhaemoglobin (HbO2 - haemoglobin with oxygen) and deoxyhaemoglobin (Hb – a form of haemoglobin without oxygen) absorb the two lights differently. The light absorption of oxyhaemoglobin is higher for infrared, i.e., at 940 nm. Similarly, the light absorption of deoxyhaemoglobin is higher for the red light, i.e., at 660 nm. The photo detector on the other end measures the amount of unabsorbed light of each wavelength passing through the finger and the microprocessor does the further calculations.

The microprocessor first computes the concentration of oxyhaemoglobin and deoxyhaemoglobin, and then the percentage of oxyhaemoglobin, which is the arterial blood oxygen saturation, which is then displayed on the screen as SpO2.

Arterial Blood Oxygen Saturation OR Oxygen Concentration OR SpO2 = HbO* 100 / HbO2 + Hb

What to Look for in an Oximeter?

The kind of specifications you want in your oximeter would depend on how you expect to use it. There are basically 4 types of oximeters available in the market.
  • Fingertip Oximeter – This is the simplest and cheapest option if all you want to do is a spot check your oxygen concentration. It runs on battery and the probe has a screen on itself that displays the oxygen levels and the heart rate.
  • Handheld Oximeter – The probe of this oximeter is connected to the screen via a cord. It can be used for both spot check and continuous monitoring. These are widely used by the paramedics.

  • Wrist Pulse Oximeter – Ideal of continuous use, this one has the probe is pinned onto the index finger and the screen is worn around the wrist like a watch. 

  • Tabletop Oximeter – These are usually used in hospitals. They can be used at home if the patient is being nursed at home. These are larger devices with a probe connected to a bright LED screen that is placed on a tabletop at the bedside. Since the table top oximeters are used for constant monitoring, they have a long battery life of 14-16 hours. They can be completely recharged within 4-5 hours and also have a memory to store the stats recorded during several hours for analysis at a later date.
The larger and more sophisticated oximeters are highly precise as compared to their portable counterparts. The portable fingertip and write-worn oximeters are known to show a deviation of up to ±2% in the blood oxygen saturation.

It would be really smart of you to look for an oximeter that runs on electricity instead of batteries if you are going to need constant monitoring. It will save you the trouble of recharging or replacing the batteries again and again.

The fingertip oximeters are very handy and widely used. Most brands offer very versatile fingertip oximeters that can be used by children as well as adults with the utmost ease. To get accurate readings, it is very important that the oximeter probe fits your finger properly. Too loose or too tight, it will display incorrect results. The Nonin Go2 can accommodate fingers as thin as 0.3” and as thick as 1”, making it an ideal oximeter for both children and adults.

Other Specifications to Look For

  • Alarm – Having an alarm in your oximeter would be an added advantage. They produce high pitch and low pitch sounds for increasing and decreasing oxygen saturation respectively.
  • Warning mechanism – Some oximeters come with a warning light or produce an audible alert beep indicating some sort of interference or erroneous readings.
  • Display – Pick an oximeter with a good, clear and vibrant screen so that you can read the results correctly.

Lastly, discuss it with your doctor what kind of oximeter would be the best for you. Once you buy it, take it to your doctor’s office and compare its readings with those of the doctor’s oximeter. This will validate the functionality and accuracy of your oximeter. Make sure it comes with an easy return policy, just in case it turns out to be defective or inaccurate.

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