Lately, researchers have decided to take the smartphone technology to the next level: why not use these gadgets for monitoring vital signs? As you probably know, vital signs are a set of various physiological measurements, usually conducted by health care professionals for assessing the functionality of our body. They include heart rate and respiratory rate, body temperature, blood pressure and the SpO2 (or the oxygen levels in your blood).

So modern smartphones will be able to capture all these vital signs (and maybe others as well). How is this possible, technically? I am not an engineer and I won’t be able to dive into complex technical details, but I will certainly give you the basics.

As you already know, an oxygen monitor is a medical device that measures the oxygenation in our blood by using two different wavelengths: red and infrared. The instrument sends light beams through a translucent body part (fingertip or earlobe) and then the receiver collects the data, calculating the difference between the absorption rate of each wavelength: saturated hemoglobin (the oxygenated blood) absorbs the infrared light, while the non-saturated hemoglobin absorbs the red light.

For operating the new smart phone app, you will need a special ‘plug-in’ that needs to be connected to your phone (or the doctor’s phone). Being similar to the classical oxygen monitor, this little device can be clipped to your finger and plugged into the smartphone.

There is also another way of doing this – by using the video camera of your iPhone. The necessary app for this was developed by a researcher from Worcester Polytechnic Institute. In order to get the readings, all you have to do is press your fingertip on the lens of the camera. It works like a standard oximeter – by capturing and calculating the changes in the light wavelengths which are reflected by the blood in the capillaries. Then, these measurements will be translated into actual vital signs, just like in professional models of oxygen monitors. The screen will display instantly your pulse rate, respiration rate and blood oxygen levels.

As you see, in comparison with a simple oxygen monitor, the functions of the smart phone app are more complex, imitating the possibilities of a vital signs monitor: it will display live information and graphs about the physiological parameters of the patient, being extremely helpful not only for preventing hypoxia, but also for offering a complex assessment of the real-time state of our health, no matter where we are: in a hospital, at work, on vacation, in an airplane, in the gym or on the top of a mountain.

The PhoneOximeter can also prove useful in extreme situations and in rural areas – where professional help is not available.

This technology will be featured by the next generation of iPhones and iPads. I also read that FDA (the Food and Drug Administration) is currently considering approving or not these applications.

So, let’s see! The oxygen monitor is definitely a life-saving device, especially in the present conditions of continual oxygen depletion and worsening of the environmental balance. Having an iPhone with an oxygen monitoring app could be really useful!

On the long run, regular trainings increase our blood oxygen levels, also making our heart stronger. However, we should also be aware that strenuous physical effort (for example, long distance running) can sometimes lower our blood oxygen saturation, which can lead to mild or even severe cases of oxygen deficiency (hypoxia). This happens because during effort, the oxygen from our blood is burned faster than usual in order to help our body to cope with the effort. If we cannot supply our body the amounts of oxygen it needs during the exercise, we start feeling exhaustion, our breathing rate and heart rate increase and in some cases we can even feel dizzy and nauseous (other signs of oxygen deficiency). These symptoms are used by our body to tell us when to reduce the effort or stop the exercise. Failing to do so can have serious consequences on our health – our training, instead of making us healthier, can cause further dysfunctions.

Unfortunately, some people are not used to listen to their bodies. Being eager to attain new performances (this happens very often in case of professional athletes), they can sometimes push their bodies beyond their current level of endurance, which in turn can lead to oxygen deprivation and dangerous acceleration of their heart rate.

Fortunately, the oxygen monitoring industry has come with a convenient device which allows all individuals involved in athletic activities to monitor their oxygen saturation and pulse rate even during their training: the wrist oxygen monitor.

This type of pulse oximeter is extremely comfortable for continuous or spot-check oxygen monitoring. It is worn on the wrist (like a watch) and it has a finger sensor which is connected to the main unit with a small wire. Its Velcro fastening system ensures that the monitor will not fall even during the most intense trainings.

During running or exercising, the wrist oxygen monitor will continuously measure, display and record (optionally) the blood oxygen levels (SpO₂) and pulse rate (PR) of the athlete. If these values drop (or rise) to dangerous levels, the device will emit an alarm that will warn the person that he/she should stop the exercise or at least reduce its intensity.

These devices are extremely useful for people suffering from minor cardiac or pulmonary dysfunctions. Training is very important for them as well, because it helps them gradually overcome their conditions and be healthier. However (especially at the beginning) they need to be really careful about the intensity of their exercising, because pushing their bodies too much can cause them serious problems. Monitoring their pulse rate and oxygen saturation by using a wrist pulse oximeter is a wonderful way of ensuring their safety during their daily running and/or physical exercises. The claim that the oxygen monitor can save lives is not a metaphor or an exaggerated affirmation – it is the simple truth.

The wrist oxygen monitor can also record the history of the heart rate and blood oxygen levels of the runner/athlete. This information can be later uploaded to a computer and used as a reference point for monitoring the fitness and health progress.

Fitness monitoring, however, is not the only application of the wrist pulse oximeters. Because they can be securely fastened to the wrist of the user, these oxygen monitors are also being used for sleep monitoring, especially for individuals suffering from sleep apnea. The device can be programmed to record the heart rate and oxygen levels throughout the night; later, the doctor can analyze this information in order to have a better understanding of the patient’s condition.

The wrist oxygen monitor can be used everywhere: in health centers, gyms, hospitals, at home or while running in the park. A wrist oximeter is more expensive than a simple fingertip model – its price can vary between $160 and $700.

What is dissolved oxygen?

I’m sure you already know that all aerobic (oxygen dependant) organisms – including those inhabiting liquid environments – need oxygen for their survival and harmonious development. Without oxygen, there would be no life in oceans, rivers and lakes. Fish and plants, invertebrates and water aerobic bacteria need oxygen for their respiration. However, in order to be used by all these organisms, the atmospheric oxygen needs to be “mixed” with water first. When the gaseous oxygen is physically distributed into a liquid solution, it is called dissolved oxygen.

Dissolved oxygen (DO) is the measure of the amount of O₂ dissolved in a given liquid environment.

But how does oxygen get from the air to the water? Actually, it’s very simple. Most dissolved oxygen comes directly from the atmosphere by diffusion, being afterwards distributed by waves and currents. Dissolved oxygen is also a product of photosynthesis, being released by various algae and other aquatic plants.

Oxygen depletion – the dangerous decreasing of the oxygen saturation in water or air – is a burning issue nowadays, threatening the frail balance of our ecosystem. When organic or chemical waste is allowed to decompose in water, it consumes dissolved oxygen, directly affecting aquatic organisms.

What is a Dissolved Oxygen Monitor?

During the last decades, oxygen measurement in aquatic environments was facilitated by the invention of dissolved oxygen monitors (meters) – electronic devices which use special sensors to determine the oxygen concentration in water or another liquid.

Dissolved oxygen is one of the main indicators of water quality. The amount of O₂ that can be dissolved in water depends on several factors: salinity, temperature and altitude (and therefore – pressure). Oxygen solubility increases as the temperature and the salinity are decreasing. Cold water can hold more oxygen than warm or hot water; fresh water can hold more oxygen than saltwater. Oxygen is absorbed better at low altitudes; its saturation in water decreases as the altitude increases.

Dissolved oxygen monitors, therefore, besides displaying the oxygen saturation, can also indicate water temperature and salinity, calibrating the results depending on these variable factors. Most models can display the dissolved oxygen levels in two different ways: as a percentage and as a ppm measurement. The user can toggle between these two display modes depending on his purpose.

There are three main types of sensors used in dissolved oxygen analyzers: galvanic, polarographic and optical. The surface of the sensor requires regular maintenance, because it’s necessary to remove any build-up accumulated on the membrane that could affect the accuracy of the measurements.

Many dissolved oxygen monitors come with an incorporated Auto-Cleaner: every two hours (or another time interval that you can program according to your needs) a blast of compressed air will clean the head of the sensor. This way, the monitor will be able to function without maintenance for many months to come.

Just like other types of oxygen monitors, dissolved oxygen meters come in portable and wall-mounted models.

Which are the main applications of dissolved oxygen monitors?

Because of the increasing pollution and the continual worsening of the air and water quality on a global level, these monitors started to have a wide range of applications:

• determining the quality of drinking water
• observing the oxygen levels in waste water treatment plants
• pollution control in rivers, lake and seawater
• fish farming
• measuring dissolved oxygen in ultrapure water in the semiconductor industry etc.

When necessary, the dissolved oxygen meter can even display the oxygen saturation in the ambient air.

The usual price of a dissolved oxygen monitor varies between $100 and $400; however, complex models can even reach $2000 and more.