Simply saving lives: A deep look at the simple but brilliant pulse oximeter

Smart connected devices are being deployed in all industries, but the one that could have the greatest impact for individuals is within healthcare. In this article we will take a deep dive into the smart connected pulse oximeter, which is a super-low power system that can accurately measure blood oxygen levels in patients. We will take a look at the system’s components, the unique features of the design, and why this solution is just the beginning in a bright future for smart medical devices.

What is a pulse oximeter?

A pulse oximeter measures the oxygen saturation of the blood in order to determine how well the heart is pumping oxygenated blood to the furthest extremities, such as the arms and legs ^[1]. Common devices clip a probe onto the patient’s ear or fingertip to measure blood oxygen levels. Traditionally, these devices were attached to a monitor directly, or are often seen as part of a blood pressure machine in doctor’s offices and hospitals. 

Healthcare professionals use oximeters quite frequently. They can be used to monitor a patient’s current condition if they are suspected of having or diagnosed with a heart attack, heart failure, anemia, lung cancer, asthma, or pneumonia. In addition, patients that have undergone surgery that required sedation or are being subjected to a stress test to assess their cardiovascular abilities will also be monitored using a pulse oximeter ^[1]. The data captured by the oximeter provides crucial feedback to doctors, nurses, and technicians, which can help treat and monitor patients every day.

During the COVID-19 pandemic, doctors began using at-home pulse oximeters to monitor blood oxygen levels of high-risk patients with the virus, such as those with diabetes, those who were pregnant, those with chronic illnesses, and those who were elderly. By taking readings on the portable sensor twice a day, patients were asked to let their doctor know if the reading dropped below 95%. If at any point a patient’s blood oxygen level dropped to 90% or lower, they were told to seek immediate attention and to get to the emergency department. Early detection of lower blood saturation limits led to better outcomes in patients who used a pulse oximeter. A study in South Africa determined that a 50% reduction in patient mortality was possible if pulse oximeters were used to get patients the care they required as soon as blood oxygen levels dropped ^[2].   

Case Study: Renesas Smart Oximeter design

To bring smart wireless technology to a commonly used medical tool, Renesas developed the Smart Connected Pulse Oximeter. Improving on traditional wired probes, the Smart Connected Pulse Oximeter uses a super-low power Bluetooth® Low Energy (LE) System-on-Chip to relay the data to a smartphone app. The company has developed both iOS and Android applications that patients can download for free, and the software itself is open source for the reference design, allowing for future app improvements and collaborations within the industry. 

For example, healthcare practitioners could work together with app developers to create an interface that would serve their patient population and their own record-keeping needs. Doctors would have the best idea of how tech-savvy their patient population is and how simple the user interface would need to be. Bluetooth® connection, for instance, may need to be automatic, or there may need to be tutorials in place for patients. In addition, doctors would be able to help direct the ideal frequency of checks per day and work with developers to add in notifications for the patient, so they don’t forget to check their blood oxygen saturation. Because the device records the levels in the app, it could be further developed to connect to servers that the doctor has access to in order to help monitor the patient. 

The Smart Oximeter by Renesas is powered by two AAA batteries on the back of the board. Patients connect their smartphone to the oximeter using the Bluetooth® module and can then rest their fingertip on an OB1203 biosensor. The biosensor on the chip is the smallest available at 4.2mm x 2 mm x 1.2 mm. A red light can be seen under the fingertip while measurements are taken, including heart rate, blood oxygen concentration, profusion index, and battery level, which show up in the smartphone application. Measurements take approximately six seconds, and through the use of a medical-grad algorithm have been shown to be accurate on even the most difficult-to-measure patients.

Previously, pulse oximeters were not wireless devices that could connect to smartphones. They were small devices that patients used to measure their blood oxygen levels at home. But with advances in Bluetooth® technology, including the size of the chip and the minimal energy it consumes, the pulse oximeter can now be brought online. Currently, this allows for a small device to be used at home, and it allows for greater accuracy in readings helping more patients get to the hospital if their blood oxygen levels get too low. Adding the Bluetooth® capability also opens the door to remote monitoring both by healthcare practitioners and loved ones who are keeping track of their friends’ and family’s health. The data can now be transmitted to the caretaker’s phone.

Layout of the system. Image credit; Renesas

Benefits of the Smart Oximeter for the healthcare industry and end consumers

The Smart Oximeter with the available mobile applications is a complete solution available to different healthcare providers. While hospital departments and doctor’s offices may have traditional wired oximeters in place, they can be bulky and cumbersome to move from room to room. The Smart Oximeter offers a compact and portable solution for healthcare professionals, and those who are providing their services in patient’s homes. They can easily transport the Smart Oximeter on their person and can rest assured it will be using the very little battery energy throughout the day.

Because of the lightweight design and mobile monitoring characteristics, the Smart Oximeter could also be used on gym or physiotherapy equipment, like treadmills, ellipticals, and stationary bikes. Patients would be able to monitor their blood oxygen levels, and healthcare providers could receive the data from their patients even between appointments. 

As a wearable device, patients can rest assured that they can check if their blood oxygen saturation is sufficient or not. This will also ensure patients get to their doctor or local emergency department when blood oxygen levels are too low. The simplicity of the Smart Oximeter by Renesas means it can be used in multiple settings to assist the maximum number of people afflicted with conditions or undergoing treatments and surgeries that may lower their blood oxygen saturation.

Expanding IoT and smart healthcare solutions to save lives

While engineers have been expanding the Internet of Things (IoT) into all technical realms, the most common examples that seem to be at the forefront are those in manufacturing or smart home systems or even industrial energy applications. But by taking health monitors, sensors, and the latest wireless technology into the IoT domain, many people will benefit from the advances, and not just select high-tech industries. 

A simple, but powerful, device like the oximeter could be made readily available to patients and their healthcare professionals to more effectively monitor them. For example, if a patient sees their specialist once every two weeks to have their blood oxygen saturation measured, there is a large time lapse within which the patient may decline. Putting the Smart Oximeter into the hands of healthcare frontline professionals and patients could truly save many lives. And with the adoption of smart mobile monitoring, the industry and patients will grow more comfortable of the technology and the elevated level of monitoring and care they will have access to, resulting in many more smart applications in the years to come. 

Summary

The Renesas Smart Oximeter is a complete solution to monitoring a patient’s blood oxygen saturation wirelessly. Powered by two AAA batteries on the back of the chip, the Renesas Smart Oximeter uses a super-low power Bluetooth® System-on-Chip to connect to a smartphone app where the heart rate, blood oxygen concentration, profusion index, and battery levels are displayed. The biosensor on the chip is the smallest available at just 4.2 mm x 2 mm x 1.2 mm, where a patient rests their fingertip. 

By bringing a smart mobile solution to the healthcare industry, Renesas has made the oximeter more portable, more energy efficient, and more accurate than traditional oximeters. If deployed to healthcare practitioners and their patients more widely, monitoring accuracy and frequency would increase to ensure adequate patient blood oxygen levels, meaning the Renesas Smart Oximeter could literally save lives.   

References:

[1] Johns Hopkins Medicine. Pulse Oximetry [Internet]. Maryland: The Johns Hopkins University; 2022 [cited 2022 May 12]. Available from: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/pulse-oximetry

[2] Parker-Pope, Tara. Do I Still Need a Pulse Oximeter? A new study shows just how lifesaving home monitoring of oxygen levels can be. [Internet]. New York: The New York Times; 2021 [cited 2022 May 15]. Available from: https://www.nytimes.com/2021/10/05/well/live/covid-pulse-oximeter.html