Whether they use rigid or soft technology, wearable devices have drastically expanded remote patient monitoring capabilities to the entire population, according to Andrea Aliverti, a professor of bioengineering who teaches Sensors and Instrumentation Technologies and Bioengineering of the Respiratory System at the Polytechnic University in Milan, Italy.
“Consumer-grade wearable sensors are changing the model of patient assistance and monitoring,” he said.
Certification remains an issue
Many systems are being developed that can help monitor respiratory functions remotely. Clinicians need to understand which tools can be considered biomedical sensors, especially with the new regulation on medical devices now being fully applied in the EU. “This will be the basis for products to transition from gadgets that are used for personal use into medical devices, with specific pre- and post-market requirements and the certification released after proper evaluation,” he said.
A few wearable solutions have received FDA approval and can help evaluate cardiac and respiratory functions, for example, tools using photo-plethysmography (PPG) enable measuring of the heart rate, heart rate reserve (HRR), and cardiac output stroke volume with high accuracy. “These solutions also offer the possibility to collect information about oxygen saturation and pulse-based parameters in the finger and the wrist,” Aliverti said.
For arrhythmia detection, systems that integrate a medical-grade electrocardiogram (ECG) with a smartwatch have also received FDA approval.
Pulse oximeters that enable positioning of optical systems can help evaluate oxygen saturation close to the wrist, with different levels of accuracy. “Interesting solutions that don’t interfere much with daily life activities are being launched,” he said and added that these systems, however, “Are only partly certified.”
Regarding physical activity and actigraphy, a basic accelerometer allows measuring step count, speed and time. Barometers and GPS systems can help detect and estimate the level of patient activity.
Measuring different parameters
A more daunting task is to measure respiratory parameters, such as tidal volume, which is measured at each breath during inspiration or expiration. “This is not completely solved, but there are solutions out there,” said Aliverti, who presented a system he recently developed with an international team of researchers.
The solution uses continuous and real-time breathing pattern monitoring boosted (recognized) by artificial intelligence to measure tidal volume and respiratory rate with different levels of activity during the day. “It’s important to combine multiple measurements to obtain parameters that are related to the level of activity and the posture that the patient assumes,” he said.
Another multimodal system Aliverti has helped create is a home telemedicine tool for continuous respiratory monitoring, integrating different sensors not only on the body but also in the environment, for instance, sensors for air quality. “The solution shows the variability of the respiratory rate with respect to the changes in the environmental parameters,” he said.
Several papers have shown that combining different measurements taken with wearables enable early diagnosis of Covid-19 four or five days before the onset of symptoms.
For COPD, promising preliminary data is available, but better designed clinical trials are necessary to show how wearables can identify signs of exacerbation. Measuring the respiratory rate by placing sensors on the skin could also help detect neuromuscular disorders. “It’s an indication, but it’s often forgotten.”
Another important area is sleep monitoring technology, with promising solutions that can collect ECG, respiratory rate, and other measurements in garments during daily activities and sleep. “These devices open new perspectives in monitoring sleep with a very low level of intrusiveness,” he said. “Wearables will allow transitioning from very cumbersome systems to new, less obstructive solutions.”
Evaluating these tools’ efficiency will be key in the future. “We need to develop solutions that provide medical-grade measurements, are certified as medical devices, and provide the highest safety to protect patient privacy,” he concluded.
Andrea Aliverti (MSc in Electronic Engineering, Ph.D. in Bioengineering) is a Full Professor at the Department of Electronics, Information and Bioengineering (DEIB) at the Politecnico di Milano where he teaches Sensors and Instrumentation Technologies and Bioengineering of the Respiratory System.