Over the last decade, several studies have explored the use of smartphones to measure blood pressure and monitor patients with hypertension.
Hypertension is a cardiovascular disease that affects more than 1.2 billion adults between the ages of 30 and 79 in the world. In this sense, it is a serious public health problem worldwide, which requires the extension of tools that favor its diagnosis and monitoring through blood pressure measurement.
Because hypertension often has no symptoms, early detection is challenging. There are various methods to control hypertension, such as invasive blood pressure monitoring, or non-invasive monitoring with device support, however, the latter are not always accurate.
The study "Blood pressure measurement using only a smartphone", presents a review of articles published from November 2011 to November 2021 where various approaches that use smartphones for blood pressure estimation are analyzed.
In this period of time, 333 published articles were identified, from which the authors selected 25 relevant articles. The articles included approaches such as signal processing techniques, features extracted from constructed signals, or algorithms to estimate blood pressure.
In fact, 23 articles propose an approach that requires direct contact between the sensor and the patient and another two articles propose a non-contact measurement method, based on facial videos.
One of the methods of direct contact is the construction of signals through a video recording of a finger. This method requires the subject to place their finger on the phone's camera with the LED light on, in this way the images are extracted from the video and the average brightness of the pixels in three color channels, red, green and blue, is evaluated.
On the other hand, the facial video recording method requires a recording of its determined time of the patient's face, and in the same way each frame is divided among the three color channels, and the hemoglobin concentration signals are extracted.
The signal construction approach of phonocardiogram and seismocardiogram is carried out through recordings of sounds and vibrations of the heart. To do this, the mobile phone is placed at chest height and the vibrations are measured by means of the mobile phone's accelerometer.
Learn more by consulting the full review at the following link: https://www.nature.com/articles/s41746-022-00629-2
