Remote and non-invasive monitoring of patients with COVID-19 by smartphone

Received on: Oct.12th, 2020. Approved on: Mar. 26th, 2021. Published on: April. 13th, 2021. Abstract: The pandemic caused by the new coronavirus (SARS-COV-2) has led to more than two million deaths in the world by March 2021. The worldwide call to reduce transmission is enormous. Recently, there has been a rapid growth of telemedicine and the use of mobile health (mHealth) in the context of the COVID-19 pandemic. Smartphone accessories such as a flashlight, camera, microphone, and microprocessor can measure different clinical parameters such as oxygen saturation, blood pressure, heart rate, breathing rate, fever, pulmonary auscultation, and even voice analysis. All these parameters are of great clinical importance when evaluating suspected patients of COVID-19 or monitoring infected patients admitted in various hospitals or in-home isolation. In remote medical care, the results of these parameters can be sent to a call center or a health unit for interpretation by a qualified health professional. Thus, the patient can receive orientations or be immediately referred for in-patient care. The application of machine learning and other artificial intelligence strategies assume a central role in signal processing and are gaining much space in the medical field. In this work, we present different approaches for evaluating clinical parameters that are valuable in the case of COVID-19 and we hope that soon all these parameters can be measured by a single smartphone application, facilitating remote clinical assessments.


Abstract:
The pandemic caused by the new coronavirus (SARS-COV-2) has led to more than two million deaths in the world by March 2021. The worldwide call to reduce transmission is enormous. Recently, there has been a rapid growth of telemedicine and the use of mobile health (mHealth) in the context of the COVID-19 pandemic. Smartphone accessories such as a flashlight, camera, microphone, and microprocessor can measure different clinical parameters such as oxygen saturation, blood pressure, heart rate, breathing rate, fever, pulmonary auscultation, and even voice analysis. All these parameters are of great clinical importance when evaluating suspected patients of COVID-19 or monitoring infected patients admitted in various hospitals or in-home isolation. In remote medical care, the results of these parameters can be sent to a call center or a health unit for interpretation by a qualified health professional. Thus, the patient can receive orientations or be immediately referred for in-patient care. The application of machine learning and other artificial intelligence strategies assume a central role in signal processing and are gaining much space in the medical field. In this work, we present different approaches for evaluating clinical parameters that are valuable in the case of COVID-19 and we hope that soon all these parameters can be measured by a single smartphone application, facilitating remote clinical assessments.

Introduction
The initial cases of coronavirus disease 2019 , caused by SARS-COV-2, appeared in Wuhan, China, and quickly spread to more than The disease progression is rapid, capable of causing diffuse alveolar lesions, large inflammatory infiltrates, desquamation of pneumocytes, pulmonary edema, leading to acute respiratory distress. Other organs such as the liver, kidney, or nervous system, for example, can also be affected.
This occurrence demonstrates the destructive power of this virus or its interaction with the immune system. It can be asymptomatic in many cases but, the initial symptoms can be similar to a flu syndrome (runny nose, cough, fever, etc.). However, when the disease progresses to a serious form, the presence of high fever, dyspnea, fatigue, anorexia, a significant decrease in oxygen saturation, and as well as the processing capacity, allow these devices to monitor vital signs and even diseases such as diabetes (12,13) and anemia (14). Here, we present different approaches using the smartphone to monitor patients with COVID-19.

Oxygen saturation with smartphone
The decrease in oxygen saturation (SpO 2 ) is associated with dyspnea and hypoxemia. This condition has been related to a high mortality rate among patients who have been diagnosed with COVID-19. When the SpO 2 value is below 93%, oxygen therapy is commonly indicated (18).
A pulse oximeter is a small portable device that allows continuous and non-invasive monitoring of oxygen saturation (19). Red and infrared LEDs (wavelength ranging from 660 to 900nm) are the most commonly used in pulse oximeters (20).

One of the manifestations of COVID-19
pneumonia is silent hypoxia, a condition in which there is a reduction in oxygen saturation, but the patient does not experience respiratory discomfort or pain, common to other types of pneumonia.
The virus causes the alveoli to collapse instead of filling with fluid or pus, as in other infections.
One way for early detection of silent hypoxia is by using the smartphone, which has shown correction between 96-99% with a commercial pulse oximeter (21).

Breathing sounds and functions with the smartphone
The use of a smartphone coupled with a microphone allows low-cost analysis of respiratory function. The Spiro Smart is an example of a smartphone app that allowed to perform the spirometry test reliably (30).

Fever detected by the smartphone
Fever is another signal commonly seen in people with COVID-19 (28,32,33). Intelligent sensors can transmit body temperature to the smartphone via Bluetooth. These smart thermometers are hardware that consists of a single microcomputer chip associated with an infrared thermometer.
This system communicates with smartphones through an installed Android application for interpreting the signal (34). It is expected that, in a short period, smartphone applications will be available to monitor body temperature, and this will certainly involve smartphone-based photoplethysmography or even smartphonebased wearable sensors. At the present moment, the temperature monitoring needs additional hardware and cannot be evaluated using the smartphone alone.

Orofacial manifestations photo analysis by smartphone
The use of photos obtained with a smartphone can also be a useful tool to assess COVID-19, especially in the progression of the disease.
Orofacial manifestations may be present in cases of COVID-19 infection, such as ulcerative lesions (38). For example, the color and texture of the tongue can indicate whether a patient is healthy or may be infected with the new coronavirus.

Funding
This study did not receive financial support from external sources

Conflicts of interest disclosure
The authors declare no competing interests relevant to the content of this study.