P14 - Contactless Determination of Respiratory Rate Based on an Ultra High Frequency Sensor

16. Dresdner Sensor-Symposium 2022
2022-12-05 - 2022-12-07
(Bio-)Medizinische Sensorik
J. Chen, J. Ringkamp, L. Behrend, P. Lebhardt, J. Langejürgen - Fraunhofer IPA, Mannheim/D
115 - 119


Every patient journey in the hospital starts with the anamnesis. During anamnesis, patient information is collected and basic vital signs are examined. Usually, patients report their symptoms and medical history to a doctor in an interview and nurses measure relevant vital parameters with different devices. The goal of the TEDIAS (Test- und Entwicklungszentrum für Digitale Aufnahmesysteme) project is to support medical staff during anamnesis by implementing an automated, digitized system for vital data recording in the University Medical Centre Mannheim. In a continuous field test, the TEDIAS system collects physiological data of patients thereby assessing the technical performance of novel sensors as well as the clinical applicability of the system. When a patient admitted to the clinic for internal medicine takes a seat in the armchair of the TEDIAS system, shown in Figure 1, the TEDIAS process is started. An avatar displayed on the screen guides the patient through the process and asks relevant questions. Patients can enter their answers on a tablet attached to the armchair. Different sensors are integrated in the armchair to acquire vital data such as blood pressure, body temperature, blood oxygen saturation and electrical cardiac activity. Another critical vital parameter is the respiratory rate giving immediate insights into respiratory illnesses and other medical conditions. Especially in the context of the COVID-19 pandemic, it has played a crucial role for triage decisions, as an early indicator for clinical deterioration, and as an important predictor for pneumonia. Assessing respiratory rates is often performed by counting the breaths per minute (bpm). Since manual counting is time consuming, it has been reported that respiratory rate screening is regularly omitted. Alternatively, some healthcare professionals measure arterial haemoglobin saturation through pulse oximetry and incorrectly equate normal haemoglobin levels with adequate ventilation. Pulse oximetry is no replacement for measuring respiratory rate and complete omission can have serious clinical consequences. The problem is reinforced by the fact that there is no gold standard technique for measuring and monitoring respiratory rates. Recent research has focused on contactless measurement methods. Contactless systems offer several advantages over contact-based systems: No skin irritations caused by sensor elements placed on the skin and less patient discomfort. A major disadvantage of contactless sensors is that they are often prone to motion artifacts. Different contactless respiratory rate measurement techniques have been developed that can be categorized into four main classes: Techniques that measure environmental respiratory sounds, air temperature, chest wall movements, or cardiac activity modulation. We present a novel technique that measures permittivity changes in the thorax for contactless determination of respiratory parameters. The non-invasive sensor system was shown to be feasible for detecting small dynamic changes of thoracic parameters in a lung phantom. In this work, the contactless sensor system’s capability to detect physiological respiratory rates in human subjects is assessed. By incorporating the sensor system into the TEDIAS system, the respiratory rate could be automatically determined without direct patient contact.