Methods for measuring respiratory rate based on the analysis of chest wall movements

Aim of the review to discuss the respiratory rate (RR) measurement methods that use sensors for analyzing chest wall movements. Strain and movement sensors can be successfully used in real clinical practice, since they can be easily integrated into clothes and garments (electronic textiles) for measuring the respiratory rate in both inpatients and outpatients. Meanwhile, magnetometers, gyroscopes and accelerometers must be located in specific places. One of the main limitations of strain and motion sensors is their sensitivity to patient's breathing-unrelated movements. In order to reduce this limitation, the sensors should most often be placed in the upper part of the chest and integrated into mechanical supports. In addition, it is recommended to use hybrid systems consisting of multiple different sensors. Such systems allow separate analysis of the thoracic and abdominal breathing patterns, providing for wide opportunities to use these sensors for scientific purposes. The use of special polymers and protective materials in a piezoresistive sensors design will allow to overcome their other drawback the possible influence of environmental factors (for example, temperature or humidity). Conclusion. All types of the sensors presented in this review showed generally good quality of respiratory curves at rest during normal breathing. However, in most cases, the bias increased in physical activity. The choice of a certain type of sensor for RR assessment should obviously be based on the specific clinical situation, monitoring duration, monitoring conditions (intensive care unit, inpatient, outpatient department), taking into consideration the advantages and disadvantages.