Automated Non-Contact Respiratory Rate Monitoring of Neonates Based on Synchronous Evaluation of a 3D Time-of-Flight Camera and a Microwave Interferometric Radar Sensor

Abstract

This paper introduces an automatic non-contact monitoring method based on the synchronous evaluation of a 3D time-of-flight (ToF) camera and a microwave interferometric radar sensor for measuring the respiratory rate of neonates. The current monitoring on the Neonatal Intensive Care Unit (NICU) has several issues which can cause pressure marks, skin irritations and eczema. To minimize these risks, a non-contact system made up of a 3D time-of-flight camera and a microwave interferometric radar sensor is presented. The 3D time-of-flight camera delivers 3D point clouds which can be used to calculate the change in distance of the moving chest and from it the respiratory rate. The disadvantage of the ToF camera is that the heartbeat cannot be determined. The microwave interferometric radar sensor determines the change in displacement caused by the respiration and is even capable of measuring the small superimposed movements due to the heartbeat. The radar sensor is very sensitive towards movement artifacts due to, e.g., the baby moving its arms. To allow a robust vital parameter detection the data of both sensors was evaluated synchronously. In this publication, we focus on the first step: determining the respiratory rate. After all processing steps, the respiratory rate determined by the radar sensor was compared to the value received from the 3D time-of-flight camera. The method was validated against our gold standard: a self-developed neonatal simulation system which can simulate different breathing patterns. In this paper, we show that we are the first to determine the respiratory rate by evaluating the data of an interferometric microwave radar sensor and a ToF camera synchronously. Our system delivers very precise breaths per minute (BPM) values within the norm range of 20–60 BPM with a maximum difference of 3 BPM (for the ToF camera itself at 30 BPM in normal mode). Especially in lower respiratory rate regions, i.e., 5 and 10 BPM, the synchronous evaluation is required to compensate the drawbacks of the ToF camera. In the norm range, the ToF camera performs slightly better than the radar sensor.

Non-invasive sensor methods used in monitoring newborn babies after birth, a clinical perspective

“…Pulse oximeters produce a plethysmogram (pleth) trace reflecting the instantaneous volume of blood in the extremity under the probe. Changes in the respiratory effort can affect the pleth trace due to multiple mechanisms involved in cardiorespiratory interactions [ 21 ]. Using a low pass filtering technique (LPF), the dominant heart rate component of the pleth trace can be removed to yield a trace that contains the lower frequency components [ 64 , 65 ].…”

Laser spectroscopic method for remote sensing of respiratory rate

“…The present work also demonstrates the applicability of using the mechanical platform for simulating chest movement. In Previous studies, the simulated respiration signal was frequently generated by a speaker membrane [ 27 ]. In contrast, in this research, the movement of the chest is simulated by a mechanical stage which resembles to a large extent the real chest wall movement making it a more realistic simulator, particularly for large displacements.…”

Sensor Fusion for the Robust Detection of Facial Regions of Neonates Using Neural Networks

“…This is not ideal due to the varying sizes of the neonates the distance to the cameras can differ. Therefore, it is our aim to develop an indirect fusion approach using the Time of Flight camera of our sensor setup from [ 62 ] as the third sensor. The advantage of the 3D ToF camera is that it can take the depth into account.…”