Development of a noncontact and long-term respiration monitoring system using microwave radar for hibernating black bear.

The aim of this study is to develop a prototype system for noncontact, noninvasive and unconstrained vital sign monitoring using microwave radar and to use the system to measure the respiratory rate of a Japanese black bear (Ursus thibetanus japonicus) during hibernation for ensuring the bear's safety. Ueno Zoological Gardens in Tokyo planned to help the Japanese black bear (female, approximately 2 years of age) going into hibernation. The prototype system has a microwave Doppler radar antenna (10-GHz frequency, approximately 7 mW output power) for measuring motion of the body surface caused by respiratory activity without making contact with the body. Monitoring using this system was conducted from December 2006 to April 2007. As a result, from December 18, 2006, to March 17, 2007, similar behaviors reported by earlier studies were observed, such as sleeping with curled up posture and not eating, urinating or defecating. During this hibernation period and also around the time of hibernation, the prototype system continuously measured cyclic oscillations. The presence of cyclic vibrations at 8-sec intervals (about 7 bpm) was confirmed by the system before she entered hibernation on December 3, 2006. The respiratory rate gradually decreased, and during the hibernation period the respiratory rate was extremely low at approximately 2 bpm with almost no change. The results show that motion on the body surface caused by respiratory activity can be measured without touching the animal's body. Thus, the microwave radar employed here can be utilized as an aid in observing vital signs of animals.

Noncontact vital sign monitoring system for isolation unit (casualty care system).

For measuring the vital signs of casualties inside an isolation unit, we developed a noncontact vital sign monitoring system using a microwave radar. The system was tested on eight healthy volunteers ranging in age from 30 to 48 years. The heart and respiratory rates derived by the microwave radar correlated with the heart and respiratory rates determined by electrocardiogram and respiratory sensor (r = 0.98, p < 0.0001 for heart rate; r = 0.84, p < 0.01 for respiratory rate). The exhaled CO and CO2, as a measure of trauma injury, were measured using an exhaled gas analyzer. The CO and CO2 concentrations were found to average 3.8 +/- 4.3 ppm and 2.9 +/- 0.4%, respectively. The expired air temperature and body temperature, as indicators of hemorrhagic hypothermia, averaged 31.8 +/- 1.7 degrees C and 36.2 +/- 0.4 degrees C, respectively. The results show that our system is promising for future prehospital application in determining casualty conditions for fluid infusions by the Casualty Care System intravenous lines.

Non-contact determination of parasympathetic activation induced by a full stomach using microwave radar.

In order to evaluate parasympathetic activation which causes driving errors, without placing any burden on the monitored individuals, we conducted a non-contact parasympathetic activation monitoring through the back of a chair using a compact 24-GHz microwave-radar. We measured the high-frequency (HF, 0.15-0.4 Hz) power spectrum of heart rate variability (HRV) which reflects parasympathetic activation, induced by a full stomach. All participants had a large all-you-can-eat meal with beverages for lunch within 20 min. Before and after the large meals for durations of 10 min, the non-contact measurement was conducted for seven healthy male volunteers (mean age: 23 +/- 1-year-old). In both non-contact (microwave radar) and contact (ECG as a reference) measurement, HF shows similar variations before and after large meal. Large meal significantly (p < 0.05) increased non-contact-derived HF from 1,026 +/- 510 to 1,893 +/- 613 ms(2) (922 +/- 628 to 1,861 +/- 940 ms(2), p < 0.05). This technique allows parasympathetic activation monitoring for safety precautions.

A non-contact vital sign monitoring system for ambulances using dual-frequency microwave radars.

We developed a novel non-contact monitoring system to measure the vital signs of casualties inside a moving ambulance. This system was designed to prevent exposure of patients to infectious organisms under biochemical hazard conditions. The system consists of two microwave radars: a 10-GHz respiratory-monitoring radar is positioned 20 cm away from the surface of the isolator. The 24-GHz cardiac-monitoring radar is positioned below the stretcher underneath the isolator. The subject (22.13 +/- 0.99 years) was placed inside the isolator on a stretcher in the simulated ambulance. While the ambulance was in motion at a speed of approximately 10 km/h, the heart rates determined by the cardiac-monitoring radar correlated significantly with those measured by ECG (r = 0.69, p < 0.01), and the respiratory rates derived from the respiratory-monitoring radar correlated with those measured by the respiration curves (r = 0.97, p < 0.0001). The proposed system appears promising for future on-ambulance monitoring of the vital sign of casualties exposed to toxins.