Abstract: Uterine activity is sensed by passing light through the patient's abdominal wall and detecting the light reflected from abdominal tissues. The intensity of the reflected light varies with the state of contraction of the patient's uterus. The use of light for monitoring uterine activity avoids the problems of size, fixation, and measurement accuracy exhibited by the conventional tocodynamometer technique.

Abstract: A wireless patient monitoring apparatus uses low frequency inductive coupling to couple signals from a transducer to monitoring and analysis instrumentation. Signals indicative of physiological functions are modulated onto a low frequency carrier and output from a self-contained portable transducer assembly via a transducer coil. A corresponding receiver coil receives the signals by electromagnetic induction. The received signals are demodulated and processed by instrumentation coupled to the receiver coil. A mattress pad containing the receiver coil is also disclosed. In a fetal monitor implementation, both wireless ultrasound and tocodynamometer transducers are provided.

Abstract: Uterine activity is sensed by passing light through the patient's abdominal wall and detecting the light reflected from abdominal tissues. The intensity of the reflected light varies with the state of contraction of the patient's uterus. The use of light for monitoring uterine activity avoids the problems of size, fixation, and measurement accuracy exhibited by the conventional tocodynamometer technique.

Abstract: A wireless patient monitoring apparatus uses an optical signal to transmit information from a transducer to a photodetector of an optical receiver. The photodetector converts the optical signal to an electrical signal which is then provided to monitoring and analysis instrumentation. Signals which are indicative of physiological functions are modulated onto a carrier, and the resulting modulated signal is provided, in turn, to the optical source, which may be a light-emitting diode (LED) which emits in the infrared band. A self-contained portable transducer assembly which is strapped or otherwise secured to the patient may house the transducer, modulator and optical source, and is adapted for underwater use. Optionally, the optical source can be positioned remote from the assembly. In a fetal monitor implementation, both wireless ultrasound and tocodynamometer transducers are provided.

Abstract: A method and apparatus for quantitative measurement of the long-term and short-term variability of a subject's heart rate. Long-term variability is measured by apparatus which receives a signal having a magnitude proportional to a subject's instantaneous heart rate with each successive heart beat during a measuring interval consisting of a fixed number of heartbeats. Each heart rate signal magnitude is compared with the previous maximum and minimum heart rate signal magnitudes in the measuring interval and the sampled heart rate magnitude is substituted for the previous maximum signal magnitude if the maximum is exceeded and for the previous minimum signal magnitude if it exceeds the magnitude of the instant sampled heart rate signal. The difference between the maximum and minimum heart rate signal magnitudes, after occurrence of the predetermined number of heartbeats, is a measure of long-term heart rate variability.

Abstract: An alert system continuously monitors the heartbeat rate of a fetus and pressure in the maternal uterus and from this information measures parameters indicative of the condition of the fetus including heart rate, heart rate variability, heart rate deceleration, and uterine pressure, both steady state and peak. The measured parameters are compared with corresponding outer limits of acceptability and when those limits are exceeded the system alerts, sounding an audio alarm and actuating an appropriate indicator lamp which identifies the condition parameter that has transcended its assigned tolerance for more than a permissible time period.