Abstract: A medical monitor, such as a fetal monitor, is provided with a code reader, e.g. a bar code reader. A manual contains clear text instructions as well as predefined codes in their correct sequential form. The instructions help the unskilled user to operate the monitor, and the actual monitor functions are triggered by scanning the codes, instead of pushing buttons, turning knobs etc. A questionnaire may also be provided to enter answers to anamnesis data. These answers, together with vital signs data, may be transmitted via telephone lines to a hospital, which makes the medical monitor ideally suited for home monitoring applications.

Abstract: A transducer for medical monitoring comprises a box (73) which contains a floating section, a non-floating section and a transformer or optical coupler for converting a floating signal into a non-floating signal. The box (73) provides a non-floating signal to an associated monitor. The common-mode rejection ratio is drastically improved, so that electrode gel between the reference electrode and the patient, and possibly even the reference electrode itself, may be omitted.

Abstract: Determining the fetal heart rate comprises irradiating an ultrasound beam in the direction of the fetal heart. The moving parts of the fetal heart cause a Doppler shift which is used to determine the fetal heart rate via an autocorrelation function. Moving parts of the fetal heart with different velocities and Doppler shifts originating from other physiological sources generate secondary maxima in the autocorrelation function, so that an accurate heart rate determination becomes nearly impossible. This problem is overcome by parallel processing of the demodulated ultrasound signal in various pass-bands, for which purpose the signal is fed to filters (28, 30) of different frequency characteristics. The output of the pass band with the better result is used for fetal heart rate circulation.

Abstract: A circuit for heartbeat detection derives the heartbeat frquency from ultrasonic signals reflected from the heart and frequency-shifted due to the Doppler effect. The circuit allows for the automatic determination of the distance between the heart and an ultrasonic transducer located on the body of the patient, so that the evaluation of the reflected ultrasonic signals can be limited to a small body range and spurious signals from other ranges can be suppressed. The circuit comprises at least two channels which are enabled by a transmitting/receiving control circuit during receiving intervals for receiving and further processing the reflected ultrasonic signals. The receiving intervals of the different channels are time shifted toward one another so that the respectively received ultrasonic signals originate from different depth ranges within the body.

Abstract: A transducer for extra-uterine monitoring of fetal heart rate and labor activity comprises a casing the lower portion of which carries ultrasound crystals. Additional crystals are carried by a movable base plate which is connected with tension-measuring means.