Metabolic-demand pacemaker and method of using the same to determine minute volume
First Claim
1. A metabolic-demand pacemaker comprising means for pacing a patient'"'"'s heart at a controlled rate, means for placement in a blood vessel in the vicinity of the patient'"'"'s pleural cavity and for monitoring the impedance of the blood therein, the blood impedance varying in accordance with the patient'"'"'s pleural pressure, means responsive to said monitoring means for determining the patient'"'"'s minute volume, and means for changing said controlled rate in accordance with the patient'"'"'s minute volume.
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Accused Products
Abstract
A metabolic-demand pacemaker in which the standby rate is a function of minute volume. Electrodes are placed in a blood vessel in the vicinity of the patient'"'"'s pleural cavity, a known current field is established in the blood, and the impedance in the field is measured. The impedance is a function of the pleural pressure which, in turn, is a function of the patient'"'"'s minute volume. The system also includes a mechanism for calibrating the standby rate to equal the nominal standby rate for a minute volume which equals a long-term average value, with the standby rate being changed in accordance with the deviation of the minute volume from the long-term average value.
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Citations
28 Claims
- 1. A metabolic-demand pacemaker comprising means for pacing a patient'"'"'s heart at a controlled rate, means for placement in a blood vessel in the vicinity of the patient'"'"'s pleural cavity and for monitoring the impedance of the blood therein, the blood impedance varying in accordance with the patient'"'"'s pleural pressure, means responsive to said monitoring means for determining the patient'"'"'s minute volume, and means for changing said controlled rate in accordance with the patient'"'"'s minute volume.
- 23. A method of determining a patient'"'"'s minute volume comprising the steps of placing electrodes in a blood vessel in the vicinity of the patient'"'"'s pleural cavity, monitoring the blood impedance between predetermined points, the blood impedance varying in accordance with the patient'"'"'s pleural pressure, and deriving the patient'"'"'s minute volume from the variations in the monitored blood impedance.
Specification