Body-worn vital sign monitor
The invention provides a body-worn monitor featuring a processing system that receives a digital data stream from an ECG system. A cable houses the ECG system at one terminal end, and plugs into the processing system, which is worn on the patient's wrist like a conventional wristwatch. The ECG system features: i) a connecting portion connected to multiple electrodes worn by the patient; ii) a differential amplifier that receives electrical signals from each electrode and process them to generate an analog ECG waveform; iii) an analog-to-digital converter that converts the analog ECG waveform into a digital ECG waveform; and iv) a transceiver that transmits a digital data stream representing the digital ECG waveform (or information calculated from the waveform) through the cable and to the processing system. Different ECG systems, typically featuring three, five, or twelve electrodes, can be interchanged with one another.
1. A system for measuring vital signs and motion from a patient, comprising:
(a) a first module comprising a housing configured to be worn on the chest of the patient and an electrocardiogram (ECG) circuit and a three axis accelerometer contained within the housing, wherein (i) the ECG circuit is in electrical communication with at least three ECG leads and generates therefrom a time-dependent digital ECG waveform for each of the ECG leads and transmits the resulting time-dependent digital ECG waveforms as network packets comprising a header portion that indicates the origin of the packet, and a data portion, and (ii) the three axis accelerometer generates a time-dependent digital motion waveform for each of the three axes and transmits the resulting time-dependent digital motion waveforms as network packets comprising a header portion that indicates the origin of the packet, and a data portion; and
(b) a processing component comprising a housing configured to be worn on the patient's lower arm and a microprocessor and a serial transceiver within the housing and a display on a surface of the housing, wherein the processing component is configured to communicate with the first module to receive the network packets containing the time-dependent digital ECG waveforms and the network packets containing the time-dependent digital motion waveforms;
wherein the processing component communicates with the first module to transmit a timing synchronizing packet that is received and used by the first module to time-synchronize the network packets containing the time-dependent digital ECG waveforms and the network packets containing the time-dependent digital motion waveforms for processing by the processing component such that there is a maximum 40-microsecond timing error in the synchrony between the time-dependent digital ECG waveforms and the time-dependent digital motion waveforms, and
wherein the processing component is configured to display the time-dependent digital ECG waveforms and a motion state determined using the time-dependent digital motion waveforms on the processing component display.