Body-worn vital sign monitor

Inventors

Moon, Jim • VISSER, II, Henk • Hunt, Robert Kenneth • McCOMBIE, Devin • Dhillon, Marshal Singh • Banet, Matthew J.

Assignees

Sotera Wireless Inc

Abstract

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.

Core Innovation

The disclosure describes a body-worn vital sign monitoring system that includes a first module configured to be worn on the chest and a processing component configured to be worn on the patient’s lower arm. The first module contains an electrocardiogram (ECG) circuit and a three axis accelerometer contained within the housing, and the ECG circuit is in electrical communication with at least three ECG leads and generates time-dependent digital ECG waveforms for each ECG lead as network packets with a header portion indicating the origin of the packet and a data portion. The three axis accelerometer generates time-dependent digital motion waveforms for each of the three axes and transmits the time-dependent digital motion waveforms as network packets with a header portion indicating the origin and a data portion.

The processing component includes a microprocessor and a serial transceiver within a housing, and a display on a surface of the housing. The processing component communicates 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, and transmits a timing synchronizing packet that is received and used by the first module to time-synchronize the network packets. This synchronization provides a maximum 40-microsecond timing error in the synchrony between the time-dependent digital ECG waveforms and the time-dependent digital motion waveforms for processing by the processing component.

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. The disclosure also describes thumb optical sensing using red and infrared LEDs to compute pulse transit time (PTT) and to determine continuous noninvasive blood pressure (cNIBP) using the “Composite Technique,” alongside SpO2 and respiratory rate in a distributed, body-worn architecture intended to reduce motion and noise artifacts.

Claims Coverage

Independent claim clm-00001 covers a wearable system that measures vital signs and motion by transmitting time-dependent digital ECG and three-axis accelerometer waveforms as network packets, synchronizing the streams using a timing synchronizing packet with a stated maximum timing error, and displaying ECG waveforms and a motion state derived from motion waveforms. The core inventive coverage includes one primary inventive combination of ECG, accelerometer motion sensing, packetized transmission, precise timing synchronization, and on-device display of ECG and motion state.

Across the independent claim, the inventive concept is the combination of packetized, origin-tagged digital ECG and three-axis motion waveforms from a chest-worn module to a lower-arm processing/display component, together with stream timing synchronization using a timing synchronizing packet to achieve a maximum 40-microsecond timing error, and the display of time-dependent ECG waveforms together with a motion state derived from the accelerometer motion waveforms.

Stated Advantages

Documented Applications