Vital signs monitor

• US 4,860,759 A
• Filed: 09/08/1987
• Issued: 08/29/1989
• Est. Priority Date: 09/08/1987
• Status: Expired due to Fees

• Current Assignee: Criticare Systems Incorporated Milwaukee Wisconsin
• Original Assignee: Criticare Systems, Inc. (Opto Circuits (India) Ltd.)
• Inventors: Kahn, Alan R., Chandler, Jennifer K.
• Primary Examiner(s): Hindenburg, Max
• Assistant Examiner(s): Citrin, Randy
• Application Number:
  US07/093,952
• Time in Patent Office: 721 Days
• Field of Search: 128/632-634, 128/664, 128/665, 128/668, 128/670, 128/696, 128/700, 128/706
• US Class Current: 600/481
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: G16H 10/60 for patient-specific data, e.g. for electronic patient records
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A vital signs monitor includes an ECG sensor, an oximetric finger probe, a respiration impedance sensor, a respiration strain gauge, and a blood pressure cuff with a pressure sensor. Signals generated by these sensors are processed by a microcomputer which is programmed to cross-reference data from multiple channels in order to improve accuracy. The microcomputer is programmed to select the more regular pulses from the ECG sensor and the finger probe to arrive at a better measure of heart rate. In addition, the microcomputer is programmed to use the strain gauge signal to remove artifacts from the signal generated by the impedance sensor. In this way a more artifact-free measure of respiration rate is obtained. Blood pressure is measured by using timing information derived from pulses sensed by the oximetric finger probe in combination with signals generated by the blood pressure cuff pressure sensor to determine systolic and diastolic pressures of the subject. A calibrated blood pressure waveform is generated automatically from the oximetric finger probe and the blood pressure cuff.

Claims

1. In a monitor of the type comprising an ECG signal channel and an oximeter signal channel, the improvement comprising:

means, responsive to the ECG signal channel, for generating a series of first pulses indicative of heart pulses of a subject as indicated by the ECG signal channel;

means, responsive to the oximeter signal channel, for generating a series of second pulses indicative of heart pulses of the subject as indicated by the oximeter signal channel;

means, responsive to both the first and second pulses, for identifying those pulses having more regularly repeating pulse intervals, said identifying means comprising;

means for storing a previous pulse rate measure;

means for determining a first pulse rate measure in response to the first pulses during a selected interval;

means for determining a second pulse rate measure in response to the second pulses during the selected interval; and

means for selecting the one of the first and second pulse rate measures which is closer to the previous pulse rate measure; and

means, responsive to the identified pulses, for generating a pulse rate signal indicative of pulse rate of the subject.

2. The invention of claim 1 wherein the identifying means comprises:

means, operative when the first pulses are absent, for identifying consecutive ones of the second, pulses to the pulse rate signal generating means; and

means, operative when the second pulses are absent, for identifying consecutive ones of the first pulses to the pulse rate signal generating means.

3. In a monitor of the type comprising first and second heart pulse sensors, the improvement comprising:

means, responsive to the first heart pulse sensor, for generating a series of first pulses indicative of heart pulses of a subject;

means, responsive to the second heart pulse sensor, for generating a series of second pulses indicative of heart pulses of the subject;

means, responsive to both the first and second pulses, for identifying selected pulses having regularly repeating pulse intervals, said identifying means comprising;

means for storing a previous pulse rate measure;

means for determining a first pulse rate measure in response to the first pulse during a selected interval;

means for determining a second pulse rate measure in response to the second pulses during the selected interval; and

means for selecting the one of the first and second pulse rate measures which is closer to the previous pulse rate measure; and

means, responsive to the identified pulses, for generating a pulse rate signal indicative of pulse rate of the subject.

4. The invention of claim 3 wherein the identifying means comprises:

means, operative when the first pulses are absent, for identifying consecutive ones of the second, pulses to the pulse rate signal generating means; and

means, operative when the second pulses are absent, for identifying consecutive ones of the first pulses to the pulse rate signal generating means.