Method and apparatus for detecting optical pulses

Claims

We claim:

1. An improved method for photoelectrically detecting arterial pulses of a patient comprising:

detecting the blood flow, which may include arterial pulses and artifacts, at the patient's body tissue using a device that calculates blood constituents from the detected blood flow;

detecting the occurrence of a selected portion of the patient's EKG waveform as the occurrence of the heartbeat of the patient;

correlating the occurrence of the heartbeat with the detection of pulses by the blood constituent calculating device by determining a period of time in which an arterial pulse is likely to be detected after the occurrence of a selected portion of the EKG waveform; and

determining whether or not a detected pulse is likely to be a detected arterial pulse by determining that a detected pulse is one of either a first pulse acceptable for processing as an arterial pulse when the pulse is detected in the determined period of time after the selected portion of the EKG waveform occurs, or a second pulse not acceptable for processing as an arterial pulse when it is detected other than in the determined period of time after the selected portion of the EKG waveform occurs.

2. The method of claim 1 wherein the selected portion of the patient's EKG waveform is the R wave portion.

3. The method of claim 1 further comprising:

calculating amounts of blood constituents from the portion of the blood flow detected during the determined period of time.

4. The method of claim 1 wherein the the device that calculates blood constituents is adapted for calculating oxygen saturation of hemoglobin in arterial blood, and the method further comprises measuring oxygen saturation of hemoglobin in arterial blood.

5. Improved apparatus for detecting arterial pulses of a patient comprising:

means for photoelectrically detecting the blood flow, which may include arterial pulses and artifacts, at the body tissue;

means for detecting the electrical heart activity of the patient in the form of an EKG waveform;

circuit means for filtering and processing the EKG waveform to detect a selected component of the EKG waveform, so that the occurrence of that selected component represents the occurrence of a heartbeat;

means for correlating detected arterial pulses with the occurrence of the heartbeat, said correlating means being adapted to establish a time period by which a detected arterial pulse is likely to follow the occurrence of a selected component of the EKG waveform; and

means for confirming whether or not a detected pulse is likely to be an arterial pulse, said confirming means being responsive to the detected arterial pulse and a detected heartbeat and adapted to confirm that a detected pulse is acceptable as an arterial pulse by determining that the detected pulse occurs within the established time period.

6. The apparatus of claim 5 wherein the selected component of the EKG waveform is the R wave component.

7. The apparatus of claim 5 further comprising means for determining the amount of blood constituents and heart rate, responsive to the detected blood flow during the established time period.

8. A method for photoelectrically measuring the amount of a blood constituent from the blood flow characteristics in the body tissue of a patient using a device that is transmitting light through the body tissue, detecting and converting the amount of light transmitted from analog blood flow signals having arterial pulses and artifacts to digital signals, comprising:

digitally processing the digital signals to detect arterial pulses and determine an arterial pulse rate and the amount of a blood constituent present in the arterial blood;

detecting the patient's EKG waveform having a selected component corresponding to the onset of a heartbeat;

converting the EKG waveform into a digital EKG waveform having a digital heart pulse corresponding to each occurrence of the selected component of the EKG waveform, determining a digital heart pulse rate, comparing the digital EKG waveform and digital heart pulse rate to the digital signals and the arterial pulse rate to establish a time period by which an arterial pulse follows the occurrence of a digital heart pulse as the period of time after the occurrence of a digital heart pulse when it is likely that an arterial pulse will be detected; and

thereafter digitally processing the digital signals detected during the established time period to determine the amount of a blood constituent present in the blood.

9. The method of claim 8 wherein processing of all digital signals re-commences when the digital heart pulse is not detected in a time when a selected number of heartbeats should have occurred based upon the determined heart rate.

10. The method of claim 8 wherein processing of all of the digital signals re-commences when an arterial pulse is not detected during a selected number of time periods.

11. The method of claim 8 wherein the method of measuring amounts of a blood constituent further comprises measuring the oxygen saturation of hemoglobin in arterial blood.

12. An improved non-invasive device for measuring the amount of blood constituents in body tissue of a patient by photoelectrically detecting changes in blood flow characteristics having arterial pulses and artifacts in the form of digital signals, including a microprocessor, comprising:

EKG circuit means for