Method and apparatus for measuring capillary refill time and carrying out pulse oximetry with a single device

• US 20070282182A1
• Filed: 06/02/2006
• Published: 12/06/2007
• Est. Priority Date: 06/02/2006
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Hutchinson, George M., Messerges, Joanne L.
• Granted Patent: US 8,082,017 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/02241 of small dimensions, e.g. adapted to fingers
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A device for measuring the capillary refill time of a patient and for use in determining an amount of oxygen in the blood of the patient has light sources and a light detector for use in carrying out pulse oximetry. The device also includes an actuator for applying pressure to a selected portion of the body of the patient, such as the nail bed of a finger or toe of the patient, to cause the removal of blood from the nail bed when actuated. A timer commences a time interval with a deactuation of the actuator. The deactuation relieves the pressure applied by the actuator to the body portion of the patient and allows blood to return to the portion. The timing interval is terminated by a reduction in the amount of light received by the light detector as a result of the restoration of blood to the body portion. The time interval so determined comprises an indication of the capillary refill time of the patient. Compensation in accordance with a skin temperature measurement may be provided.

Claims

1. A device for measuring the capillary refill time of a patient and for use in determining an amount of oxygen in the blood of the patient by pulse oximetry, said device comprising:

light sources for providing light of selected wavelengths suitable for use in pulse oximetry, at least one of said light sources applying light to a selected portion of the body of the patient at which the application of pressure will cause a removal of blood from the tissue of the portion;

a light detector for receiving light from the tissue of the patient, said light detector being connectable to signal processing means for determining an amount of oxygen in the blood of the patient by pulse oximetry;

an actuator for applying pressure to the selected body portion when actuated to compress the portion and cause removal of blood from the tissue of the portion, the pressure being relieved when the actuator is deactuated to allow restoration of blood to the tissue of the portion;

control means coupled to said actuator for controlling the actuation and deactuation of said actuator, said control means being coupled to said light detector for determining the amount of light received by said light detector that has been provided by at least said one light source; and

a timer coupled to said control means for determining a time interval that is commenced with a deactuation of said actuator and terminated by a reduction in the amount of light received by said light detector as a result of the restoration of blood to the selected body portion, the time interval comprising an indication of the capillary refill time of the patient.

2. The device according to claim 1 further including a comparison means coupled to said timer for terminating the time interval by comparing a signal value of the amount of light received by said light detector following deactuation of said actuator with a stored value.

3. A device according to claim 2 wherein said comparison means is further defined as carrying out a comparison using a stored value comprising a measurement of the amount of light received by said light detector prior to actuating said actuator.

4. A device according to claim 2 further including a memory means for storing said stored value.

5. A device according to claim 1 wherein said control means is further defined as deactuating said actuator responsive to a characteristic of an increased amount of light received by said light detector following actuation of said actuator.

6. A device according to claim 1 wherein said control means is further defined as deactuating said actuator when increases in the amount of light received by said light detector lessen or no longer occur.

7. A device according to claim 1 further including a temperature sensor for measuring skin temperature of the patient proximate to the selected body portion, the indication of capillary refill time being altered in accordance with the measured temperature.

8. A device according to claim 1 wherein said control means comprises a microprocessor.

9. A device according to claim 1 wherein said actuator forms an integral component of said device.

10. A device according to claim 1 wherein said actuator comprises an attachment for said device.

11. A device according to claim 1 wherein said device employs light transmitted through the tissue of the patient.

12. A device according to claim 1 wherein said device employs light reflected from the tissue of the patient.

13. A device according to claim 1 wherein at least one of said light sources applies light to the nail bed of a finger or toe of the patient and said actuator applies pressure to the nail of the patient when actuated.

14. A device for measuring the capillary refill time of a patient and for use in determining an amount of oxygen in the blood of the patient by pulse oximetry, said device comprising:

light sources for providing light of selected wavelengths suitable for use in pulse oximetry, at least one of said light sources applying light to the nail bed of a nail of a finger or toe of the patient;

a light detector for receiving light from the tissue of the patient, said light detector being connectable to signal processing means for determining an amount of oxygen in the blood of the patient by pulse oximetry;

an actuator for applying pressure to the nail of the patient when actuated to compress the nail bed and cause removal of blood from the nail bed, the pressure being relieved when the actuator is deactuated to allow restoration of blood to the nail bed;

control means coupled to said actuator for controlling the actuation and deactuation of said actuator, said control means being coupled to said light detector for determining the amount of light received by said light detector that has been provided by at least said one light source, said controls means deactuating said actuator responsive to a characteristic of an increased amount of light received by said light detector following actuation of said actuator; and

a timer coupled to said control means for determining a time interval that is commenced with a deactuation of said actuator;

comparison means coupled to said timer for terminating the time interval by comparing a signal value of the amount of light received by said light detector following deactuation of said actuator with a stored value comprised of a measurement of the amount of light received by said light detector prior to actuating said actuator, the time interval comprising an indication of the capillary refill time of the patient; and

a temperature sensor for measuring skin temperature of the patient proximate to the nail, the indication of capillary refill time being altered in accordance with the measured temperature.

15. A method for determining the capillary refill time of a patient utilizing apparatus suitable for carrying out pulse oximetry, said method comprising the steps of:

applying light to a selected portion of the body of the patient at which the application of pressure will cause removal of blood from the tissue of the patient, the application of light being carried out using at least one light source suitable for carrying out pulse oximetry;

measuring the light received by a light detector suitable for carrying out pulse oximetry;

storing the received light as a reference value;

actuating an actuator to compress the selected body portion of the patient;

measuring the light received by the light detector with the patient'"'"'s body portion in the compressed condition;

detecting changes in the amount of received light resulting from the compression of the patient'"'"'s body portion;

deactuating the actuator responsive to changes in the amount of received light;

starting a timing interval upon deactuating the actuator;

measuring the amount of received light following deactuation of the actuator;

comparing the amount of light received following deactuation with the reference value;

stopping the timing interval based on the comparison of the light received following deactuation with the reference value; and

providing the time interval as an indication of the capillary refill time of the patient.

16. A method according to claim 15 wherein said control means is further defined as deactuating the actuator responsive to a lessening or termination of increases in the amount of received light.

17. A method according to claim 15 wherein the method employs light transmitted through the tissue of the patient.

18. A method according to claim 15 wherein the method employs light reflected from the tissue of the patient.

19. A method according to claim 15 further defined as including the steps of measuring the skin temperature of the patient and altering the indication of capillary refill time based on the measured skin temperature of the patient.

20. A method according to claim 15 wherein the step of applying light is further defined as applying light to a nail bed of a nail of a patient'"'"'s finger or toe and the step of actuating the actuation is further defined as comprising the nail bed of the nail of the patient'"'"'s finger or toe.