SYSTEM AND METHODS FOR MANAGING BLOOD LOSS OF A PATIENT

• US 20130303870A1
• Filed: 05/14/2013
• Published: 11/14/2013
• Est. Priority Date: 05/14/2012
• Status: Active Grant

• Current Assignee: Gauss Surgical, Gauss Surgical, Inc. (Stryker Corporation)
• Original Assignee: Gauss Sergical
• Inventors: Satish, Siddarth, Zandifar, Ali, Miller, Kevin J.
• Granted Patent: US 9,936,906 B2
• Time in Patent Office: Days
• US Class Current: 600/371
• CPC Class Codes: A61B 2576/00 Medical imaging apparatus involving image processing or analysis A61B1/00009, A61B6/52 and A61B8/52 take precedence; image processing per se G06T; details of algorithms for analysing medical images G06T7/0012
• CPC Class Codes: A61B 5/0082 adapted for particular medical purposes
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: G01N 2015/1472 with colour
• CPC Class Codes: G01N 33/49 Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80
• CPC Class Codes: G16H 30/40 for processing medical images, e.g. editing

Abstract

One variation of the method for managing blood loss of a patient includes: receiving an image of a physical sample; extracting a feature from an area of the image corresponding to the physical sample; estimating a blood volume indicator of the physical sample according to the extracted feature; estimating a patient blood loss based on the blood volume indicator; estimating a euvolemic patient hematocrit based on an estimated patient blood volume and the estimated patient blood loss; receiving a measured patient hematocrit; and generating a volemic status indicator based on a comparison between the measured patient hematocrit and the estimated euvolemic patient hematocrit.

Claims

1. A method for managing blood loss of a patient, comprising:

receiving an image of a physical sample;

extracting a feature from an area of the image corresponding to the physical sample;

estimating a blood volume indicator of the physical sample according to the extracted feature;

estimating a patient blood loss based on the blood volume indicator;

estimating a euvolemic patient hematocrit based on an estimated patient blood volume and the estimated patient blood loss;

receiving a measured patient hematocrit; and

generating a volemic status indicator based on a comparison between the measured patient hematocrit and the estimated euvolemic patient hematocrit.

2. The method of claim 1, further comprising tracking a quantity of a fluid administered to the patient intravenously and estimating an intracirculatory patient hematocrit based on a previous patient hematocrit, the estimated patient blood loss, a quantity of a fluid administered to the patient, and the estimated patient blood volume.

3. The method of claim 2, further comprising extrapolating a volume of insensible patient fluid loss from a difference between the estimated intracirculatory patient hematocrit and the measured patient hematocrit.

4. The method of claim 2, further comprising estimating an effectiveness of the fluid administered to the patient to replenish blood volume losses based on a difference between the estimated intracirculatory patient hematocrit and the estimated euvolemic patient hematocrit.

5. The method of claim 2, further comprising plotting the estimated intracirculatory patient hematocrit and a set of previous estimated intracirculatory patient hematocrits in a first time-dependent chart and plotting a volume of fluid administered to the patient in a second time-dependent chart.

6. The method of claim 2, wherein tracking the quantity of the fluid administered to the patient intravenously comprises tracking intravenous administration of allogeneic blood from a blood transfusion bag to the patient, wherein estimating the intracirculatory patient hematocrit comprises estimating the intracirculatory patient hematocrit further based on a hematocrit of allogeneic blood in the transfusion bag.

7. The method of claim 6, wherein tracking the quantity of the fluid administered to the patient intravenously comprises receiving a second image of the blood transfusion bag, extracting a color-related feature from an area of the second image corresponding to the blood transfusion bag, and estimating the hematocrit of allogeneic blood in the blood transfusion bag based on the color-related feature.

8. The method of claim 1, wherein estimating the patient blood loss further comprises displaying a total estimated blood loss within a time-dependent chart according to the estimated patient blood loss and previous estimated blood volumes of a set of previous physical samples.

9. The method of claim 1, further comprising triggering an alarm in response to a volemic status indicator that exceeds a threshold volemic status indicator.

10. The method of claim 1, wherein estimating the euvolemic patient hematocrit comprises estimating the euvolemic patient hematocrit according to a euvolemic blood model specifying intracirculatory replenishment of a total estimated volume of patient blood loss with saline.

11. The method of claim 1, wherein generating the volemic status indicator comprises generating a time-dependent chart comprising the volemic status indicator and a set of previous volemic status indicators.

12. The method of claim 11, further comprising predicting a future volemic status indicator according a difference between the volemic status indicator and a previous volemic status indicator and triggering an alarm in response to the previous volemic status indicator that exceeds a threshold volemic status indicator.

13. The method of claim 1, wherein estimating the euvolemic patient hematocrit comprises estimating an initial patient blood volume according to a weight of the patient, a height of the patient, a gender of the patient, and an age of the patient.

14. The method of claim 1, wherein generating the volemic status indicator comprises receiving measured patient hematocrits from an optical intracirculatory hematocrit monitor on a regular time interval, and wherein estimating the euvolemic patient hematocrit comprises estimating the euvolemic patient hematocrit further based on a previous measured patient hematocrit output by the optical intracirculatory hematocrit monitor.

15. The method of claim 1, wherein receiving the image of the physical sample comprises receiving a static color image, from an optical sensor, of the physical sample that comprises one of a surgical gauze sponge, a surgical towel, a surgical dressing, a surgical suction canister, and a cell salvage canister.

16. The method of claim 1, wherein extracting the feature from the area of the image comprises extracting a color intensity value of a set of pixels within the area of the image, wherein estimating the blood volume indicator of the physical sample comprises implementing a parametric model to transform the color intensity value into a quantity of red blood cells in the physical sample.

17. The method of claim 1, wherein estimating the patient blood loss comprises updating a total estimated blood loss volume of the patient with an estimated blood volume in the physical sample according to the extracted feature from the area of the image.

18. A method for managing blood loss of a patient, comprising:

tracking a quantity of a fluid administered to the patient intravenously;

receiving an image of a physical sample;

extracting a feature from an area of the image correlated with the physical sample;

estimating a red blood cell content of the physical sample based on the extracted feature;

estimating an extracorporeal blood content of the physical sample based on the estimated red blood cell content of the physical sample; and

estimating a hematocrit of the patient based on a previous hematocrit of the patient, the quantity of the fluid administered to the patient, and the estimated extracorporeal blood content of the physical sample.

19. The method of claim 18, wherein tracking the quantity of the fluid administered to the patient intravenously comprises recording an initial time of administration of a crystalloid fluid, of a known composition, to the patient and tracking the quantity of the crystalloid fluid administered to the patient according to a transfusion rate, wherein estimating hematocrit of the patient comprises estimating the hematocrit of the patient further based on the known composition of the crystalloid fluid.

20. The method of claim 18, wherein extracting the feature from the area of the image correlated with the physical sample comprises extracting a subset of pixels from a set of pixels within the area of the image, wherein estimating the red blood cell content of the physical sample comprises matching the subset of pixels with a template image in a library of template images of known red blood cell content.

21. The method of claim 20, wherein receiving the image of the physical sample comprises receiving an image a surgical sponge gauze and correlating a time stamp of the image with a time of use of the surgical sponge gauze, wherein estimating the extracorporeal blood content of the physical sample comprises converting the estimated red blood cell content of the physical sample into an extracorporeal blood volume according to a patient hematocrit estimated at a time approximate the time of use of the surgical sponge gauze.

22. The method of claim 18, wherein receiving the image of the physical sample comprises receiving a subsequent image, in a set of sequential images, of a surgical suction canister, each image in the set of images associated with a time, wherein estimating the extracorporeal blood content of the physical sample comprises estimating the extracorporeal blood content of the surgical suction canister according to estimates of the volume of the surgical suction canister based on each image in the set of sequential images, estimated hematocrits of the patient based on each image in the set of sequential images, and estimated red blood cell contents of the surgical suction canister based on each image in the set of sequential images over time.

23. A system for managing blood loss of a patient, comprising:

an interface that receives data related to intravenous administration of a fluid to the patient;

an optical sensor;

a processor coupled to the optical sensor and to the interface;

a software module executing on the processor and instructing the optical sensor to capture an image of a physical sample, the software module further instructing the processor to track a quantity of the fluid administered to the patient according to data received by the interface, to estimate a red blood cell content of the physical sample based on a feature extracted from the image, and to estimate a hematocrit of the patient based on a previous hematocrit of the patient, the fluid administered to the patient, and the estimated red blood cell content of the physical sample; and

a display coupled to the processor and receiving instruction from the software module to display the estimated hematocrit of the patient.