Method of estimating blood volume

Abstract

Disclosed are methods, materials and devices for approximation of blood volume in a fluid, such as in a biological fluid collected during a surgical procedure. The method and devices include the use of a RBC flocculant, such as polyDADMAC, and an approximate blood hematocrit for the type of animal, as well as a calculated RBC packing ratio corresponding to the collection device being used. Also provided is a Blood Indicator Panel (BIP), comprising a series of markings calculated from an observed red blood settlement volume, the average animal type hematocrit, and a calculated RBC packing ratio “η” value for the collection device. Pediatric (about 200 ml or 250 ml size container), adult human (about 1,000 ml-1,500 ml) and veterinary (about 500 ml-2,500 ml) collection containers are also disclosed, that include a RBC flocculant, for use in approximating blood volume in a fluid. Methods of detecting blood in a sample, such as a fluid sample, and kits for performing the methods, are also provided.

1 . A method for approximating blood volume in a fluid comprising:
 determining a stable sedimentation level of red blood cells from the fluid in a container; and   approximating blood volume in the fluid,   
       wherein the approximate blood volume in the fluid is provided by dividing the volume of sedimented red blood cells by a value of an average blood hematocrit multiplied by a red blood cell packing ratio of the container. 
     
     
         2 . The method of  claim 1  wherein the fluid is contacted with a red blood cell flocculant. 
     
     
         3 . The method of  claim 2  wherein the red blood cell flocculant comprises polyDADMAC. 
     
     
         4 . The method of  claim 1  wherein the fluid comprises about 20% blood, 30% blood, 50% blood, or about 65% blood by volume. 
     
     
         5 . The method of  claim 1  wherein the fluid comprises about 50% or less blood by volume. 
     
     
         6 . The method of  claim 2  wherein the stable sedimentation level of red blood cells in the fluid in the presence of the red blood cell flocculant is provided at a rate at least two times faster than red blood cell sedimentation in the absence of the red blood cell flocculant. 
     
     
         7 . The method of  claim 2  wherein contact of the fluid and the red blood cell flocculant comprise combining the fluid and red blood cell flocculant to form a mixture at room temperature. 
     
     
         8 . The method of  claim 2 , wherein stable red blood cell sedimentation in a fluid is determined within about 10 minutes. 
     
     
         9 . The method of  claim 7  wherein the subject is a horse, a human or a cow. 
     
     
         10 . The method of  claim 2  wherein the amount of the red blood cell flocculant is about 320 mg. 
     
     
         11 . The method of  claim 1  wherein the red blood cells are human red blood cells. 
     
     
         12 . The method of  claim 1  wherein the fluid comprises saline and human red blood cells. 
     
     
         13 . (canceled) 
     
     
         14 . A kit for identifying blood in a fluid sample comprising:
 a container containing an amount of a red blood cell flocculant capable of sedimenting red blood cells in a fluid; and   an instructional insert.   
     
     
         15 . The kit of  claim 14  wherein the red blood cell flocculent comprises polyDADMAC. 
     
     
         16 . The kit of  claim 14  wherein the container is a collapsible container. 
     
     
         17 - 19 . (canceled) 
     
     
         20 . The method of  claim 1  wherein fluid is a human fluid sample comprising urine. 
     
     
         21 . A method for more rapidly approximating a volume of blood in a fluid comprising:
 combining a volume of a fluid from a subject with an amount of a red blood cell flocculant to provide a mixture;   determining a volume of settled red blood cells in the mixture at room temperature without centrifugation to provide a volumetric measurement of a stable red blood cell sedimentation level; and   approximating the volume of blood in the fluid from the volumetric measurement, wherein the presence of the red blood cell flocculant provides a more rapid method for approximating the volume of blood volume in the fluid compared to a method in the absence of the red blood cell flocculant.   
     
     
         22 - 23 . (canceled) 
     
     
         24 . The method of  claim 1  wherein saline is added to the fluid. 
     
     
         25 - 26 . (canceled) 
     
     
         27 . The method of  claim 1  herein the volume of blood in a fluid is determined according to a formula:
     V   b   =V   m /( Hct ×η)
 
 
       wherein V b  is the blood volume measured in milliliters, V m  is the sedimentation level of red blood cells measured in milliliters, Hct is the average hematocrit, and η is the red blood cell packing ratio of the container.