Measuring blood loss: the fist beats the eye
A research team at the University of Medicine and Dentistry of New Jersey and the Robert Wood Johnson University Hospital have criticised health care workers who use visual estimation to determine volumes of blood loss, saying it can be highly inaccurate.
They report developing a new, simple and more accurate method - the MAR Method - that relies on a person's fist to determine external blood loss.
They measured increments of human whole blood in a clinical trial by comparing the anterior surface of the fist to the surface area of blood present and created a formula averaging blood per fist. They determined that a fist covers a surface area of blood that equals about 20mL.
Then two scenarios were staged, using 750mL of blood, with 78 participants who were asked to estimate blood volumes before and after being taught the new method. The first estimate was based on a visual assessment. Additional estimates were made using the MAR Method.
The participants got as close to the blood pool as possible and estimated the blood volume by counting how many fists it would take to cover the blood pool. The researchers reported that, after less than one minute of instruction, the participants were able to determine blood volumes with improved accuracy and precision.
Their study has been reported in the American Journal of Emergency Medicine.
Published: 15 Feb 2010