Basic Principle of Blood Volume Measurement
Blood volume analysis is based on the fundamental concept of the indicator dilution technique, whereby a tracer substance, in this case albumin I-131, is mixed into an unknown volume. An identical amount of tracer is placed into a known volume. By comparing the concentration of the indicator between the known and unknown volumes, an exact measurement of the unknown volume can be obtained.
How Does the BVA Provide Accurate Blood Volume Measurement?
The BVA-100 is a semi-automated blood volume analyzer. The instrument is used in conjunction with a single-use injection kit consisting of a precisely measured standard and matching injectate. The injectate is packaged in a patented flow chamber designed to ensure 99.8%+ delivery. The kit improves accuracy and eliminates the many time-consuming and difficult steps required for on-site standard preparation.
The BVA-100 utilizes five separate sampling points taken at regular intervals starting approximately 12 minutes after injection. In effect, each sample measurement is a separate, single-point blood volume determination. The BVA-100 computes the transudation time for the tracer and calculates the true zero point blood volume with an accuracy of approximately ± 2.5%. The BVA-100 provides interim blood volume results while the samples are being measured; preliminary data is available within 30 minutes and may be used to guide decisions in emergency situations.
Summary of the Basic Technical Steps to Perform a Blood Volume Analysis
- Enter patient data (patient’s name, hospital number, accurate height and weight measurement)
- Inject tracer through IV line, record injection time for the beginning of the blood volume measurement
- Collect blood sample into anti-coagulated tube via specialized collection kit requiring a single venipuncture
- Obtain microhematocrit and centrifuge samples to separate plasma
- Pipette 1 cc plasma samples and place into Blood Volume Analyzer
- Repeat steps 3, 4, and 5 for samples 2 through 5; preliminary results will be available within 30 minutes after injection. Blood volume analysis is complete, with final results available after 90 minutes.
Technical Requirements of Personnel
- Ability to establish an intravenous line and collect blood samples
- Basic technical expertise in performing hematocrits and familiarity with accurate pipetting technique.
Videos of the Process
Setup and patient preparation
Baseline sample collection and injecting Volumex
Blood sample collections
Using the BVA-100