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Protecting fragile veins: the new, smaller design of microtubes is advancing safety, accuracy and turnaround time of low volume blood collection and testing in patients with fragile veins.

Medically fragile patients, particularly those in ICU or with chronic disease states, as well as neonatal patients, require low-volume blood collection for sample testing. But, certain challenges present themselves when collecting blood from these difficult venous access (DVA) patients.


Challenges in low-volume blood sampling can include sample misidentification when small microtubes are used, hemolysis, clotting, inappropriate sample volume (QNS or "Quantity Not Sufficient" for testing) and inappropriate blood-to-additive mixture when full-size tubes are partially filled.


The most common lab problems are associated with mislabeling (because the smaller-sized tubes cannot accommodate a full-sized label) and inefficiencies associated with manual sample processing, which is often necessary because microtubes cannot be processed using automated processing systems calibrated to accommodate full-sized tubes. Additional manual handling increases the risk of label error and sample compromise and can also increase the risk of exposure to bloodborne pathogens.

Challenging sample collection

While the focus on reducing waste in sample collection is a rapidly growing trend in healthcare, the issue has been an important consideration in treating patients with difficult venous access for many years. In these patients, veins are hidden or compromised, making it difficult or impossible to collect a full-sized peripheral blood sample. DVA affects thousands of patients each year, including neonates, seniors, intravenous drug users and patients in treatment for cancer, cystic fibrosis, chronic kidney disease and other disease states. Traditionally, sample collection for these patients include options such as short draw using a full-sized tube. In this option, a full-sized tube is not filled to the recommended level. This results in a smaller volume sample, but also changes the ratio of additive to blood. Incorrect blood-to-additive ratio can lead to inaccurate results in sample analysis. Syringe draw for a low-volume sample is also an option. The use of a syringe in sample collection can improve control of the blood collected. However, the use of a syringe can also increase the risk of hemolysis or clotting if transfer to a tube with anti-coagulant is delayed. This process requires that a blood sample be transferred to a tube after collection, increasing the need for manual handling and the risk of label error, sample compromise and exposure to bloodborne pathogens.

Another option is tubes with reduced vacuum (i.e., partial draw tubes). These are full size tubes that, when filled, contain reduced volume of blood. Using a vacuum tube designed for a partial draw results in a lower volume; however, these tubes are not often widely available and cannot be used at higher altitudes. Microtubes designed to hold smaller volume samples are yet another option. Using this option, collection can be completed via heel or finger stick, but the smaller tubes cannot be processed in automated mode and cannot accommodate a full-sized label. According to recent estimates, approximately 1% of all errors in the lab are associated with labeling problems and 70% of all label errors involve the use of microtubes.

Based on input from clinicians as well as laboratory scientists around the world, BD Diagnostics designed the BD Microtainer MAP Microtube for Automated Process specifically to enhance skin puncture collection, improve lab efficiency and reduce error and safety risks in low volume blood sample collection. With this advance, laboratories are positioned to expand the use of lower volume blood samples using tubes that offer the critical advantages of a full-sized BD Vacutainer tube in labeling, automated processing and reduced manual handling.

The BD Microtainer MAP Microtube for Automated Process with K2EDTA was introduced last year after a multi-year research and product engineering effort. The MAP tube size and design differ from standard-sized microtubes in several ways. It has a false bottom so the exterior shell is the same size as a standard-sized (13 x 75 mm) BD Vacutainer tube, making it possible to process samples using most hematology analyzers. The exterior shell can also accommodate a full-sized label. The interior tube with integrated collector includes a pierceable cap that is compatible with instrument probes, clearly visible fill lines to ensure proper fill volume and guidance on the number of inversions required for sample processing right on the label. The tube has an integrated collector and markings to clearly indicate fill volumes of 250, 375 and 500 [micro]l. The tube contains 1.0 mg of K2EDTA, which is sufficient to anticoagulate 250 to 500 [micro]l of skin puncture blood. The design makes it possible for labs to process smaller volume samples using the automated analyzer equipment they have in place, while reducing the risk of label errors and the need for manual processing steps often associated with the use of standard-sized microtubes.

BD Microtainer MAP tubes are used to collect, anticoagulate, transport and store blood specimens for measurement of hematology parameters including WBC, RBC, Hgb, HCT, MCV, MCH, MCHC, Platelets, 5-part WBC differential (neutrophils, lymphocytes, monocytes, eosinophils, basophils) and Reticulocytes, as well as Whole Blood Lead Testing.

Reducing errors one label at a time

The experience at a 185-bed children's hospital in Pennsylvania highlights the impact that MAP Microtainer tubes can have on lab operations. The hospital followed a nine-step process for microcollection hematology testing using a standard microtube.

In recent years the hospital has processed 37,000 samples annually, 18,000 of which were collected in microtubes. The lab reports a label error rate of 0.3% (an estimated 1,110 errors), clotting or other specimen quality issues in about 4.7% of all samples and a specimen rejection rate of about 5%. In the lab, manual sample processing accounts for about 50% of daily workload for technicians.

The laboratory has identified challenges with both labeling and manual processing. While the laboratory team uses a bar code label for both full draw tubes and microtubes, a standard-sized label extends beyond the bottom of the microtube. Unless the label end is manually "tucked in," it can stick to the rack or can be easily torn or damaged. In addition, all information on the label may not be visible when compared to full draw tubes. The microtubes require about three minutes of manual handling per sample, while automated processing requires only 2.5 minutes per sample and involves significantly less hands-on time by laboratory staff.

In this example, the use of BD Microtainer MAP tubes would have a significant impact on efforts to reduce label errors and improve efficiency. Because the MAP microtube is specially designed to accommodate a full-sized label, there is no need to "tuck" the ends in. All of the information on the label remains visible, and proper positioning can reduce the risk that a label will tear and stick to the rack causing work stoppage. Based on the volume of samples processed, the reduction in manual handling in this laboratory would reduce the time required for overall sample processing by 150 hours per year, while reducing testing turnaround time by 17%.



* Mislabeling is one of the most common problems associated with low volume blood sampling.

* One percent of all lab errors are associated with labeling; 70% of all errors involve the use of microtubes.

* An incorrect blood-to-additive ratio can lead to inaccurate results in sample analysis.

* BD Diagonistics-designed microtubes for automated process (MAP) are smaller than standard size tubes.


For additional information on the company discussed in this article, see Laboratory Equipment magazine online at or the following web site:


by Ana Stankovic, Worldwide Vice President, Medical Affairs, BD Diagnostics - Preanalytical Systems
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Title Annotation:Life Science & Biomedical Labs
Author:Stankovic, Ana
Publication:Laboratory Equipment
Date:May 1, 2011
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