Microsampling is the procedure of collecting and processing minute samples of blood, as small as 10 or 20 μL (microliters), for analysis. This approach has been around for about 60 years in pharmaceutical, clinical and life sciences, but some outside of the field may wonder why they haven’t been offered to give a single pin drop of blood via microsampling instead multiple tubes when visiting a phlebotomist. Although some challenges still need to be overcome with Microsampling, it has major advantages over venipuncture, especially for instances such as in-home testing for the critically ill, elderly/immobile, or pediatric patients.
Lower Stress Levels
An obvious benefit is that microsampling minimizes the stress on a patient. Drawing blood directly from the vein can feel very invasive to certain patients who have anxiety and fear about giving blood, plus comes with its own risks. Some complications include conditions like cellulitis, bacterial infection of the skin; phlebitis, inflammation of the vein; diaphoresis, perspiring from sweat glands; hypotension, low blood pressure; syncope, fainting; or seizures, uncontrolled electrical disturbances in the brain.
Carried out by a simple prick of the finger, a microsample can be taken from the small drop of blood to rise to the skin surface. On the contrary, a sample drawn via venipuncture may require a sample that is 500 to 1,000 times the size of the microsample, around 10 ml (milliliters).
Remote Sampling
If we learned anything from COVID-19, we understand the importance of safe access to care and healthcare flexibility, including virtual and remote care. With microsampling almost anyone can collect a sample, including the patient. One technique is accomplished by using a pipette or capillary tube to transfer a dot of blood to a card. This is called a dried blood spot (DBS) sample and can be collected without a trained phlebotomist or nurse and requires minimal materials compared with traditional phlebotomy collection, facilitating at-home self-collection. According to a survey completed by the Journal of Applied Bioanalysis, “…after DBS, volumetric absorptive microsampling (VAMS) is the second most applied microsampling technology…” VAMS differentiates itself from DBS as is allows the accurate and precise collection of a fixed volume of blood with microsampling devices. One of the large advantages to this method as it eliminates the hematocrit effect. The Journal goes on to say “…A good third up is capillary microsampling followed by dried matrix microsampling of a plethora of biofluids such as saliva, urine, plasma, and others.”
Simplified Storage, Transportation and Disposal Requirements
These sampling methods have much less stringent requirements when it comes to storage, transportation and disposal. In the care of the most common microsampling technique, DBS, storage and transportation requirements are not as strict as they are for a wet blood. NIH states that if immediate freeze is an option, DBS samples should be frozen at a temperature of -20 °C or lower. If freezers are not available under field conditions, or in the case of an individual collecting their own sample at home, storage at -4 °C is acceptable. NIH also says that a frozen DBS sample should be transported in temperatures as cold as dry ice. It is not clear as to the need for transportation that is as cold as dry ice, when storage is only required at -4 °C, we recommend transporting at the required temperature for storage to avoid the potential for temperature variation. Temperature variation can alter the unique structure of proteins and lead to invalid results.
https://www.cdc.gov/nceh/dls/pdf/poster_dried_shipping.pdf
