“The ultimate idea is to obtain a sample that’s separated in accordance to the test you will perform, whether that’s manual or automated,” says Vernita Moore, senior marketing analyst for Blood Banking at Beckman Coulter (Irving, TX).
In regulated medical settings, instrumentation and assays dictate the method down to sample handling, pretreatment, spin time, g-value, centrifugation vessel, and sometimes specific test instrument. Labs must document strict adherence to these specifications, or tests will be declared invalid or blood products deemed unusable. Sample integrity and acceptability are defined by the manufacturer of the assay or test instrument.
Compared with academic chemistry or biology labs, methods developed for blood bank and clinical lab centrifuges must be validated, which includes assessing centrifuge performance and suitability for particular applications.
Following safety protocols is critical for protecting centrifuge operators from blood-borne pathogens. “When handling a sample it’s always assumed to be infected, and that’s how labs should handle them,” Moore notes. Hospitals, blood banks, and clinical labs follow OSHA guidelines on worker exposure to blood-borne pathogens and may institute additional safety or best-practice measures. “In most cases employees wear protective clothing: gloves, coats, and sometimes even goggles depending on what they are testing.”
In developing their own centrifuge line suitable for blood banks and clinical labs, Beckman Coulter relies on customer input and on analysis by experts like Moore. Instruments must not only be suitable for tests and preparative work, but facilitate typical workflows in laboratories that may process thousands of samples per day.
“They want large-capacity centrifuges that spin multiple samples at once,” Moore explains. “They need programmability because they’ll often use the same centrifuge to spin samples that will be used in a variety of tests on a range of instruments.”
Also at the top of the list is safe usability. Experienced lab workers will have heard of centrifuges that “got away” from operators, self-destructing and taking a good part of the lab with them. Such stories may be apocryphal and their horrors multiplied by their retelling, but centrifuges are arguably the riskiest instruments you’ll find in most labs. “Most operators are not highly degreed and learn on the job, so centrifuges must be easy to use,” Moore adds.
Blood banks spin a variety of containers as small as serology tubes and as large as blood collection bags. The things that set blood bank centrifuges apart are the need for temperature control, ergonomics, noise reduction, and high capacity.
“Particularly with bags, maintaining a temperature between three and six degrees Celsius is critical,” says Jeff Antonucci, regional manager at Hettich Instruments (Beverly, MA). “For many applications, samples are considered ruined if they rise above ten degrees.”
Centrifuges generate considerable heat, so maintaining temperatures within safe ranges involves refrigeration and multiple temperature sensors. Hettich centrifuges provide a level of assurance by indicating both ambient and sample temperatures.
Ergonomics are high priority because blood bank centrifuges tend to be larger than ordinary lab units. “They have to be accessible by workers of all sizes,” Antonucci explains. Features as straightforward as positioning controls and access on the front of the centrifuge, as opposed to the top or rear, eliminate reaching and leaning to enter parameters or samples. Another strategy involves replacing the windshield, which typically resides between the lid and the buckets, with an integrated cover. “This both reduces a step—lifting the shield—and provides improved aerodynamics,” Antonucci continues.
The larger the centrifuge, the more noise it makes. Reducing physical layout is not an option, however, as blood banks operate at high throughputs. “It’s difficult to balance for capacity while maximizing safety and minimizing noise,” Antonucci says.
For additional resources on centrifuges, including useful articles and a list of manufacturers, visit www.labmanager.com/centrifuges