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Clinical evaluation of serial blood processing at point of care.

The Axial Separation Module (ASM[TM]), which separates whole blood in Axial Process Containers (APC[R]) (Dupont Canada, Mississauga, ON) [1, 2], was evaluated for clinical performance at the University of Virginia Health Sciences Center (UVA HSC) in a community-based outpatient laboratory. (1) We utilized the ASM to serially process blood specimens at point of care. We wanted to determine the effects of point-of-care blood separation on turnaround time.

Our previous evaluation [2] had three significant findings: (a) axial separation of heparin-containing whole blood gave equivalent chemistry values when compared with conventional specimen separation; (b) axial separation yielded a 69% time savings at the centrifugation bench (time on the centrifugation bench is a small portion of turnaround time); (c) the ASM, because of the increased speed and efficiency of axial separation, was calculated to allow a labor savings of up to one-half a full-time laboratory employee. The ASM separates one tube of whole blood in ~1 min with minimum operator effort.

In the previous study we did not measure test result turnaround time (previously, only time spent on the centrifuge bench top was considered). We studied turnaround time at UVA HSC main clinical laboratory for specimens separated at point of care. We chose to study specimens originating from a typical outpatient center because we anticipate that the UVA HSC will serve up to 18 remote facilities in the next year. The ease of use and compact design of the ASM was well-suited for use at our North Ridge outpatient clinic (located 5 miles away from the main hospital laboratory).

Conventionally, specimens arrive at the main laboratory accessioning area and are subjected to preanalytical delays caused by bottlenecks at the centrifugation station. We hypothesized that moving blood separation to point of care would reduce turnaround time because separated specimens could bypass the centrifugation step of the preanalytical process in the main laboratory.

Materials and Methods

All blood was drawn by trained phlebotomists. The APC has been approved by the FDA and it gives equivalent chemistries when compared with the Vacutainer Tube[TM] (Becton Dickinson, Franklin Lakes, NJ) [2]. All specimens in this study were used for patient care.

Blood drawn into an APC was separated in the ASM at the North Ridge Clinic. Blood drawn into a Vacutainer Tube was separated in a conventional centrifuge (Accuspin[TM] ; Beckman Instruments, Palo Alto, CA) at the main laboratory. Therefore, blood in an APC arrived to the main laboratory separated, whereas a Vacutainer Tube arrived containing whole blood. Turnaround time was calculated for the "chem 17" test from files stored in our laboratory information system (LIS) (Sunquest, Tucson, AZ).

Specimen transportation to the main laboratory from the North Ridge Clinic was performed by human messengers. Average turnaround time was calculated for both the conventional system and the ASM/APC at the North Ridge Clinic. The time period of interest (turnaround time, Fig. 1) for this study started with specimen arrival at the accessioning area of the main laboratory and ended with result availability to the LIS.

A time comparison between blood specimens serially separated at point of care vs conventional batch centrifugation at the main laboratory was performed. We adopted sequential time periods of 3 weeks. The ASM was placed in the laboratory 1 week before the test period to allow technologists to become accustomed to the new technology. All data points were collected from the 3-week periods to obviate any bias from data selection. The two systems could not be operated in parallel because sorting out ASM tubes from conventional tubes after transportation would have biased the timing studies.

The turnaround times were compared by the Student's Mest, and P <0.01 was taken to be significant.


North Ridge Clinic: The average turnaround time for the conventional system was 1 h 45 min [+ or -] 4.4 min (mean [+ or -] SE, n = 49) compared with 1 h 20 min [+ or -] 6.3 min (mean [+ or -] SE, n = 34) for the ASM, an average of 24% time savings (P <0.01, unpaired Mest) (Fig. 1). None of the turnaround times for the conventional system was <1 h, whereas 41% of the turnaround times for blood specimens separated at point of care were <1 h.



The faster turnaround times for the APCs were primarily a result of the elimination of the batch centrifugation step in the main laboratory, historically a major bottleneck in the preanalytical process. Conventional specimen separation includes specimen queuing before and after centrifugation, centrifuge balancing, loading, and unloading. Our conventional centrifuges at the main laboratory run for 10 min. For the North Ridge Clinic specimens, an average of 25 min per specimen was saved by incorporating point-of-care centrifugation. Point-of-care blood separation saved not only the 10 min of centrifugation time in the main laboratory, but additional time necessary for accessioning, sorting, and conventional centrifuge tasks such as balancing, loading, and unloading. Any remote laboratory that provides phlebotomy services (but has specimen centrifugation and analysis performed elsewhere) could benefit from the faster turnaround times provided by point-of-care separation. Once the APCs are mass produced, it is assumed they would be cost justifiable (understanding that they would still be at a premium compared with conventional tubes because of the advantages they offer). When the technology becomes commercially available (projected for the third quarter of 1997), we plan to incorporate it in as many of our 18 remote sites as possible.

The technologists indicated that processing specimens serially in the ASM did not require appreciable effort or delay their daily routine, unlike conventional centrifugation. In fact, in the past the North Ridge Clinic centrifuged their own specimens (conventionally), but that responsibility was eliminated when it was found to be too laborious. Previously, the technologists often batched specimens when separating by conventional centrifugation. Those batches that were in the process of centrifugation when the messenger arrived had to wait until the next delivery time (at least 1 h later).

We observed that our present laboratory protocol (in the main laboratory, after delivery) requires medical technologists to transport routine specimens from the accessioning/ centrifugation area to the analytical area approximately every 30 min. APCs and Vacutainer Tubes arrive at the accessioning/ centrifugation area in the same manner. Although blood in an APC was already separated, it remained in the accessioning area queue until delivery to the analyzer. So, at our main laboratory, turnaround time could be further reduced up to 30 min if the APCs could be streamlined directly to the analyzers after accessioning is complete. The process then is analyzer time dependent and nonanalytical time is minimized.

Hemolysis causes analytical problems [3] and is a common problem with patient specimens originating from another remote facility at the UVA HSC, our Cancer Treatment Center. Hemolysis requires a redraw of a patient specimen. With conventional centrifugation, hemolysis is not discovered until preanalytical specimen processing is complete at the main laboratory. A lengthy time delay results before a patient can receive medication. Thus, the ability to immediately detect hemolysis (and possibly other problems such as lipemia and icterus) at the time of phlebotomy is desirable. This can be accomplished with point-of-care centrifugation.

The ASM processes blood specimens serially. Its design is well suited for point of care. Conventional centrifuges are much more labor intensive [2]. The APC technology allows for quick visual inspection of the plasma at point of care within minutes of phlebotomy completion. The need for a redraw is determined immediately. This can potentially save a patient hours of time. For example, a Cancer Treatment Center patient cannot receive chemotherapy until the analytical results are obtained. A new study being conducted at the UVA HSC Cancer Center clinic will seek to quantify the effect of point-of-care blood separation on patient care.

Point-of-care blood separation has another potential benefit: Specimens originating from remote locations are subject to analytical problems associated with delays of specimen separation [3, 4]. Therefore, blood specimens should be centrifuged as soon as possible. Electrolyte concentrations decrease over time in whole blood because of the concentration gradients that exist between cells and serum (or plasma) [4]. Glucose is metabolized by leukocytes and erythrocytes in whole blood [3]. The use of antiglycolytic agents is commonplace for glucose measurements. However, immediate blood separation may help eliminate analytical error due to whole-blood separation delays and may obviate the need for metabolic inhibitors. Furthermore, plasma is permanently separated from cells by a plastic separator in the APCs. We believe this to be superior to traditional gel tubes, especially during transportation in hot weather.

In conclusion, prior studies demonstrated that the serial nature of the ASM system more efficiently separates whole-blood specimens on the bench top. Our clinical evidence now demonstrates that serial point-of-care blood separation reduces specimen turnaround time at the main laboratory. The ASM/APC was found to be better suited for point-of-care blood separation than a conventional centrifuge. Furthermore, we speculate that this technology has the potential to help improve the quality of analytical results by facilitating centrifugation immediately after phlebotomy at point of care. A study to assess the effect point-of-care centrifugation has on patient care is ongoing.

This study was supported by a grant from Dupont Canada. We thank James C. Boyd for his statistical expertise. We also thank the laboratory staff at both the North Ridge Clinic and the Cancer Treatment Center for their invaluable assistance with these studies.

Received May 28, 1996; revised October 1, 1996; accepted October 2, 1996.


[1.] McEwen JA, Godolphin W, Bohl RM, Dance MN, Furse ML, Osborne JC. Apparatus and method for separating the phases of blood. US Patent 4 929 716, 1989.

[2.] Estey CA, Felder RA. Clinical trials of a novel centrifugation method: axial separation. Clin Chem 1996;42:402-9.

[3.] Ladenson JH. Nonanalytical sources of variation in clinical chemistry results. In: Sonnenwirth AC, Jarrett L. Gradwohl's clinical laboratory methods and diagnosis. St. Louis: C.V. Mosby Co., 1980:149-92.

[4.] Heins M, Heil H, Withold W. Storage of serum or whole blood samples? Eur J Clin Chem Clin Biochem 1995;33:231-8.


The University of Virginia Health Sciences Center, Medical Automation Research Center, Box 168, Charlottesville, VA 22908.

(1) Nonstandard abbreviations: ASM, Axial Separation Module; APC, Axial Process Containers; UVA HSC, University of Virginia Health Sciences Center; and US, laboratory information system.

* Author for correspondence. Fax 804-924-5718; e-mail
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Title Annotation:Automation and Analytical Techniques
Author:Estey, Christopher A.; Felder, Robin A.
Publication:Clinical Chemistry
Date:Feb 1, 1997
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