Q & A

June 2002

"Q&A" editor’s note: A laboratory specialist asked the CAP to indicate whether a specified manufacturer’s urinalysis microscopic examination system met CAP approved procedural standards. Questions of this type are periodically submitted to "Q&A" and the CAP Laboratory Accreditation Program. The CAP’s position on whether an instrument or procedure is acceptable under CAP standards is outlined in the response by Edward J. Gruber, MT (ASCP), and reflects the views of this editor.

A.  The College does not endorse instrumentation or procedures. The CAP’s philosophy is that a laboratory director should be responsible for evaluating the appropriateness of laboratory instruments and establish and monitor the standards for performance and quality control. Alternative quality control systems, such as electronic QC or internal QC, must be evaluated on-site by the laboratory director to verify that they are scientifically valid and function effectively based on the data from the manufacturer and their own internal validation studies. CAP policy states, "The Commission on Laboratory Accreditation does not evaluate instruments, devices, materials, or other laboratory systems with respect to whether or not such items satisfy the standards for laboratory accreditation."¹

The inspection checklists contain guidelines that inspectors use to verify that laboratories are meeting the CAP’s standards for laboratory accreditation. The checklists also contain notes, commentary, and references that laboratories may use in evaluating new instrumentation and establishing quality control protocols and procedures. The checklists are sent to laboratories prior to their inspection and self-inspection and are available on the CAP’s Web site.

The College also welcomes the opportunity to discuss checklist question interpretation with laboratories on an individual basis. Technical assistance is available to LAP participants at 800-323-4040 ext. 6065.

Reference
1.  Commission on Laboratory Accreditation Policy Manual. Northfield, Ill.: College of American Pathologists; 1994:Policy 5.01a.

Edward J. Gruber,
MT(ASCP), CLS(NCA)
Technical specialist II
CAP Laboratory Accreditation Program

Q.  In our performance improvement efforts in the laboratory, we are continually monitoring percentages of specimens that demonstrate significant hemolysis. This has been a particular issue for nurse draws received from the emergency department. We have been unable to find in the literature a threshold of minimal percentage of specimens that should show hemolysis. Can you comment?

A.  Hemolysis, or the degradation of red cells in clinical blood samples, may alter laboratory-generated analytical results¹and thus might necessitate repeat collection by phlebotomy. The rate of hemolysis will vary among institutions and is dependent on two important factors: the phlebotomists’ background and the method used for specimen collection.

Some hospitals have successfully implemented patient-focused care, which is a team-oriented approach to health care delivery.^2-4The primary goal is to promote quality and customer satisfaction that is measured more by the patient’s standards than the caregiver’s standards.^2-4The overall strategy is to increase the time nursing staff spends in patient care and to decrease the number of employees who have contact with a patient.

A major disadvantage to this approach is the lack of educational institutions providing a curriculum that focuses on all of the responsibilities of a patient care technician, including phlebotomy, ambulation, point-of-care testing, physical therapy, and occupational therapy. For example, Evans describes how the typical six-week-long laboratory phlebotomy training program had to be reduced to three weeks and then to 80 hours if adult patients only were to be drawn, with the addition of 40 hours if pediatric patients were included.⁵

Authors have reported an increase in unacceptable specimens, including hemolysis, after implementing a patient-focused care program.^6,7 The specimen-rejection rate rose from an average of 210 specimens per month to 300 specimens per month after nurses and clerks started performing phlebotomy.⁶ After nurses performed phlebotomy, programs reported a 50 percent reduction in stat laboratory requests and a significant increase in unacceptable specimens.⁷Adequate initial training and retraining, if necessary, are important elements of the vigilance system required to maintain quality when using part-time phlebotomists.

A blood specimen may be collected with a syringe or an evacuated tube system directly from the vein or from an intravenous catheter. The literature indicates that registered nurses prefer to draw blood from an intravenous line.^8,9 Hemolysis is a common complication when blood is drawn from an intravenous catheter—it may occur at a rate ranging from 42 percent for Teflon catheters to 55 percent for Vialon catheters, depending on the material used to manufacture the intravenous catheter.^9-12 The frequency of hemolysis may be reduced to 12 percent when a stainless steel needle is used.¹² Kennedy et al reported a significant (P=0.03) reduction in hemolysis when blood was drawn through a 21-gauge needle into vacuum specimen collection tubes (3.8 percent), compared with 13.7 percent when blood was collected through intravenous catheters ranging from 24-gauge to 14-gauge into a syringe. In general, the smaller the intravenous catheter diameter, the higher the rate of hemolysis secondary to increased shear stress.^9,13

The rate of hemolysis varies, therefore, with the degree of phlebotomy training and the method used to collect the blood specimen. The range varies in the literature from 3.8 percent for a 21-gauge needle into vacuum specimen collection tubes to 100 percent when a 24-gauge intravenous catheter is used.⁹ The rate of hemolysis in one study varied from 12.4 percent for emergency department personnel versus 1.6 percent for laboratory personnel.¹⁴ A change in phlebotomy practice should be closely monitored for a change in the rate of hemolysis—for example, the combination of drawing blood from newly placed intravenous catheters into vacuum specimen collection tubes and the introduction of a whole blood electrolyte method (i-Stat, Abbott, Bedford, Mass.) masked a potassium abnormality.

Because it is impossible to visually inspect a whole blood specimen for hemolysis, we have introduced a centrifuge to spin down the cells to facilitate visual inspection of plasma. In this case, the plasma revealed hemolysis and the hemolysis-free serum sample demonstrated hypokalemia in the presurgical patient. A marked reduction in the rate of hemolysis was observed after a vacuum specimen, which has less vacuum and thus is only partially filled, was introduced to remove blood from the intravenous catheter.

References
1.  Young DS. Hemolysis. In: Effects of Preanalytical Variable on Clinical Laboratory Tests. 2nd ed. Washington, DC: AACC Press; 1997:(4)228-234.
2.  Lark S. Patient-focused care. Is it working? Is it here to stay? Laboratory Medicine. 1997;28:644-651.
3.  Murphy R. Work re-engineering: the benefits and the barriers, an analytical review. J Soc Health Syst. 1994;5:73-84.
4.  McQueen J. Overcoming the barriers to implementing patient-focused care. Journal of Healthcare Information Management Systems. 1993;7(2):17-21.
5.  Evans VJ. The laboratory in a restructured environment. In: Parsons ML, Murdaugh CL, eds. Patient-Centered Care. A Model for Restructuring. Gaithersburg, Md.: Aspen Publishers; 1994: 435-453.
6.  Gable JT, Pyevac ZP. Paradigm shift: phlebotomy belongs to nursing. Clinical Laboratory Management Review. 1995; 9: 286-297.
7.  Marchwinski J. Transferring inpatient specimen collection to nursing: the multidisciplinary path to success. Clinical Laboratory Management Review. 1997; 11: 368-373.
8.  Eyherabide A. Intermediate care/telementary case study. In: Parsons ML, Murdaugh CL, eds. Patient-Centered Care. A Model for Restructuring. Gaithersburg, Md.: Aspen Publishers; 1994: 362-384.
9.  Kennedy C, Angermuller S, King R, et al. A comparison of hemolysis rates using intravenous catheters versus venipuncture tubes for obtaining blood samples. Journal of Emergency Nursing. 1996;22:566-569.
10.  Herr RD, Bossart PJ, Blaylock RC, et al. Intravenous catheter aspiration for obtaining basic analytes during intravenous infusion. Ann Emerg Med. 1990;19: 789-792.
11.  Fincher RK, Strong JS, Jackson JL. Accuracy of measurements of hemoglobin and potassium in blood samples from peripheral catheters. Am J Crit Care. 1998;7: 439-443.
12.  Raisky F, Gauthier C, Marchal A, et al. Haemolyzed samples: responsibility of short catheters. Ann Biol Chem. 1994;52: 523-527.
13.  Sharp MK, Mohammad SF. Scaling of hemolysis in needles and catheters. Ann Biomed Eng. 1998;26: 788-797.
14.  Burns ER, Yoshikawa N. Hemolysis in serum samples drawn by emergency department personnel versus laboratory phlebotomists. Laboratory Medicine. 2002;33: 378-380.

Frederick L. Kiechle, MD, PhD
Chairman, Department of Clinical Pathology
William Beaumont Hospital
Royal Oak, Mich.

Member, CAP Publications Committee

Q.  How can an albumin/creatinine ratio on a random specimen (urine) be reported in units of number of grams creatinine when urinary total protein and creatinine are generally mg/dL?

A.  Units for albumin and creatinine are converted to mg/L and g/L, respectively. The value for albumin is divided by the value for creatinine, resulting in milligrams of albumin divided by grams of creatinine.

Martin H. Kroll, MD
Pathology and Laboratory Medicine Service
VA Medical Center
Dallas

Member, CAP Chemistry
Resource Committee