Blood Bank Colleagues:
Clinical laboratories usually have a list of 'critical lab values' for laboratory testing that trigger phone calls to attending physicians. Please review the following two definitions of 'critical laboratory values' and indicate to me any test result (or lab test result in concert with a specific scenario) that you would consider a 'critical laboratory value' for a transfusion service laboratory. This issue has recently come up at my institution, as we are revising our institutional list of 'critical lab values'. For the values you list, please let me know if these are merely hypothetical or if the listed values are in actual use in a hospital (or center) where you practice.
Definitions:
A critical laboratory value is a test result that requires immediate evaluation by the physician responsible for the care of the patient to determine the need for appropriate action to protect the welfare of the patient.
or
A test result that is so abnormal that it reflects a potentially emergent situation to a patient AND the failure to report this result within minutes could unnecessarily delay appropriate emergent interventive therapy.
I appreciate your input and insight. Please e-mail me your answers.
I.A. Shulman [1] M.L. Zucker [2] ,G. Mitani<1>, J. Walker [3]
[1] Division of Transfusion Medicine, Immunology and Infectious Disease Diagnostics, Los Angeles County University of Southern California Medical Center; [2] Research and Development Department, International Technidyne Corp.; [3] Blood Bank, Morristown Memorial Hospital
ABSTRACT
Background: Blood collection tubes containing clot-promoting reagents are used in clinical chemistry laboratories to clot anticoagulated blood samples rapidly. The utility of a clot promoting "cocktail" consisting of thrombin, snake venom, and protamine (SuperSerum¨; ITC) in obtaining serum samples for blood banking applications was examined.
Study design and methods: This study was performed in two phases at two sites. Study 1 used both fresh and heparinized samples from normal individuals; study 2 used normal donor samples and samples from patients on anticoagulant therapy. In both studies, duplicate samples from all individuals were collected, one in a red-top (plain glass) evacuated blood collection tube and the second in a tube containing SuperSerum¨. Each sample was tested for ABO, Rh, and unexpected alloantibodies. At one site, samples were cross-matched with an ABO/Rh-matched donor and retested after storage.
Results: SuperSerum¨-treated samples and those collected in red-top tubes yielded equivalent results when tested within 24 hours of sample collection, with the exception of two samples containing low levels of alloantibodies. In one of these cases, the SuperSerum¨-treated sample showed W+ reactivity, while the red-top tube sample was nonreactive. In the second case, the opposite was observed--only the red-top tube sample showed W+ reactivity. After three days' storage at 4ˇC, SuperSerum¨-treated samples from both normal donors and warfarin-treated patients exhibited varying degrees of hemolysis and decreased strength of agglutination in some ABO serum grouping and Rh typing reactions; these changes were most pronounced after 10 days of storage.