Editor: Deborah Sesok-Pizzini, MD, MBA, adjunct professor, Department of Clinical Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia.
Use of low titer O whole blood in infants and young children undergoing cardiopulmonary bypass
February 2025—Low titer group O whole blood is commonly used for severe bleeding in trauma patients. It may also benefit pediatric patients undergoing cardiopulmonary bypass who are at risk for massive bleeding and coagulopathies. Circuit anticoagulation, hypothermia, hemodilution, coagulation factor, platelet loss and dysfunction, an underdeveloped hemostasis system in patients younger than two years old, and other factors lead to a higher risk of bleeding. Compared with component therapy, whole blood contains higher concentrations of RBCs, platelets, and coagulation factors, as well as cold platelets with enhanced hemostatic function. Due to the logistical challenges of donor centers providing ABO-specific whole blood for cardiopulmonary bypass (CPB), the use of longer storage-age low titer group O whole blood (LTOWB) may be an option for younger pediatric patients with severe bleeding on CPB. The authors conducted a study to review their institution’s experience with LTOWB in neonates, infants, and children younger than two years old undergoing CPB. They hypothesized that using LTOWB would reduce blood product transfusion without increasing adverse events. The authors performed a retrospective study in children younger than two years old who underwent cardiac surgery with CPB. They compared pediatric patients who received component therapy (CT) with those who received LTOWB plus CT (LTOWB + CT). They also conducted a subset analysis to compare outcomes in group O versus blood group non-O recipients. The outcome measures were drainage tube output and total transfusion volume. The authors used optimization-based weighting for adjusted analyses between groups. A total of 117 patients were transfused with CT and 127 with LTOWB + CT. In the LTOWB + CT group, 66 were group non-O and 61 were group O. The transfusion volume from the start of the operation until the first 24 hours in the cardiac intensive care unit was a median (interquartile range [IQR]) of 41 (10–93) mL/kg in the CT group and 48 (28–77) mL/kg in the LTOWB + CT group (p=.28). The median (IQR) drainage tube output was 22 (15–32) mL/kg in the CT group and 22 (16–28) mL/kg in the LTOWB + CT group (p=.70). Of importance, no differences were noted in rates of death, renal failure, and a composite of death and renal failure between the two groups. However, statistically fewer re-explorations for bleeding occurred in the LTOWB + CT group (p<.001). The authors concluded that use of LTOWB appears to be safe in children younger than two years old undergoing cardiac surgery. It may even reduce re-explorations for severe bleeding. However, the authors noted that large trials are needed to determine the efficacy and safety of LTOWB in these pediatric patients.
Griselli M, Said SM, Spinella PC, et al. Use of low titer O whole blood in infants and young children undergoing cardiac surgery with cardiopulmonary bypass. Transfusion. 2024;64:2075–2085.
Correspondence: Dr. Marie E. Steiner at stein083@umn.edu
Laboratorian interpretation of drug testing results in pain management
Drug testing is important in several settings, including managing patients with chronic pain who are using prescribed controlled substances like opioids or benzodiazepines. It can be challenging to interpret drug testing results, however, due to immunoassays generating false-positive or false-negative results. Literature demonstrates the clinical utility of drug testing in pain management, but there is little consensus between clinical guidelines on how best to perform drug testing, including which methodology (presumptive/screening versus definitive/confirmation) to use, how often to sample, and which drugs to include. The implications from drug test results can be serious in terms of ensuring compliance with drug dosage, timing, and route of administration, and for demonstrating the absence of nonprescribed drugs that could indicate a substance use disorder. The 2018 AACC (now Association for Diagnostics and Laboratory Medicine) laboratory medicine practice guideline for drug monitoring in pain management strongly recommends that clinicians contact the laboratory regarding any test result that is inconsistent with the clinical picture or use of prescribed medications. The authors conducted a study to evaluate participating laboratories’ performance in the College of American Pathologists’ Drug Monitoring for Pain Management (DMPM) proficiency testing program. They claim that the DMPM interpretive, or “dry,” challenges provide a unique opportunity to evaluate laboratories’ expertise in interpreting drug testing. The dry challenges include testing for opioids, benzodiazepines, and other therapeutic drugs that would require compliance monitoring. The authors analyzed all dry drug testing challenges (n=23) from 2012 to 2023. The challenges required that reviewers identify whether drug test results were consistent or inconsistent with prescribed medications in the patient’s history. The case studies were adapted from de-identified patient scenarios, so a variety of medications and test results were included in the challenges. Following the review, all relevant medications, presumptive and confirmatory test results, and participant responses were extracted from program summary reports. These data were examined to assess participant performance and find common themes. The study results showed that 91.8 percent (6,821 of 7,431) of participant responses noted whether drug testing was consistent with patient medications. Participant scores of less than 91.8 percent (range, 59.8–88.9 percent) were found in only eight of the challenges. The common knowledge gaps identified for labs providing drug test interpretation in pain management involved false-positive screens, minor opiate metabolism, and noncompliance indicated by the presence of nonprescribed and prescribed drugs. Although some participants repeatedly responded incorrectly, no associations between laboratory type, personnel responding, analytical performance, or incorrect responses to interpretative challenges were found. The authors concluded that the program participants performed well overall, but several educational gaps exist. Therefore, ongoing education is necessary to ensure competence in the areas of medication compliance and pain management and to enable the laboratory to be an even more valuable resource for drug test interpretation.
Snozek CLH, Langman LJ, Dizon A, et al. Laboratorian interpretation of drug testing results in pain management. Arch Pathol Lab Med. 2024;148:1292–1298.
Correspondence: Dr. Christine L. H. Snozek at snozek.christine@mayo.edu