From Transfusion Is the 30-minute rule still applicable in the 21st century?Donny Dumani MD, MS, Dennis Goldfinger MD and Alyssa Ziman MDArticle first published online: 10 JUN 2013 DOI: 10.1111/trf.12220 © 2013 American Association of Blood Banks Issue TransfusionVolume 53, Issue 6, pages 1150–1152, June 2013 This is a little long for a forum but... Many blood bankers have questioned the validity of the 30-minute rule for reissuing blood, and the possibility of lengthening the exposure period for red blood cell (RBC) units to be out of refrigerated temperature storage and subsequently returned to inventory. The current hesitation is that extending this rule could compromise the quality and safety of the units. In the current issue of TRANSFUSION, Thomas and colleagues take a fresh look at the impact of RBC quality after repeated exposures up to 60 minutes. This study provides a strong case to finally acknowledge that the 30-minute rule is outdated, allowing consideration to a 60-minute cutoff with no impact on RBC quality. To address this issue, we must understand the origins of the 30-minute rule. It gained notoriety following a publication by Pick and Fabijanic in 1971, who incorporated findings from two earlier studies that illustrated the importance of maintaining “optimal” storage temperatures to prevent deleterious effects to RBCs.[3, 4] In the Pick study, temperature changes of whole blood units stored in ACD preservative solution were monitored at 15-minute intervals. It was shown with subsequent incubation at room temperature that both the surface and the core temperatures of these units exceeded 10°C after approximately 30 and 60 minutes, respectively. Based on these findings, Pick and Fabijanic concluded that to maintain RBC viability (as defined by Hughes-Jones and Matthes et al.) at room temperature, a period not to exceed 30 minutes outside 4°C −10°C was necessary. However, the study did not report any outcome results regarding the quality of RBCs, nor did it provide any data regarding bacterial proliferation. Additionally, the whole blood units studied are not equivalent to present-day RBC products, given current collection and storage practices (i.e., using RBC concentrates with CPDA or CPD with additive solution [AS]). A review by Brunskill and coworkers further highlighted significant discrepancies in these published studies. As stated above, Hughes-Jones used 10- to 15-mL aliquots of RBCs stored in ACD at temperatures up to 10°C for 34 days and demonstrated that the viability of RBCs diminished significantly when stored at 10°C for these extended periods of time. Brunskill and colleagues argued that exposure of such small volumes to temperature changes cannot be considered equivalent to the larger transfusion-sized RBC units, as it is well known that smaller samples warm more quickly. In addition, using different anticoagulants, such as ACD versus CPDA, is also known to influence adenosine triphosphate (ATP) maintenance, and hence the viability of the RBCs during longer storage periods. These same authors also identified five studies[6-10] from 1987 to 2010 that reported on the outcome of blood products exposed to various temperatures in relation to the 30-minute rule. Of those five studies, only two reported data on variables of RBC quality, which included the rate of hemolysis (n = 2), ATP concentration (n = 2), and/or in vivo RBC recovery (n = 1).[6, 7] They argued that although these two studies utilized current collection practices (RBCs with CPD with AS), the conclusions that could be drawn from these publications were limited due to small or undefined sample volumes. The remaining three studies[8-10] illustrated data involving the rate of warming, but without reporting any effect on RBC quality or bacterial proliferation. In comparison to the previously published studies, Thomas and associates conducted an extensive study to resolve these limitations and investigate whether the in vitro quality of RBCs is adversely affected by 30- and/or 60-minute exposures to extreme ambient temperatures of 30°C. The study design included ABO/D-matched, leukoreduced RBCs stored in CPD and SAGM preservative solution that were pooled into a transfer bag and then split into adult-sized (300 mL) or pediatric-sized (65 mL) units. Units were exposed to various temperature fluctuations to mimic the transport, issue, and return processes and the duration of a transfusion episode. In vitro assessments included hemolysis, supernatant potassium levels, and ATP and glucose levels. Their findings indicate that these variables were stable following a pattern typical of a unit with no exposures, despite multiple temperature deviations up to 30°C. Furthermore, these variables did not show any significant differences for in vitro assessment of potassium and glucose and were within acceptable limits for hemolysis and ATP up to Storage Day 35 specifically for units with three or fewer 60-minute exposures. These findings demonstrate that the 30-minute rule is unnecessarily restrictive even under the extreme conditions reported by the authors and provide the catalyst to move forward with a new rule, which still provides a safe and viable RBC component for transfusion. Finally, the authors comment that additional studies may be required to investigate temperature fluctuations on bacterial growth. We would argue that these studies are not necessary. First, several published reports[11-13] showed no difference in bacterial growth between Gram-negative and/or Gram-positive bacterially inoculated RBC units exposed to room temperature for at least 2 hours versus those that remained in refrigerated storage. Second, the effect of temperature relative to the type of bacterial contaminant must be considered. The most common contaminants, which are Gram-positive skin flora, do not survive in refrigerated blood, and therefore most units containing these bacteria have a tendency to self-sterilize.[14-16] While Gram-negative contaminants, psychrophilic bacteria (such as Yersinia enterocolitica, Pseudomonas sp., and Serratia liquefaciens) can escape this bactericidal action under refrigerated storage conditions, it has been reported that such bacteria do not undergo accelerated proliferation or reach clinically significant levels after at least 2 hours of room temperature exposure.[11, 12, 15, 17] This aspect of psychrophilic organisms was recently validated by Ramirez-Arcos and colleagues who demonstrated no difference in growth or endotoxin production between psychrophilic-contaminated RBC units exposed to room temperature multiple times for 30- versus 60-minute periods. Finally, the current risk of transfusion-transmitted sepsis secondary to bacteria in RBC units is extremely low. In the most recent report by the Food and Drug Administration, there were no cases of transfusion fatalities secondary to bacterially contaminated RBC units between 2007 and 2011. The decreasing trend of bacterial contamination could be partly explained by the adoption of several strategies to prevent such a catastrophic event including improved blood donor screening, donor skin preparation and disinfection, initial aliquot diversion, and leukoreduction. Based on the aforementioned studies and statistics, extending the rule to 60 minutes would not increase the incidence of bacterially contaminated RBC units in inventory. In conclusion, the 30-minute rule is based on old observations that are no longer valid in today's practice. For the past 20 years, many have attempted to address this issue without much resounding success, but several experts have recognized that the rule is weak and unnecessarily burdensome. Thomas and coworkers present compelling data showing no detriment to increasing this time period and therefore provide a strong argument to change the rule without compromising the viability of the RBCs. Blood bankers are obligated to ensure not only the quality and safety of blood units, especially when considering a significant change in our guidelines of reissuance, but are also charged with the responsibility of conserving a scarce resource. Unnecessary wastage should not occur based on an obsolete rule that is not relevant to current practice. With the growing concerns of costs involved in acquiring and maintaining a safe and sufficient RBC inventory, adopting the 60-minute rule is simply the right decision for the 21st century.