Discussion
Resuscitation of hemorrhagic shock requires uncrossmatched PRBCs to be readily available. Need for uncrossmatched transfusion in the ED is one of the strongest predictors of the need for massive transfusion in trauma.1 12 13 Our institution’s rate of massive transfusion following uncrossmatched blood transfusion from our ED refrigerator was 23.4%, which is slightly lower than the published rate of 30% by Inaba et
al.1
Overall, patients who received blood from the ED refrigerator had a 24-hour mortality rate of 26.6%, confirming that as a cohort they are at significantly increased risk of early death. However, patients needing two units or less in the first 24 hours were less likely to have a clinical picture of shock as demonstrated by a higher mean SBP. Their mean HR was lower but did not reach statistical significance, correlating with other studies that have shown that blood pressure is more predictive than HR for the need for massive transfusion.5 14 15 A lower base deficit and a higher hematocrit were also observed, but are not clinically relevant, as these lab values would not be available immediately during resuscitation.
Because early initiation of the MTP is critical to reducing mortality in hemorrhage, uncrossmatched PRBC transfusion should prompt activation of the MTP. Therefore, the criteria used during the study period for ED refrigerator use (table 5) were the same as for activating our MTP, which included 14 different clinical and laboratory criteria. Protocols requiring weighing of variables, calculation of scores such as ISS, and dependence of laboratory values can lead to variability in MTP activation among providers.2 16 17 This was also demonstrated in our study, as only one-third of the patients in the ≤2 units group who met the MTP criteria had it activated. Significantly more patients in the >2 units group had the MTP activated, but still barely over half (59%). This would suggest that providers were activating the MTP based on their own clinical judgment, not the established activation criteria.
Therefore, we reviewed the clinical scenarios of the 29 patients in the ≤2 units group, and concluded that uncrossmatched PRBC transfusion was clinically indicated in 19 (65.5%) of those cases. We made several observations regarding the patients in this group. Of the 19, 17 had “stable” initial vital signs that became unstable, meeting either the HR or SBP criteria for the ABC Score. Three of those 17 met both. There were four positive FASTs, as well as four negative FASTs that had hemoperitoneum on CT scan requiring emergent operative management. There were also two patients with pelvic fractures, one with large hemothorax, one with a postoperative arterial bleed from a surgical site, and one with a penetrating neck injury with arterial bleed. Finally, there were two patients found to have a shock other than hemorrhagic (a blunt trauma patient with neurogenic shock and a cirrhotic with a GI bleed in septic shock).
Ten patients were determined to have received an uncrossmatched transfusion not clinically indicated. These included three blunt trauma victims with hypotension, but who had an HR <120 and no source of bleeding identified on initial assessment; two patients were transfused with uncrossmatched PRBCs to correct medical anemia; one blunt trauma patient had reported prehospital hypotension but a normal blood pressure on arrival; one patient had a gunshot wound to the abdomen with stable vital signs; one blunt trauma victim had an ascending aortic pseudoaneurysm with normal vital signs managed non-operatively; in the final instance, the obstetrician-gynecologist service used uncrossmatched refrigerator units for surgical bleeding during a cesarean section performed in the resuscitation bay for non-trauma-related fetal distress.
Since the study period, our institution has changed to the ABC Score for MTP activation as well as for uncrossmatched blood use. The ABC Score is easier to use due to it having fewer variables (4), all of which can be assessed within minutes of patient arrival.2 Only 6 of the 18 patients in the ≤2 units group who met our institutional MTP criteria were ABC-positive, suggesting that had the ABC Score been implemented during the study period, less MTPs may have been called and less uncrossmatched blood may have been transfused.
Inappropriate transfusion was associated with a significant traumatic mechanism but absence of shock, and shock in non-trauma patients. Other forms of shock, such as sepsis, are more likely than hemorrhagic shock in the non-trauma population, and therefore use of uncrossmatched transfusion in the non-trauma population should be limited. However, it is important to note that there are non-trauma cases in which uncrossmatched transfusion in the ED is appropriate: in this study, six patients with AAAs and six patients with GI bleeds received blood from the ED refrigerator. Four (66.7%) of the six ruptured AAAs and two (33.3%) of the GI bleeds died within 24 hours.
Ultimately, good clinical judgment is required for appropriate use of uncrossmatched PRBCs stored in the ED and subsequent MTP activation. Patients should have evidence of ongoing non-compressible hemorrhage and evidence of shock. The ABC Score can guide this decision-making; however, it has only been validated to predict massive transfusion in trauma2 and is limited in some cases of blunt trauma and all non-trauma, limiting its usefulness as institution-wide MTP activation criteria. At our institution, the ABC Score can be expanded to include significant hemoperitoneum not found with FAST, hemothorax, pelvic fracture, ruptured AAAs, and massive GI bleeds.
This study is limited due to its retrospective nature. There is no standard definition for what constitutes an inappropriate transfusion of uncrossmatched blood. Use of our definition (two or less units of RBCs transfused in 24 hours) resulted in a study group that was large enough to detect major differences, but was not large enough to determine possible risk factors for inappropriate uncrossmatched transfusion through statistical analysis. It is impossible to tell what percentage of these patients would have received an uncrossmatched transfusion in the absence of an ED refrigerator. Also, massive transfusion definitions have changed over time and use of other definitions would potentially change the comparisons. Furthermore, the data set obtained only collected initial vital signs and did not allow for the identification of patients who presented with normal vital signs, but were transient responders. Finally, our case review of the possibly inappropriately transfused patients is subjective and is limited by the quality of the available documentation.
In conclusion, an ED blood refrigerator is an effective way to provide easily available uncrossmatched blood for resuscitation of hemorrhagic shock. Receiving uncrossmatched blood from the ED refrigerator is associated with a high rate of early mortality. However, its accessibility could result in some instances of unnecessary use of uncrossmatched blood, which was unusual in this study (6.3%). Clinicians should use objective criteria when possible, but good clinical judgment remains essential. Patients who receive ED refrigerator blood and who require no more than two units in 24 hours do not necessarily represent cases of inappropriate use, but warrant review as part of blood bank quality assurance.