Rebirth of the cool: the modern renaissance of low titer group O whole blood for treating massively bleeding civilian patients

What has been will be again, what has been done will be done again; there is nothing new under the sun. Is there anything of which one can say, “Look! This is something new”? It was here already, long ago; it was here before our time. —Ecclesiastes 1:9-10

The rationale for intervening early in the resuscitation with blood products

Traumatic hemorrhage is a leading cause of death and disability, especially in younger adults (1), and traumatic hemorrhagic shock in adults has a mortality approaching 20% at 24 hours post-injury (2). More than half of civilian preventable prehospital deaths are due to hemorrhage (3), and approximately 85% of the 30,000 preventable deaths that occur every year in the US happen before the patient arrives at the hospital (4,5). A massively bleeding patient should be resuscitated with fluids that closely resemble what they are bleeding in order to maintain tissue oxygenation and promote hemostasis. However, for many years, resuscitation protocols focused on the early and aggressive use of crystalloids, such as normal saline, because they were inexpensive, easily transported at room temperature in resilient plastic bags, and did not carry with them the infectious and non-infectious risks of transfusing human blood products (6). It was thought that if the patient’s hemodynamics could be maintained using crystalloids then the large physiologic reserve of hemoglobin in red blood cells (RBCs) and clotting factors in plasma and the extravascular space would reach their respective tissue destinations and perform their functions (7). Guided by this dogma, liters of crystalloid fluids were routinely transfused to massively bleeding patients, as neither the acidic nature of normal saline nor the potentially beneficial effects of permissive hypotension had yet been appreciated (8-10).

Several studies have highlighted the disadvantages of overzealous crystalloid resuscitation in trauma compared to resuscitation strategies using early intervention with blood products (11-15). Perhaps the most influential study supporting this notion was that of Bickell et al. (16). In this study, hypotensive patients with gunshot or stab wounds to the torso were randomized to receive crystalloid therapy during transport to the hospital and while at the hospital but before their surgery (early) or to only receive fluids during their surgical procedure (delayed). There was an 8% reduction in mortality in the delayed group compared to the early fluid resuscitation group, and the delayed group also had a significantly shorter average hospital length of stay, without an increase in postoperative complications (16).

Building on these data, and supporting the early intervention with blood products instead of crystalloid in traumatically injured patients, a study of 502 military combat casualties demonstrated that the provision of primarily RBCs within approximately 30 minutes of injury improved both 24-hour and 30-day survival compared to patients who did not receive any blood products or who received them later in the resuscitation (17). In the multicenter Prehospital Air Medical Plasma (PAMPER) trial, civilian trauma patients, whose median helicopter transport time to the hospital was approximately 40 minutes, were randomized to receive two units of plasma in addition to the standard of care treatment while en route to the hospital. This study found that 30-day mortality was improved compared to patients who received the pre-hospital standard of care, which in many cases was crystalloid fluid only (18). In a secondary analysis of this trial, the greatest survival benefit was demonstrated amongst those who received RBCs and plasma compared to those who received plasma alone (19). In fact, receipt of any blood product during pre-hospital resuscitation yielded a significantly improved 30-day survival rate compared to patients who received crystalloids alone. Additionally, compared to those who received any blood products during the helicopter transport, each liter of crystalloid that was administered was associated with a 65% increase in 30-day mortality. Interestingly, other secondary analyses of the PAMPER trial demonstrated that the greatest mortality reduction following the administration of pre-hospital occurred in patients who suffered from blunt injuries (20), who required >20 minutes to arrive at the hospital (21), and who had traumatic brain injury (22). A second randomized controlled trial that investigated the survival effects of pre-hospital plasma administration in civilian trauma patients has also been reported (23). Known as the Control Of Major Bleeding After Trauma trial (COMBAT), it did not find a survival benefit following pre-hospital plasma administration although there were significant differences between the PAMPER and COMBAT studies in terms of the patients’ severities of injuries, the transport time to the hospital, and the amount of pre-hospital plasma administered. Other military and civilian studies have also underscored the importance of the prompt resuscitation of injured patients with blood products (24-27), although additional randomized trials are needed to determine the efficacy of the pre-hospital use of other products such as RBCs and LTOWB (28).

The story of LTOWB—an important rediscovery of an old idea

Although coming from the same source, not all blood products are created equally. While it might seem reasonable to assume that transfusing a unit of RBCs, plasma, and whole blood derived platelets (PLTs) would be functionally and volumetrically equivalent to transfusing a unit of whole blood, there are major differences between these products (29). Table 1 demonstrates the quantities of anticoagulant-preservative and additive solutions (AS) that are added to different blood components. For example, if a patient receives a massive transfusion of 10 units each of RBCs, plasma and whole blood derived PLTs, an estimated 1,800 mL of citrate, phosphate, and dextrose (CPD) solution and AS would be infused along with the blood components themselves. This extra fluid does not carry oxygen nor does it promote hemostasis. By contrast, a resuscitation using 10 units of whole blood would infuse only 700 mL of CPD, which represents the least amount of extraneous fluid that can be administered in such a resuscitation. This extra CPD and AS fluid can be significant: a computer simulation of a 20-unit massive transfusion event demonstrated that when whole blood was used starting in the pre-hospital phase of the resuscitation and continued until the bleeding was controlled in the operating room, the patient’s total extracellular fluid compartment was nearly one liter smaller than if conventional components had been utilized (29,30). Avoiding increased extracellular fluid is essential in critically ill patients since it increases the risk of acute respiratory distress syndrome (ARDS) and organ failure related to anasarca (31). LTOWB also simplifies the logistics of the resuscitation as all three components are contained in one bag instead of three. This simplification also allows for the provision of balanced resuscitation as soon as the transfusion begins: in a study of pediatric trauma patients, it was found that the time to receipt of a single unit of RBCs, plasma, and platelets was significantly shorter when LTOWB was used compared to component therapy despite the availability of a massive transfusion protocol (MTP) that contained all three conventional components at this hospital (32).

Whole blood units also contain PLTs if prepared using a platelet-sparing leukoreduction (LR) filter, or if the WB is not leukoreduced at all. There have been concerns about the detrimental effects of cold storage on the PLTs in whole blood, since cold-stored PLTs are cleared from circulation much more quickly than conventional room temperature stored PLTs due to changes in the sialyation of certain membrane receptors (33). However, these cold stored PLTs demonstrate superior in vitro hemostatic properties compared to room temperature PLTs (34-36), suggesting that they might be primed to promote coagulation once transfused. Unlike hematology/oncology patients who require prolonged hemostasis over several days to prevent spontaneous bleeding, a massively bleeding patient needs short term hemostatic support until the bleeding can be permanently controlled during surgery and the few hours that the cold-stored PLTs from whole blood circulate should be enough to provide hemostasis for a patient experiencing an acute massive bleed (see below) (37). In addition, several studies have hinted at the in vivo superiority of cold-stored PLTs compared to room temperature PLTs (38-40), but this assertion awaits definitive clinical confirmation in the trauma or massively bleeding patient populations. Furthermore, the aforementioned computer simulation of a massive transfusion event indicated that the exclusive use of whole blood during the resuscitation facilitates a higher and more consistent PLT count in the recipient, avoiding the peaks and troughs that are associated with transfusing PLTs in a goal-directed manner, that is, based on conventional laboratory testing such as a PLT concentration determination (29).

Table 2 lists many of the advantages of transfusing whole blood compared to conventional components.

Whole blood collection, manufacturing and storage practices

Previously, the AABB (formerly known as the American Association of Blood Banks) Standards for blood banks and transfusion services required that WB had to be ABO-identical with the recipient. This Standard greatly limited the use of WB in massive bleeding patients, as early in the resuscitation the ABO group of many such recipients is not known, yet their need for blood products can be high (41). However, starting with the 31^st edition of the Standards in 2018, the RBC part of the WB only had to be ABO-compatible with the recipient (42). Effectively, a unit of WB must be group O in order to be safely transfused to any recipient whose ABO group might not be known at the time of the transfusion (43). However, group O WB necessarily contains anti-A and anti-B in its approximately 250 mL plasma part, which will be incompatible with all non-group O recipients. Therefore, another section of the Standard for transfusing WB in a potentially plasma-incompatible manner involves mitigating the risk of hemolysis caused by the anti-A and anti-B that are present in all group O WB units. Hemolysis risk mitigation comes in two parts: the transfusing hospital must have a policy on what antibody threshold constitutes a low titer, and the hospital must determine the number of LTOWB units that each patient can receive (44,45).

Antibody titers

A group O WB unit that that has anti-A and -B titers below the hospital’s threshold is known as a LTOWB unit. The AABB Standard that governs LTOWB administration does not specify what constitutes a low titer (46), so how a hospital determines their titer threshold is based on their tolerance of risk and the blood center’s ability to supply these units. Several surveys have demonstrated that the titer thresholds for LTOWB in the USA ranged from <50 to <256 (47-49). A more recent survey of American Level 1 trauma centers found that the most common titer threshold was <200 (50). It is likely that any titer <256 will be safe in these bleeding patients based on the experience of transfusing ABO minor-incompatible PLTs (51), and of using LTOWB itself (see below) (52).

It is important to note that there are several methods for performing antibody titers, and the method selection is determined by the needs and capabilities of each hospital or blood bank; the AABB Standard does not specify which titer method should be utilized. A multicenter study compared how well different methods for performing one-dilution anti-A and -B titers compared to a reference method of incubating the plasma/reagent RBC mixture at room temperature for an hour without agglutination enhancement solutions (53). Anti-human globulin (AHG) was not utilized in any of these experiments. In this study, the manual tube, manual and automated buffered gel cards, and automated microplate methods demonstrated ≥90% accuracy compared to the reference method suggesting that these were all suitable methods for performing a one-dilution titer. Similarly, a different study of the anti-A titer in group O plasma from 34 individuals found that the there was a high degree of correlation between the titers detected by the manual gel card and automated solid phase methods, but that the manual method consistently produced higher titer values for both the IgM and IgG titers (54). Therefore, it is important to be aware of the method that was used to perform the titers when comparing results between studies and when selecting a method for use in a hospital or blood bank.

The serological safety of transfusing ABO minor-incompatible plasma was demonstrated in the safety of the use of group A plasma in trauma (STAT) study (55). This study found no differences in a variety of mortality outcomes, and also the length of hospital stay between group A recipients of group A plasma during their trauma resuscitation compared with group B and AB recipients of group A plasma. A larger retrospective study in bleeding trauma patients also demonstrated similar findings (56); to be included in this trial, adult trauma patients had to have received at least one RBC and at least one plasma-containing product, or a unit of LTOWB, during their first 24 hours of hospitalization, as well having had a type and screen performed during this admission to determine their ABO group. In this study, outcomes amongst 1,282 injured patients who received any incompatible plasma were compared to those amongst 1,336 trauma patients who received only ABO-compatible plasma during their resuscitation. The main finding was that receipt of a median (5^th–95^th percentile) of 342 [40–2,003] mL of incompatible plasma did not lead to higher 6- or 24-hour mortality, or 30-day mortality compared to recipients of ABO-identical or compatible plasma.

From a laboratory perspective, several reports of transfusing LTOWB to adult civilian trauma casualties have not found evidence of hemolysis amongst the non-group O recipients, who are potentially at risk of hemolysis from the anti-A and -B in an LTOWB unit, compared to the group O recipients whose RBCs are not at risk of hemolysis from receipt of LTOWB (57-60). There was also no indication of hemolysis amongst the non-group O pediatric trauma recipients of LTOWB compared to the group O LTOWB recipients (61). These findings are consistent with the few reports of hemolysis following the transfusion of minor-incompatible platelets (51). It should be noted from these and other studies that the biochemical markers of hemolysis, when measured in injured patients receiving massive transfusions, tend to be perturbed in the same manner as a patient who is experiencing immune hemolysis such as during an acute hemolytic transfusion due to the administration of ABO-incompatible plasma (62,63). This fact confounds the laboratory identification of hemolysis and clinical correlation with the changes observed in these biochemical markers is required.

Hospital policy specifying the maximum quantity of LTOWB units per patient

The new AABB Standard also requires each hospital to determine how many units of LTOWB each patient can receive per transfusion episode to mitigate the risk of hemolysis. Note that a policy that does not specify a maximum number of LTOWB units that a patient can receive would be compliant with the Standard, as long as the policy was clear that the hospital does not desire to limit the number of LTOWB units that each patient can receive. For example, a recent case report detailed the transfusion of 38 units of LTOWB to an injured recipient at a hospital where their policy does not specify the maximum number of LTOWB units per patient, and their inventory consists of up to 40 units of LTOWB (64).

Other safety considerations for LTOWB

As an entire unit of plasma is transfused with each LTOWB unit, any transfusion related acute lung injury (TRALI) risk mitigation strategies that a blood center employs for conventional plasma or apheresis PLT units should also be employed when selecting LTOWB donors. Typically these strategies involve collecting LTOWB units from females without a pregnancy history or those who have been tested and found not to have become HLA-sensitized, or from male donors who naturally have a low risk of HLA alloimmunization because the main etiology of HLA sensitization is pregnancy (65,66). The question of how frequently to titer each donor has also not been answered. In two studies of healthy Danish volunteers and dialysis patients, the anti-A and -B titers did not fluctuate significantly when measured in each individual every three months over the course of a year (67,68). Similarly, in a multicenter trial, periodicity of high titer donors was not observed over a 2-year time frame suggesting that seasonal variation in titer levels does not occur (69), although some seasonable variability (i.e., both increases and decreases in titer levels) was detected in US Army Rangers over an approximately 20-month period (70). There was also a report of a very large change in the anti-B titer of a group A platelet donor that resulted in hemolytic two reactions when they were transfused to group B recipients, and the increase was linked to probiotic dietary supplements (71). Thus, the decision as to how frequently to titer the antibodies in each donor should be determined locally.

Other considerations for selecting LTOWB donors include whether the donor should be RhD-positive or D-negative; this is a controversial issue and once again the decision requires a balance between the transfusing center’s tolerance of the risk of RhD alloimmunization amongst RhD-negative recipients of RhD-positive LTOWB versus the blood center’s ability to supply RhD-negative LTOWB units that also meet all of the other qualifying criteria (43). Some organizations, such as the Israeli Air Force’s search and rescue unit 669 (72), the Texas Ranger special operations group (73), and the city of San Antonio, Texas, USA and some of its surrounding areas (74), can provide RhD-positive LTOWB to eligible trauma patients regardless of their gender and age (as long as the recipient is ≥5 years old in San Antonio). This practice is supported by a review of MTP activations at a San Antonio trauma hospital: of the 124 MTP activations over a 30 month period, there was only one woman of childbearing age who underwent pre-transfusion testing and was found to be RhD-negative (75). Similarly, the two adult Level 1 trauma centers of the University of Pittsburgh Medical Center (UPMC) in Pittsburgh, Pennsylvania, USA provide RhD-positive LTOWB to injured male and female patients who are ≥18 years old. In a computer simulation of 100 years of trauma patients based on data from a Level 1 UPMC hospital, it was calculated that the overall rate of hemolytic disease of the fetus and newborn (HDFN) would be 1.2 cases per 100 RhD-negative females of childbearing potential who were transfused with RhD-positive RBCs or LTOWB (76). The exception to this policy is at the Children’s Hospital of Pittsburgh of UPMC in Pittsburgh where RhD-negative LTOWB is provided to all traumatically injured boys and girls who are ≥1 year old (children who are <1 year old are resuscitated using conventional components at this center). In a survey of American adult Level 1 trauma centers, 51% of the respondents indicated that they would administer RhD-positive LTOWB to females of childbearing age of unknown or negative RhD-type during her trauma resuscitation (50). In contrast, a survey of some of the largest children’s specialty hospitals in the US found that only 20% of transfusion service directors and 37.5% of trauma service directors would be willing to transfuse RhD-negative girls with RhD-positive LTOWB in the setting of a clinical trial of blood resuscitation strategies in trauma (77). Further details of other American and international LTOWB programs can be found elsewhere (47-49).

Ideally, all females of childbearing potential whose RhD type is unknown should receive RhD-negative cellular blood products until they are shown to be RhD-positive. Unfortunately, only approximately 8% of the US donor population is O RhD-negative (78). Thus, finding qualified donors who have low antibody titers, are not HLA alloimmunized, and are blood group O RhD-negative is very difficult. As alluded to above, the calculus on whether to provide RhD-positive LTOWB (or RhD-positive uncrossmatched RBCs for that matter) for patients of unknown RhD type who require urgent transfusion requires balancing a variety of parameters including the probabilities that she survives her trauma, becomes alloimmunized and pregnant with a RhD-positive fetus, and that HDFN occurs. In one model of fetal mortality from HDFN following the transfusion of RhD-positive RBCs to a female of childbearing potential during her trauma resuscitation, the risk of fetal demise was calculated to be 0.3% (79). Including other adverse outcomes such as requiring an intrauterine transfusion or neonatal exchange transfusion increases the risk to 2%. However, the age of the female at the time of her transfusion, along with other societal factors that are involved in childbearing, should also be considered as these factors tend to lead to higher risk estimates for HDFN (76). These HDFN risks must be balanced against the mortality reduction when blood products are used early in the resuscitation, especially in the pre-hospital phase of the resuscitation (17-19,24-27). Interestingly, it was recently demonstrated that the risk of RhD-alloimmunization did not increase when RhD-negative hospitalized recipients were transfused with multiple RhD-positive RBC/LTOWB units compared to the rate following the transfusion of one RhD-positive unit (80). In this study, the 335 patients received a median (5^th–95^th percentile) of 3 [1–32] RhD-positive RBCs/LTOWB units and had an overall rate of RhD-alloimmunization of 34.9%. The rate after receiving one unit was 30.6% while the rate after receipt of >20 RhD-positive units was 34.8%, and there was no significant trend in the RhD-alloimmunization rates across the ordered groups of RhD-positive primary RBC-containing products transfused. This suggests that the inciting event in RhD-alloimmunization is the first RhD-positive unit and that the patient should be maintained on RhD-positive units following the first exposure so as to preserve the inventory of RhD-negative units, although confirmation of this finding awaits a larger trial.

Leukoreduction of LTOWB units

The decision to leukocyte reduce whole blood units for transfusion should consider regulatory requirements that may differ by jurisdiction and the proven benefits of LR (lower rates of alloimmunization, febrile transfusion reactions, and cytomegalovirus transmission) against the potential detrimental effects of LR on the hemostatic potential of the stored whole blood unit. To date, the literature has not demonstrated a clear morbidity or mortality benefit of transfusing leukoreduced RBCs in the trauma setting: in two randomized controlled trials (RCTs), leukoreduced RBCs did not reduce the rate of infections, organ dysfunction, mortality or lung complications amongst transfused trauma patients (81,82), and in two retrospective studies LR also failed to improve mortality and a variety of morbidity markers such as organ dysfunction, and hospital and ICU length of stay (83,84), although in another retrospective study LR was associated with a reduction in all types of infections including nosocomial pneumonia (85). An observational, single center study of trauma patients found that the patients who received an average (SD) of 1.42 (0.57) units of non-leukoreduced LTOWB during their initial resuscitation did not have worse mortality than those who received an average (SD) of 1.68 (1.47) units of leukoreduced LTOWB (86).

In vitro data have shown mixed results when evaluating platelet function following leukoreduction, with some studies finding a significant reduction in hemostatic function as measured by thromboelastography (TEG) and thrombin generation assays, especially early during storage, compared with non-LR WB units although other markers of PLT function were unchanged following LR (87,88), while others have found relatively normal TEG tracings for up to 14 days of storage compared with units that were leukoreduced with a non-PLT sparing filter (89). Further details of PLT function in LTOWB are reviewed elsewhere (90,91).

Storage of, and wastage reduction strategies for, LTOWB units

Whole blood units collected in CPD are stored between 1 and 6 ℃ for up to 21 or 35 days (depending on the solution into which it is collected), ideally in a refrigerator in the emergency department or the trauma bay so that they are readily accessible early in the resuscitation. Units can also be stored in validated coolers for transportation in emergency vehicles (92). The keys to minimizing the wastage of whole blood are several-fold. While trauma patients are episodic and their arrival in the ED is often unpredictable other than to say that injuries are more common in certain seasons, not over collecting these units will prevent them from expiring on the shelf unused. Other systems for reducing wastage involve moving the units from relatively low usage emergency medical system helicopter and ground ambulance bases to higher usage hospitals when they approach their expiration date. The efficient use of such a system can reduce expiration to 1–2% (93,94). Another approach to reducing wastage if the LTOWB units are not maintained as such for the maximum duration possible depending on the nature of the storage solution into which it is collected (i.e., 21 or 35 days), is to remove the platelet-rich plasma from the RBCs and use the group O RBCs for patients who need only RBC transfusions. Perhaps in the future these recovered RBCs can be resuspended in AS and their shelf life extended to 42 days (95). While this approach necessarily wastes the plasma and platelets, at least the RBC can be recycled and some of the costs of producing the LTOWB unit defrayed. This recycling system has been shown to lead to wastage rates of slightly more than 10% at one large hospital transfusion system, however, given the small number of units that are actually wasted and the overall benefits of using LTOWB, this wastage is acceptable (58).

Although not specific to the transfusion of LTOWB, there is a theoretical concern that the provision of group O RBCs to patients who are subsequently shown to be non-group O might lead to an increase in the number of patients with initially uninterpretable ABO types following its administration. This concern would be the highest for pre-hospital group O RBC transfusions or those that are administered very early in the in-hospital course before a sample for a type and screen has been obtained. A multicenter retrospective study of 695 non-group O patients who received at least one uncrossmatched group O RBC before the type and screen sample was procured demonstrated that in over 95% of the patients, the patient’s ABO group could be determined in the first sample submitted following the transfusion of the uncrossmatched group O RBCs (96). Similarly, a study of trauma patients on whom the hospital’s MTP had been activated demonstrated that the number of samples in which mixed field agglutination was detected did not increase following the implementation of pre-hospital group O RBC transfusions (97). This study also found that the percentage of non-group O patients whose 24-hour RBC transfusion needs were fulfilled with >95% group O RBCs did not increase after group O RBCs became available in the MEDEVAC helicopter. Hospitals should have a policy whereby non-O ABO groups can be resolved despite the presence of mixed field agglutination.

Blood collectors might be concerned about the effect of collecting LTOWB on their inventory of conventional group O RhD-positive units. Perhaps if the group O donors are utilized for LTOWB then there could be a shortage of conventional RBC units. Luckily, this is unlikely to be the case for most blood collectors (98). A computer model of (I) Blood collector factors including the number of O RhD-positive units collected, the collection:import and the whole blood:apheresis ratios etc., (II) Hospital factors including the number of patients who receive LTOWB, the average number of LTOWB units, and the trauma seasonality etc., as well as (III) LTOWB program factors including the percentage of donors who have a high titer, the LTOWB shelf life, and the ability to recycle unused LTOWB units into RBCs etc. was performed to estimate the impact of LTOWB collections on RBC availability. After simulating over 1.2 million possible combinations of these three factors, it was determined that for almost 95% of the simulated blood collectors, the maximum increase in the number of additional O+ RBC units that blood collectors would have to import or collect through special donation campaigns as a result of implementing an LTOWB program was 2.5%. The number of LTOWB unit shortages and days of shortages were also quite small, and as the number of O RhD-positive collections increased from 20,000 per year to 160,000 per year, these parameters were further reduced. Also, the expected median number of wasted LTOWB units was predicted to be 1.0 unit. While this model was based on the experience of one large American blood collector, the results indicate that a well-considered LTOWB program can have a minimal impact on the blood collector. This model is available to use free of charge online at https://jnsanalytics.shinyapps.io/ltowb_sim_app/ so that blood collectors that are considering implementing an LTOWB program can estimate the impact of the program on their group O RBC collections using their local data.

Is transfusing LTOWB efficacious?

One of the first studies of whole blood use in the civilian trauma setting was a randomized pilot trial of leukoreduced ABO-identical WB compared to standard, fixed ratio component therapy in trauma patients (99). As the WB was leukoreduced using a filter that also removed the PLTs, for every six WB units transfused a single apheresis PLT that was stored at room temperature was also administered. The WB in this study was stored for a maximum of 5 days. In this study, there were no differences in the primary outcome, the quantity of blood products transfused in the first 24 hours, between the recipients of WB and components in both the intent to treat and per-protocol analyses. There were also no mortality differences between the groups. When patients with severe traumatic brain injury were excluded in a post hoc analysis, significantly fewer blood products were transfused to the patients in the WB group compared to the component group. However, as the WB units were PLT-depleted, it is not clear what role the WB itself might have had in reducing the number of products transfused as all of the PLTs that were transfused in both groups had been stored at room temperature.

A review of the American College of Surgeons Trauma Quality Improvement Program (TQIP) database during the calendar years of 2015 and 2016 revealed that 280 patients had received LTOWB in conjunction with conventional component therapy during their resuscitation (100). Outcomes were compared to 8,214 patients who received only component therapy. In this analysis, 95% of the LTOWB recipients received only 1 unit, yet receipt of LTOWB in the multivariate analysis was associated with significantly decreased 24-hour and in-hospital mortality, as well as significantly reduced complications such as acute kidney injury, ARDS, deep vein thrombosis/pulmonary embolism, myocardial infarction, pneumonia, sepsis etc., as well as shorter hospital length of stay.

A single-center, year-long, observational trial of administering up to four units of LTOWB versus balanced resuscitation using conventional components in 253 injured adults found no difference in survival between these two groups, although the LTOWB group received fewer RBC and plasma units (101). There were also no differences in other important clinical outcomes such as the development of venous thromboembolism, pneumonia, sepsis, ARDS, and acute kidney injury between the two groups thereby demonstrating that receipt of a median (IQR) of 2 [1–3] units of LTOWB does not predispose recipients to these adverse outcomes.

In a single center observational study of 86 injured adults, administration of a median dose of 23.6 mL/kg (approximately 3 units in a 70 kg person) LTOWB was associated with improved 24-hour and 28-day survival compared to those who were resuscitated with conventional components in an adjusted analysis (102). In a different single center analysis of 198 injured LTOWB patients who received a median of one unit either pre-hospital or early in their in-hospital course, 30-day mortality was reduced in a multivariate logistic regression compared to 152 conventional component recipients (103). In another single-center study of trauma patients, the LTOWB recipients, who received a median (IQR) of 6.5 [3–11] units, had generally similar laboratory and thromboelastogram (TEG) values from the time of their admission through the first 24 hours in the hospital compared to recipients of conventional components (104). There was also no difference in 24-hour or 30-day survival between these two groups, indicating that receipt of LTOWB did not lead to worse outcomes compared to a conventional component resuscitation strategy. This same institution also reported on the safety of transfusing nearly 40 units of LTOWB to one patient during his resuscitation from a motor vehicle accident, although the recipient in this case was group O and so would not have hemolyzed from receipt of the LTOWB (64).

In a propensity-matched study, trauma patients who received a median (IQR) of 2 [1–2] units of LTOWB did not demonstrate worse mortality or other outcome measures compared to trauma patients who received conventional components (105). In this study, there was a trend towards a faster normalization of an elevated plasma lactate amongst the LTOWB recipients, with the difference between the median normalization times of the two groups approximately 5 hours. A similar finding was also demonstrated in injured children, where the median time to the resolution of the base deficit was approximately 4 hours faster amongst the 28 children who received LTOWB compared to the 28 propensity matched children who were resuscitated using conventional components (106). An analysis using propensity score matching and coarsened exact matching between adult trauma recipients of a median (5^th to 95^th percentiles) of 4 [3–8] LTOWB units compared to those resuscitated using conventional components did not reveal statistically significant differences in 6-, 24-hour mortality or 30-day mortality between groups, nor were there differences in the frequency of other clinical outcomes such as acute kidney injury, sepsis, venous/arterial thromboembolism; in fact, the delta multiorgan dysfunction score (MODS) was significantly lower for the LTOWB recipients in the exact match group compared to the conventional components group (107). There have also been several case reports describing the use of LTOWB in specific conditions (64,108-110).

A study of the thromboelastogram tracings of pediatric trauma patients did not find a statistically significance difference in the maximum amplitude (MA) between patients who received only LTOWB compared to those who received only conventional warm stored PLTs, but clinical outcomes were not measured in this study (111). In a study of 220 trauma patients who received at least one unit of non-leukoreduced LTOWB in the pre-hospital phase of the resuscitation, the patients who received LTOWB that had been stored for ≤14 days had some significantly improved TEG parameters in a univariate analysis compared to those who received LTOWB that had been stored for >14 days (112). Receipt of shorter stored LTOWB was not a predictor of alpha-angle <60° or maximum amplitude <55 mm in multivariate analysis, the number of blood products transfused in the ED and after the ED was not different based on the storage duration of the LTOWB, and there was not a significant difference in mortality between these two groups. In addition, the use of a rapid blood infuser did not affect the platelet function in LTOWB in terms of aggregometry and TEG parameters (113), which was consistent with the results of an earlier study on the topic (114). In addition, the thrombin generation parameters were actually improved after passing through the rapid infuser, although the platelet count was reduced at higher settings of the rapid infuser (113).

LTOWB has also been used in massive bleeding settings other than trauma, such as post-partum hemorrhage (115-117).

Prospective RCTs comparing the use of LTOWB to conventional component therapy in massively bleeding trauma patients are currently underway. One trial is a single center pilot study of LTOWB transfusion to traumatically injured patients who are transported to the hospital by helicopter, entitled the Pragmatic Prehospital Group O Whole Blood Early Resuscitation Trial (PPOWER; clinicaltrials.gov identifier: NCT03477006). This American trial’s primary outcome is 28-day all-cause mortality in patients who receive two units of LTOWB in the pre-hospital setting along with up to four more LTOWB units once the patient arrives at the hospital versus those who receive that standard of care for pre-hospital resuscitation followed by fixed ratio blood component resuscitation in the hospital. The results of this trial are expected in late 2021.

Another RCT that is in the advanced stage of planning is the STORHM trial (Sang Total pour la Réanimation des Hémorragies Massives), which will employ a non-inferiority design to compare LTOWB to conventional blood components transfused in a 1:1:1 ratio in severely bleeding trauma patients (118). The primary endpoint will be a thromboelastographic parameter (maximum amplitude, MA) assessed at the sixthhour after admission. Secondary endpoints will include early and overall mortality, lactate clearance (a reflection of the effectiveness of resuscitation) and organ failure at 24 hours post-admission. This trial will begin recruiting 200 patients at six French trauma centers in March 2021.

Summary

In civilian medicine, the use of whole blood as a therapeutic blood component for the resuscitation of traumatic patients has until recently been supplanted in favor of component therapy. However, there is increasing evidence that the use of LTOWB is a safe and effective intervention for emergency transfusions when aggressive resuscitation is required in the treatment of acutely hemorrhaging patients. Whole blood provides all of the components of blood in a convenient package that is easy to store and transport, and its use should be expanded from the trauma population to other massively bleeding patients where replacement of RBCs, plasma, and PLTs is desirable. Despite the successful and increasing civilian use of LTOWB to date, there is still the need for randomized controlled trials to determine its efficacy and safety in the resuscitation of massively bleeding patients.

Acknowledgments

The authors thank Drs. Pierre Tiberghien and Sylvain Ausset for providing information on the STORHM trial.

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editor (Paul D. Mintz) for the series “Transfusion Therapy: Principles and Practices” published in Annals of Blood. The article has undergone external peer review.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aob.amegroups.com/article/view/10.21037/aob-21-34/coif). The series “Transfusion Therapy: Principles and Practices” was commissioned by the editorial office without any funding or sponsorship. MHY received academic lectures (with reimbursed travel expenses) for Terumo, the manufacturer of a platelet-sparing whole blood leukoreduction blood collection kit. DJT has no relevant relationships/activities/interests to disclose other than the indicated NIH R34 grant. Some of this material has been previously published in: Yazer MH, Seheult JS, Bahr MP, Beckett A, Triulzi DJ, Spinella PS. Whole blood for the resuscitation of massively bleeding civilian patients. In: HB Moore, EE Moore, MD Neal eds. Trauma Induced Coagulopathy. 2^nd edition, 2021. Springer Nature Publications. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Murphy SL, Xu J, Kochanek KD, et al. Mortality in the United States, 2017. Hyattsville, MD: National Center for Health Statistics, 2018.
2. Holcomb JB, Tilley BC, Baraniuk S, et al. Transfusion of plasma, platelets, and red blood cells in a 1:1:1 vs a 1:1:2 ratio and mortality in patients with severe trauma: the PROPPR randomized clinical trial. JAMA 2015;313:471-82. [Crossref] [PubMed]
3. Drake SA, Holcomb JB, Yang Y, et al. Establishing a Regional Trauma Preventable/Potentially Preventable Death Rate. Ann Surg 2020;271:375-82. [Crossref] [PubMed]
4. Spinella PC, Cap AP. Whole blood: back to the future. Curr Opin Hematol 2016;23:536-42. [Crossref] [PubMed]
5. Kauvar DS, Lefering R, Wade CE. Impact of hemorrhage on trauma outcome: an overview of epidemiology, clinical presentations, and therapeutic considerations. J Trauma 2006;60:S3-11. [Crossref] [PubMed]
6. Delaney M, Wendel S, Bercovitz RS, et al. Transfusion reactions: prevention, diagnosis, and treatment. Lancet 2016;388:2825-36. [Crossref] [PubMed]
7. Myburgh JA, Mythen MG. Resuscitation fluids. N Engl J Med 2013;369:1243-51. [Crossref] [PubMed]
8. Feinman M, Cotton BA, Haut ER. Optimal fluid resuscitation in trauma: type, timing, and total. Curr Opin Crit Care 2014;20:366-72. [Crossref] [PubMed]
9. Reuter DA, Chappell D, Perel A. The dark sides of fluid administration in the critically ill patient. Intensive Care Med 2018;44:1138-40. [Crossref] [PubMed]
10. Blumberg N, Cholette JM, Pietropaoli AP, et al. 0.9% NaCl (Normal Saline) - Perhaps not so normal after all? Transfus Apher Sci 2018;57:127-31. [Crossref] [PubMed]
11. Edwards MJ, Lustik MB, Clark ME, et al. The effects of balanced blood component resuscitation and crystalloid administration in pediatric trauma patients requiring transfusion in Afghanistan and Iraq 2002 to 2012. J Trauma Acute Care Surg 2015;78:330-5. [Crossref] [PubMed]
12. Young JB, Utter GH, Schermer CR, et al. Saline versus Plasma-Lyte A in initial resuscitation of trauma patients: a randomized trial. Ann Surg 2014;259:255-62. [Crossref] [PubMed]
13. Ley EJ, Clond MA, Srour MK, et al. Emergency department crystalloid resuscitation of 1.5 L or more is associated with increased mortality in elderly and nonelderly trauma patients. J Trauma 2011;70:398-400. [Crossref] [PubMed]
14. Harada MY, Ko A, Barmparas G, et al. 10-Year trend in crystalloid resuscitation: Reduced volume and lower mortality. Int J Surg 2017;38:78-82. [Crossref] [PubMed]
15. Neal MD, Hoffman MK, Cuschieri J, et al. Crystalloid to packed red blood cell transfusion ratio in the massively transfused patient: when a little goes a long way. J Trauma Acute Care Surg 2012;72:892-8. [Crossref] [PubMed]
16. Bickell WH, Wall MJ Jr, Pepe PE, et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. N Engl J Med 1994;331:1105-9. [Crossref] [PubMed]
17. Shackelford SA, Del Junco DJ, Powell-Dunford N, et al. Association of Prehospital Blood Product Transfusion During Medical Evacuation of Combat Casualties in Afghanistan With Acute and 30-Day Survival. JAMA 2017;318:1581-91. [Crossref] [PubMed]
18. Sperry JL, Guyette FX, Brown JB, et al. Prehospital Plasma during Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock. N Engl J Med 2018;379:315-26. [Crossref] [PubMed]
19. Guyette FX, Sperry JL, Peitzman AB, et al. Prehospital Blood Product and Crystalloid Resuscitation in the Severely Injured Patient: A Secondary Analysis of the Prehospital Air Medical Plasma Trial. Ann Surg 2021;273:358-64. [Crossref] [PubMed]
20. Reitz KM, Moore HB, Guyette FX, et al. Prehospital plasma in injured patients is associated with survival principally in blunt injury: Results from two randomized prehospital plasma trials. J Trauma Acute Care Surg 2020;88:33-41. [Crossref] [PubMed]
21. Pusateri AE, Moore EE, Moore HB, et al. Association of Prehospital Plasma Transfusion With Survival in Trauma Patients With Hemorrhagic Shock When Transport Times Are Longer Than 20 Minutes: A Post Hoc Analysis of the PAMPer and COMBAT Clinical Trials. JAMA Surg 2020;155:e195085. [Crossref] [PubMed]
22. Gruen DS, Guyette FX, Brown JB, et al. Association of Prehospital Plasma With Survival in Patients With Traumatic Brain Injury: A Secondary Analysis of the PAMPer Cluster Randomized Clinical Trial. JAMA Netw Open 2020;3:e2016869. [Crossref] [PubMed]
23. Moore HB, Moore EE, Chapman MP, et al. Plasma-first resuscitation to treat haemorrhagic shock during emergency ground transportation in an urban area: a randomised trial. Lancet 2018;392:283-91. [Crossref] [PubMed]
24. Meyer DE, Vincent LE, Fox EE, et al. Every minute counts: Time to delivery of initial massive transfusion cooler and its impact on mortality. J Trauma Acute Care Surg 2017;83:19-24. [Crossref] [PubMed]
25. Howard JT, Kotwal RS, Stern CA, et al. Use of Combat Casualty Care Data to Assess the US Military Trauma System During the Afghanistan and Iraq Conflicts, 2001-2017. JAMA Surg 2019;154:600-8. [Crossref] [PubMed]
26. Rehn M, Weaver A, Brohi K, et al. Effect of Prehospital Red Blood Cell Transfusion on Mortality and Time of Death in Civilian Trauma Patients. Shock 2019;51:284-8. [Crossref] [PubMed]
27. Brown JB, Sperry JL, Fombona A, et al. Pre-trauma center red blood cell transfusion is associated with improved early outcomes in air medical trauma patients. J Am Coll Surg 2015;220:797-808. [Crossref] [PubMed]
28. van Turenhout EC, Bossers SM, Loer SA, et al. Pre-hospital transfusion of red blood cells. Part 2: A systematic review of treatment effects on outcomes. Transfus Med 2020;30:106-33. [Crossref] [PubMed]
29. Seheult JN, Stram MN, Sperry J, et al. In silico model of the dilutional effects of conventional component therapy versus whole blood in the management of massively bleeding adult trauma patients. Transfusion 2019;59:146-58. [Crossref] [PubMed]
30. Cap AP, Beckett A, Benov A, et al. Whole Blood Transfusion. Mil Med 2018;183:44-51. [Crossref] [PubMed]
31. Cotton BA, Guy JS, Morris JA Jr, et al. The cellular, metabolic, and systemic consequences of aggressive fluid resuscitation strategies. Shock 2006;26:115-21. [Crossref] [PubMed]
32. Leeper CM, Yazer MH, Cladis FP, et al. Use of Uncrossmatched Cold-Stored Whole Blood in Injured Children With Hemorrhagic Shock. JAMA Pediatr 2018;172:491-2. [Crossref] [PubMed]
33. Rumjantseva V, Hoffmeister KM. Novel and unexpected clearance mechanisms for cold platelets. Transfus Apher Sci 2010;42:63-70. [Crossref] [PubMed]
34. Pidcoke HF, McFaul SJ, Ramasubramanian AK, et al. Primary hemostatic capacity of whole blood: a comprehensive analysis of pathogen reduction and refrigeration effects over time. Transfusion 2013;53:137S-49S. [Crossref] [PubMed]
35. Reddoch KM, Pidcoke HF, Montgomery RK, et al. Hemostatic function of apheresis platelets stored at 4°C and 22°C. Shock 2014;41:54-61. [Crossref] [PubMed]
36. Nair PM, Pandya SG, Dallo SF, et al. Platelets stored at 4°C contribute to superior clot properties compared to current standard-of-care through fibrin-crosslinking. Br J Haematol 2017;178:119-29. [Crossref] [PubMed]
37. Vostal JG, Gelderman MP, Skripchenko A, et al. Temperature cycling during platelet cold storage improves in vivo recovery and survival in healthy volunteers. Transfusion 2018;58:25-33. [Crossref] [PubMed]
38. Manno CS, Hedberg KW, Kim HC, et al. Comparison of the hemostatic effects of fresh whole blood, stored whole blood, and components after open heart surgery in children. Blood 1991;77:930-6. [Crossref] [PubMed]
39. Becker GA, Tuccelli M, Kunicki T, et al. Studies of platelet concentrates stored at 22 C nad 4 C. Transfusion 1973;13:61-8. [Crossref] [PubMed]
40. Strandenes G, Sivertsen J, Bjerkvig CK, et al. A Pilot Trial of Platelets Stored Cold versus at Room Temperature for Complex Cardiothoracic Surgery. Anesthesiology 2020;133:1173-83. [Crossref] [PubMed]
41. Yazer MH, Cap AP, Spinella PC. Raising the standards on whole blood. J Trauma Acute Care Surg 2018;84:S14-S17. [Crossref] [PubMed]
42. Standards for blood banks and transfusion services. 31st ed. Bethesda, Maryland: AABB, 2018.
43. Yazer MH, Waters JH, Spinella PC, et al. Use of Uncrossmatched Erythrocytes in Emergency Bleeding Situations. Anesthesiology 2018;128:650-6. [Crossref] [PubMed]
44. Yazer MH, Cap AP, Spinella PC, et al. How do I implement a whole blood program for massively bleeding patients? Transfusion 2018;58:622-8. [Crossref] [PubMed]
45. Apelseth TO, Strandenes G, Kristoffersen EK, et al. How do I implement a whole blood-based blood preparedness program in a small rural hospital? Transfusion 2020;60:2793-800. [Crossref] [PubMed]
46. Standards for blood banks and transfusion services. 32nd ed. Bethesda, Maryland: AABB, 2020.
47. Yazer MH, Spinella PC. An international survey on the use of low titer group O whole blood for the resuscitation of civilian trauma patients in 2020. Transfusion 2020;60:S176-9. [Crossref] [PubMed]
48. Yazer MH, Spinella PC. Review of low titer group O whole blood use for massively bleeding patients around the world in 2019. ISBT Science Series 2019;14:276-81. [Crossref]
49. Yazer MH, Spinella PC. The use of low-titer group O whole blood for the resuscitation of civilian trauma patients in 2018. Transfusion 2018;58:2744-6. [Crossref] [PubMed]
50. Yazer MH, Spinella PC, Anto V, et al. Survey of group A plasma and low-titer group O whole blood use in trauma resuscitation at adult civilian level 1 trauma centers in the US. Transfusion 2021;61:1757-63. [Crossref] [PubMed]
51. Cid J, Harm SK, Yazer MH. Platelet transfusion - the art and science of compromise. Transfus Med Hemother 2013;40:160-71. [Crossref] [PubMed]
52. Yazer MH, Seheult J, Kleinman S, et al. Who's afraid of incompatible plasma? A balanced approach to the safe transfusion of blood products containing ABO-incompatible plasma. Transfusion 2018;58:532-8. [Crossref] [PubMed]
53. Yazer MH, Dunbar NM, Bub CB, et al. Comparison of titer results obtained using immediate spin one-dilution techniques to a reference method. Transfusion 2019;59:1512-7. [Crossref] [PubMed]
54. Sprogoe U, Assing K, Nielsen C, et al. Quantification of anti-A of IgM or IgG isotype using 3 different methodologies. Transfusion 2021;61:S214-S222. [Crossref] [PubMed]
55. Dunbar NM, Yazer MHBiomedical Excellence for Safer Transfusion (BEST) Collaborative and the STAT Study Investigators. Safety of the use of group A plasma in trauma: the STAT study. Transfusion 2017;57:1879-84. [Crossref] [PubMed]
56. Seheult JN, Dunbar NM, Hess JR, et al. Transfusion of blood components containing ABO-incompatible plasma does not lead to higher mortality in civilian trauma patients. Transfusion 2020;60:2517-28. [Crossref] [PubMed]
57. Seheult JN, Triulzi DJ, Alarcon LH, et al. Measurement of haemolysis markers following transfusion of uncrossmatched, low-titre, group O+ whole blood in civilian trauma patients: initial experience at a level 1 trauma centre. Transfus Med 2017;27:30-5. [Crossref] [PubMed]
58. Seheult JN, Bahr M, Anto V, et al. Safety profile of uncrossmatched, cold-stored, low-titer, group O+ whole blood in civilian trauma patients. Transfusion 2018;58:2280-8. [Crossref] [PubMed]
59. Yazer MH, Jackson B, Sperry JL, et al. Initial safety and feasibility of cold-stored uncrossmatched whole blood transfusion in civilian trauma patients. J Trauma Acute Care Surg 2016;81:21-6. [Crossref] [PubMed]
60. Harrold IM, Seheult JN, Alarcon LH, et al. Hemolytic markers following the transfusion of uncrossmatched, cold-stored, low-titer, group O+ whole blood in civilian trauma patients. Transfusion 2020;60:S24-30. [Crossref] [PubMed]
61. Morgan K, Yazer MH, Triulzi DJ, et al. Safety Profile of Low Titer Group O Whole Blood in Pediatric Patients with Massive Hemorrhage. Transfusion 2021;61:S8-S14. [Crossref] [PubMed]
62. LANGLEY GR. OWEN JA, PADANYI R. The effect of blood transfusions on serum haptoglobin. Br J Haematol 1962;8:392-400. [Crossref] [PubMed]
63. Nishiyama T, Hanaoka K. Free hemoglobin concentrations in patients receiving massive blood transfusion during emergency surgery for trauma. Can J Anaesth 2000;47:881-5. [Crossref] [PubMed]
64. Condron M, Scanlan M, Schreiber M. Massive transfusion of low-titer cold-stored O-positive whole blood in a civilian trauma setting. Transfusion 2019;59:927-30. [Crossref] [PubMed]
65. Triulzi DJ, Kakaiya R, Schreiber G. Donor risk factors for white blood cell antibodies associated with transfusion-associated acute lung injury: REDS-II leukocyte antibody prevalence study (LAPS). Transfusion 2007;47:563-4. [Crossref] [PubMed]
66. Kakaiya RM, Triulzi DJ, Wright DJ, et al. Prevalence of HLA antibodies in remotely transfused or alloexposed volunteer blood donors. Transfusion 2010;50:1328-34. [Crossref] [PubMed]
67. Sprogøe U, Yazer MH, Rasmussen MH, et al. Minimal variation in anti-A and -B titers among healthy volunteers over time: Implications for the use of out-of-group blood components. J Trauma Acute Care Surg 2017;82:S87-S90. [Crossref] [PubMed]
68. Assing K, Sprogoe U, Nielsen C, et al. Increased but stable isoagglutinin titers in hemodialysis patients. J Nephrol 2019;32:121-7. [Crossref] [PubMed]
69. Harm SK, Yazer MH, Bub CB, et al. Seasonal variability is not observed in the rates of high anti-A and anti-B titers in plasma, apheresis platelet, and whole blood units tested by different methods. Transfusion 2019;59:762-7. [Crossref] [PubMed]
70. Bailey JD, Fisher AD, Yazer MH, et al. Changes in donor antibody titer levels over time in a military group O low-titer whole blood program. Transfusion 2019;59:1499-506. [Crossref] [PubMed]
71. Daniel-Johnson J, Leitman S, Klein H, et al. Probiotic-associated high-titer anti-B in a group A platelet donor as a cause of severe hemolytic transfusion reactions. Transfusion 2009;49:1845-9. [Crossref] [PubMed]
72. Nadler R, Tsur AM, Yazer MH, et al. Early experience with transfusing low titer group O whole blood in the pre-hospital setting in Israel. Transfusion 2020;60:S10-6. [Crossref] [PubMed]
73. Fisher AD, Dunn J, Pickett JR, et al. Implementation of a low titer group O whole blood program for a law enforcement tactical team. Transfusion 2020;60:S36-44. [Crossref] [PubMed]
74. Zhu CS, Pokorny DM, Eastridge BJ, et al. Give the trauma patient what they bleed, when and where they need it: establishing a comprehensive regional system of resuscitation based on patient need utilizing cold-stored, low-titer O+ whole blood. Transfusion 2019;59:1429-38. [Crossref] [PubMed]
75. McGinity AC, Zhu CS, Greebon L, et al. Prehospital low-titer cold-stored whole blood: Philosophy for ubiquitous utilization of O-positive product for emergency use in hemorrhage due to injury. J Trauma Acute Care Surg 2018;84:S115-S119. [Crossref] [PubMed]
76. Seheult JN, Stram MN, Pearce T, et al. The risk to future pregnancies of transfusing Rh(D)-negative females of childbearing potential with Rh(D)-positive red blood cells during trauma resuscitation is dependent on their age at transfusion. Vox Sang 2021;116:831-40. [Crossref] [PubMed]
77. Kolodziej JH, Leonard JC, Josephson CD, et al. Survey to inform trial of low-titer group O whole-blood compared to conventional blood components for children with severe traumatic bleeding. Transfusion 2021;61:S43-8. [Crossref] [PubMed]
78. Yazer MH, Jackson B, Beckman N, et al. Changes in blood center red blood cell distributions in the era of patient blood management: the trends for collection (TFC) study. Transfusion 2016;56:1965-73. [Crossref] [PubMed]
79. Yazer MH, Delaney M, Doughty H, et al. It is time to reconsider the risks of transfusing RhD negative females of childbearing potential with RhD positive red blood cells in bleeding emergencies. Transfusion 2019;59:3794-9. [Crossref] [PubMed]
80. Yazer MH, Triulzi DJ, Sperry JL, et al. Rate of RhD-alloimmunization after the transfusion of multiple RhD-positive primary red blood cell containing products. Transfusion 2021;61:S150-S158. [Crossref] [PubMed]
81. Nathens AB, Nester TA, Rubenfeld GD, et al. The effects of leukoreduced blood transfusion on infection risk following injury: a randomized controlled trial. Shock 2006;26:342-7. [Crossref] [PubMed]
82. Watkins TR, Rubenfeld GD, Martin TR, et al. Effects of leukoreduced blood on acute lung injury after trauma: a randomized controlled trial. Crit Care Med 2008;36:1493-9. [Crossref] [PubMed]
83. Phelan HA, Sperry JL, Friese RS. Leukoreduction before red blood cell transfusion has no impact on mortality in trauma patients. J Surg Res 2007;138:32-6. [Crossref] [PubMed]
84. Englehart MS, Cho SD, Morris MS, et al. Use of leukoreduced blood does not reduce infection, organ failure, or mortality following trauma. World J Surg 2009;33:1626-32. [Crossref] [PubMed]
85. Friese RS, Sperry JL, Phelan HA, et al. The use of leukoreduced red blood cell products is associated with fewer infectious complications in trauma patients. Am J Surg 2008;196:56-61. [Crossref] [PubMed]
86. Fadeyi EA, Saha AK, Naal T, et al. A comparison between leukocyte reduced low titer whole blood vs non-leukocyte reduced low titer whole blood for massive transfusion activation. Transfusion 2020;60:2834-40. [Crossref] [PubMed]
87. Remy KE, Yazer MH, Saini A, et al. Effects of platelet-sparing leukocyte reduction and agitation methods on in vitro measures of hemostatic function in cold-stored whole blood. J Trauma Acute Care Surg 2018;84:S104-S114. [Crossref] [PubMed]
88. Sivertsen J, Braathen H, Lunde THF, et al. Cold-stored leukoreduced CPDA-1 whole blood: in vitro quality and hemostatic properties. Transfusion 2020;60:1042-9. [Crossref] [PubMed]
89. Haddaway K, Bloch EM, Tobian AAR, et al. Hemostatic properties of cold-stored whole blood leukoreduced using a platelet-sparing versus a non-platelet-sparing filter. Transfusion 2019;59:1809-17. [Crossref] [PubMed]
90. Mack JP, Miles J, Stolla M. Cold-Stored Platelets: Review of Studies in Humans. Transfus Med Rev 2020;34:221-6. [Crossref] [PubMed]
91. van der Meer PF, Klei TR, de Korte D. Quality of Platelets in Stored Whole Blood. Transfus Med Rev 2020;34:234-41. [Crossref] [PubMed]
92. Bjerkvig C, Sivertsen J, Braathen H, et al. Cold-stored whole blood in a Norwegian emergency helicopter service: an observational study on storage conditions and product quality. Transfusion 2020;60:1544-51. [Crossref] [PubMed]
93. Schaefer R, Long T, Wampler D, et al. Operationalizing the Deployment of Low-Titer O-Positive Whole Blood Within a Regional Trauma System. Mil Med 2021;186:391-9. [Crossref] [PubMed]
94. Pokorny DM, Braverman MA, Edmundson PM, et al. The use of prehospital blood products in the resuscitation of trauma patients: a review of prehospital transfusion practices and a description of our regional whole blood program in San Antonio, TX. ISBT Science Series 2019;14:332-42. [Crossref]
95. Pulliam KE, Joseph B, Veile RA, et al. Save it-don't waste it! Maximizing utilization of erythrocytes from previously stored whole blood. J Trauma Acute Care Surg 2020;89:665-72. [Crossref] [PubMed]
96. Yazer MH, Spinella PC, Doyle L, et al. Transfusion of Uncrossmatched Group O Erythrocyte-containing Products Does Not Interfere with Most ABO Typings. Anesthesiology 2020;132:525-34. [Crossref] [PubMed]
97. Wolf S, Morris J, Kennedy K, et al. The impact of providing blood to the scene of an accident on transfusion laboratory practice. Transfus Med 2018;28:56-9. [Crossref] [PubMed]
98. Seheult JN, Tysarczyk M, Kaplan A, et al. Optimizing blood bank resources when implementing a low-titer group O+ whole blood program: an in silico study. Transfusion 2020;60:1793-803. [Crossref] [PubMed]
99. Cotton BA, Podbielski J, Camp E, et al. A randomized controlled pilot trial of modified whole blood versus component therapy in severely injured patients requiring large volume transfusions. Ann Surg 2013;258:527-32; discussion 532-3. [Crossref] [PubMed]
100. Hanna K, Bible L, Chehab M, et al. Nationwide analysis of whole blood hemostatic resuscitation in civilian trauma. J Trauma Acute Care Surg 2020;89:329-35. [Crossref] [PubMed]
101. Duchesne J, Smith A, Lawicki S, et al. Single Institution Trial Comparing Whole Blood vs Balanced Component Therapy: 50 Years Later. J Am Coll Surg 2021;232:433-42. [Crossref] [PubMed]
102. Shea SM, Staudt AM, Thomas KA, et al. The use of low-titer group O whole blood is independently associated with improved survival compared to component therapy in adults with severe traumatic hemorrhage. Transfusion 2020;60:S2-S9. [Crossref] [PubMed]
103. Williams J, Merutka N, Meyer D, et al. Safety profile and impact of low-titer group O whole blood for emergency use in trauma. J Trauma Acute Care Surg 2020;88:87-93. [Crossref] [PubMed]
104. Gallaher JR, Dixon A, Cockcroft A, et al. Large volume transfusion with whole blood is safe compared with component therapy. J Trauma Acute Care Surg 2020;89:238-45. [Crossref] [PubMed]
105. Seheult JN, Anto V, Alarcon LH, et al. Clinical outcomes among low-titer group O whole blood recipients compared to recipients of conventional components in civilian trauma resuscitation. Transfusion 2018;58:1838-45. [Crossref] [PubMed]
106. Leeper CM, Yazer MH, Triulzi DJ, et al. Whole Blood is Superior to Component Transfusion for Injured Children: A Propensity Matched Analysis. Ann Surg 2020;272:590-4. [Crossref] [PubMed]
107. Yazer MH, Freeman A, Harrold IM, et al. Injured recipients of low-titer group O whole blood have similar clinical outcomes compared to recipients of conventional component therapy: A single-center, retrospective study. Transfusion 2021;61:1710-20. [Crossref] [PubMed]
108. Mapp JG, Manifold CA, Garcia AM, et al. Prehospital blunt traumatic arrest resuscitation augmented by whole blood: a case report. Transfusion 2020;60:1104-7. [Crossref] [PubMed]
109. Yazer MH, Gorospe J, Cap AP. Mixed feelings about mixed field agglutination: A pathway for managing females of childbearing potential of unknown RhD-type who are transfused RhD-positive and RhD-negative red blood cells during emergency hemorrhage resuscitation. Transfusion 2021;61:S326-S332. [Crossref] [PubMed]
110. Allon R, Epstein D, Shavit I. Prehospital transfusion of low titer cold-stored whole blood through the intraosseous route in a trauma patient with hemorrhagic shock. Transfusion 2020;60:875-8. [Crossref] [PubMed]
111. Leeper CM, Yazer MH, Cladis FP, et al. Cold-stored whole blood platelet function is preserved in injured children with hemorrhagic shock. J Trauma Acute Care Surg 2019;87:49-53. [Crossref] [PubMed]
112. Clements T, McCoy C, Assen S, et al. The prehospital use of younger age whole blood is associated with an improved arrival coagulation profile. J Trauma Acute Care Surg 2021;90:607-14. [Crossref] [PubMed]
113. Zaza M, Meyer DE, Wang YW, et al. The impact of rapid infuser use on the platelet count, platelet function, and hemostatic potential of whole blood. J Surg Res 2021;260:76-81. [Crossref] [PubMed]
114. Alley T, Taylor G, Owens A, et al. Whole blood administration: comparison of in vitro platelet function of pressure bag, pressure bag with fluid warming device, and rapid infuser methods. J Trauma Nurs 2020;27:351-4. [Crossref] [PubMed]
115. Hulse W, Bahr TM, Morris DS, et al. Emergency-release blood transfusions after postpartum hemorrhage at the Intermountain Healthcare hospitals. Transfusion 2020;60:1418-23. [Crossref] [PubMed]
116. Morris DS, Braverman MA, Corean J, et al. Whole blood for postpartum hemorrhage: early experience at two institutions. Transfusion 2020;60:S31-5. [Crossref] [PubMed]
117. Bahr TM, DuPont TL, Morris DS, et al. First report of using low-titer cold-stored type O whole blood in massive postpartum hemorrhage. Transfusion 2019;59:3089-92. [Crossref] [PubMed]
118. Martinaud C, Tiberghien P, Bégué S, et al. Rational and design of the T-STORHM Study: A prospective randomized trial comparing fresh whole blood to blood components for acutely bleeding trauma patients. Transfus Clin Biol 2019;26:198-201. [Crossref] [PubMed]