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Early Blood‐Based Resuscitation after Traumatic Injury: the Good, the Bad…not so Ugly?
Scott C. Brakenridge MD
UT Southwestern Medical Center, Dallas, TX
Introduction
Control of hemorrhage and appropriate volume resuscitation from hemorrhagic shock
are the cornerstones of initial treatment for the severely injured trauma patient. The rapid
identification of sources of hemorrhage necessitating surgical control, and subsequent timely
initiation of operative intervention, are unarguably the primary concerns for the surgeon
evaluating the severely injured patient. The primary goals of acute volume resuscitation from
hemorrhagic shock, restoration of intravascular volume and oxygen carrying capacity, have
remained unchanged since the Vietnam War era. However, what has shifted over the past 20
years is the role of blood products in early post‐injury resuscitation.
Early physiologic experiments and clinical experiences, including work published by
Alfred Blalock, suggested that whole blood is indeed the best resuscitative fluid for
hemorrhagic shock.1‐3 However, a combination of issues including risk of transfusion reactions,
transmission of infectious agents and the cost and logistical difficulties of storage and delivery
led to an isotonic crystalloid‐based resuscitation strategy since the Vietnam War era. In
addition, over the past 20 years multiple studies have shown an association of transfusion with
increased mortality, infection and risk of multiple organ dysfunction (MOD) in injured patients.
These findings have led several authors to advocate avoidance of the use of blood products in
injured patients whenever possible.4, 5
Despite the numerous concerns regarding blood product usage in the trauma
population there has been a rekindling of interest in early blood‐based resuscitation. Recent
evidence from the theatres of the Iraq and Afghanistan conflicts have suggested that a shift
from crystalloid to blood‐based resuscitation from hemorrhagic shock shows improved
survival.6‐8 These findings have accelerated the investigation of so‐called “damage‐control
resuscitation”, which focuses on the early and aggressive utilization of blood component
therapy in combinations approaching that of whole blood, primarily to address early
coagulopathy. Interestingly, there have been anecdotal reports that patients receiving this type
of resuscitative therapy have clinical evidence of a less vigorous systemic immune response,
including less pulmonary dysfunction and faster weaning from mechanical ventilation.9 These
conflicting outcomes results raise a serious dilemma regarding our approach towards trauma
resuscitation. The question that has yet to be completely answered remains how do we best
resuscitate patients with severe traumatic injury from hemorrhagic shock and prevent trauma‐
associated early coagulopathy without exacerbating the post‐traumatic systemic inflammatory
response or increasing the risk for multiple organ failure?
The past – “The Bad”
Transmissible diseases & Transfusion reactions
While theoretically considered the most physiologically effective method of
resuscitation from acute hemorrhagic shock, there have been several historical limitations and
risks that have limited its use as a primary resuscitative fluid. Transfusion‐transmitted diseases
remain a small, but nonetheless real, risk associated with transfusion of blood products. The
recognition of transfusion‐associated hepatitis and HIV transmission during the 1980’s had a
profound impact on the overall utilization of allogeneic blood product transfusion in the United
States. Both collections and transfusions decreased significantly from the late 1980’s to the
mid 1990’s, reaching a nadir in 1996.10 The most recent estimates for risk of transmission of
Hepatitis B (1:350,000), Hepatitis C (1:1,800,000) and HIV (1:2,300,00) per unit transfused in the
United States remain extremely low as a consequence of donor screening mechanisms that
have become standard practice.11 While positive bacterial cultures of apheresis platelet units
have been reported as high as 1:5000, septic complications are also extremely rare at
approximately one fatal case per million.11 Transmission of emerging diseases such as West‐
Nile virus and prion diseases remain anecdotal at this time, but may pose larger risks in the
future as our understanding of these diseases evolves.
While transmission of infectious diseases may have had a more visceral emotional
impact on transfusion practice in the past, non‐infectious complications such as acute
hemolytic reactions, and especially transfusion‐related acute lung injury continue to pose a
much more significant risk to the transfused trauma patient. The majority of acute hemolytic
reactions are provoked by ABO incompatibilities, which are the result of avoidable systems
failures.12, 13 Transfusion related lung injury (TRALI) is defined as the onset of Acute Lung Injury
(acute onset, bilateral radiographic infiltrates, hypoxemia and lack of pulmonary vasculature
overload/congestion) within six hours of a transfusion.14 TRALI is thought to be mediated by
donor anti‐granulocyte antibodies which trigger pulmonary inflammation, pulmonary vascular
permeability and ultimately pulmonary edema. Contrasted against the risks of transmissible
infectious diseases, TRALI poses a much larger statistical risk, estimated at approximately
1:5000 of all blood product units transfused.15 While TRALI is a well‐described entity in the
overall transfusion population, the actual incidence in the sub‐population of trauma and
critically ill patients remains an unresolved question. A recent multi‐center retrospective
analysis of 1351 intensive care unit patients receiving transfusion revealed suspected TRALI (ALI
without other suspected sources) rates of 1:1271 units transfused, possible TRALI (ALI with
other possible risk factors for lung injury) at 1:534 units transfused, and transfusion associated
circulatory overload (TACO) at 1:356 units transfused.16 While these numbers appear striking,
they also illustrate the point that isolating TRALI as the cause of pulmonary failure in the
critically ill and injured patient population is made extremely difficult by other possible causes
of pulmonary dysfunction such as resuscitative volume overload, injury or septic related
systemic inflammation, and thoracic injuries. There is currently no literature on the incidence
of TRALI specifically addressing the trauma population.
Mortality
One of the major predictors of mortality after injury is transfusion of blood products.
This has been shown repeatedly in both retrospective and prospective studies attempting to
identify risk factors predictive of mortality after injury. Injured patients requiring blood
transfusion have been found to have between 3 to 5 fold increased odds of death compared to
those not requiring transfusion.4, 17‐19 In addition, there also appears to be a dose‐dependent
association between transfusion requirements and mortality. In a single‐center, 4‐year
retrospective analysis of 316 patients with blunt liver and/or splenic injury the overall risk of
death increased with each unit of transfused PRBC (OR 1.16, 95% CI 1.10‐1.24).17 Not
surprisingly then, requirement of massive transfusion, most often defined as >10 Units PRBC
within 24 hours of injury, is an even stronger predictor of mortality.20‐22
Poor outcomes after transfusion have also been well described in the general critical
care population.23‐25 A single center prospective cohort study of 248 patients admitted to both
surgical and medical intensive care units meeting the 1994 American European Consensus
Conference criteria of acute respiratory distress syndrome (ARDS) showed similar findings to
the risks reported in the trauma population. They reported that these patients had an
approximate 3‐fold increased odds of mortality with transfusion of ≥1 unit of PRBC (OR 3.12,
95% CI 1.28‐7.58) after adjusting for age, gender, APACHE III score, and inciting event of lung
injury.24 They also found a dose‐dependent relationship of PRBC with mortality showing a 5%
increased adjusted odds of death per unit of PRBC transfused (OR 1.06, 95% CI 1.04‐1.09).
Interestingly, in subgroup multivariate analysis, transfusion after onset of ARDS was associated
with an odds ratio for mortality of 1.13 (95% CI 1.07 to 1.29), while transfusion prior to onset of
ARDS was found not to be a risk factor for mortality.24
One of the most influential studies changing the practice of critical care medicine was
the Canadian Critical Care Trials Group multi‐center randomized‐controlled trial of transfusion
requirements in the intensive care unit population. The Transfusion Requirements in Critical
Care (TRICC) trial randomized 838 intensive care unit patients to either a restrictive (transfusion
trigger Hgb <7 g/dL) or a liberal PRBC transfusion strategy (transfusion trigger Hgb <10 g/dL)
powered for their primary outcome of 30‐day all cause mortality. While there was no
significant difference in overall 30‐day mortality, subgroup analysis suggested less ill patients
(APACHE II score ≤20) and patients over the age of 55 showed lower mortality rates.26 In‐
hospital mortality, a secondary endpoint, was lower in the restrictive strategy group (22% vs.
28%).27 Also not powered for a definitive analysis, a subsequent retrospective study of the
subset of 203 critically ill injured patients from the TRICC cohort found no significant difference
between restrictive and liberal strategies for 30‐day all cause mortality, multiple organ
dysfunction, and length of hospital and ICU stay.26 The overall applicability of the TRICC trial
data specifically to the trauma population remains unknown.
Infectious complications
A suspected adverse immunosuppressive effect of allogenic transfusion of packed red
blood cells manifesting as increased rates of postoperative wound infection has been described
in several different surgical settings including after cardiac, colorectal and general surgical
procedures.28‐30 The association between blood product transfusion and infectious
complications has also been shown in the critical care population. Taylor et al described a
retrospective 2‐year cohort of 1,717 intensive care unit patients and showed those receiving
transfusion of greater than 1 unit of PRBC had a greater risk (15.4% vs. 2.9%) of nosocomial
infection.31 Blood products other than PRBCs have also been associated with infectious
complications. In a non‐trauma surgical ICU population, analysis of a 380 patient retrospective
cohort revealed fresh frozen plasma (FFP) as an independent risk factor for infectious
complications after controlling for transfusion of PRBCs and illness severity (APACHE II).32
Interestingly, in this study there was no association between FFP and infectious complications
in those receiving both FFP and PRBCs.
An association between transfusion of blood products and infectious complications has
also been described specifically within the trauma literature. This association was first
described in a post‐hoc analysis of a randomized‐controlled trial comparing the effectiveness of
single vs. dual‐agent antibiotic prophylaxis for postoperative septic complications in patients
with intestinal perforation after penetrating abdominal trauma.33 In this study, receiving
greater than 10 Units of PRBCs was a significant predictor of infectious complications. Many
subsequent retrospective descriptive and prospective cohort studies have also shown an
association between transfusion and infectious complications after both penetrating and blunt
injury.34‐37 In a 5‐year prospective cohort of 482 patients with both blunt and penetrating liver
injuries, Fabian showed the Abdominal Trauma Index Score and number of units of transfused
PRBCs to be independently associated with increased risk of peri‐hepatic abcess.35
Subsequently, in a 1‐year prospective cohort study of all trauma patients with a length of stay
greater than 3 days, Edna & Bjerkeset noted a six‐fold greater odds of infectious complications
(urinary tract infection, pneumonia and/or pneumonia) in patients receiving >4 units PRBCs.36
In another large retrospective cohort study, Agarwal noted that injury severity score (ISS) and
the number of units of PRBCs transfused as the only independent predictors of occurrence of
infectious complications.37
Multiple organ dysfunction
The previously mentioned risks associated with the utilization of blood products for
traumatic resuscitation have no doubt had significant impact on the resuscitation practice of
trauma surgeons. However, some of the most vigorous investigation, as well as debate, within
the trauma community over the past two decades has centered around the association of blood
product transfusion with post‐traumatic multiple organ dysfunction. The development of
multiple organ dysfunction (MOD) is associated with significantly increased morbidity and
mortality after severe blunt traumatic injury.38, 39 MOD manifests as progressive dysfunction of
multiple organ systems (pulmonary, renal, cardiac and hepatic) in critically injured and septic
patients. Advances in trauma systems, volume resuscitation, “damage‐control” surgical
procedures and advanced critical care supportive measures over the past five decades continue
to contribute to the survival of patients with progressively increasing severity of injuries.
However, even as these interventions improve upon survival in the immediate post‐injury
period, MOD continues to impact the long term morbidity and mortality of severely injured
patients. Despite being an area of intense active investigation, MOD remains the leading cause
of late post‐injury deaths in the intensive care unit.40‐42
Multiple organ dysfunction is associated with an early, systemic hyper‐inflammatory
response to severe injury known as the systemic inflammatory response syndrome (SIRS).
Almost immediately after severe injury there is activation of the immunologic cascade leading
to significant elevation in pro‐inflammatory cytokines, such as TNF‐α, IL‐1 and IL‐6, in both
animal models and injured patients.43‐46 In some instances, systemic inflammation is so severe
there is progression to early MOD within the first 2‐3 days. In others, this dysfunctional, robust
inflammatory response is countered by a delayed compensatory anti‐inflammatory response
(CARS) associated with anti‐inflammatory cytokines such as TGF‐β, IL‐4 and IL‐10.47, 48 This
leads to the development of an extended period of post‐traumatic immunosuppression which is
associated with increased risk of infection, sepsis and subsequent late MOD.48‐50 Despite
continuing active investigation, the triggers of this immunologic response and why it occurs in
some patients, but not others, remain unknown.
Given the hypothesis of dysfunctional inflammation as the driving force of the SIRS
response and MOD, the suspected immunomodulatory effects of allogenic blood transfusion
made it an early suspect as a potential contributor to complications after trauma associated
with immune dysfunction. Since the early 1990’s, the transfusion of blood products after
traumatic injury has repeatedly been shown to be associated with the subsequent onset of
MOD.51‐53 Most prominently, Moore and his colleagues were able to consistently report an
association between transfusion and MOD in a series of studies from an ongoing prospective
cohort of severely injured patients spanning over more than ten years.39, 42, 52‐55 In multiple
different analyses of their ongoing prospective cohort of severely injured patients, this group
consistently showed that >6 Units of PRBCs transfused within the first 24 hours of resuscitation
after injury was a independent predictor of multiple organ failure. In the first of these studies,
Sauaia performed a retrospective cohort analysis of 394 trauma patients over a 3‐year period
with an injury severity score (ISS) >15 and found that age greater than 55 years, Injury Severity
Score (ISS) ≥25 and >6 Units of PRBC in the first 12 hours after injury were independent
predictors of MOD.52 They were also subsequently able to show that the transfusion of >6 units
PRBC within the first 12 hours after injury remained an independent predictor of MOD while
controlling for injury severity (ISS) and severity of shock (base deficit, lactate).53 As our
understanding of the natural history of MOD progressed, attention also turned to evaluating
the association of transfusion with Acute Respiratory Distress Syndrome (ARDS) as pulmonary
dysfunction is often a bellwether of progression to MOD. Similar to the previous MOD data,
Silverboard described a dose‐effect type association between transfusion of PRBC and
occurrence of ARDS in a prospective cohort analysis of 102 severely injured patients requiring
intubation.56
The Present – “The Good”
Damage control resuscitation
Damage control surgery is now a well described and widely practiced concept in trauma
and emergency general surgery. This strategy consists of immediate limited surgical
intervention including control of hemorrhage and enteric spill, temporary shunting of complex
vascular injuries, debridement of devitalized tissue and temporary abdominal closure, with the
goal of expedited transfer to the intensive care unit for physiologic resuscitation. Definitive
surgical repairs are then deferred for 24‐72 hours after resuscitation is complete and the
patients’ physiology has been stabilized.57‐60 Recently, data from the theatres of conflict in Iraq
and Afghanistan have sparked a new interest in aggressive blood‐based resuscitation for
hemorrhagic shock.6‐8, 61‐64 This concept of “damage control resuscitation” consists of
resuscitation from hemorrhagic shock with packed red blood cells, fresh frozen plasma and
platelets in ratios approaching the composition of whole blood.7, 9, 62, 65 In fact, several reports
from military surgeons in the combat theatre described the safe and efficacious use of donated
fresh whole blood, primarily driven by shortages of blood product components.6, 8, 64, 65 The use
of isotonic crystalloid solution, the mainstay of traumatic volume resuscitation since the
Vietnam War, is minimized.
Advocated by Holcomb, among others, the driving thought process behind damage
control resuscitation is to address the early coagulopathy of trauma thought to be attributed to
the dilution of clotting factors by resuscitation with crystalloid solutions and packed red blood
cells, compounded with hypothermia and acidosis.9, 66, 67 Data from both civilian and military
literature have shown that the “lethal triad” of coagulopathy, hypothermia and acidosis after
injury is associated with increased mortality.9, 63, 68 In an effort to evaluate the concept of
damage control resuscitation, Borgman and colleagues performed a retrospective cohort
analysis of 246 trauma patients admitted over a 2‐year period to a combat support hospital in
Iraq. They reported that in patients requiring more than 10 units of PRBC over a 24 hour
period, those receiving a high ratio of plasma to packed red blood cells (median 1:1.4) had
significantly lower rates of overall (19% vs. 65%) and hemorrhage‐related mortality (37% vs.
92.5%) compared to those with lower ratios (median 1:8).6 After implementation of damage
control resuscitation clinical practice guidelines in Iraq in 2006, Fox and Holcomb performed a
retrospective cohort analysis comparing outcomes in patients requiring extremity
revascularization before and after initiation of the protocol. They found that while the two
cohorts were similar with regards to injury severity and physiologic parameters, patients
resuscitated after implementation of the damage control resuscitation guidelines had more
complete post‐operative physiologic recovery as measured by post‐operative heart rate,
systolic blood pressure, base deficit and international normalized ratio (INR).62
Following closely in the footsteps of the military, civilian trauma centers have also now
started to report on outcomes after initiating their own damage control resuscitation protocols.
After implementing changes in their massive transfusion protocols to adopt the concept of
damage control resuscitation, Cotton also performed a retrospective historical cohort analysis
to compare outcomes before and after initiation of the damage control resuscitation protocol.
They found that patients resuscitated under their “trauma exanguination protocol”, while using
more intra‐operative blood products and less crystalloid solution, had significantly lower
amounts of total 24 hour blood product utilization (31.2 vs. 38.7 Units). These severely injured
patients also had significantly lower 30‐day mortality (37.6% vs. 56.8%), as well as lower rates
of complications thought to be caused by dysfunctional inflammation including abdominal
compartment syndrome (0% vs. 9.9%), sepsis (10.0% vs. 19.8%), ventilator‐associated
pneumonia (27.2% vs. 39.0%), and multiple organ dysfunction (15.6% vs. 37.2%).69
The Future – “The Unknown”
Limitations of existing outcomes data
The large body of literature described above has clearly shown an association of blood
product administration after injury with adverse outcomes such as multiple organ failure and
death. However, there are significant limitations to these observational studies that preclude
the assumption that blood products are the actual causative factor for these poor outcomes.
Many of the studies linking blood product transfusion to these outcomes failed to control for
one or more obvious confounding factors such as severity of shock, injury or illness severity and
patient age.18, 23, 31, 33‐37, 51, 70 While the most prominent studies have utilized advanced
multivariate statistical analyses to attempt to control for these obvious confounders, there is no
way to account for unknown or unmeasured confounders which could have a significant effect
on outcomes in these type of observational studies. Consistently, indices of shock severity such
as base deficit and lactate are among the strongest risk factors associated with outcomes such
as mortality and multiple organ failure. However, in many of these studies there is a significant
amount of missing data for these shock indicators and the timing of their measurement is
highly variable.52‐54 Additionally, the methods utilized to deal with missing data in several of
these studies are debatable and the combination of these factors could have lead to biased
results.21, 52‐54 Also, these studies fail to control for other components utilized in volume
resuscitation such as crystalloid and colloid. This makes it impossible to determine if blood
products are truly causative factors of these adverse outcomes as their use may merely be an
indicator of those patients with increased resuscitation requirements. Finally, while statistically
significant, the odds ratios for blood products as a predictive risk factor are relatively modest,
and much too small to draw causative conclusions from these types of observational studies.
Analyses of large multi‐institutional prospective cohort studies such as the “trauma glue grant”
(Inflammation and the Host Response to Injury) and PROMMTT (Prospective Observational
Multicenter Massive Transfusion sTudy) study groups will hopefully be able to more
comprehensively tease apart these relationships.
Leukoreduction
Over the past decade there has been much interest in whether or not pre‐storage
leukoreduction of packed red blood cells improves outcomes in trauma patients requiring
transfusion. Levels of inflammatory mediators such as bioactive lipids and cytokines have been
found to increase after routine blood product storage.71, 72 These findings led some to
hypothesize that mediators released from residual leukocytes may be responsible for the
detrimental immunologic sequelae associated with transfusion of packed red blood cells.
Leukoreduction has been shown to significantly reduce bioactive lipids, cytokines, and to
attenuate priming of recipient neutrophils.73, 74 However, observational studies assessing how
these laboratory findings translate to clinical outcomes such as ARDS, infectious complication,
multiple organ dysfunction and mortality have yielded mixed results.75‐79 The only randomized‐
controlled trial of leukoreduced blood transfusion in trauma patients found no difference on
incidence of infectious complications within 28 days of injury.80 While the debate over
whether leukoreduction improves outcomes remains contentious, it may be moot in the United
States given the trend toward universal leukoreduction. In 2006 the percentage of
leukoreduced whole blood and PRBC units transfused was reported at greater than 70% and
continues on an upward trend.10
Blood storage age
The time blood products remain in storage prior to transfusion has also been an area of
recent interest. Several observational studies have revealed an association between packed
red blood cells that have been stored longer than 14 to 28 days with worse outcomes after
injury, including infection, multiple organ failure, increased ICU length of stay, and mortality.81‐
84 A leading hypothesis was that this was primarily due to release of inflammatory mediators
from residual leukocytes. Recently, Weinberg reported results on a retrospective cohort study
of 2,062 transfused trauma patients that suggests there may be other mechanisms involved.
They found that over a 7.5 year period that PRBC units stored 14 days or longer remained a
significant predictor of mortality despite universal leukoreduction.85 This suggests that there
are factors within stored blood products other than leukocytic mediators which may have
detrimental effects on clinical outcomes. Prospective interventional studies are necessary to
determine whether the utilization of freshly collected blood products effects outcomes in
injured patients requiring transfusion.
Component Ratios & whole blood utilization
While the overall concept of blood‐based “damage control resuscitation” is becoming
accepted, the optimal ratio of blood product components utilized in these protocols is still
widely debated, and under continuing investigation. As mentioned previously, recent military
data has reported that the utilization of blood product component resuscitation in ratios
approaching that of whole blood was found to be associated with improved outcomes.6‐9, 64
Holcomb found similar results in a retrospective analysis of 466 injured patients at 16 Level I
civilian trauma centers receiving massive transfusion (>10 Units PRBC 1st 24 hrs.). In this study
both plasma and platelet to PRBC ratios were classified as either low (<1:2) or high (≥1:2).
Shown by survival analysis, patients with high FFP:PRBC and high platelet:PRBC ratios had
significantly higher 24‐hour and 30‐day survival rates than those with low FFP and platelet to
PRBC ratios.86 Other authors have had similar findings in subsequent retrospective studies.
Zink and colleagues reported in a 6‐year single institution review that higher 6‐hour ratios of
FFP:PRBC and platelet:PRBC ratios was associated with improved 6‐hour and in‐hospital
mortality.87 In another large multi‐center retrospective analysis, Teixeira reported that in
patients receiving >10 units PRBCs, mortality decreased significantly with increased ratio of
FFP:PRBC. However, they failed to find any additional survival advantage once a FFP:PRBC ratio
of 1:3 was reached.88 The previously mentioned PROMMTT study will hopefully yield data to
build upon the current retrospective literature and be the foundation for controlled clinical
trials in this area.
Given that ratios of blood products approaching whole blood are associated with
improved outcomes, a logical next step is consideration of whole blood resuscitation. The
military has had significant interest in this area given a common situation of limited component
supply in the midst of mass‐casualty scenarios. Recently, Spinella reported that a retrospective
analysis of combat casualties between 2004 and 2007 requiring transfusion revealed that
patients receiving warm fresh whole blood in addition to component therapy were associated
with improved 24‐hour and 30‐day survival compared to those receiving component therapy
alone.8 Proponents argue that utilization of fresh whole blood may allow for efficient
correction of coagulopathy while minimizing the amount of transfusion of components with
advanced storage age. While this type of utilization of whole blood appears advantageous at
multiple levels there are still many outstanding issues regarding safety and feasibility which
need to be addressed before its utilization can be transferred to the civilian realm. Civilian
blood banks and trauma centers would require a significant investment in capital, personnel
and donor recruitment to deal with issues such as rapid infectious disease screening.
Significant advancements in storage technology and donor recruitment to maintain supply
would also be required given the current 72‐hour average storage life of fresh whole blood.
Logistical Constraints & Utilization
Limited supply, logistical constraints in component production and storage, and
increasing costs, have complicated the utilization of blood products both historically and in the
present era. In general, overall blood component demand is greater than available supply.
While blood collections are increasing, between 2000 and 2006 approximate 10% of hospitals in
the United States reported having to cancel elective surgeries at secondary to blood bank
inventory shortages.10 Most urban Level One trauma centers have protocols in place keeping
sufficient product available for routine emergent use. Situations of mass casualty or facilities in
more austere environments can make the use of any type of blood product problematic. As
mentioned previously, combat support hospitals in Iraq and Afghanistan have had to resort to
the use of freshly donated whole blood when demand outstrips supply or component products
are unavailable.64 In the current area of fiscally‐conscious medicine, costs remain a legitimate
concern. In 2006 the reported mean amount paid per unit of PRBC ($213.94) increased
approximately 6% while average CMS reimbursement covered only 76% of these costs.10 As
mentioned previously, the logistical issues surrounding possible utilization of fresh whole blood
in trauma resuscitation protocols are even more complex. The impact of cost and availability of
all allogenic blood products on the feasibility of future blood‐based trauma resuscitation
protocols is yet to be determined.
Hemoglobin substitutes
Within the past 10 years there has been a significant amount of excitement and
enthusiasm for the potential use of hemoglobin‐based oxygen carriers (HBOCs) as an
alternative to packed red blood cells to restore oxygen carrying capacity after hemorrhage.
Solutions containing polymerized purified human hemoglobin (PolyHeme; Northfield
Laboratories, Inc., Evanston, Illinois) and glutaraldehyde cross‐linked bovine hemoglobin
(HBOC‐201; Biopure Corporation, Cambridge, Massachusetts) have been the most thoroughly
studied of these agents. These synthetic molecules have several potential theoretical
advantages over human allogenic PRBCs. These include the avoidance of infectious particle
transmission, elimination of the need for blood typing or cross‐match prior to administration,
and a lack of antigenic stimulus and potential immunomodulation associated with blood
transfusion. These formulations also have the potential to be easily stored for extended
periods of time and can be immediately available for use.
However, thus far results from clinical trials evaluating these agents have not lived up to
expectations and concerns have been raised about several potential adverse effects. Results
from a multi‐center phase III clinical trial comparing a Polyheme/crystalloid to a
PRBC/crystalloid based initial resuscitation protocol found no significant difference in their
primary endpoint of 30‐day mortality.89 Although total allogenic PRBC use was lower in the
Polyheme group, MOF rates were similar between the two groups and serious adverse cardiac
events appeared to be greater in the Polyheme group.
Although several animal studies showed promise for the utilization of HBOC‐201 after
hemorrhagic shock, results from human trials have raised concerns about increases in systemic
vascular and pulmonary resistance after administration of this agent.90 A recent meta‐analysis
of 16 randomized‐controlled trials enrolling a combination of surgical, stroke and trauma
patients reinforced these concerns after finding a significantly increased risk of mortality or
myocardial infarction associated with HBOC administration.91 The use of HBOCs may still play a
role in austere environments or situations where blood products are unavailable, but further
technical advancements and more robust clinical data is required before routine allogenic
blood product use is supplanted by this technology.
Conclusions
The role of blood product therapy in resuscitation from hemorrhagic shock continues to
evolve. Results from recent damage control resuscitation protocols utilizing early and
aggressive of blood component therapy in ratios approaching the consistency of whole blood to
combat early trauma‐associated coagulopathy appear promising. However, concerns linger
regarding the possible adverse effects associated with blood product administration.
Continuing investigation into this area will be required to determine whether or not blood
products are the actual causative factor leading to adverse outcomes such as infectious
complications and multiple organ dysfunction. While development of blood product
alternatives such as hemoglobin‐based oxygen carriers continues, their role in resuscitation of
the trauma patient is yet to be defined and it will be some time before their use becomes
widespread. Although promising, clinical trials determining the efficacy of early blood‐based
resuscitation from hemorrhagic shock will be required to fully determine its role in the care of
the severely injured trauma patient.
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