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Sloan EP, Koenigsberg M, Gens D, et al. Diaspirin Cross-Linked Hemoglobin (DCLHb) in the Treatment of Severe Traumatic Hemorrhagic Shock: A Randomized Controlled Efficacy Trial. JAMA. 1999;282(19):1857–1864. doi:10.1001/jama.282.19.1857
Context Severe, uncompensated, traumatic hemorrhagic shock causes significant
morbidity and mortality, but resuscitation with an oxygen-carrying fluid might
improve patient outcomes.
Objective To determine if the infusion of up to 1000 mL of diaspirin cross-linked
hemoglobin (DCLHb) during the initial hospital resuscitation could reduce
28-day mortality in traumatic hemorrhagic shock patients.
Design and Setting Multicenter, randomized, controlled, single-blinded efficacy trial conducted
between February 1997 and January 1998 at 18 US trauma centers selected for
their high volume of critically injured trauma patients, but 1 did not enroll
Patients A total of 112 patients with traumatic hemorrhagic shock and unstable
vital signs or a critical base deficit, who had a mean (SD) patient age of
39 (20) years. Of the infused patients, 79% were male and 56% were white.
An exception to informed consent was used when necessary.
Intervention All patients were to be infused with 500 mL of DCLHb or saline solution.
Critically ill patients who still met entry criteria could have received up
to an additional 500 mL during the 1-hour infusion period.
Main Outcome Measures Twenty-eight day mortality, 28-day morbidity, 48-hour mortality, and
24-hour lactate levels.
Results Of the 112 patients, 98 (88%) were infused with DCLHb or saline solution.
At 28 days, 24 (46%) of the 52 patients infused with DCLHb died, and 8 (17%)
of the 46 patients infused with the saline solution died (P = .003). At 48 hours, 20 (38%) of the 52 patients infused with DCLHb
died and 7 (15%) of the 46 patients infused with the saline solution died
(P = .01). The 28-day morbidity rate, as measured
by the multiple organ dysfunction score, was 72% higher in the DCLHb group
(P = .03). There was no difference in adverse event
rates or the 24-hour lactate levels.
Conclusions Mortality was higher for patients treated with DCLHb. Although further
analysis should investigate whether the mortality difference was solely due
to a direct treatment effect or to other factors, DCLHb does not appear to
be an effective resuscitation fluid.
Death from trauma frequently results from hemorrhagic shock that is
refractory to optimal resuscitation efforts.1
Patients with uncompensated hemorrhagic shock, especially those with large
base deficits, are at the greatest risk of multisystem organ failure and death.2-6
Standard therapies, including the rapid infusion of large volumes of crystalloid
solutions or blood, may exacerbate the morbidity caused by severe trauma.7-10 Studies
suggest that small-volume resuscitation, slow resuscitation, delayed resuscitation,
or the use of an oxygen-carrying resuscitation fluid might improve outcome
in hemorrhagic shock.11-18
This clinical trial was conducted to determine if diaspirin cross-linked
hemoglobin (DCLHb), a purified and chemically modified human hemoglobin solution,
could improve cellular perfusion and reduce mortality and morbidity when used
as an adjunct to standard therapy in severely injured hemorrhagic shock patients.
It was studied for use in trauma because it can be easily stored in the emergency
department and immediately infused in trauma patients without the need for
The primary objective of this efficacy trial was to reduce 28-day mortality
of traumatic hemorrhagic shock patients by 25%, from 40% to 30%, through the
additional infusion of 500 to 1000 mL of DCLHb during the initial hospital
resuscitation period. The study also attempted to demonstrate a significant
reduction in 28-day morbidity, 48-hour mortality rates, and 24-hour lactate
This was a multicenter, randomized, single-blinded, normal saline procedure-controlled,
efficacy and safety study of DCLHb in severe traumatic hemorrhagic shock (Figure 1). This clinical trial was conducted
in compliance with the regulations governing good clinical trials and good
clinical practice. Study sites were selected based on the presence of a high
volume of critically injured trauma patients, as measured by the need for
immediate blood transfusion, urgent operative intervention, and overall trauma
The study was designed to include approximately 850 trauma patients
with presumed or proven hemorrhage and persistent hypoperfusion at the time
of initial hospital presentation. Cellular hypoxia was demonstrated by vital-sign
instability or a critical base deficit, as measured by systolic blood pressure
of no more than 90 mm Hg and a heart rate of at least 120/min; systolic blood
pressure of no more than 90 mm Hg and a heart rate of less than 60/min (preterminal
rhythm); or a base deficit of more than 15 mEq/L. These patients were expected
to have a 40% mortality rate based on the prior experience and trauma registry
data of the participating investigators. These patients could arrive either
directly from the prehospital setting or as a result of hospital transfer.
There was no restriction in the use of fluids, blood, or any other intervention
prior to enrollment in this study.
Patients with significant traumatic brain injury, as determined by clinical
criteria (ie, posturing, blown pupil) that suggest a space-occupying lesion,
were excluded. Patients whose death was thought to be imminent, suggesting
a futile resuscitation effort, were also excluded, as were patients whose
injury occurred more than 4 hours prior to infusion. Also excluded from the
protocol were minors, pregnant women, and patients opposed to study participation
or the use of blood or blood products. Although there was an attempt to enroll
all eligible patients into this study, the data do not reflect a consecutive
patient series. Outcome data for patients who either refused participation
or were missed as potential study participants were not collected.
Randomization was stratified by clinical site, using permuted blocks
of 4 or 6 patients.21 The investigators were
informed of this randomization scheme in the study protocol. Each site was
provided with a sequential set of sealed envelopes containing treatment assignments.
The act of opening the envelope constituted randomization of the patient.
Two patients were inadvertently given the alternate solution instead of the
one they were randomized to receive. In these cases, data were analyzed based
on the actual solution received.
Investigators were blinded to the treatment allocation prior to patient
randomization. The study personnel who obtained consent to continue, patients,
and their proxies were to remain blinded to treatment group whenever possible.
The expert who did the centralized injury severity scoring was also blinded
to treatment assignment, as were members of the data monitoring committee,
the lead investigators, and the sponsor. The health care workers who treated
the patients were not blinded to treatment because of the red color of the
The new biological entity tested in this study was a 10-g/dL solution
of modified tetrameric hemoglobin (DCLHb) in a balanced electrolyte solution.22 The product was prepared from units of human red
blood cells from volunteer donors whose blood had been tested and found to
have negative results for hepatitis B surface antigen, human immunodeficiency
virus 1 and 2, and hepatitis C virus. The 500- to 1000-mL dose (50 to 100
g of hemoglobin) given in this study provided 714 to 1428 mg/kg of hemoglobin
to a 70-kg person. After randomization, patients were infused unless they
became ineligible or could not be infused for other clinically relevant reasons.
Trauma patients who met the specified criteria within 60 minutes of hospital
arrival received up to 1000 mL of either the 10% DCLHb solution or normal
saline through a dedicated central or peripheral intravenous line. The infusion
was to begin no later than 30 minutes after the patient first met the entry
criteria in the study hospital and within 60 minutes of hospital arrival.
The entire dosing of the study solution was to be completed within 60 minutes
of its onset, such that no patient received study solution after being in
the hospital for more than 2 hours.
Each patient was to receive a minimum of 500 mL, which was 2 units of
study solution. If, after the infusion of 500 mL, the patient still met entry
criteria, up to 2 additional 250-mL infusions could be given. Study solution
infusion was discontinued if adverse events such as uncontrolled hypertension
occurred. No standard therapies were mandated or withheld by the study protocol.
The primary end point of the study, as determined by the investigators,
sponsor, and federal regulators and their advisors, was 28-day mortality.
The secondary end points included 28-day morbidity, as measured by the multiple
organ dysfunction (MOD) score,23 48-hour mortality,
and the 24-hour lactate level.
Patient symptoms and adverse events were evaluated by the study investigators
using a graded severity index.24,25
Investigators reported to the sponsor and their institutional review board
any serious adverse event that occurred within the 28-day study period, and
the sponsor notified the US Food and Drug Administration (FDA) and all investigators
of unexpected serious adverse events associated with the use of DCLHb.
An independent data monitoring committee reviewed aggregate safety data
to identify potential patient safety issues. The data monitoring committee
members remained blinded to treatment group during the data review, until
it was necessary to be informed of the treatment group assignment. The data
monitoring committee also was to review the results of the interim analyses
planned to occur after enrollment of 10%, 25%, 50%, and 75% of the 850 patients.
These results were to be compared with the prospectively defined stopping
The primary efficacy analysis of 28-day mortality vs assigned treatment
was performed using the log rank test, censoring all patients at 28 days.
In addition, Cox proportional hazard models and multiple logistic regression
were used to examine the effect of baseline variables on the relationship
between treatment group and outcome.26,27
Variables used in the Cox models included the hospital site, age, injury severity
score, revised trauma score, and injury mechanism (blunt vs penetrating).28-30 The revised trauma
score was determined at the time of initial hospital evaluation. The Glasgow
Coma Scale score was calculated in patients who required intubation by carrying
forward the last verbal score recorded prior to intubation. A similar adjustment
was made when paralysis was required as an adjunct to patients' management.
The injury severity scores were determined centrally by a single expert with
extensive experience in injury severity scoring. This person was blinded to
treatment allocation and used copies of pertinent portions of the medical
The logistic regression models used other important anatomic and physiologic
variables, such as individual abbreviated injury scale scores, the penetrating
abdominal trauma index score, prehospital cardiac arrest, immediate mechanical
ventilation, preinfusion systolic blood pressure, and baseline laboratory
values including hemoglobin, hematocrit, lactate, and base deficit levels.31,32 These models were developed to determine
if individual or multiple-baseline covariates altered the overall observed
Treatment comparisons for continuous variables were performed using
the Wilcoxon rank sum test, and the Pearson χ2
test for categorical variables. Similar analyses were completed for the 48-hour
mortality end point. Baseline mortality risk prediction also used the trauma
related injury severity score (TRISS) methodology.33
The area under the curve was calculated for the MOD scores across days
1, 4, 7, 10, 14, 21, and 28 for both groups using the trapezoidal rule, omitting
the hepatic component from the day-1 score due to DCLHb interference. For
nonsurvivors, the maximum MOD score of 24 was assigned at the time of death
and carried forward through the remaining time points. Patients who were discharged
early and lost to follow-up had their last in-hospital day MOD score carried
forward for analysis. Any missing organ system scores were interpolated using
nonmissing values from other time points. For sample size estimation, a 28-day
mortality rate of 40% was assumed for the standard therapy group, with an
expected 25% reduction in mortality to 30% in the DCLHb group. This difference
can be detected with 850 patients at 85% power (α = .05, 2-sided).
An exception from informed consent was used when it was not feasible
to obtain prospective informed consent from the patients, their families,
or their legally authorized representatives. The consent procedures followed
FDA regulation 21 CFR 50, based on the prospect of direct benefit to the study
subjects, the expected favorable risk-benefit profile of DCLHb, the frequent
lack of feasibility in obtaining prospective informed consent in this severely
injured patient population, and the unproven or unsatisfactory nature of current
available therapies for severe, uncontrolled traumatic hemorrhagic shock.34-36 The community consultation
and public disclosure requirements established in the regulations were fulfilled
in each institution based on local needs, as determined by the institutional
review board. Once completed, a summary of these activities was provided to
the FDA and the data monitoring committee chairman. The study protocol and
the patient consent procedures were also approved by each hospital institutional
review board prior to the initiation of patient enrollment.
Patients were enrolled in the study by 17 of 18 approved hospitals between
February 1997 and January 1998. Patient enrollment was suspended on January
1, 1998, and terminated on March 17, 1998, by the study's sponsor, based on
the recommendation of the data monitoring committee. A total of 112 patients
were randomized, and 98 (88%) were infused (Figure 1). Consent was withdrawn for 1 patient, a minor, whose data
are excluded from all analyses. The following data are based on the treatment
received in the remaining 98 infused patients, including the 2 patients who
were inadvertently infused with the alternate solution.
The mean (SD) patient age was 39 (20) years, 79% were men, and 56% white
(Table 1). The most common injury
mechanisms were motor vehicle crash (36%) and gunshot wound (32%), with blunt
trauma present in 56% of patients. The enrollment criteria distribution did
not differ between the 2 groups, with vital signs suggestive of uncompensated
shock (systolic blood pressure ≤90 mm Hg, heart rate ≥120/min) present
in 72% of the patients at the time of study eligibility
(Table 1). The number of prior traumatic arrests was higher (13%
vs 2%, P = .04), and the mean (SD) preinfusion diastolic
blood pressure tended to be lower in the DCLHb group (50  vs 61  mm
Hg, P = .06). No other baseline variables differed
significantly in the 2 groups (Table 1
and Table 2). This lack of observed
difference in these other variables (such as the revised trauma score and
Glasgow Coma Scale ) was true for the mean and median values, as well as the
overall data distributions.
The mean (SD) number of 250-mL study–solution units infused was
2.5 (0.9), and only 35% of patients were infused with more than 2 units of
study solution. These quantities did not differ by treatment group.
Among all randomized patients, at 28 days, there were 27 deaths (47%)
in the 58 patients assigned to receive DCLHb, and 13 deaths (25%) in the 53
patients assigned to receive standard therapy (odds ratio [OR], 2.7; 95% confidence
interval [CI], 1.2-6.0; P = .015)
(Table 3). In the 98 infused patients, 32 died for an overall mortality
rate of 33%, with 27 (84%) of 32 deaths occurring within 48 hours of infusion.
At 28 days, there were 24 deaths (46%) in the 52 patients infused with DCLHb,
and 8 deaths (17%) in the 46 control patients (OR, 4.1; 95% CI, 1.6-10; P = .003). The covariate-adjusted hazard ratio, using a
Cox proportional hazard model, was 3.8 (95% CI, 1.4-11; P = .012). Using logistic regression, the adjusted mortality OR was
14 (95% CI, 2.8-67; P = .001). In the regression
model that included only the 4 variables used to develop the TRISS model,
the adjusted mortality OR was 6.0 (95% CI; 1.6-22; P
Using the original TRISS-model coefficients, the predicted overall mortality
in the DCLHb group was 41%, and in the control group it was 34%. Using the
actual observed and expected TRISS-mortality rates, the adjusted relative
risk due to DCLHb treatment was 2.07.
The Kaplan-Meier curves display the effect of treatment on mortality
over the 28-day study period, with the higher survival rate noted in the control
group (Figure 2). The mortality
odds ratio associated with infusion of DCLHb (vs saline) was consistent across
a variety of clinically relevant subgroups. The only patients receiving DCLHb,
for whom the 28-day mortality OR was not increased, were those who were randomized
to receive DCLHb but were not infused (Figure
3). In none of the 17 centers was the observed mortality rate for
patients infused with DCLHb lower than for those treated with normal saline.
The overall mortality rate at 48 hours was 28%. There were 20 deaths
(38%) among the 52 patients who were infused with DCLHb, and 7 deaths (15%)
among the 46 patients infused with saline (OR, 3.5; 95% CI, 1.3-9.2; P = .01) (Table 3).
Morbidity, as measured by the MOD/time curve, was 72% higher in the DCLHb
group over the 28-day study period (mean [SD], 348  vs 202 ; P = .03). This occurred, in part, as a result of the convention
that patients who died were given the highest MOD score and the higher mortality
rate in the DCLHb group. In the 55 patients whose arterial lactate levels
were obtained at 24 hours, the levels were comparable 2.9 (2.0) vs 2.6 (1.9)
mmol/L; DCLHb vs control; P = .29).
The rate of serious adverse events (SAEs), including death, did not
differ by treatment group (48% vs 35%, DCLHb vs control, P = .18). The adverse event rates by body system also did not differ
by treatment group, although the overall proportion of life-threatening adverse
events (including death) was greater in the DCLHb group (46% vs 24%, P = .04).
Even when the resuscitation of patients with severe, uncompensated,
traumatic hemorrhagic shock is optimal, many patients die, either acutely
or as a result of significant postoperative morbidity.1
Crystalloids, colloids, and blood have been used with variable success in
these critically injured patients.37-39
A number of different hemoglobin-based oxygen carriers have been developed
with the goal of improving cellular perfusion through the use of a modified,
stroma-free hemoglobin solution that carries oxygen.40
In preclinical models, DCLHb has been shown to be effective in enhancing
cellular perfusion in small volumes, suggesting a pharmacologic effect that
is independent of the actual number of hemoglobin molecules carried in the
solution.41,42 DCLHb has also
been demonstrated to be effective in improving acute trauma resuscitation
in preclinical models.41-46
In this study, DCLHb was tested not as a substitute for blood but rather as
an adjunct to the currently used therapies for enhancing oxygen delivery:
fluids, blood, and operative intervention.45
This study was designed to determine whether the use of DCLHb could
enhance the standard of care and decrease the number of acute deaths and late
multisystem organ failure deaths caused by severe, uncompensated traumatic
The study protocol was developed with the input of clinicians, scientists,
regulators, and lay persons over a 2-year period. Several iterations were
reviewed to maximize the likelihood that the question of efficacy could be
answered with minimal patient risk. Review of this protocol by the Blood Products
Advisory Committee of the FDA in 1996 allowed the FDA to determine that the
risk-benefit potential of this clinical trial and the use of the new consent
regulations were appropriate.
This was the first clinical trial conducted using the new informed consent
regulations, which were published in October 1996.36
This study merited the use of a consent exception because it was believed
that DCLHb had the potential to improve survival in trauma patients whose
mortality risk was high despite the delivery of optimal standard care.34,35 As was required by the regulations,
this protocol and the informed consent process was approved by each hospital's
institutional review board. Information regarding the use of the consent exception
was disseminated by the investigators using community consultation and public
The majority of patients were enrolled with vital signs indicative of
acute hemorrhage and uncompensated vascular collapse. Although hypotension
may not consistently herald severe hemorrhage, this clinical finding was chosen
because of its clinical relevance and the lack of other easily obtained acute
markers of uncompensated hemorrhage. The base deficit criterion of 15 mEq/L
was chosen because it was correlated with a high-mortality risk, with the
understanding that it may result in the inclusion of patients with greater
injury severity than those enrolled by vital sign criteria.2,3
The overall mortality rate of 33% in the 98 infused patients was comparable
to the pretrial projected mortality rate of 40% and rates seen in comparable
hemorrhagic shock patients.1 Both the 28-day
and 48-hour mortality rates were higher in the subgroup that was infused with
DCLHb. No subgroup analysis or covariate adjustment altered this mortality
imbalance. The hypothesis that DCLHb would improve outcome in severe traumatic
shock could not be proven, despite the fact that beneficial DCLHb effects
were observed in preclinical studies and other clinical trials.
The 28-day MOD score and the 24-hour lactate clearance end points also
did not demonstrate a beneficial DCLHb effect. The absence of morbidity and
perfusion marker improvements was due, in part, to the higher mortality rate
in the DCLHb group, which limited the ability to measure morbidity independently
using these 2 clinical markers.
Although the results strongly suggest an adverse treatment effect, for
several reasons, we believe it is not possible to conclude definitively that
the mortality imbalance was due solely to a DCLHb-treatment effect. Because
no data exist that confirm a plausible effect mechanism (such as accelerated
hemorrhage), other contributing factors, including baseline mortality risk
differences, study design, and study conduct, all must be considered. The
finding that preinfusion cardiac arrest rates differed between treatment groups
suggests that baseline mortality risk might have differed in other ways, and
that type 2 errors might have caused these other baseline differences to remain
undetected. For example, although the difference was not statistically significant,
9 additional patients in the DCLHb group presented with a Glasgow Coma Scale
score of 3. Death in these patients likely did not result from treatment assignment
but rather from severe traumatic brain injury or profound hemorrhage. Also,
study conduct issues detected during patient enrollment and the data review
process suggest potential study biases. Finally, both the preclinical studies
and the clinical trials of DCLHb failed to demonstrate increased mortality
when using DCLHb in various other settings, including hemorrhagic shock.41,43,44,46,49-53
The most commonly suggested mechanism for a direct untoward DCLHb-treatment
effect is the known pressor effect of this and other hemoglobin solutions.54-56 The pressor effect
could have adversely influenced outcome either by accelerating hemorrhage
or by scavenging nitric oxide, both of which could have caused vascular effects
that diminished cellular perfusion.57,58 Although
accelerated hemorrhage is the more plausible mechanism given the early timing
of the majority of deaths, neither theory could be substantiated with the
data from the study. Neither uncontrolled bleeding nor higher blood pressures
were systematically demonstrated in patients who received DCLHb. Similarly,
neither accelerated hemorrhage nor uncontrolled hypertension were demonstrated
in perioperative patients treated with DCLHb or in those treated in the prehospital
traumatic hemorrhagic shock clinical trial conducted in Europe59
(Baxter Hemoglobin Therapeutics, Boulder, Colo; US Peri-operative DCLHb efficacy
trial and European Host DCLHb efficacy trial, unpublished data, 1999).
Based on the belief that DCLHb might be able to improve perfusion dramatically
even in patients who have only a minimal chance of survival, the study allowed
the enrollment of prehospital traumatic arrest patients who had arrived at
the hospital with vital signs. This was allowed despite the fact that traumatic
arrest patients have a uniformly poor outcome, with survival rates of less
than 5%.60 The difference in the preinfusion
diastolic blood pressure between groups occurred, in part, due to the fact
that some of the patients treated with DCLHb had no measurable diastolic blood
pressure at the time of infusion. As with the preinfusion cardiac arrest data,
this observation suggests that the preinfusion physiologic status of the DCLHb
patients may have differed from those in the control group, possibly affecting
the mortality results. However, regardless of their being some baseline differences
suggested, the models used to adjust for these covariates showed a consistent
Certain factors of the study design and conduct, such as the unavoidable
knowledge of the infused study solutions and the inherent difficulty of conducting
research in the emergency setting, may also have led to study biases. Some
of the patients who were randomized were ultimately not infused, most often
because they met exclusion criteria after randomization. The observation that
the 7 randomized, noninfused control patients had the highest mortality rate
(71%) suggests a possible infusion bias. The inclination to infuse more aggressively
patients randomized to receive DCLHb is a reflection of the earnest desire
of the investigators to increase the survival chances of patients for whom
standard therapy appeared to offer little hope.
There may also have been differences in the way patients were treated
based on treatment group assignment. For example, the volume of blood and
fluid administration during the first 8 hours of resuscitation differed by
treatment group in the subgroup of patients who died within 24 hours of infusion.
The tendency to delay the infusion of blood for patients receiving DCLHb may
have resulted from its looking like blood. This delay might also have occurred
because DCLHb was reported to cause patients to improve clinically (improved
vital signs, skin color, and mental status), although no data supported this
clinical observation. Concern that the Hawthorne effect might have caused
a treatment bias was highlighted by the observation that the trauma center
personnel had heightened expectations for the study's success as a result
of extensive prestudy public disclosure.61
These findings will be further explored to better understand to what
extent DCLHb toxicity, baseline mortality differences, study design, and study
conduct may have influenced these efficacy results.
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