Effect of diaspirin crosslinked hemoglobin (DCLHb HemAssist) during high blood loss surgery on selected indices of organ function

A Novel Cross-Linked Hemoglobin-Based Oxygen Carrier, YQ23, Extended the Golden Hour for Uncontrolled Hemorrhagic Shock in Rats and Miniature Pigs

Background: Hypotensive resuscitation is widely applied for trauma and war injury to reduce bleeding during damage-control resuscitation, but the treatment time window is limited in order to avoid hypoxia-associated organ injury. Whether a novel hemoglobin-based oxygen carrier (HBOC), YQ23 in this study, could protect organ function, and extend the Golden Hour for treatment is unclear. Method: Uncontrolled hemorrhagic shock rats and miniature pigs were infused with 0.5, 2, and 5% YQ23 before bleeding was controlled, while Lactate Ringer's solution (LR) and fresh whole blood plus LR (WB + LR) were set as controls. During hypotensive resuscitation the mean blood pressure was maintained at 50-60 mmHg for 60 min. Hemodynamics, oxygen delivery and utilization, blood loss, fluid demand, organ function, animal survival as well as side effects were observed. Besides, in order to observe whether YQ23 could extend the Golden Hour, the hypotensive resuscitation duration was extended to 180 min and animal survival was observed. Results: Compared with LR, infusion of YQ23 in the 60 min pre-hospital hypotensive resuscitation significantly reduced blood loss and the fluid demand in both rats and pigs. Besides, YQ23 could effectively stabilize hemodynamics, and increase tissue oxygen consumption, increase the cardiac output, reduce liver and kidney injury, which helped to reduce the early death and improve animal survival. In addition, the hypotensive resuscitation duration could be extended to 180 min using YQ23. Side effects such as vasoconstriction and renal injury were not observed. The beneficial effects of 5% YQ23 are equivalent to similar volume of WB + LR. Conclusion: HBOC, such as YQ23, played vital roles in damage-control resuscitation for emergency care and benefited the uncontrolled hemorrhagic shock in the pre-hospital treatment by increasing oxygen delivery, reducing organ injury. Besides, HBOC could benefit the injured and trauma patients by extending the Golden Hour.

Nanomedicines: A Potential Treatment for Blood Disorder Diseases

Blood disorder diseases (BDDs), also known as hematologic, is one of the diseases owing to hematopoietic system disorder. Chemotherapy, bone marrow transplantation, and stem cells therapy have been used to treat BDDs. However, the cure rates are still low due to the availability of the right type of bone marrow and the likelihood of recurrence and infection. With the rapid development of nanotechnology in the field of biomedicine, artificial blood or blood substitute has shown promising features for the emergency treatment of BDDs. Herein, we surveyed recent advances in the development of artificial blood components: gas carrier components (erythrocyte substitutes), immune response components (white blood cell substitutes), and hemostasis-responsive components (platelet substitutes). Platelet-inspired nanomedicines for cancer treatment were also discussed. The challenges and prospects of these treatment options in future nanomedicine development are discussed.

Pharmacokinetics and mechanisms of plasma removal of hemoglobin-based oxygen carriers

The circulatory persistence, distribution, and metabolism of hemoglobin-based oxygen carriers (HBOCs) is a major determinant of their safety and efficacy. In this communication, published data on the pharmacokinetics and routes of plasma elimination of HBOCs are summarized and evaluated. The circulating half-life of HBOCs is dose-dependent in both animals and humans. Half-life also increases with molecular weight in animals, at least up to the MDa range. The functional half-life of HBOCs is diminished by as much as 40% due to oxidation of the heme group relative to the overall rate of removal of hemoglobin (Hb) from plasma. Kidney excretion of HBOCs is greatly diminished compared to that of unmodified Hb, but the liver remains a primary site of catabolism. Both hepatocytes and Kupffer cells have been implicated in receptor-mediated HBOC uptake. Removal also occurs in the spleen and/or bone marrow and probably at dispersed sites in the endothelium as well. HBOCs extravasate into the lymph at a rate inversely proportional to their molecular weight and are taken up by monocyte/macrophage CD163 receptors, both as free Hb and in complexes with haptoglobin (Hp). The interactions with both Hp and the CD163 receptor are altered by Hb modification. However, monocyte/macrophage uptake may not be a quantitatively important route for the removal of clinically relevant doses of HBOCs. The relative contributions of different removal pathways have yet to be comprehensively determined, particularly in humans.

Oxygen delivery during extreme anemia with ultra-pure earthworm hemoglobin

AIM

Lumbricus terrestris (earthworm) erythrocruorin (LtEc) is a naturally occurring extracellular hemoglobin (Hb) with high molecular weight (3.6MDa), low autoxidation rate, and limited nitric oxide (NO) dioxygenation activity. These properties make LtEc a potential candidate for use as red blood cell (RBC) substitute, i.e. Hb-based oxygen carrier (HBOC). Previous studies have shown that small amounts of LtEc can be safely transfused into mice, rats, and hamsters without eliciting major side effects. Therefore, this study was designed to understand oxygen (O(2)) transport to tissues and systemic/microvascular hemodynamics induced by LtEc during anemic conditions.

MAIN METHODS

Hamsters fitted with dorsal window chambers were hemodiluted to 18% hematocrit (Hct) using 6g/dL dextran 70kDa (Dex70). Hemodilution was then continued to 11% Hct using 10g/dL LtEc, 6g/dL Dex70 or 10g/dL human serum albumin (HSA). Blood pressure, heart rate, blood gas parameters, microvascular hemodynamics, microvascular blood flow, functional capillary density (FCD), intravascular pO(2) and perivascular pO(2) were studied.

KEY FINDINGS

LtEc maintained blood pressure without inducing vasoconstriction while increasing microvascular perfusion and FCD relative to Dex70 and HSA. LtEc increased blood O(2) carrying capacity and maintained systemic and microvascular parameters without decreasing arteriolar diameter or increasing vascular resistance with during extreme anemia. LtEc increased O(2) delivery compared to conventional plasma expanders.

SIGNIFICANCE

LtEc or synthetic molecules that replicate the characteristics of LtEc could be effective O(2) carriers with potential to be used in transfusion medicine to prevent tissue anoxia resulting from severe anemia.

Diaspirin cross-linked hemoglobin infusion did not influence base deficit and lactic acid levels in two clinical trials of traumatic hemorrhagic shock patient resuscitation

BACKGROUND

Diaspirin cross-linked hemoglobin (DCLHb) has demonstrated a pressor effect that could adversely affect traumatic hemorrhagic shock patients through diminished perfusion to vital organs, causing base deficit (BD) and lactate abnormalities.

METHODS

Data from two parallel, multicenter traumatic hemorrhagic shock clinical trials from 17 US Emergency Departments and 27 European Union prehospital services using DCLHb, a hemoglobin-based resuscitation fluid.

RESULTS

In the 219 patients, the mean age was 37.3 years, 64% of the patients sustained a blunt injury, 48% received DCLHb resuscitation, and the overall 28-day mortality rate was 36.5%. BD data did not differ by treatment group (DCLHb vs. normal saline [NS]) at any time point. Study entry BD was higher in patients who died when compared with survivors in both studies (US: -14.7 vs. -9.3 and European Union: -11.1 vs. -4.1 mEq/L, p < 0.003) and at the first three time points after resuscitation. No differences in BD based on treatment group were observed in either those who survived or those who died from the hemorrhagic shock. US lactate data did not differ by treatment group (DCLHb vs. NS) at any time point. Study entry lactates were higher in US patients who ultimately died when compared with survivors (82.4 vs. 56.1 mmol/L, p < 0.003) and at all five postresuscitation time points. No lactate differences were observed between DCLHb and NS survivors or in those who died based on treatment group.

CONCLUSIONS

Although patients who died had more greatly altered perfusion than those who survived, DCLHb treatment of traumatic hemorrhagic shock patients was not associated with BD or lactate abnormalities that would indicate poor perfusion.

The lack of consistent diaspirin cross-linked hemoglobin infusion blood pressure effects in the US and EU traumatic hemorrhagic shock clinical trials

Hemoglobin solutions have demonstrated a pressor effect that could adversely affect hemorrhagic shock patient resuscitation through accelerated hemorrhage, diminished perfusion, or inadequate resuscitation. Data from two parallel, multicenter traumatic hemorrhagic shock clinical trials in 17 US emergency departments and in 27 EU prehospital systems using diaspirin cross-linked hemoglobin (DCLHb), a hemoglobin-based resuscitation fluid. In the 219 patients, patients were 37 years old, 64% sustained blunt injury, 48% received DCLHb, and 36% expired. Although mean systolic blood pressure (SBP) and diastolic blood pressure values differed at 2 of the 10 measured time points, blood pressure (BP) curve analysis showed no SBP, diastolic blood pressure, or MAP differences based on treatment. Although SBP values 160 and 120 mmHg or greater were 2.2x and 2.6x more frequently noted in survivors, they were not more common with DCLHb use or in DCLHb patients who expired in US study nonsurvivors or in any EU study patients. Systolic blood pressure values 160 and 120 mmHg or greater were 2.8x and 1.3x more frequently noted in DCLHb survivors as compared with normal saline survivors. Only 3% of the BP variation noted could be attributed to DCLHb use, and as expected, injury severity and baseline physiologic status were stronger predictors. In the United States alone, treatment group was not correlated by regression with BP at any time point. Neither mean BP readings nor elevated BP readings were correlated with DCLHb treatment of traumatic hemorrhagic shock patients. As such, no clinically demonstrable DCLHb pressor effect could be directly related to the adverse mortality outcome observed in the US study.

Evaluation of Angiotensin Converting Enzyme (ACE)-Like Activity of Acellular Hemoglobin

Despite the tremendous progress in research on hemoglobin (Hb) cellular and molecular responses, the current understanding of Hb's overall intrinsic toxicity is still limited. The complete mechanism of Hb-induced vasoconstriction has not yet been established, particularly the involvement of the renin-angiotensin system (RAS). Some studies emphasized that Hb may augment the vascular responsiveness to angiotensin (Ang)-II. It was also reported that Hb, as well as Ang-II, influences the synthesis of 8-iso prostaglandin F2 alpha, which has an impact on renal flow and possibly RAS. Hb in the presence of H(2)O(2) gains enzymatic activity. Thus, it is possible that Hb directly and/or indirectly can activate RAS. In this study, we monitored the effect of ferrous- and ferryl-Hb, and H(2)O(2) alone, on conversion of Ang-I to its active metabolites. The structural and immunological identity of the resulting products were evaluated by reversed phase C-18 HPLC and ELISA, respectively. Additionally, ACE-like activity of Hbs was measured spectrophotometrically by determining their ability to react with the ACE substrate, the synthetic tripeptide N-[3-(2-furyl)acryloyl]-L-phenylalanylglycylglycine. Results indicate that while ferrous-Hb can serve as a receptor for Ang-I, its ferryl form possesses ACE-like activity, being able to convert, within minutes, Ang-I to Ang-II, Ang-III, Ang-IV, Ang (1-7) and other unresolved fragments. H(2)O(2) itself had a very limited hydrolyzing effect on Ang-I. Based on this study, it can be concluded that ACE-like activity of Hb with rapid formation of active angiotensins may be a contributor to the still unexplained vasoconstrictive response observed immediately after Hb administration.

Hemoglobin-based oxygen carrying compound-201 as salvage therapy for severe neuro- and polytrauma (Injury Severity Score = 27-41)

OBJECTIVE

A prehospital trial in trauma patients has been proposed to evaluate Hemopure (hemoglobin glutamer-250 [bovine], hemoglobin-based oxygen carrying compound [HBOC]-201, Biopure). We tested the hypothesis that HBOC-201 would improve cerebrovascular resuscitation in a unique polytrauma model.

DESIGN

Prospective, randomized, blinded animal study.

SUBJECTS

Thirty-two anesthetized swine (42 +/- 1 kg).

INTERVENTIONS

Blunt trauma to the head, right chest, and bilateral femurs (Injury Severity Score = 27-41) with captive bolt guns was followed by hypoventilation. Resuscitation was divided into phases to simulate conventional treatment in the prehospital, emergency room, and early intensive care unit. For 30-60 mins postinjury, 500 mL of either normal saline (control, n = 14) or HBOC-201 (n = 14) was administered. All received similar care thereafter. For 60-120 mins, normal saline maintained systolic arterial pressure >100 mm Hg and heart rate <100 beats/min plus mannitol (250 mg/kg) for intracranial hypertension. For 120-480 mins, phenylephrine, normal saline, and dextrose were administered to maintain cerebral perfusion pressure >70 mm Hg, filling pressure >12 mm Hg, and plasma glucose >60 mg%, respectively. Two formulations of HBOC-201 (average MW = 250 kDa) were tested: one with <3% 65 kDa tetramers (n = 7) and the other with <0.3% 65 kDa tetramers (n = 7).

MEASUREMENTS AND MAIN RESULTS

Injury severity is reflected by the death of 2 of 32 swine within 30 mins. In survivors (n = 30), systolic arterial pressure was 83 +/- 6 mm Hg, heart rate was 115 +/- 5 beats/min, and lactate was 5.8 +/- 0.4 mM. Intracranial pressure rose from 8 +/- 1 to 18 +/- 1 mm Hg and brain tissue PO2 fell from 17 +/- 1 to 2 +/- 1 mm Hg. Without immediate resuscitation, death occurred within 60 mins (n = 2). With normal saline resuscitation (n = 14), systemic hemodynamics, mixed venous oxygen, renal oxygen, portal oxygen, and muscle oxygen corrected but there were four deaths (two at 45 mins, one at 100 mins, and one at 200 mins). Cerebral perfusion pressure was not restored until mannitol and pressor therapy were initiated at 120 mins. In contrast, with HBOC-201 at 30 mins (n = 14), systolic arterial pressure and cerebral perfusion pressure corrected immediately (both p < 0.05) and there were no deaths (p = 0.0978). After 8 hrs, in both groups, cerebral perfusion pressure, systolic arterial pressure, and heart rate were stable; peripheral oxygen saturations were near normal; lactate was cleared; urine output was adequate. However, with HBOC-201, pressor and fluid requirements were reduced by half, which improved intracranial pressure and brain tissue PO2 (all p < 0.05 vs. control). Reducing tetramer content had no significant effect on the actions of HBOC-201.

CONCLUSIONS

1) A single bolus of HBOC-201 at initial resuscitation rapidly restored cerebral perfusion pressure and stabilized hemodynamics with improved intracranial pressure and brain oxygen for the first 8 hrs; and 2) HBOC-201 could be an effective salvage therapy after severe neurotrauma or as a temporizing measure during prolonged transport of a polytrauma patient.

Pharmacologic Interventions for the Management of Critical Bleeding

Hospital pharmacists are often consulted for their knowledge about coagulation and therapeutic interventions for the management of critical bleeding. Many pharmacotherapies are available for this purpose, both systemic and topical, and others are in development. These agents and their mechanisms of action are reviewed, and perspectives are provided regarding their use in various clinical settings. Also provided are associated precautions to promote safe use. Current controversies surrounding pharmacotherapeutic agents used to control serious bleeding (e.g., in various types of surgery, trauma, obstetrics, and intracranial hemorrhage) are also discussed.

Toxicity and hemodynamic effects after single dose administration of MalPEG-hemoglobin (MP4) in rhesus monkeys

Maleimide-polyethylene glycol-modified (MalPEG) hemoglobin, 4.3 g/dL (MP4; Hemospan), is a hemoglobin-based oxygen carrier consisting of human hemoglobin (Hb) modified with maleimide polyethylene glycol. This study evaluates the potential toxicity and hemodynamic actions of a single dose of MP4 administered by exchange transfusion to rhesus monkeys. Monkeys were administered MP4 (21 mL/kg, or approximately 30% of estimated blood volume) or an equivalent volume of lactated Ringer's solution (LR). In the toxicity study, blood samples were obtained predose and 3, 7, and 13 days after dosing for clinical chemistry and hematology. Animals were euthanized for complete necropsy and histopathology on day 3 or day 13. A separate group of animals was used for evaluation of arterial pressure, core temperature, and electrocardiogram, by telemetry, for 7 days after dosing with MP4. The results demonstrate no significant toxicity, with only modest, transient elevation of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) on day 3. Mild anemia caused by hemodilution was observed at each time point in both groups, but to a slightly greater degree in the MP4-treated animals. Histologic observations included foamy or vacuolated macrophages in the spleen and marrow of the sternum, rib, and femur, representing the accumulation of test article or a metabolite. In the telemetry study, no changes occurred in arterial pressure, heart rate, or electrocardiogram attributable to administration of MP4 at any time for 7 days after administration. These results demonstrate that MP4 is safe and is without hemodynamic effects when administered as an exchange transfusion of 30% of estimated blood volume.

Blood doping: present procedures and detection techniques

Blood doping represents a serious risk in endurance athletes. Blood transfusion practices (either autologous or homologous) have been used since 1960 and, despite the significant improvement in the laboratory methods, only homologous blood transfusion can be detected currently, while for autologous blood transfusion, no validated methods exist. In the last 15 years, a number of drugs have been developed to treat anemic patients. From recombinant erythropoietin to synthetic hemoglobin, all the developed tools are potentially useful to increase the oxygen transport to peripheral tissues in endurance athletes. Thus, the availability of doping-detection methods can only be sustained by the knowledge of any novel therapeutic approach in this field. The identification of the doping molecule is the gold standard of any antidoping campaign; despite this, indirect methods based on the detection of the effects induced by the doping procedure will be a very powerful tool in the near future. Nevertheless, while direct methods are only affected by the sensitivity and the specificity of the method itself (deterministic methods), indirect approaches are affected by the statistic weight of the results (probabilistic methods). Thus, blood doping will be better controlled by the combination of the two approaches.

Profiling biochemical and hemodynamic markers using chronically instrumented, conscious and unrestrained rats undergoing severe, acute controlled hemorrhagic hypovolemic shock as an integrated in-vivo model system to assess new blood substitutes

The aim of the present study was to assess several biochemical and physiological endpoint parameters alongside controlled hemorrhagic and recovery phases of chronically instrumented, conscious and unrestrained healthy rats. Male Sprague-Dawley rats (12-14 weeks; 430+/-20 g; n=22-18) were instrumented with a saline-perfused femoral arterial catheter and placed individually in a metabolic cage for up to 20 days, allowing instant assessments of the hemodynamic profile and blood and urine sampling for hematological profile and biochemical measurements to assess hepatic, renal and metabolic functions. In addition, body weight, food and water intake, and diuresis were monitored daily. After a 7-day stabilization period, the rats underwent severe and acute hemorrhagic shock (HS) (removal of 50% of total circulating blood volume), kept in hypovolemic shock for an ischemic period of 50 min and then resuscitated over 10 min. Gr. 1 was re-infused with autologous shed blood (AB; n=10) whereas Gr. 2 was infused 1:1 with a solution of sterile saline-albumin (SA; 7% w/v) (n=8-12). Ischemic rats recovered much more rapidly following AB re-infusion than those receiving SA. Normal hemodynamic and biochemical profiles were re-established after 24 h. Depressed blood pressure lasted 4-5 days in SA rats. The hematological profile in the SA resuscitated rats was even more drastically affected. Circulating plasma concentrations of hemoglobin (-40%), hematocrit (-50%), RBC (-40%) and platelets (-41%) counts were still severely decreased 24 h after the acute ischemic event whereas WBC counts increased 2.2-fold by day 4. It took 5-9 days for these profiles to normalize after ischemia-reperfusion with SA. Diuresis increased in both groups (by 45+/-7% on day 1) but presented distinct electrolytic profiles. Hepatic and renal functions were normal in AB rats whereas altered in SA rats. The present set of experiments enabled us to validate a model of HS in conscious rats and the use of an integrated in vivo platform as a valuable tool to characterize HS-induced stress and to test new classes of blood substitutes in real time, post-event, over days.

Chemical physiology of blood flow regulation by red blood cells: the role of nitric oxide and S-nitrosohemoglobin

Blood flow in the microcirculation is regulated by physiological oxygen (O2) gradients that are coupled to vasoconstriction or vasodilation, the domain of nitric oxide (NO) bioactivity. The mechanism by which the O2 content of blood elicits NO signaling to regulate blood flow, however, is a major unanswered question in vascular biology. While the hemoglobin in red blood cells (RBCs) would appear to be an ideal sensor, conventional wisdom about its chemistry with NO poses a problem for understanding how it could elicit vasodilation. Experiments from several laboratories have, nevertheless, very recently established that RBCs provide a novel NO vasodilator activity in which hemoglobin acts as an O2 sensor and O2-responsive NO signal transducer, thereby regulating both peripheral and pulmonary vascular tone. This article reviews these studies, together with biochemical studies, that illuminate the complexity and adaptive responsiveness of NO reactions with hemoglobin. Evidence for the pivotal role of S-nitroso (SNO) hemoglobin in mediating this response is discussed. Collectively, the reviewed work sets the stage for a new understanding of RBC-derived relaxing activity in auto-regulation of blood flow and O2 delivery and of RBC dysfunction in disorders characterized by tissue O2 deficits, such as sickle cell disease, sepsis, diabetes, and heart failure.

Influence of heme-based solutions on stress protein expression and organ failure after hemorrhagic shock

OBJECTIVE

Hemoglobin-based oxygen carriers (e.g., diaspirin-cross-linked hemoglobin [DCLHb] and hemoglobin glutamer-200 [HbG]) may have potential in the treatment of hemorrhagic shock. The nitric oxide scavenging and direct vasoconstrictive side effects of free hemoglobin of currently available preparations may increase organ injury after shock in contrast to non-oxygen-carrying heme solutions (e.g., hemin arginate [HAR]). However, both classes of substances might induce the protective enzyme heme oxygenase (HO)-1, particularly in the liver. The aim of the study was to assess the role of pretreatment with DCLHb, HbG, or HAR on HO-1 expression and organ injury after hemorrhagic shock.

DESIGN

Prospective controlled laboratory study.

SETTING

Animal research laboratory at a university hospital.

SUBJECTS

Male Sprague-Dawley rats (200-300 g body weight, n = 5-12/group).

INTERVENTIONS

Twenty-four hours after different doses of DCLHb, HbG (each 1, 2, or 3 g/kg of body weight), or HAR (5, 25, or 75 mg/kg of body weight), the protein expression of HO-1 and heat shock protein-70 in liver, kidney, heart, lungs, and aorta was determined. Twenty-four hours after pretreatment with DCLHb, HbG, or HAR, rats were subjected to hemorrhage (mean arterial blood pressure, 35-40 mm Hg for 1 or 2 hrs)/resuscitation (5 or 4 hrs, respectively). Animals treated with Ringer's solution (30 mL/kg of body weight) served as controls. In additional experiments, HO activity was blocked with tin mesoporphyrin-IX.

MEASUREMENTS AND MAIN RESULTS

DCLHb, HbG, and HAR dose-dependently induced HO-1 protein but not heat shock protein-70. Pretreatment with DCLHb or HbG shortened the onset of decompensation in shock (DCLHb, 40 +/- 11 mins; HbG, 36 +/- 4 mins) compared with vehicle (68 +/- 4 mins, p < .05) and HAR pretreatment (81 +/- 7 mins, p < .05). High doses of DCLHb pretreatment increased mortality (2 hrs of shock, 80%; p < .05 vs. vehicle or HAR). Pretreatment with HAR led to higher shed blood volumes (p < .05) and higher hepatocellular ATP levels (2 hrs of shock, p < .05 vs. DCLHb and HbG). Blockade of HO activity by tin mesoporphyrin-IX abolished the protection mediated by HAR.

CONCLUSIONS

Although DCLHb, HbG, and HAR induce HO-1 in the absence of an unspecific stress response, only HAR pretreatment protects against shock-induced organ failure. Although the underlying mechanisms of positive HAR priming are not completely understood, the induction of HO-1 expression and the lack of nitric oxide scavenging through HAR may play an important role.

Fluid resuscitation from severe hemorrhagic shock using diaspirin cross-linked hemoglobin fails to improve pancreatic and renal perfusion

BACKGROUND

Fluid resuscitation from hemorrhagic shock is intended to abolish microcirculatory disorders and to restore adequate tissue oxygenation. Diaspirin cross-linked hemoglobin (DCLHb) is a hemoglobin-based oxygen carrier (HBOC) with vasoconstrictive properties. Therefore, fluid resuscitation from severe hemorrhagic shock using DCLHb was expected to improve perfusion pressure and tissue perfusion of kidneys and pancreas.

METHODS

In 20 anesthetized domestic pigs with an experimentally induced coronary stenosis, shock (mean arterial pressure 45 mmHg) was induced by controlled withdrawal of blood and maintained for 60 min. Fluid resuscitation (replacement of the plasma volume withdrawn during hemorrhage) was performed with either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). Completion of resuscitation was followed by a 60-min observation period. Regional blood flow to the kidneys and the pancreas was measured by use of the radioactive microspheres method at baseline, after shock and 60 min after fluid resuscitation.

RESULTS

All animals (10/10) resuscitated with DCLHb survived the 60-min observation period, while 5/10 control animals died within 20 min due to persisting subendocardial ischemia. In contrast to HSA survivors, pancreas and kidneys of DCLHb-treated animals revealed lower total and regional organ perfusion and regional oxygen delivery. Renal and pancreatic blood flow heterogeneity was higher in the DCLHb group.

CONCLUSION

DCLHb-induced vasoconstriction afforded superior myocardial perfusion, but impaired regional perfusion of the kidneys and the pancreas.

Diaspirin-crosslinked hemoglobin reduces blood transfusion in noncardiac surgery: a multicenter, randomized, controlled, double-blinded trial

In this randomized, prospective, double-blinded clinical trial, we sought to investigate whether diaspirin-crosslinked hemoglobin (DCLHb) can reduce the perioperative use of allogeneic blood transfusion. One-hundred-eighty-one elective surgical patients were enrolled at 19 clinical sites from 1996 to 1998. Selection criteria included anticipated transfusion of 2-4 blood units, aortic repair, and major joint or abdomino-pelvic surgery. Once a decision to transfuse had been made, patients received initially up to 3 250-mL infusions of 10% DCLHb (n = 92) or 3 U of packed red blood cells (PRBCs) (n = 89). DCLHb was infused during a 36-h perioperative window. On the day of surgery, 58 of 92 (64%; confidence interval [CI], 54%-74%) DCLHb-treated patients received no allogeneic PRBC transfusions. On Day 1, this number was 44 of 92 (48%; CI, 37%-58%) and decreased further until Day 7, when it was 21 of 92 (23%; CI, 15%-33%). During the 7-day period, 2 (1-4) units of PRBC per patient were used in the DCLHb group compared with 3 (2-4) units in the control patients (P = 0.002; medians and 25th and 75th percentiles). Mortality (4% and 3%, respectively) and incidence of suffering at least one serious adverse event (21% and 15%, respectively) were similar in DCLHb and PRBC groups. The incidence of jaundice, urinary side effects, and pancreatitis were more frequent in DCLHb patients. The study was terminated early because of safety concerns. Whereas the side-effect profile of modified hemoglobin solutions needs to be improved, our data show that hemoglobin solutions can be effective at reducing exposure to allogeneic blood for elective surgery.

IMPLICATIONS

In a randomized, double-blinded red blood cell controlled, multicenter trial, diaspirin-crosslinked hemoglobin spared allogeneic transfusion in 23% of patients undergoing elective noncardiac surgery. The observed side-effect profile indicates a need for improvement in hemoglobin development.