Clinical utility of human polymerized hemoglobin as a blood substitute after acute trauma and urgent surgery

A new era in oxygen therapeutics? From perfluorocarbon systems to haemoglobin-based oxygen carriers

Blood transfusion is the key to life in case of traumatic emergencies, surgeries and in several pathological conditions. An important goal of whole blood or red blood cell transfusion is the fast delivery of oxygen to vital organs and restoration of circulation volume. Whole blood or red blood cell transfusion has several limitations. Free haemoglobin not only loses its tetrameric configuration and extracts via the kidney leading to nephrotoxicity but also scavenges nitric oxide (NO), leading to vasoconstriction and hypertension. PFC based formulations transport oxygen in vivo, the contribution in terms of clinical outcome is challenging. The oxygen-carrying capacity is not the only criterion for the successful development of haemoglobin-based oxygen carriers (HBOCs). This review is a bird's eye view on the present state of the PFCs and HBOCs in which we analyzed the current modifications made or which are underway in development, their promises, and hurdles in clinical implementation.

Intraosseous infusion of liposome-encapsulated hemoglobin (HbV) acutely prevents hemorrhagic anemia-induced lethal arrhythmias and its efficacy persists with preventing proarrhythmic side effects in subacute phase of severe hemodilution model

BACKGROUND

Artificial oxygen carriers (HbV) can treat hemorrhagic shock with lethal arrhythmias (VT/VF). No reports exist on subacute HbV's effects.

METHODS

Acute and subacute resuscitation effects with anti-arrhythmogenesis of HbV were studied in 85% blood exchange rat model (85%-Model). Lethal 85%-Model was created by bone marrow transfusion and femoral artery bleeding in 80 SD rats in HbV-administered group (HbV-group), washed erythrocyte-administered group (wRBC-group), and 5% albumin-administered group (ALB-group). Survival rates, anti-arrhythmic efficacy by optical mapping analysis (OMP) with electrophysiological stimulation (EPS) in Langendorff heart, cardiac autonomic activity by heart rate variability (HRV) and ventricular arrhythmias by 24-hour electrocardiogram telemetry monitoring (24h-ECG) in awake, and left ventricular function by echocardiography (LVEF) were measured.

RESULTS

All rats in HbV- and wRBC-groups survived for 4 weeks whereas no rats in ALB-group. HbV and wRBC acutely suppressed VT/VF in Langendorff heart through ameliorating action potential duration dispersion (APDd) analyzed by OMP with EPS. For subacute analysis, 50% blood exchange by 5% albumin was utilized (ALB-group 50). Subacute salutary effect on APDd and VT/VF inducibility was confirmed in HbV- and wRBC-groups. 24h-ECG showed that HbV and wRBC suppressed none-sustained VT (NSVT) and sympathetic component of HRV (LF/HF) with preserved LVEF (HbV-group, wRBC-group vs. ALB-group 50;NSVT numbers/days, 0.5±0.3, 0.4±0.3 vs. 3.9±1.2*; LF/HF, 1.1±0.2, 0.8±0.2 vs. 3.5±1.0*;LVEF, 84±5, 83±4, vs. 77±4%*; *p<0.05).

CONCLUSIONS

Collectively, HbV has sustained antiarrhythmic effect in subacute 85%-Model by ameliorating electrical remodeling and improving arrhythmogenic modifying factors (HRV and LVEF). These findings are useful in now continuing clinical trials of HbV.

A Multicentric, Randomized, Controlled Phase III Study of Centhaquine (Lyfaquin®) as a Resuscitative Agent in Hypovolemic Shock Patients

Introduction

Centhaquine (Lyfaquin^®) showed significant safety and efficacy in preclinical and clinical phase I and II studies.

Methods

A prospective, multicentric, randomized phase III study was conducted in patients with hypovolemic shock, systolic blood pressure (SBP) ≤ 90 mmHg, and blood lactate levels ≥ 2 mmol/L. Patients were randomized in a 2:1 ratio to the centhaquine group (n = 71) or the control (saline) group (n = 34). Every patient received standard of care (SOC) and was followed for 28 days. The study drug (normal saline or centhaquine 0.01 mg/kg) was administered in 100 mL of normal saline infusion over 1 h. The primary objectives were to determine changes (mean through 48 h) in SBP, diastolic blood pressure (DBP), blood lactate levels, and base deficit. The secondary objectives included the amount of fluids, blood products, and vasopressors administered in the first 48 h, duration of hospital stay, time in intensive care units, time on ventilator support, change in acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome (MODS), and the proportion of patients with 28-day all-cause mortality.

Results

The demographics of patients and baseline vitals in both groups were comparable. The cause of hypovolemic shock was trauma in 29.4 and 47.1% of control group and centhaquine group patients, respectively, and gastroenteritis in 44.1 and 29.4%, respectively. Shock index (SI) and quick sequential organ failure assessment at baseline were similar in the two groups. An equal amount of fluids and blood products were administered in both groups during the first 48 h of resuscitation. A lesser amount of vasopressors was needed in the first 48 h of resuscitation in the centhaquine group. An increase in SBP from baseline was consistently higher up to 48 h (12.9% increase in area under the curve from 0 to 48 h [AUC_0–48]) in the centhaquine group than in the control group. A significant increase in pulse pressure (48.1% increase in AUC_0–48) in the centhaquine group compared with the control group suggests improved stroke volume due to centhaquine. The SI was significantly lower in the centhaquine group from 1 h (p = 0.032) to 4 h (p = 0.049) of resuscitation. Resuscitation with centhaquine resulted in a significantly greater number of patients with improved blood lactate (control 46.9%; centhaquine 69.3%; p = 0.03) and the base deficit (control 43.7%; centhaquine 69.8%; p = 0.01) than in the control group. ARDS and MODS improved with centhaquine, and an 8.8% absolute reduction in 28-day all-cause mortality was observed in the centhaquine group.

Conclusion

Centhaquine is an efficacious resuscitative agent for treating hypovolemic shock. The efficacy of centhaquine in distributive shock is being explored.

Trial Registration

Clinical Trials Registry, India; ctri.icmr.org.in, CTRI/2019/01/017196; clinicaltrials.gov, NCT04045327.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40265-021-01547-5.

A multicentric, randomized, controlled phase III study of centhaquine (Lyfaquin ® ) as a resuscitative agent in hypovolemic shock patients

INTRODUCTION

Centhaquine (Lyfaquin ^® ) showed significant safety and efficacy in preclinical and clinical phase I and II studies.

METHODS

A prospective, multicentric, randomized phase III study was conducted in patients with hypovolemic shock having systolic blood pressure (SBP) of ≤90 mm Hg and blood lactate levels of ≥2 mmol/L. Patients were randomized in a 2:1 ratio, 71 patients to the centhaquine group and 34 patients to the control (saline) group. Every patient received standard of care (SOC) and was followed for 28 days. The study drug (normal saline or centhaquine (0.01 mg/kg)) was administered in 100 mL of normal saline infusion over 1 hour. The primary objectives were to determine changes (mean through 48 hours) in SBP, diastolic blood pressure (DBP), blood lactate levels, and base deficit. The secondary objectives included the amount of fluids, blood products, vasopressors administered in the first 48 hours, duration of hospital stay, time in ICU, time on the ventilator support, change in patient's Acute Respiratory Distress Syndrome (ARDS), Multiple Organ Dysfunction Syndrome (MODS) scores, and the proportion of patients with 28-day all-cause mortality.

RESULTS

The demographics of patients and baseline vitals in both groups were comparable. Trauma was the cause of hypovolemic shock in 29.41% of control and 47.06% of centhaquine, gastroenteritis in 44.12% of control, and 29.41% of centhaquine patients. An equal amount of fluids and blood products were administered in both groups during the first 48 hours of resuscitation. A lesser amount of vasopressors was needed in the first 48 hours of resuscitation in the centhaquine group. An increase in SBP from the baseline was consistently higher in the centhaquine group than in the control. A significant increase in pulse pressure in the centhaquine group than the control group suggests improved stroke volume due to centhaquine. The shock index was significantly lower in the centhaquine group than control from 1 hour (p=0.0320) till 4 hours (p=0.0494) of resuscitation. Resuscitation with centhaquine had a significantly greater number of patients with improved blood lactate and the base deficit than the control group. ARDS and MODS improved with centhaquine, and an 8.8% absolute reduction in 28-day all-cause mortality was observed in the centhaquine group.

CONCLUSION

Centhaquine is a highly efficacious resuscitative agent for treating hypovolemic shock. The efficacy of centhaquine in distributive shock due to sepsis and COVID-19 is being explored.

TRIAL REGISTRATION

Clinical Trials Registry, India; ctri.icmr.org.in, CTRI/2019/01/017196; clinicaltrials.gov, NCT04045327 .

KEY SUMMARY POINTS

A multicentric, randomized, controlled trial was conducted to evaluate the efficacy of centhaquine in hypovolemic shock patients.One hundred and five patients were randomized 2:1 to receive centhaquine or saline. Centhaquine was administered at a dose of 0.01 mg/kg in 100 mL saline and infused over 1 hour. The control group received 100 mL of saline over a 1-hour infusion.Centhaquine improved blood pressure, shock index, reduced blood lactate levels, and improved base deficit. Acute Respiratory Distress Syndrome (ARDS) and Multiple Organ Dysfunction Syndrome (MODS) score improved with centhaquine.An 8.8% absolute reduction in 28-day all-cause mortality was observed in the centhaquine group. There were no drug-related adverse events in the study.

Five-coordinate H64Q neuroglobin as a ligand-trap antidote for carbon monoxide poisoning

Carbon monoxide (CO) is a leading cause of poisoning deaths worldwide, with no available antidotal therapy. We introduce a potential treatment paradigm for CO poisoning, based on near-irreversible binding of CO by an engineered human neuroglobin (Ngb). Ngb is a six-coordinate hemoprotein, with the heme iron coordinated by two histidine residues. We mutated the distal histidine to glutamine (H64Q) and substituted three surface cysteines with less reactive amino acids to form a five-coordinate heme protein (Ngb-H64Q-CCC). This molecule exhibited an unusually high affinity for gaseous ligands, with a P50 (partial pressure of O2 at which hemoglobin is half-saturated) value for oxygen of 0.015 mmHg. Ngb-H64Q-CCC bound CO about 500 times more strongly than did hemoglobin. Incubation of Ngb-H64Q-CCC with 100% CO-saturated hemoglobin, either cell-free or encapsulated in human red blood cells, reduced the half-life of carboxyhemoglobin to 0.11 and 0.41 min, respectively, from ≥200 min when the hemoglobin or red blood cells were exposed only to air. Infusion of Ngb-H64Q-CCC to CO-poisoned mice enhanced CO removal from red blood cells, restored heart rate and blood pressure, increased survival, and was followed by rapid renal elimination of CO-bound Ngb-H64Q-CCC. Heme-based scavenger molecules with very high CO binding affinity, such as our mutant five-coordinate Ngb, are potential antidotes for CO poisoning by virtue of their ability to bind and eliminate CO.

The USA Multicenter Prehosptial Hemoglobin-based Oxygen Carrier Resuscitation Trial: scientific rationale, study design, and results

Human polymerized hemoglobin (PolyHeme) is a universally compatible oxygen carrier developed for use when red blood cells are unavailable and oxygen-carrying replacement is needed to treat life-threatening anemia. This multicenter phase III trial assessed survival of patients resuscitated with a hemoglobin-based oxygen carrier starting at the scene of injury. Patients resuscitated with PolyHeme had outcomes comparable to those receiving the standard of care including rapid access to stored red blood cells. Although there were more adverse events in the PolyHeme group compared with control patients receiving blood, the observed safety profile is acceptable for the intended population. The benefit-to-risk ratio of PolyHeme is favorable when blood is needed but is not available or an option.

Exsanguination in trauma: A review of diagnostics and treatment options

Trauma patients with haemorrhagic shock who only transiently respond or do not respond to fluid therapy and/or the administration of blood products have exsanguinating injuries. Recognising shock due to (exsanguinating) haemorrhage in trauma is about constructing a synthesis of trauma mechanism, injuries, vital signs and the therapeutic response of the patient. The aim of prehospital care of bleeding trauma patients is to deliver the patient to a facility for definitive care within the shortest amount of time by rapid transport and minimise therapy to what is necessary to maintain adequate vital signs. Rapid decisions have to be made using regional trauma triage protocols that have incorporated patient condition, transport times and the level of care than can be performed by the prehospital care providers and the receiving hospitals. The treatment of bleeding patients is aimed at two major goals: stopping the bleeding and restoration of the blood volume. Fluid resuscitation should allow for preservation of vital functions without increasing the risk for further (re)bleeding. To prevent further deterioration and subsequent exsanguinations 'permissive hypotension' may be the goal to achieve. Within the hospital, a sound trauma team activation system, including the logistic procedure as well as activation criteria, is essential for a fast and adequate response. After determination of haemorrhagic shock, all efforts have to be directed to stop the bleeding in order to prevent exsanguinations. A simultaneous effort is made to restore blood volume and correct coagulation. Reversal of coagulopathy with pharmacotherapeutic interventions may be a promising concept to limit blood loss after trauma. Abdominal ultrasound has replaced diagnostic peritoneal lavage for detection of haemoperitoneum. With the development of sliding-gantry based computer tomography diagnostic systems, rapid evaluation by CT-scanning of the trauma patient is possible during resuscitation. The concept of damage control surgery, the staged approach in treatment of severe trauma, has proven to be of vital importance in the treatment of exsanguinating trauma patients and is adopted worldwide. When performing 'blind' transfusion or 'damage control resuscitation', a predetermined fixed ratio of blood components may result in the administration of higher plasma and platelets doses and may improve outcome. The role of thromboelastography and thromboelastometry as point-of-care tests for coagulation in massive blood loss is emerging, providing information about actual clot formation and clot stability, shortly (10min) after the blood sample is taken. Thus, therapy guided by the test results will allow for administration of specific coagulation factors that will be depleted despite administration with fresh frozen plasma during massive transfusion of blood components.

Immune effects of decreasing low-molecular weight hemoglobin components of hemoglobin-based oxygen carriers (HBOC) in a swine model of severe controlled hemorrhagic shock

Hemoglobin-based oxygen carriers (HBOCs) show potential as safe, efficacious, pre-hospital resuscitation fluids. The major criticism of HBOC-201 is its vasoactive property, attributed partially to low-molecular weight (low-MW) tetrameric/dimeric (TD) hemoglobin (Hb) in HBOC solution. Here we sought to determine whether resuscitation with decreasing concentrations of low-MW Hb component of HBOC affects immune responses in hemorrhagic swine. 28 anesthetized swine underwent a soft muscle crush and controlled hemorrhage of 55% blood volume, followed by resuscitation with HBOC containing 31%, 2%, or 0.4% low-MW Hb in four 10 ml/kg infusions at 20, 30, 45 and 60 minutes before hospital arrival at 75 minutes. IL-10, cell activation and adhesion markers and CD4:CD8 ratio remained unchanged in all 3 groups compared to baseline. Leukocyte apoptosis was equally elevated across all groups. Purification from 31% to 0.4% low-MW Hb in HBOC solution did not alter immune effects in a swine model of severe controlled hemorrhagic shock.

Basic science focus on blood substitutes: a summary of the NHLBI Division of Blood Diseases and Resources Working Group Workshop, March 1, 2006

In March 2006, a workshop sponsored by the National Heart, Lung, and Blood Institute was convened to identify the role of basic science research in clarifying issues that are impeding progress in the development of hemoglobin-based oxygen carrying (HBOC) solutions. These discussions resulted in a consensus that, although HBOCs have shown clinical promise, various side effects have inhibited further development and regulatory approval, with cardiovascular events being of particular concern. As a consequence, workshop participants focused on formulating research recommendations to better understand and mitigate these side effects. In addition, several important corollary issues were identified, including better understanding of the impact of HBOC infusion on human physiology; the need for rapid, noninvasive methods for the measurement of tissue oxygenation in human patients to better inform transfusion decisions; further investigation of routes and consequences of hemoglobin metabolism; optimization of clinical protocols for HBOC use; and assessment of the impact of HBOC formulation excipients. Also discussed was the possibility and desirability of developing new HBOCs with improved characteristics, such as prolonged functional intravascular persistence, greater stability, and a decreased propensity to generate reactive oxygen species. One practical limitation in this area is the consistent availability of pure, well-characterized HBOC solutions for the research community. This communication summarizes the opinion of workshop participants on these issues and concludes with a list of specific recommended areas of research that could positively impact the development of blood substitutes.

Blood substitutes: hemoglobin-based oxygen carriers

Blood product substitutes, particularly the hemoglobin-based oxygen carriers, represent one of the most exciting fields of research and development in modern medicine. The concept has been several decades in the making, and with products in phase III clinical trials, the use of hemoglobin-based oxygen carriers may be close to reality. The potential applications are limitless with interest from the military and civilian sectors.

Oxygen therapeutics: pursuit of an alternative to the donor red blood cell

CONTEXT

There is no true substitute for the many functions of human red blood cells, and synthetic products will not replace the need for blood donation in the foreseeable future. Hemoglobin-based oxygen carriers have many characteristics that would serve as a useful adjunct to red cells in clinical settings. Over time, these technologies have the potential to dramatically reshape the practice of transfusion medicine.

OBJECTIVE

To review the characteristics and potential utility of hemoglobin-based oxygen carriers and perfluorocarbon-based oxygen carriers. Several hemoglobin-based oxygen carriers are under study in phase III clinical trials. Novel uses for synthetic oxygen therapeutics are emphasized.

DATA SOURCES

All published reports with the key words oxygen therapeutics, blood substitutes, and red cell substitutes from 1933 until March 2006 were searched through Medline. Significant findings were synthesized.

CONCLUSIONS

Recognition of the true impact of red cell substitutes is still several years away. The most compelling products, hemoglobin-based oxygen carriers, have potential use in trauma, providing immediate oxygen-carrying support in the face of alloantibodies or autoantibodies, and in other clinical situations in which long-term survival of red cells is not essential. In the interim, efforts should be focused on enhancing the current blood supply system while supporting ongoing and planned blood substitute research efforts, including trials assessing novel clinical indications for these products.

Modified haemoglobins and perfluorocarbons

After decades of research activities and product improvements in the field of artificial oxygen carriers based on either haemoglobin modifications or perfluorocarbon emulsions, these products have reached a critical stage of their development. Varieties of haemoglobin-based oxygen carriers and perfluorocarbon emulsions are under current clinical investigation. Although the clinical availability of artificial oxygen carriers may result in profound changes of fluid resuscitation from haemorrhage, the transfusion of human blood components as an integral part of medical trauma management will not be replaced. However, a rapid and effective restoration of tissue oxygenation by the use of artificial oxygen carriers in the treatment of severe haemorrhage may bridge time delays until stored and cross-matched human packed red cells are available. Whether artificial oxygen carriers could provide additional clinical benefits by sustaining tissue oxygenation even under conditions of a disturbed macro- or microcirculation is the subject of current investigations. Therefore, the application of safe and effective artificial oxygen carriers would not only be restricted to the treatment of severe haemorrhage, but additional therapeutic indications of artificial oxygen carriers in emergency medicine, trauma anaesthesia and other medical specialities would emerge.

Transfusion therapy in the critically ill

Blood transfusion remains an important part of treatment in critically ill patients. While the known infectious risks continue to decrease, concerns remain about the effects of allogeneic blood on the immune system. Some patients tolerate anemia much better than others; the optimal hemoglobin level, however, is difficult to define in any individual patient.

Hemoglobin-based oxygen carriers in trauma care: scientific rationale for the US multicenter prehosptial trial

BACKGROUND

The greatest need for blood substitutes worldwide is in patients with unanticipated acute blood loss, and trauma is the most likely scenario. The blood substitutes reaching advanced clinical trials today are red blood cell (RBC) substitutes derived from hemoglobin. The hemoglobin-based oxygen carriers (HBOCs) tested currently in advanced clinical trials are polymerized hemoglobin solutions.

METHODS

In the USA, the standard approach to restoring oxygen delivery for hemorrhagic shock has been crystalloid administration to expand intravascular volume, followed by stored RBCs for critical anemia. Allogeneic RBCs, however, may have adverse immunoinflammatory effects that increase the risk of postinjury multiple organ failure (MOF). Phase II in hospital clinical trials, as well as in vitro and in vivo work, suggest that resuscitation with an HBOC--in lieu of stored RBCs--attenuates the systemic inflammatory response invoked in the pathogenesis of MOF. Specifically, an HBOC has been shown to obviate stored RBC-provoked polymorphonuclear neutrophil (PMN) priming, endothelial activation, and systemic release of interleukins (IL) 6, 8, and 10. In a 2-event rodent study of shock-induced PMN-mediated acute respiratory distress syndrome (ARDS), the simulated prehospital administration of an HBOC markedly attenuated lung injury.

RESULTS

Based on this background and work by others, we have initiated a US multicenter prehospital trial in which severely injured patients with major blood loss [systolic blood pressure (SBP)<or=90 mmHg] are randomized to initial field resuscitation with crystalloid versus HBOC. During the hospital phase, the control group is further resuscitated with stored RBCs whereas the study group receives HBOC (up to 6 units) in the first 12 hours. The primary study endpoint is decreased 30-day mortality, and secondary endpoints include reductions in administration of allogeneic RBCs and uncrossmatched RBCs; avoiding circulating hemoglobin levels<5 g/dl; and decreased ARDS and MOF.

CONCLUSIONS

To date, >500 injured patients have been enrolled in this multicenter trial, and the final interim analyses support the original target of 720.

Insights from studies of blood substitutes in trauma

Most authorities believe that the greatest need for blood substitutes is in patients with unanticipated acute blood loss, and trauma is the most likely scenario. The blood substitutes reaching advanced clinical trials today are red blood cell (RBC) substitutes, derived from hemoglobin. The hemoglobin-based oxygen carriers (HBOCs) tested currently in FDA Phase III clinical trials are polymerized hemoglobin solutions. The standard approach to restoring oxygen delivery in hemorrhagic shock has been crystalloid administration to expand intravascular volume, followed by stored RBCs for critical anemia. However, allogenic RBCs may have adverse immunoinflammatory effects that increase the risk of postinjury multiple organ failure (MOF). Phase II clinical trials, as well as in vitro and in vivo work, suggest that resuscitation with a HBOC--in lieu of stored RBCs--attenuates the systemic inflammatory response invoked in the pathogenesis of MOF. Specifically, an HBOC has been shown to obviate stored RBC provoked neutrophil priming, endothelial activation, and systemic release of interleukins 6, 8, and 10. Based on this background and work by others, we have initiated a multicenter prehospital trial in which severely injured patients with major blood loss (systemic blood pressure <90 mmHg) are randomized to initial field resuscitation with crystalloid versus HBOC. During the hospital phase, the control group is further resuscitated with stored RBCs, whereas the study group receives HBOC (up to 6 units) in the first 12 h. The primary study endpoint is 30-day mortality, and secondary endpoints include reduction in allogenic RBCs, hemoglobin levels <5 g/dL, uncrossmatched RBCs, and MOF. The potential efficacy of HBOCs extends beyond the temporary replacement for stored RBCs. Hemoglobin solutions might ultimately prove superior in delivering oxygen to ischemic or injured tissue. The current generation of HBOCs can be lifesaving for acute blood loss today, but the next generation might be biochemically tailored for specific clinical indications.

Transfusion of the injured patient: proceed with caution

Transfusion of the injured patient with packed red blood cells (PRBCs) is a dynamic process requiring vigilance during the acute resuscitative and recovery phases postinjury. Although adverse events have been reported in 2% to 10% of injured patients, the advent of new detection techniques for viral pathogens has markedly decreased the risk of infectious transmission. However, transfusions are strongly associated with immunosuppression in the host, which may occur days after the initial injury and may lead to bacterial infections. Conversely, early transfusion of stored PRBCs, > 6 units in the first 12 h postinjury, contributes to an early state of hyperinflammation that is a strong, independent predictor of multiple organ failure (MOF) in those patients with intermediate injury severity scores. The roles of prestorage leukoreduction are also reviewed with respect to the promotion of both immunosuppression and hyperinflammation. We further summarize studies with hemoglobin substitutes, whose use may obviate many of the untoward events of transfusion and promise to lead to better outcomes for injured patients.

What happened to blood substitutes?

Concerns about the safety and adequacy of the blood supply have fostered twenty years of research into the so-called "blood substitutes" among them the oxygen carriers based on modified hemoglobin. Although none of these materials has yet been licensed for use in North America or Europe, the results of research and clinical trials have increased our understanding of oxygen delivery and its regulation. In particular, the examination of the basis for the vasoactivity observed with some of the hemoglobin based oxygen carriers has led to the insight that several colligative properties of hemoglobin solutions, such as their diffusion coefficient for oxygen, viscosity and colloid oncotic pressure, are important determinants of efficacy.

Transfusions result in pulmonary morbidity and death after a moderate degree of injury

BACKGROUND

Prior studies have suggested that blood transfusion (Tx) is associated with infectious and respiratory complications in trauma patients. However, these studies are difficult to interpret because of small sample size, inclusion of severely injured patients in traumatic shock, and combination of a variety of unrelated low-morbidity/mortality infections, such as wound, catheter-related, and urinary tract infection as outcomes. To eliminate these confounding variables, this study evaluates the association between delayed Tx and serious, well-defined respiratory complications (ventilator-associated pneumonia [VAP] and acute respiratory distress syndrome [ARDS]) and death in a cohort of intensive care unit (ICU) admissions with less severe (Injury Severity Score [ISS] < 25) blunt trauma who received no Tx within the initial 48 hours after admission.

METHODS

Patients with blunt injury and ISS < 25 admitted to the ICU over a 7-year period were identified from the registry and excluded if within 48 hours from admission they received any Tx or if they died. VAP required quantitative bronchoalveolar lavage culture (> or =10(5) colonies/mL), and ARDS required Pao2/Fio2 ratio < 200 mm Hg, *** no congestive heart failure, diffuse bilateral infiltrates, and peak airway pressure > 50 cm H2O for diagnosis. Outcomes were VAP, ARDS, and death.

RESULTS

Nine thousand one hundred twenty-six with blunt injury were ICU admissions, and 5,260 (58%) met study criteria (72% male). Means for age, ISS, and Glasgow Coma Scale score were 39, 12, and 14, respectively. There were 778 (15%) who received delayed Tx. Incidences of VAP, ARDS, and death were 5%, 1%, and 1%, respectively. Logistic regression analysis identified age, base excess, chest Abbreviated Injury Scale score, ISS, and any transfusion as significant predictors for VAP; chest Abbreviated Injury Scale score and transfusion as significant predictors for ARDS; and age and transfusion as significant predictors for death.

CONCLUSION

Delayed transfusion is independently associated with VAP, ARDS, and death in trauma patients regardless of injury severity. These data mandate a judicious transfusion policy after resuscitation and emphasize the need for safe and effective blood substitutes and transfusion alternatives.

Current Status of Artificial o2 Carriers

This article describes currently evaluated artificial O2 carriers, summarizes their efficacy, and discusses their side effects, based on and restricted to published data. For compounds in phase III testing, approximately 500 to 1000 patients have been dosed, and similar numbers of control patients have been investigated. For compounds in phase I or II testing, the number of patients dosed is significantly less. Unfortunately, there is a significant amount of nonpublished data, which renders the overall assessment difficult, and the direct comparison among different types of artificial O2 carriers is significantly limited by the virtual nonexistence of studies that directly compare different products.

Kinetics of liposome-encapsulated hemoglobin after 25% hypovolemic exchange transfusion

Liposome-encapsulated hemoglobin (LEH) is being developed as an oxygen therapeutic. In this work, we evaluated a neutral formulation of PEGylated LEH for its circulation and distribution properties in rodent models of 25% hypovolemic exchange transfusion. About 25% of blood in rats and rabbits was exchanged with LEH that had been previously labeled with 99mTc radionuclide. The distribution of 99mTc-LEH was followed by gamma camera imaging and intermittent blood sampling during 48 h, and counting the tissue-associated radioactivity after necropsy at 48 h. On the basis of circulation kinetics, the half-life of 99mTc-LEH in blood was 30 and 39.8 h in rats and rabbits, respectively. Apart from blood, major organs of accumulation of LEH after 48 h included liver (rats, 10.3% and rabbits, 5.4% of injected dose) and spleen (rats, 2.4% and rabbits, 0.8% of injected dose). The results demonstrate that LEH circulates for a prolonged time after administration and that the animals tolerate at least 25% of blood exchange without any distress. Subsequent to the enhanced uptake in the RES, the rats clear LEH from the circulation faster than the rabbits.

The next generation in shock resuscitation

Resuscitation of the severely injured patient who presents in shock has improved greatly, following focused wartime experience and insight from laboratory and clinical studies. Further benefit is probable from technologies that are being brought into clinical use, especially hypertonic saline dextran, haemoglobin-based oxygen carriers, less invasive early monitors, and medical informatics. These technologies could improve the potential of prehospital and early hospital care to pre-empt or more rapidly reverse hypoxaemia, hypovolaemia, and onset of shock. Damage control surgery and definitive interventional radiology will probably combine with more real-time detection and intervention for hypothermia, coagulopathy, and acidosis, to avoid extreme pathophysiology and the "bloody vicious cycle". Although now widely practised as standard of care in the USA and Europe, shock resuscitation strategies involving haemoglobin replacement and fluid volume loading to regain tissue perfusion and oxygenation vary between trauma centres. One of the difficulties is the scarcity of published evidence for or against seemingly basic intervention strategies, such as early or large-volume fluid loading. Standardised protocols for resuscitation, representing the best and most current knowledge of the clinical process, could be devised and widely implemented as interactive computerised applications among trauma centres in the USA and Europe. Prevention of injury is preferable and feasible, but early care of the severely injured patient and modulation of exaggerated systemic inflammatory response due to transfusion and other complications of traditional strategies will probably provide the next generation of improvements in shock resuscitation.

Changing patterns in the management of penetrating abdominal trauma: the more things change, the more they stay the same

BACKGROUND

Damage control surgery (DCS) and treatment of abdominal compartment syndrome have had major impacts on care of the severely injured. The objective of this study was to see whether advances in critical care, DCS, and recognition of abdominal compartment syndrome have improved survival from penetrating abdominal injury (PAI).

METHODS

The care of 250 consecutive patients requiring laparotomy for PAI (1997-2000) was reviewed retrospectively. Organ injury patterns, survival, and use of DCS and its impact on outcome were compared with a similar experience reported in 1988.

RESULTS

Two hundred fifty patients had a positive laparotomy for PAI. Twenty-seven (10.8%) required abdominal packing and 45 (17.9%) did not have fascial closure. Seven (2.8%) required emergency department thoracotomy and 21 (8.4%) required operating room thoracotomy. Two hundred seventeen (86.8%) survived overall. Small bowel (47.2%), colon (36.4%), and liver (34.4%) were most often injured. Mortality was associated with the number of organs injured (odds ratio, 1.98; 95% confidence interval, 1.65-2.37; p < 0.001). Vascular injury was a risk factor for mortality (p < 0.001), as was need for DCS (p < 0.001), emergency department thoracotomy (p < 0.001), and operating room thoracotomy (p < 0.001). Seventy-nine percent of deaths occurred within 24 hours from refractory hemorrhagic shock. DCS was used in 17.9% (n = 45) versus 7.0% (n = 21) in 1988, with a higher survival rate (73.3% vs. 23.8%, p < 0.001). DCS was associated with significant morbidity including sepsis (42.4%, p < 0.001), intra-abdominal abscess (18.2%, p = 0.009), and gastrointestinal fistula (18.2%, p < 0.001).

CONCLUSION

Penetrating abdominal organ injury patterns and survival from PAI have remained similar over the past decade. Death from refractory hemorrhagic shock in the first 24 hours remains the most common cause of mortality. DCS and the open abdomen are being used more frequently with improved survival but result in significant morbidity.

Exchange transfusion with synthetic oxygen-carrying plasma protein ?albumin-heme? into an acute anemia rat model after seventy-percent hemodilution

Recombinant human serum albumin (rHSA) incorporating the synthetic heme "albumin-heme" is an oxygen-carrying plasma protein that has the potential to be a red blood cell substitute. The physiological responses to a 30% exchange transfusion with two types of albumin-heme (rHSA-FecycP, rHSA-FepivP) solutions after 70% isovolemic hemodilution with 5 g/dL rHSA were investigated using anesthetized rats. The circulation parameters, blood parameters, renal cortical oxygen pressure (pO2), and muscle tissue pO2 were carefully monitored for 60 min after the injection. The declined mean arterial pressure and the mixed venous partial pO2 significantly recovered to 70.8 and 91.9% of the basal values by intravenous infusion of albumin-hemes, respectively. The lowered renal cortical pO2 also increased, indicating oxygen transport by this synthetic hemoprotein. The administration of albumin-heme into the acute anemia rat model after hemorrhage improved the circulatory volume and resuscitated the shock state. Both rHSA-FecycP and rHSA-FepivP transported oxygen through the body.

Clinical potential of blood substitutes or oxygen therapeutics during cardiac surgery

Several complications and unforeseen adverse side effects have colluded to keep commercially available blood substitutes or oxygen therapeutic agents tantalizingly "just out of reach." Because the three classes of agents under development have different oxygen-delivery mechanisms and side-effect profiles, each can be expected to have its own unique clinical applications, particularly in the cardiac surgery population. The fact that South Africa recently approved one HBOC for use as a transfusion alternative in patients with chronic anemia indicates that initial clinical use is near for a number of these agents. It is to be hoped that they will be used for several applications rather than just for a "transfusion alternative." Despite some frustrating limitations, all of these agents are antigen and pathogen free, have an acceptable side-effect profile, and have a long shelf life. Increasing volunteer-blood-donor shortages, coupled with increasing blood-transfusion needs, and expanding human immunodeficiency virus and hepatitis B and C epidemics, continue to fuel the demand for further development of these products. Transfusion alternatives will eventually become commercially available--the question is "when," not "if." Equally important, these agents' potential for serving as effective oxygen-delivery agents to ischemic tissues heralds an entirely new field of clinical investigation.

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.

Use of a human polymerized hemoglobin solution as an adjunct to acute normovolemic hemodilution during complex abdominal aortic reconstruction

Oxygen-carrying hemoglobin (Hb) solutions are under intense investigation as an alternative to allogeneic red cell transfusion during surgery, with or without acute normovolemic hemodilution. We present a case in which an investigational Hb solution was used as an adjunct to acute normovolemic hemodilution, and as a replacement for surgical blood loss in a patient undergoing complex aortic reconstruction with a large blood loss.

Blood transfusion, independent of shock severity, is associated with worse outcome in trauma

BACKGROUND

We have previously shown that blood transfusion in the first 24 hours is an independent predictor of mortality, intensive care unit (ICU) admission, and increased ICU length of stay in the acute trauma setting when controlling for Injury Severity Score, Glasgow Coma Scale score, and age. Indices of shock such as base deficit, serum lactate level, and admission hemodynamic status (systolic blood pressure, heart rate) and admission hematocrit were considered potential confounding variables in that study. The objectives of this study were to evaluate admission anemia and blood transfusion within the first 24 hours as independent predictors of mortality, ICU admission, ICU length of stay (LOS), and hospital LOS, with serum lactate level, base deficit, and shock index (heart rate/systolic blood pressure) as covariates.

METHODS

Prospective data were collected on 15,534 patients admitted to a Level I trauma center over a 3-year period (1998-2000) and stratified by age, gender, race, Glasgow Coma Scale score, and Injury Severity Score. Admission anemia and blood transfusion were assessed as independent predictors of mortality, ICU admission, ICU LOS, and hospital LOS by logistic regression analysis, with base deficit, serum lactate, and shock index as covariates.

RESULTS

Blood transfusion was a strong independent predictor of mortality (odds ratio [OR], 2.83; 95% confidence interval [CI], 1.82-4.40; p < 0.001), ICU admission (OR, 3.27; 95% CI, 2.69-3.99; p < 0.001), ICU LOS (p < 0.001), and hospital LOS (Coef, 4.37; 95% CI, 2.79-5.94; p < 0.001) when stratified by indices of shock (base deficit, serum lactate, shock index, and anemia). Patients who underwent blood transfusion were almost three times more likely to die and greater than three times more likely to be admitted to the ICU. Admission anemia (hematocrit < 36%) was an independent predictor of ICU admission (p = 0.008), ICU LOS (p = 0.012), and hospital LOS (p < 0.001).

CONCLUSION

Blood transfusion is confirmed as an independent predictor of mortality, ICU admission, ICU LOS, and hospital LOS in trauma after controlling for severity of shock by admission base deficit, lactate, shock index, and anemia. The use of other hemoglobin-based oxygen-carrying resuscitation fluids (such as human or bovine hemoglobin substitutes) in the acute postinjury period warrants further investigation.

Hemoglobin-based oxygen carriers

Three types of materials have been studied as candidate blood substitutes: the perfluorocarbons, modified hemoglobins, and liposome-encapsulated hemoglobin. Progress has been greatest with the hemoglobin-based oxygen carriers. Hemoglobin is a highly active molecule; hence, modification has been required to avoid potential deleterious effects. Although there has been considerable progress toward bringing such a product to the clinic, its development has challenged understanding of oxygen delivery and use. The study of these molecules has provided new insights into basic physiologic processes.

The life-sustaining capacity of human polymerized hemoglobin when red cells might be unavailable

BACKGROUND

Human polymerized hemoglobin (PolyHeme, Northfield Laboratories, Evanston, IL) is a universally compatible, immediately available, disease-free, oxygen-carrying resuscitative fluid being developed as a red cell substitute for use in urgent blood loss. PolyHeme should be particularly useful when red cells may be temporarily unavailable. This article assesses survival at life-threatening RBC hemoglobin concentration ([Hb]) in massively bleeding patients who do not receive red cells.

STUDY DESIGN

There were 171 patients who received rapid infusion of 1 to 20 units (1,000 g, 10 L) of PolyHeme in lieu of red cells as initial oxygen-carrying replacement in trauma and urgent surgery. The protocol simulated the unavailability of red cells, and the progressive fall in RBC [Hb] in bleeding patients was quantified. Thirty-day mortality was compared with a historical control group of 300 surgical patients who refused red cells on religious grounds.

RESULTS

A total of 171 patients received rapid infusion of 1 to 2 units (n = 45), 3 to 4 units (n = 45), 5 to 9 units (n = 47), or 10 to 20 units (n = 34) of PolyHeme. Forty patients had a nadir RBC [Hb] < or = 3 g/dL (mean, 1.5 +/- 0.7 g/dL). But total [Hb] was adequately maintained (mean, 6.8 +/- 1.2 g/dL) because of plasma [Hb] added by PolyHeme. The 30-day mortality was 25.0% (10/40 patients) compared with 64.5% (20/31 patients) in historical control patients at these RBC [Hb] levels.

CONCLUSIONS

PolyHeme increases survival at life-threatening RBC [Hb] by maintaining total [Hb] in the absence of red cell transfusion. PolyHeme should be useful in the early treatment of urgent blood loss and resolve the dilemma of unavailability of red cells.

Transfusion of polymerised human haemoglobin in a patient with severe sickle-cell anaemia

Many patients with sickle-cell anaemia have red-cell alloantibodies. We could not obtain compatible blood for a 40-year-old woman with a sickle-cell crisis after a hip operation. We transfused a polymerised human haemoglobin solution, after which the patient's pain was alleviated. This treatment, in combination with erythropoietin, resulted in a rise in our patient's haemoglobin concentration, and her eventual recovery. Increased oxygen delivery to the microcirculation might have contributed to the rapid resolution of pain after the transfusion.

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

BACKGROUND

The safety of the hemoglobin based oxygen carrier diaspirin crosslinked hemoglobin (DCLHb) has been reported only in the low (50-200 mg/kg) dose range [Przybelski. R.J.; Daily, E.K.; Kisicki, J.C.; Mattia-Goldberg, C.; Bounds, M.J.; Colburn, W.A. Phase I study of the safety and pharmacologic effects of diaspirin crosslinked hemoglobin solution. Crit. Care Med. 1996, 24 (12), 1993-2000, Bloomfield, E.; Rady, M.; Popovich, M.; Esfandiari, S.; Bedocs, N. The use of diaspirin crosslinked hemoglobin (DCLHb 1996, 95, (3A), A220.]. We conducted a randomized prospective open-label trial of DCLHb and packed red blood cells (PRBCs) in high-blood loss surgical patients to show the effect of 750 ml DCLHb (approximately 1000 mg/kg) on selected indices of organ function.

METHOD

After institutional approval, 24 patients scheduled to undergo elective orthopedic or abdominal surgery, were randomized to receive either PRBCs or 10% DCLHb within 12 hours after the start of surgery. Patients with renal insufficiency, abnormal liver function, severe coronary artery disease (CAD) and ASA physical status > or = IV were excluded. The anesthetic technique was left to the judgment of the anesthesiologist. Autologous predonation and intraoperative blood conservation techniques were utilized as appropriate. The indications for blood transfusion were individualized on disease state, stage of surgery, and plasma Hb concentration. Laboratory studies were obtained preoperatively and up to 28 days postoperatively. Patients were observed daily for development of jaundice, hematuria, nausea, vomiting, gastrointestinal discomfort, cardiac, respiratory, and infectious complications. Organ effects were assessed with urinalysis, creatinine clearance, electrocardiogram (ECG), and a panel of blood and serum laboratory tests.

RESULTS

The dose of DCLHb administered ranged from 680-1500 mg/kg (mean = 999 mg/kg). Estimated blood loss was 27 +/- 13 ml/kg and 31 +/- 15 ml/kg in the control and DCLHb groups, respectively. Fewer PRBCs (1.9 +/- 1.2 vs. 3.4 +/- 2.4 units. P = 0.06) were transfused to DCLHb patients on the operative day although this difference was no longer apparent later on. In the DCLHb group, 4/12 patients avoided any allogeneic PRBC transfusion vs. none in the control group (P = 0.09). Systolic, diastolic and mean blood pressure increased moderately after DCLHb for a period of 24-30 hours. There were no occurrences of cardiac ischemia. myocardial infarction, stroke, or pulmonary edema, by clinical or laboratory parameters up to the 28th postoperative day (POD). Seven of 12 (58%) DCLHb patients had yellow skin discoloration vs. none in the PRBC group (P < 0.01). Two of four non-urologic surgery patients developed asymptomatic postoperative hemoglobinuria after DCLHb. Creatinine clearance was unchanged postoperatively. Because of hemoglobin interference, bilirubin, gamma-glutamyl transferase (GGT), and amylase could not be measured reliably on POD1; on POD2. amylase was transiently elevated to 3 times ULN along with mild elevations of bilirubin, transaminases and BUN. Mean total creatine phoshokinase (CPK) peaked at 8 times the upper limit of normal (ULN) in the DCLHb group, compared with less than twice ULN for controls. Three DCLHb patients had prolonged ileus. Two of these patients had postoperative hyperamylasemia, one of whom developed mild pancreatitis. DCLHb did not affect white blood cell count or coagulation tests.

CONCLUSION

Administration of approximately 1000 mg/kg DCLHb was associated with transient arterial hypertension, gastrointestinal side effects, laboratory abnormalities, yellow skin discoloration, and hemoglobinuria. These observations point to opportunities for improvement in future synthetic hemoglobin design.

To transfuse or not in trauma patients: a presentation of the evidence and rationale

The administration of allogeneic red blood cell transfusions to the trauma patient is an essential and potentially life-saving component of trauma care. The big question is when to transfuse, and how much? In this review, we explore the evidence and provide rationales for current and future red blood cell transfusion strategies in the trauma patient. We also discuss the changing trends and competing risks associated with transfusions as well as current evidence for different blood conservation strategies in the context of trauma.

2001 Lemieux Award Lecture Organic chemistry and hemoglobin: Benefits from controlled alteration

Hemoglobin carries oxygen in circulation within red cells but does not function outside the cells because it fails not only to release oxygen but also dissociates into dimers that make up the tetrameric protein. Bifunctional anionic acylating agents that contain a structurally rigid bridge introduce cross-links that stabilize hemoglobin and alter its oxygen affinity so that it could be used to carry oxygen outside cells. Nitric oxide binds to hemoglobin and in circulation this causes undesirable increases in blood pressure. It had been reported that higher weight collections of hemoglobin do not cause vasoconstriction. Reagents with two pairs of reaction sites joined by a rigid link connect and cross-link two hemoglobins. The resulting bis-tetramers lack the cooperativity of the native protein and bind oxygen too tightly to be useful; occupation by oxygen blocks the sites from nitric oxide. Nitric oxide may be delivered from thionitrosyl groups, which occur in hemoglobin in the red cell. Cross-linked hemoglobin can be specifically nitrosylated. These species can then serve as circulating sources of nitric oxide resulting from an internal electron transfer.Key words: proteins, hemoglobin, cross-link, red cells, cooperativity, connecting.

Comparison of transfusion with DCLHb or pRBCs for treatment of intraoperative anemia in sheep

Isoflurane-anesthetized sheep were transfused with packed red blood cells (pRBCs) or diaspirin cross-linked hemoglobin (DCLHb) for treatment of intraoperative hemorrhage. A rapid 15-min hemorrhage with lactated Ringer (LR) infusion maintained filling pressure at baseline and reduced blood hemoglobin (Hb) to ~5 g/dl. Sheep received 2 g/kg Hb, DCLHb (n = 6), or pRBCs (n = 7); control group received LR alone (n = 6). After 2 h, anesthesia was discontinued; sheep were monitored in the animal intensive care unit for 48 h. DCLHb expanded blood volume more, but increased total blood Hb less, than pRBCs. Lower Hb and increased methemoglobin resulted in lower arterial oxygen content compared with the pRBCs. DCLHb caused pulmonary hypertension (from 13 to 30 mmHg) and elevated filling pressure (from 6 to 15 mmHg). Cardiac outputs (CO) were similar for all groups during anesthesia; however, during recovery CO increased only in the LR and packed pRBCs groups. DCLHb may limit the reflex ability to increase CO after volume expansion. Hemodynamic effects of DCLHb may be exaggerated when infused after large-volume LR.

Potential of hemoglobin-based oxygen carriers in trauma patients

Injured patients have a unique requirement for early blood transfusion. A product that can be used in the prehospital setting that adequately carries and delivers oxygen to peripheral tissues would potentially be life saving for severely injured patients. Allogeneic blood is not the ideal agent in the pre-hospital setting. Present limitations in the allogeneic blood supply include the need for cross-matching, refrigeration, marginal supply, transfusion reactions, infectious disease transmission and immunomodulation increasing the risk of organ dysfunction after transfusion.Hemoglobin-based oxygen carriers have been under present development for the last 25 years. These compounds use either human or bovine hemoglobin that is then chemically altered to improve safety. These compounds exhibit many desirable characteristics that make them potential therapeutic agents in the treatment of the injured patient. These compounds do not need to be cross-matched, have favorable oxygen dissociation characteristics, long half lives, do not transmit disease, appear to be less immunoreactive than blood and theoretically can be used in the pre-hospital setting as a low volume oxygen carrying solution without need for refrigeration. There are at least three agents presently under development that use different techniques to alter the basic hemoglobin tetramer. While there is no FDA approved hemoglobin-based oxygen carrier approved for use in injured patients at this writing, phase III studies are currently either underway or being developed. There is high likelihood that one or more of these agents will be approved for clinical use in the near future.