Emergency Resuscitation of Patients Enrolled in the US Diaspirin Cross-linked Hemoglobin (DCLHb) Clinical Efficacy Trial

Mechanisms of Toxicity and Modulation of Hemoglobin-based Oxygen Carriers

Several adverse events have been associated with the infusion of hemoglobin-based oxygen carriers (HBOCs), including transient hypertension, gastrointestinal, pancreatic/liver enzyme elevation, and cardiac/renal injury in humans. Although several mechanisms have been suggested, the basis of HBOC toxicity is still poorly understood. Scavenging of vascular endothelial nitric oxide (NO) and heme-mediated oxidative side reactions are thought to be the major causes of toxicity. However, based on more recent preclinical studies, oxidative pathways (driven by the heme prosthetic group) seem to play a more prominent role in the overall toxicity of free Hb or HBOCs. HBOCs display a diversity of physicochemical properties, including molecular size/cross-linking characteristics leading to differences in oxygen affinity, allosteric, redox properties, and even oxidative inactivation by protein/heme clearing mechanisms. These diverse characteristics can therefore be manipulated independently, leaving open the possibility of engineering a safe and effective HBOC. To date, several antioxidative strategies have been proposed to counteract the redox side reactions of current generation HBOCs.

Hemoglobin-Based Blood Substitutes and the Treatment of Sickle Cell Disease: More Harm than Help?

Intense efforts have been made by both industry and academia over the last three decades to produce viable hemoglobin (Hb)-based oxygen carriers (HBOCs), also known as “blood substitutes”. Human trials conducted so far by several manufactures in a variety of clinical indications, including trauma, and elective surgeries have failed and no product has gained the Food and Drug Administration approval for human use. Safety concerns due to frequent incidences of hemodynamic, cardiac events, and even death led to the termination of some of these trials. Several second generation HBOC products that have been chemically and/or genetically modified (or in some cases ligated with carbon monoxide (CO)) found a new clinical application in conditions as complex as sickle cell disease (SCD). By virtue of higher oxygen affinity (P₅₀) (R-state), and smaller size, HBOCs may be able to reach the microvasculature unload of oxygen to reverse the cycles of sickling/unsickling of the deoxy-sickle cell Hb (HbS) (T-state), thus preventing vaso-occlusion, a central event in SCD pathophysiology. However, biochemically, it is thought that outside the red blood cell (due to frequent hemolysis), free HbS or infused HBOCs are capable of interfering with a number of oxidative and signaling pathways and may, thus, negate any benefit that HBOCs may provide. This review discusses the advantages and disadvantages of using HBOCs in SCD.

Prehospital volume therapy as an independent risk factor after trauma

Background. Prehospital volume therapy remains widely used after trauma, while evidence regarding its disadvantages is growing. The primary objective of this study was to investigate the volume administered in a prehospital setting as an independent risk factor for mortality. Material and Methods. Patients who met the following criteria were analyzed retrospectively: Injury Severity Score = 16, primary admission (between 2002 and 2010), and age = 16 years. The following data had to be available: volume administered (including packed red cells), blood pressure, Glasgow Coma Scale, therapeutic measures, and laboratory results. Following a univariate analysis, independent risk factors for mortality after trauma were investigated using a multivariate regression analysis. Results. A collective of 7,641 patients met the inclusion criteria, showing that increasing volumes administered in a prehospital setting were an independent risk factor for mortality (odds ratio: 1.34). This tendency was even more pronounced in patients without severe traumatic brain injury (TBI) (odds ratio: 2.71), while the opposite tendency was observed in patients with TBI. Conclusions. Prehospital volume therapy in patients without severe TBI represents an independent risk factor for mortality. In such cases, respiratory and circulatory conditions should be stabilized during permissive hypotension, and patient transfer should not be delayed.

Emergency Resuscitation of Patients Enrolled in the US Diaspirin Cross-linked Hemoglobin (DCLHb) Clinical Efficacy Trial

INTRODUCTION

Optimal emergent management of traumatic hemorrhagic shock patients requires a better understanding of treatment provided in the prehospital/Emergency Medical Services (EMS) and emergency department (ED) settings. Hypothesis/Problem Described in this research are the initial clinical status, airway management, fluid and blood infusions, and time course of severely-injured hemorrhagic shock patients in the EMS and ED settings from the diaspirin cross-linked hemoglobin (DCLHb) clinical trial.

METHODS

Data were analyzed from 17 US trauma centers gathered during a randomized, controlled, single-blinded efficacy trial of a hemoglobin solution (DCLHb) as add-on therapy versus standard therapy.

RESULTS

Among the 98 randomized patients, the mean EMS Glasgow Coma Scale (GCS) was 10.6 (SD = 5.0), the mean EMS revised trauma score (RTS) was 6.3 (SD = 1.9), and the mean injury severity score (ISS) was 31 (SD = 17). Upon arrival to the ED, the GCS was 20% lower (7.8 (SD = 5.3) vs 9.7 (SD = 6.3)) and the RTS was 12% lower (5.3 (SD = 2.0) vs 6.0 (SD = 2.1)) than EMS values in blunt trauma patients (P < .001). By ED disposition, 80% of patients (78/98) were intubated. Rapid sequence intubation (RSI) was utilized in 77% (60/78), most often utilizing succinylcholine (65%) and midazolam (50%). The mean crystalloid volume infused was 4.2 L (SD = 3.4 L), 80% of which was infused within the ED. Emergency department blood transfusion occurred in 62% of patients, with an average transfused volume of 1.2 L (SD = 2.0 L). Blunt trauma patients received 2.1 times more total fluids (7.4 L vs 3.5 L, < .001) and 2.4 times more blood (2.4 L vs 1.0 L, P < .001). The mean time of patients taken from injury site to operating room (OR) was 113 minutes (SD = 87 minutes). Twenty-one (30%) of the 70 patients taken to the OR from the ED were sent within 60 minutes of the estimated injury time. Penetrating trauma patients were taken to the OR 52% sooner than blunt trauma patients (72 minutes vs 149 minutes, P < .001).

CONCLUSION

Both GCS and RTS decreased prior to ED arrival in blunt trauma patients. Intubation was performed using RSI, and crystalloid infusion of three times the estimated blood loss volume (L) and blood transfusion of the estimated blood loss volume (L) were provided in the EMS and ED settings. Surgical intervention for these trauma patients most often occurred more than one hour from the time of injury. Penetrating trauma patients received surgical intervention more rapidly than those with a blunt trauma mechanism.