Diaspirin cross-linked hemoglobin is efficacious in gut resuscitation as measured by a GI tract optode

A Safety Assessment of Diaspirin Cross-Linked Hemoglobin (DCLHb) in the Treatment of Hemorrhagic, Hypovolemic Shock

Objective:

To determine the safety and possible efficacy of diaspirin cross-linked hemoglobin (DCLHb) in the treatment of patients in Class II–IV hemorrhagic, hypovolemic shock.

Design:

Multicenter, randomized, normal saline-controlled, dose-escalation study.

Setting:

Eleven hospitals in the U.S. and Belgium.

Subjects:

One hundred and thirty-nine (139) hospitalized patients with Class II–IV hemorrhagic, hypovolemic shock within the previous 4 hours who still were requiring therapy for shock.

Interventions:

Beginning with the lowest dose, patients were randomized to receive 50,100, or 200 mL of either 10% DCLHb or normal saline infused intravenously over 15 minutes. Following infusion of either treatment, further fluid resuscitation could be given, as necessary, to maintain perfusion. Vital signs, laboratory assessments, blood and fluid administration, complications, and adverse events were recorded at various times from the end of infusion through 72 hours after infusion.

Results:

A total of 29 (13 DCLHb- and 16 saline-treated) patients died during the study period. Adverse events were experienced by 61% of patients in the DCLHb group and 53% of patients in the saline group; serious adverse events occurred in 28% of DCLHb-treated patients and 30% of saline-treated patients. The incidence of prospectively defined, clinical complications, including renal insufficiency and renal failure, was similar between the treatment groups except for the occurrence of dysrhythmias/conduction disorders, which occurred significantly more frequently in the saline-treated patients than the DCLHb-treated patients (p = 0.041). At the highest dose level (200 mL), statistically significant between-group differences were observed with greater increases in serum amylase, LDH, the isoenzymes LD1,2,4 and 5, and CK-MB in the DCLHb group compared to the control group; none were of clinical significance. The volume of blood administered did not differ between the groups. Overall 24- and 72-hour survival rates were similar between treatment groups, although the hospital discharge rate was slightly higher in the DCLHb-treated patients (80%) compared with the saline-treated patients (74%).

Conclusion:

Administration of 50 to 200 mL of DCLHb to patients in hemorrhagic, hypovolemic shock was not associated with evidence of end organ toxuity or significant adverse events. Further studies involving larger doses and, perhaps, earlier administration of DCLHb are warranted.

Toxicities of hemoglobin solutions: in search of in-vitro and in-vivo model systems

Several hemoglobin-based oxygen carriers (HBOCs) have been developed with a rationale focused on exploiting one or more physicochemical properties (e.g., oxygen affinity, molecular weight, viscosity, and colloid osmotic pressure) resulting from the chemical or recombinant modification of hemoglobin (Hb). Several chemically modified Hbs have reached late stages of clinical evaluation in the United States and Canada. These Hbs, in general, demonstrated mixed preclinical safety and efficacy, and reasonable safety in Phase I trials. However, as clinical development shifted into later stages, an undesirable safety and efficacy profile became clear in patient populations studied, and as a result some products were withdrawn from further clinical pursuit. Several questions still remain unanswered regarding the safety of Hb products for their proposed clinical indication(s). For example, 1) were preclinical studies predictive of clinical outcome? And, 2) were the most appropriate preclinical studies performed to predict clinical outcome? The primary objectives of this analysis are to explore prelinical safety issues associated with HBOCs and provide an overview of the in-vitro and in-vivo models employed. The methods for obtaining data to serve as a basis for discussion are compiled from a literature-based survey of safety and efficacy derived from biochemical, cellular, and whole animal assessment of HBOCs. Results from this overview of a vast body of published data may provide a means for identifying critical preclinical safety issues, which may ultimately lead to identification of potential limitations in the effective clinical use of certain HBOCs.

Increased tissue PO2 and decreased O2 delivery and consumption after 80% exchange transfusion with polymerized hemoglobin

The O2-carrying blood substitute based on polymerized bovine hemoglobin (PBH) was used to determine efficacy in maintaining tissue Po2 after an 80% isovolemic blood exchange leading to a hematocrit of 19% [5.4 g Hb/dl from red blood cells (RBCs) and 6.3 g Hb/dl from PBH]. Effects were studied in terms of O2 delivery, O2 extraction, and tissue Po2 at the microcirculatory level at 1, 12, and 24 h after exchange transfusion in awake hamsters prepared with a window chamber model. At 1 h after exchange, arteriolar and venular diameters were decreased compared with baseline. Arteriolar diameter did not fully recover at 12 h after exchange, but venular diameter returned to normal. At 24 h after exchange, arteriolar and venular diameters were not different from baseline. Combining diameter and flow velocity data allowed us to calculate arteriolar and venular flows. At 1 h after exchange, arteriolar and venular flow was reduced compared with baseline. Arteriolar flow was lower at 12 h after exchange and recovered after 24 h. The number of capillaries with RBC passage [functional capillary density (FCD)] at 1 h after exchange with PBH was significantly lower than baseline. FCD remained decreased at 12 h; at 24 h after exchange transfusion, FCD was fully recovered. Tissue Po2 was maximal at 1 h after exchange and decreased progressively at 12 and 24 h after exchange. O2 release to the tissue was minimal at 1 h and increased at 12 and 24 h after exchange. These results suggest the impairment of tissue O2 metabolism after introduction of PBH into the circulation, which is mitigated as PBH concentration declines.

Hemoglobin-based oxygen carrier provides heterogeneous microvascular oxygenation in heart and gut after hemorrhage in pigs

BACKGROUND

In this study, the hypothesis was tested that resuscitation with hemoglobin-based oxygen carriers (HBOCs) affects the oxygenation of the microcirculation differently between and within organs. To this end, we tested the influence of the volume of an HBOC on the microcirculatory oxygenation of the heart and the gut serosa and mucosa in a porcine model of hemorrhage.

METHODS

In anesthetized open-chested pigs (n = 24), a controlled hemorrhage (30 mL/kg over 1 hour) was followed by resuscitation with 10, 20, or 30 mL/kg diaspirin-crosslinked hemoglobin (DCLHb) or isovolemic resuscitation with 30 mL/kg of a 6% hydroxyethyl starch solution (HAES). Measurements included systemic and regional hemodynamic and oxygenation parameters. Microvascular oxygen pressures (microPO2) of the epicardium and the serosa and mucosa of the ileum were measured simultaneously by the palladium-porphyrin phosphorescence technique. Measurements were obtained up to 120 minutes after resuscitation.

RESULTS

After hemorrhage, a low volume of DCLHb restored both cardiac and intestinal microPO2. Resuscitation of gut microPO2 with a low volume of DCLHb was as effective as isovolemic resuscitation with HAES. Higher volumes of DCLHb did not restore cardiac microPO2, as did isovolemic resuscitation with HAES, but increased gut microPO2 to hyperoxic values, dose-dependently. Effects were similar for the serosal and mucosal microPo2. In contrast to a sustained hypertensive effect after resuscitation with DCLHb, effects of DCLHb on regional oxygenation and hemodynamics were transient.

CONCLUSION

This study showed that a low volume of DCLHb was effective in resuscitation of the microcirculatory oxygenation of the heart and gut back to control levels. Increasing the volume of DCLHb did not cause an additional increase in heart microPO2, but caused hyperoxic microvascular values in the gut to be attained. It is concluded that microcirculatory monitoring in this way elucidates the regional behavior of oxygen transport to the tissue by HBOCs, whereas systemic variables were ineffective in describing their response.

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.

DCL-Hb for trauma patients with severe hemorrhagic shock: the European "On-Scene" multicenter study

OBJECTIVE

A major cause of death in patients with severe hemorrhagic shock following trauma is the subsequent occurrence of multiple organ failure due to tissue hypoxia. Early administration of an oxygen carrier may reduce the occurrence of organ failures and improve survival. It may also reduce the need of blood products.

DESIGN AND SETTING

Prospective multicenter study in a university clinic.

PATIENTS

121 patients with severe hemorrhagic shock.

INTERVENTIONS

Patients were randomly assigned "on-scene" to receive either up to 1000 ml of a 10% diaspirin cross-linked hemoglobin (DCLHb) solution or the study center's standard therapy.

MEASUREMENTS AND RESULTS

Demographic and physiological characteristics of the two treatment groups at baseline were comparable. Organ failures and survival rates until day 5 and day 28 showed no significant differences. The sponsor therefore terminated this trial prematurely after an interim evaluation of the data indicated no evidence of efficacy to offset concerns raised about the safety of DCLHb. Median volumes of cumulative blood products administered on 1 (1595 vs. 3716 ml) and 7 days (3139 vs. 4746 ml) after admission were lower in the DCLHb group.

CONCLUSIONS

The early application of an oxygen carrier (DCLHb) to patients with severe hemorrhagic shock following trauma had no significant effect on the occurrence of organ failure or on 5- and 28-day survival in this abbreviated trial. However, early infusion of up to 1000 ml DCLHb reduces the need for blood products without changing morbidity or survival.

Regulation of hypoxia-inducible factor 1 in enterocytic cells

BACKGROUND

Mucosal hypoxia due to intestinal hypoperfusion is characteristic of a number of clinical disorders. An early event in the adaptive response to cellular hypoxia is the binding of hypoxia-inducible factor 1 (HIF-1) to cis-acting regulatory sites in target genes.

METHODS

We characterized the expression of HIF-1 in transformed (Caco-2(BBe) and T84) and nontransformed human (FHs 74 Int) and rat (IEC-6) intestinal epithelial cell lines.

RESULTS

The electrophoretic mobility shift assay detected increased HIF-1 DNA-binding activity in each cell line within 2 h of hypoxia (1% O2). HIF-1 binding was maximal within 4 h and remained stable for 24 h. HIF-1 DNA-binding activity was maximal in the established IEC-6 cell line below 2% oxygen, but HIF-1 DNA-binding activity was not detectable above 0.5% O2 in the primary human FHs 74 Int cell line. The nonspecific protein kinase inhibitor genistein (200 microM) inhibited HIF-1 binding at 4 h. Transfection of Caco-2 cells with a wild-type, but not a mutant, HIF-1-dependent luciferase expression vector resulted in a fourfold induction of reporter gene expression during hypoxia.

CONCLUSIONS

In conclusion, HIF-1 regulates gene expression in enterocytes and an undefined phosphorylation event is important for O2 sensing.

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.

Post hoc mortality analysis of the efficacy trial of diaspirin cross-linked hemoglobin in the treatment of severe traumatic hemorrhagic shock

BACKGROUND

The efficacy trial of diaspirin cross-linked hemoglobin (DCLHb) in traumatic hemorrhagic shock demonstrated an unexpected mortality imbalance, prompting a three-step review to better understand the cause of this finding.

METHODS

Patients were enrolled in this DCLHb hemorrhagic shock study using 28-day mortality as the primary endpoint. Mortality data were primarily analyzed using the TRISS method and a nonblinded clinical review, followed by an independent Pennsylvania Trauma Outcome Study (PTOS)-derived probability of survival analyses. Finally, a trauma expert conducted a blinded clinical review of cases incorrectly predicted by these PTOS analyses.

RESULTS

More of the DCLHb patients predicted to survive using TRISS actually died than in the control subgroup (24% vs. 3%, p < 0.002). Nonblinded clinical review noted that 72% of the patients who died had prior traumatic arrest, a presenting Glasgow Coma Scale score of 3, or a base deficit > 15 mEq/L. DCLHb patients predicted to survive using PTOS also more often died than did control patients (30% vs. 8%, p < 0.04). Blinded clinical review determined that 94% of the deaths were clinically justified. Both the TRISS and the PTOS models gave an adjusted mortality relative risk of 2.3, similar to the unadjusted risk data.

CONCLUSION

Mortality analysis in this shock study involved both clinical case reviews and mortality prediction models. Despite the observation that nearly all of the deaths were clinically justified, the TRISS and PTOS models demonstrated excess unpredicted deaths in the DCLHb subgroup. A combined process, using both mortality prediction models and clinical case reviews, is useful in trauma studies that use a mortality endpoint.

Assessment of tissue oxygen tension: comparison of dynamic fluorescence quenching and polarographic electrode technique

INTRODUCTION AND METHODS

Dynamic fluorescence quenching is a technique that may overcome some of the limitations associated with measurement of tissue partial oxygen tension (PO2). We compared this technique with a polarographic Eppendorf needle electrode method using a saline tonometer in which the PO2 could be controlled. We also tested the fluorescence quenching system in a rodent model of skeletal muscle ischemiahypoxia.

RESULTS

Both systems measured PO2 accurately in the tonometer, and there was excellent correlation between them (r(2) = 0.99). The polarographic system exhibited proportional bias that was not evident with the fluorescence method. In vivo, the fluorescence quenching technique provided a readily recordable signal that varied as expected.

DISCUSSION

Measurement of tissue PO2 using fluorescence quenching is at least as accurate as measurement using the Eppendorf needle electrode in vitro, and may prove useful in vivo for assessment of tissue oxygenation.

Validation of in vivo MR measurement of oxygen saturation after resuscitation with a hemoglobin-based oxygen carrier in a rabbit model

RATIONALE AND OBJECTIVES

The authors tested whether noninvasive magnetic resonance (MR) oximetry is accurate in the in vivo measurement of oxygen saturation in a stroma-free, hemoglobin-based oxygen carrier (HBOC).

MATERIALS AND METHODS

A central venous catheter was placed in the inferior vena cava (IVC) of 10 New Zealand white rabbits (weight range, 2.5-3.2 kg). Each rabbit underwent removal of 20% of blood volume followed by resuscitation with 10 mL/kg of bovine HBOC-200. Oxygen saturation of the blood mixture was measured in vivo at the IVC with MR oximetry, with separate in vitro calibration for each animal. Blood drawn from the IVC was measured with ex vivo oximetry, which was used as the standard of reference. The in vivo and ex vivo measurements were compared.

RESULTS

There was no significant difference (P > .1) between measurements obtained with MR oximetry and ex vivo oximetry. The results with in vivo MR oximetry demonstrated excellent correlation with those from ex vivo oximetry (r = 0.99) over a wide range of physiologic oxygen saturation values (16.7%-74.9%) in venous blood.

CONCLUSION

Noninvasive in vivo MR measurement of oxygen saturation is valid for whole blood mixed with stroma-free hemoglobin. Therefore, MR oximetry may be clinically useful for assessing the oxygenation status in patients resuscitated with a HBOC.

Effects of haemoglobin-based oxygen carrier hemoglobin glutamer-200 (bovine) on intestinal perfusion and oxygenation in a canine hypovolaemia model

The objective of this investigation was to study the effects of the first marketed haemoglobin-based oxygen carrier, Hemoglobin glutamer-200 (bovine) (Hb-200) (Oxyglobin) on splanchnic perfusion and oxygenation in a canine model of acute hypovolaemia. Twelve anaesthetized dogs [mean weight 30.8 (S.D. 1.4) kg] were instrumented for recordings of heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), cardiac output and cranial mesenteric arterial (CMA) and venous blood flows (CMV). Total and plasma haemoglobin (Hb), oxygen content and saturation, lactate concentration, pH and blood gases were analysed in arterial, mixed venous and mesenteric venous blood samples. Measurements were made before (baseline) and after 1 h of haemorrhage, after which animals were resuscitated with either shed blood (controls) or Hb-200 until HR, MAP and CVP returned to prehaemorrhage levels. Recordings were repeated immediately and 3 h after termination of fluid resuscitation, after which organ specimens were obtained for microscopic examination. Haemorrhage (average 32 ml kg(-1)) reduced MAP to 50 mm Hg, increased HR and systemic vascular resistance (SVR), and was accompanied in both the systemic and the splanchnic circulation by significant decreases in blood flow, Hb content and oxygen delivery (DO2), and lactic acidosis. In controls, all variables recovered to baseline after isovolaemic resuscitation with shed blood. In dogs resuscitated with a small volume of Hb-200 (10 ml kg(-1)), HR, MAP, CVP and CMA and CMV blood flows returned to baseline. However, cardiac output, total Hb, oxygen content and systemic and mesenteric DO2 remained depressed while SVR increased further. Mesenteric and systemic acid-base status recovered in both groups, and there was no difference in microscopic tissue damage between groups. Thus, Hb-200 reconstituted splanchnic perfusion and oxidative metabolism in spite of pronounced systemic vasoconstriction and insufficient restoration of CO and DO2; it may improve diffusive oxygen transport in the microvasculature by virtue of haemodilution and its high efficiency in the uptake and release of oxygen.

Inadequacy of low-volume resuscitation with hemoglobin-based oxygen carrier hemoglobin glutamer-200 (bovine) in canine hypovolemia

Stroma-free hemoglobin-based oxygen carriers (HBOC) have been developed to overcome problems associated with transfusion of allogeneic blood. We have studied the efficacy of the first licensed veterinary blood substitute, hemoglobin glutamer-200 bovine (Oxyglobin; Biopure, Cambridge, MA, USA, Hb-200), in a canine model of acute hypovolemia and examined whether clinically commonly used criteria are adequate to guide fluid resuscitation with this product. Twelve anesthetized dogs were instrumented for measurements of physiological variables including hemodynamic, oxygenation, and blood gas and acid-base parameters. Dogs were bled to a mean arterial pressure (MAP) of 50 mmHg for 1 h followed by resuscitation with either shed blood (controls) or Hb-200 until heart rate (HR), MAP and central venous pressure (CVP) returned to baseline. Recordings were repeated immediately and 3 h after termination of fluid resuscitation. Hemorrhage (average 32 mL/kg) caused significant decreases in total hemoglobin (Hb), mean pulmonary arterial pressure (PAP), cardiac output (CO) and oxygen delivery (DO2I), increases in HR and systemic vascular resistance (SVRI), and lactic acidosis. In controls, only re-transfusion of all shed blood returned HR, MAP and CVP to prehemorrhage values, whereas in other dogs this endpoint was reached with infusion of 10 mL/kg Hb-200. Unlike blood transfusion, Hb-200 infusion failed to return CI and DO2I to baseline and to increase arterial oxygen content (CaO2) and total Hb; SVRI further increased. Thus, commonly used criteria (HR, MAP, CVP) to guide transfusion therapy in patients posthemorrhage prove insufficient when HBOCs with pronounced vasoconstrictive action are used and lead to inadequate volume repletion.

Hemoglobin solutions--not just red blood cell substitutes

OBJECTIVE

To review current knowledge about cell-free hemoglobin solutions.

DATA SOURCES

All studies involving cell-free hemoglobin were retrieved from a computerized MEDLINE search from 1980 to 1998. We also reviewed the reference lists of all available review articles and primary studies to identify references not found in the computerized search.

STUDY SELECTION

Clinical and experimental studies in which cell-free hemoglobin solutions were studied.

DATA EXTRACTION

From the selected studies, information was obtained regarding the experimental model or the study population in which cell-free hemoglobin solutions were investigated, the type of cell-free hemoglobin solution, their deleterious or beneficial effects, and their possible indications.

DATA SYNTHESIS

In many studies, hemoglobin solutions were considered as efficient resuscitative agents and good alternatives to red blood cell transfusion, because of their marked vasopressor effect coupled with their capacity to improve the microcirculation and quickly restore metabolic parameters. Nevertheless, potential problems include an increased susceptibility to infection, immunosuppression, oxidative damage, excessive pulmonary and systemic vasoconstriction, and platelet activation.

CONCLUSIONS

Hemoglobin solutions are more than mere blood substitutes. Promising effects on oxygen transport and the microcirculation need to be confirmed, and the results of continuing research are eagerly awaited.

A critical assessment of endpoints of shock resuscitation

Modern hemodynamic therapy is not only the recognition and treatment of hypotension but also the avoidance and treatment of shock in its broadest sense. The major issues include the recognition of hypoperfusion of the body as a whole or its individual tissues and organ systems and the determination of the best endpoints for the treatment of shock. Even if all of the commonly used clinical indicators of shock are "normal," shock on a cellular, tissue, or organ basis may still be present. Whether "organ-specific" assessments, such as gastric tonometry or tissue oxygen tension measurement, are the ultimate answer to this problem remains to be seen. The determination of adequate intravascular volume (preload) continues to present major difficulties in the care of critically ill or injured patients. Although PCWP is frequently helpful, it is not a gold standard. A bedside ultrasonic technique, such as esophageal Doppler sonography, may replace the Swan-Ganz catheter technique in many patients.

Diaspirin-crosslinked hemoglobin reduces mortality of severe hemorrhagic shock in pigs with critical coronary stenosis

OBJECTIVE

To evaluate the effects of resuscitation with a 10% diaspirin-crosslinked hemoglobin (DCLHb) solution on global hemodynamic variables, systemic and myocardial oxygen transport and tissue oxygenation, and contractile function of the left ventricle in an experimental model of severe hemorrhagic shock and critical stenosis of the left anterior descending coronary artery (LAD).

DESIGN

Prospective, placebo-controlled, randomized study.

SETTING

Experimental animal laboratory.

SUBJECTS

A total of 20 anesthetized pigs.

INTERVENTIONS

After implementation of a permanent critical LAD stenosis (ie, maintenance of basal blood flow but absence of reactive hyperemia after a 10-sec complete vessel occlusion), hemorrhagic shock (target mean aortic pressure, 45 mm Hg) was induced within 15 mins by programmed withdrawal of blood and maintained for 60 mins. Subsequently, the volume of plasma lost during hemorrhage was replaced by either a balanced electrolyte solution containing 10 g/dL DCLHb (DCLHb group; n = 10) or an 8 g/dL human albumin solution (HSA) oncotically matched to DCLHb (HSA group; n = 10). Data were collected immediately after the infusion of the different solutions and again after 60 mins had elapsed.

MEASUREMENTS AND MAIN RESULTS

Although five of ten HSA-treated animals died of acute left ventricular failure within the first 20 mins after complete fluid resuscitation, all of the DCLHb-treated animals survived the 60-min observation period after resuscitation (p < .05). This significant difference in mortality is explained by higher coronary perfusion pressure in DCLHb-treated animals (75 +/- 17 vs. 27 +/- 17 torr DCLHb vs. HSA group; p < .05) and persistence of subendocardial ischemia and hypoxia (radioactive microspheres method) in HSA-treated animals on resuscitation particularly affecting the LAD-supported myocardium (subendocardial oxygen delivery: 20 +/- 11 vs. 3 +/- 1 mL oxygen x g(-1) x min(-1), DCLHb vs. HSA group; p < .05). Except for enhanced myocardial contractility immediately on infusion of DCLHb (maximal left ventricular pressure increase: 2373 +/- 782 vs. 1730 +/- 543 torr x sec(-1) DCLHb vs. HSA group; p < .05), no differences were detected between groups concerning the variables of systemic oxygen transport, tissue oxygenation, and regional contractile function of the myocardium (determined with microsonometry).

CONCLUSIONS

Fluid resuscitation with 10% DCLHb solution completely reverses hemorrhagic shock-induced subendocardial ischemia and hypoxia in the presence of compromised coronary circulation and thereby prevents early death after resuscitation.

Diaspirin cross-linked hemoglobin improves mucosal perfusion in the ileum of septic rats

OBJECTIVE

To determine the effect of a bolus infusion of diaspirin cross-linked hemoglobin (DCLHb or hemoglobin crosfumaril) on the ileal mucosal microcirculation in septic rats.

DESIGN

Prospective, randomized, single-blinded study.

SETTING

University-affiliated animal research laboratory.

SUBJECTS

Twenty-four male Sprague-Dawley rats, weighing 320-380 g.

INTERVENTIONS

Under inhalational anesthesia, arterial and venous catheters were inserted and sepsis was created by cecal ligation and perforation (CLP). Twenty-four hours later, animals were reanesthetized and ventilated. Via midline abdominal incision, the ileum was mobilized and prepared for intravital microscopy. Post-CLP hemodynamic values were obtained, and videomicroscopy was performed on four to ten villi. Animals were then randomized to receive 2 mL of DCLHb solution (100 mg/mL; n = 12) or pentastarch (n = 12) intravenously, and measurements were repeated after 20 mins. Rats treated with DCLHb then received nitroprusside to restore mean arterial pressure to post-CLP levels, and final measurements were obtained 15 mins later.

MEASUREMENTS AND MAIN RESULTS

Cardiac index increased with both treatments (p < .001), whereas systemic vascular resistance index and mean arterial blood pressure were augmented only with DCLHb (p < .0001 compared with pentastarch). Intercapillary areas (ICA; inversely related to capillary density) were determined using computerized image analysis. ICA size decreased after treatment, from 974 +/- 79 to 791 +/- 106 microm2 with DCLHb and from 1044 +/- 90 to 840 +/- 82 microm2 with pentastarch (both p < .05). Red blood cell velocity in terminal arterioles, as assessed by velocimetry from the recorded images, increased by 15% with both treatments (p < .05). Restoration of mean arterial pressure to post-CLP levels in DCLHb animals by nitroprusside infusion abolished the effects of the hemoglobin solution on ICA size and red blood cell velocity.

CONCLUSION

Both DCLHb and pentastarch infusion improved microcirculatory perfusion in the ileum of septic rats. In addition, DCLHb also exhibited vasopressor properties, which in combination with improved perfusion may be particularly useful in the treatment of sepsis.

Tissue perfusion and oxygenation with blood substitutes

As an alternative to transfusion of red blood cells, intravenously (iv) administered artificial oxygen (O(2)) carriers are intended to increase the reduced O(2) carrying capacity of blood in the case of acute severe anemia, i.e. hemorrhagic shock or extreme normovolemic hemodilution (ANH). Actually, two groups of artificial O(2) carriers are investigated: ultrapurified, stroma-free hemoglobin solutions (SFH) of human or bovine origin and synthetically produced perfluorocarbons (PFC). SFH may be administered in large amounts and are suitable for 1:1 replacement of blood losses in case of hemorrhage as well as for isovolemic exchange of blood during ANH. In both situations SFH solutions effectively restore (hemorrhagic shock) and maintain (extreme ANH) tissue oxygenation despite extremely low hematocrit values. The vasopressor property of the isolated Hb molecule leads to a species-dependent (rodent>pig>human) increase in systemic and pulmonary vascular resistance, but leaves overall distribution of cardiac output uninfluenced. Due to the particulate nature of PFC emulsions, iv administration has to be restricted to small doses (3-4.5 ml/kg body weight for the actually investigated 60% w/v perflubron emulsion) in order to avoid overload of the reticuloendothelial system. Thus PFC emulsions are unsuitable for isovolemic blood replacement in hemorrhagic shock or ANH. Low-dose iv PFC administration in already hemodiluted subjects, however, creates an additional margin of safety to guarantee adequate tissue oxygenation which allows for further, extreme ANH, without risking tissue hypoxia.

Effects of diaspirin crosslinked hemoglobin infusion in treadmill-exercised swine

The hemodynamic and metabolic effects of diaspirin crosslinked hemoglobin (DCLHb) were investigated using graded treadmill exercise in swine (n = 5/group). Swine received DCLHb (10% solution, 5 ml/kg) or oncotically-matched human serum albumin (HSA, 5ml/kg). Baseline metabolic and hemodynamic data were similar. In both groups exercise increased hemodynamic parameters. Exercise increased heart rate (HR) from 139 +/- 12 to 293 +/- 28 bpm with DCLHb and from 136 +/- 13 to 314 +/- 13 bpm with HSA. Exercise increased cardiac output (CO) from 5.7 +/- 0.75 to 15.6 +/- 2.01/min in the DCLHb group and from 5.3 +/- 0.48 to 15.7 +/- 0.881/min in the HSA group. However, CO returned to baseline faster with DCLHb upon stopping exercise. The DCLHb-treated group demonstrated a significantly higher oxygen extraction during exercise (12.04 +/- 0.38 vs 9.48 +/- 0.99 ml O2/100 ml blood) and a lower oxygen delivery throughout recovery (74.6 +/- 6.6 vs 102.2 +/- 7.21 O2/min), indicating enhanced oxygen delivery during exercise in the treatment group. DCLHb infusion did not impair metabolic or hemodynamic functions. These data indicate that DCLHb may increase oxygen delivery to working tissue more efficiently than HSA during treadmill exercise in swine.

Comparison of resuscitation with diaspirin crosslinked hemoglobin (DCLHb) vs fresh blood in a rat burn shock model

Diaspirin crosslinked hemoglobin (DCLHb; Baxter Healthcare Corp, Deerfield, IL) is hemoglobin-based oxygen carrier which, in our laboratory, improved hemodynamic parameters in a rat burn shock model. Our objective was to compare the effects on hemodynamic parameters and metabolic acidosis of resuscitation with different doses of fresh blood (FB) vs DCLHb. Male Wistar rats (200 to 250 g), surgically prepared for an acute study, were randomly assigned to one of five treatment groups. (n = 8): I. SHAM (not burned, not resuscitated), II. DCLHb 2 ml/kg/% Total Body Surface Area (TBSA) burn and 2 ml/kg/% TBSA burn of Lactated Ringers (LR), III. DCLHb 1 ml/kg/% TBSA burn and 1 ml/kg/% TBSA burn of LR IV. FB 2 ml/kg/% TBSA burn and 2 ml/kg/% TBSA burn of LR V. FB 1 ml/kg/% TBSA burn and 1 ml/kg/% TBSA burn of LR After placement of indwelling catheters, the following baseline hemodynamic values were obtained mean arterial pressure (MAP), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR) and base excess (BE). The animals were immediately intravenously resuscitated after receiving a 30% scald burn and were followed for 6 hours. Resuscitation was based on the Parkland formula. Blood was obtained from donor male Wistar rats. The animals were euthanized at 6 hours. MAP remained within normal range in all groups. The SVR, CO, SV and BE were normalized earlier in the LR-DCLHb groups when compared to the LR-FB groups (p < 0.05). Early resuscitation with DCLHb is superior to FB in improving hemodynamics in this model. There appears to be a direct relationship between dose and effect with the use of DCLHb. DCLHb could be useful in decreasing resuscitation fluid requirements in acute burns without compromising general tissue perfusion.

The effects of diaspirin cross-linked hemoglobin on hemodynamics, metabolic acidosis, and survival in burned rats

OBJECTIVE

Diaspirin cross-linked hemoglobin (DCLHb) is a vasoactive hemoglobin-based oxygen carrier or "blood substitute" that has been shown to improve base deficit in several experimental studies of hemorrhagic shock. Our objective was to determine if the addition of DCLHb to the resuscitation regimen would improve hemodynamic parameters, metabolic acidosis, and survival in our rat burn shock model compared with currently used resuscitation therapy.

METHODS

This was a randomized, controlled, experimental rat study. Male Wistar rats, weighing 200 to 250 g, were surgically prepared for an acute study. After placement of indwelling catheters, baseline hemodynamic values (mean arterial pressure, cardiac output, systemic vascular resistance, stroke volume, and base excess) were obtained. Thirty-two rats were used in the study, and they were either subjected to a 30% scald burn (experimental group) or sham burned (control group). The experimental animals were immediately intravenously resuscitated and followed for 6 hours. The resuscitation was based on the Parkland formula (4 mL/kg for each 1% of total body surface area [TBSA] burn), with 50% of the calculated fluid amount to be administered at a constant rate during the first 8 hours after burn. The animals were resuscitated for 6 hours and received between 9.00 and 11.25 mL of fluid depending on weight. The experimental animals were randomly assigned to one of three treatment groups: group I, lactated Ringer's solution; group II, lactated Ringer's solution-human serum albumin; group III, lactated Ringer's solution-DCLHb. Group I (n = 8) received 4 mL/kg lactated Ringer's solution for each 1% of TBSA burn. Group II (n = 8) received 2 mL/kg lactated Ringer's solution and 2 mL/kg human serum albumin for each 1% of TBSA burn. Group III (n = 8) received 2 mL/kg lactated Ringer's solution and 2 mL/kg DCLHb for each 1% of TBSA burn. The sham group (n = 8) was not burned and was not resuscitated. Animals that survived up to 6 six hours were killed.

RESULTS

We found that mean arterial pressure, cardiac output, stroke volume, and base excess were all improved in the DCLHb-lactated Ringer's solution-treated animals compared with the other experimental treatment groups. The 6-hour mortality rates were zero of eight (lactated Ringer's solution-DCLHb group), zero of eight (sham group), three of eight (lactated Ringer's solution-human serum albumin group), and six of eight (lactated Ringer's solution only group).

CONCLUSION

Early resuscitation with DCLHb is superior to non-oxygen-carrying resuscitative fluids in improving hemodynamics and survival in this model of burn shock. DCLHb might improve general tissue perfusion in the acute postburn period, and it could be useful in the early management of patients with severe burns.

Low-volume resuscitation with a hemoglobin-based oxygen carrier after hemorrhage improves gut microvascular oxygenation in swine

Using palladium-porphyrin quenching of phosphorescence, we investigated the influence of diaspirin cross-linked hemoglobin (DCLHb) on gut microvascular oxygen pressure (microPO2) in anesthetized pigs. Values of gut microPO2 were studied in correlation with regional intestinal as well as global metabolic and circulatory parameters. A controlled hemorrhagic shock (blood withdrawal of 40 mL/kg) was followed by resuscitation with either a combination of lactated Ringer's solution (75 mL/kg) and modified gelatin (15 mL/kg)(lactR/Gel) or 10% DCLHb (5 mL/kg). After resuscitation, gut microPO2 was similarly improved in the lactR/Gel group (from 25 +/- 10 mm Hg to 53 +/- 8 mm Hg) and the DCLHb group (from 23 +/- 9 mm Hg to 46 +/- 6 mm Hg), which was associated with increased gut oxygen delivery. However, the improvement after resuscitation with DCLHb was sustained for longer periods of time (75 vs 30 min). Mesenteric venous PO2 was increased after resuscitation with lactated Ringer's solution and modified gelatin but not with DCLHb, which was associated with an increased gut oxygen consumption in the latter group. We conclude that measurement of microPO2 by the palladium-porphyrin phosphorescence technique revealed DCLHb to be an effective carrier of oxygen to the microcirculation of the gut. Also, this effect can be achieved with a lower volume than is currently used in resuscitation procedures.

Effect of alpha(alpha)-cross-linked hemoglobin and pyridoxalated hemoglobin polyoxyethylene conjugate solutions on gastrointestinal regional perfusion in hemorrhagic shock

BACKGROUND

Hemoglobin-based blood substitutes may cause vasoconstriction, which could limit organ perfusion during trauma resuscitation. We investigated the effect of two hemoglobin solutions on regional blood flow and mucosal perfusion in the gastrointestinal tract in a hemorrhagic shock model.

METHODS

Twenty-four swine were bled 30% of blood volume over 1 hour. Six additional animals were anesthetized and monitored but did not undergo hemorrhage. Bled animals were resuscitated with alpha(alpha)-hemoglobin (alpha(alpha)Hb), pyridoxalated hemoglobin polyoxyethylene conjugate (PHP), shed blood, or lactated Ringer's solution. Regional blood flow was measured by radiolabeled microspheres. Gastric mucosal perfusion was estimated by measuring intramucosal pH (pHi) by tonometry.

RESULTS

PHP and shed blood restored small-bowel flows to sham values, whereas lactated Ringer's solution and alpha(alpha)Hb did not. Shed blood and PHP, but not alpha(alpha)Hb, restored cardiac index (CI) to baseline (p < 0.05). Mean pulmonary artery pressure was elevated over baseline with alpha(alpha)Hb and PHP and remained elevated with alpha(alpha)Hb (p < 0.05). pHi was significantly lower after resuscitation with PHP than with other fluids.

CONCLUSION

PHP was efficacious in restoring CI and small-bowel flow, but the pHi remained low, indicating possible continued mucosal ischemia. Alpha(alpha)Hb led to limited recovery of CI and small-bowel blood flow but restored pHi close to baseline. Shed blood was efficacious in restoration of pHi, gastrointestinal blood flows, and systemic hemodynamics.

Attenuation of postischemic reperfusion injury in striated skin muscle by diaspirin-cross-linked Hb

Hemoglobin-based oxygen carriers have been suggested to enhance the formation of oxygen free radicals, especially under conditions of ischemia-reperfusion (I/R), in which activation and adhesion of leukocytes play a pivotal role for propagation of reperfusion injury. This study investigates the effects of the hemoglobin-based oxygen carrier diaspirin-cross-linked hemoglobin (DCLHb) in an I/R model of hamster striated skin muscle. The dorsal skinfold chamber model in the awake Syrian golden hamster was used for analysis of the microcirculation and local tissue PO2 in striated skin muscle utilizing the technique of intravital fluorescence microscopy and a multiwire platinum surface (Clark type) electrode. Measurements were made before 4 h of pressure-induced ischemia and at 0.5, 2, and 24 h of reperfusion. Animals were treated with 5 ml/kg body wt of either 10% DCLHb (n = 8), 6% Dextran 60 (Dx-60; 60 kDa, n = 8), or 0.9% NaCl (n = 7), which was given intravenously 15 min before reperfusion. In animals treated with DCLHb or Dx-60, a significant decrease of leukocytes rolling along and sticking in postcapillary venules, associated with a recovery of functional capillary density and red blood cell velocity, was observed compared with saline-treated controls. In the early reperfusion period (0.5 h), DCLHb and Dx-60 efficiently restored local tissue PO2, whereas tissue PO2 decreased from 18.3 +/- 1.9 to 15.3 +/- 5.3 mmHg in 0.9% NaCl-treated animals. Electron microscopic analysis of the postischemic tissue at 24 h of reperfusion revealed markedly reduced tissue damage in animals treated with DCLHb compared with Dx-60 or isotonic saline. These results indicate that DCLHb attenuates postischemic reperfusion injury of striated skin muscle, presumably through alterations of leukocyte-endothelial cell interactions.

Initial evaluation of diaspirin cross-linked hemoglobin (DCLHb) as a vasopressor in critically ill patients

OBJECTIVE

To evaluate the hemodynamic effects and any toxicologic effects of diaspirin cross-linked hemoglobin (DCLHb) in critically ill patients.

DESIGN

A prospective, observational study.

SETTING

A seven-bed intensive care unit (ICU) in a University teaching hospital.

PATIENTS

Fourteen critically ill patients requiring vasopressor therapy to maintain adequate mean arterial pressure (MAP). All patients had secondary organ dysfunction.

INTERVENTIONS

Administration of 100 mL boluses of 10% diaspirin cross-linked hemoglobin, up to a maximum of 500 mL, given over 15 mins and separated by 60 to 90 mins.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic parameters, norepinephrine and inotropic requirements, arterial and mixed venous blood gases, urine output, and biochemical and hematologic analyses were measured before diaspirin cross-linked hemoglobin administration and at multiple time points up to 72 hrs. MAP was maintained at approximately preinfusion values and the reduction in norepinephrine requirements was used as the main end point to assess the efficacy of diaspirin cross-linked hemoglobin as a vasopressor. Diaspirin cross-linked hemoglobin demonstrated a marked vasopressor action, allowing norepinephrine requirements to be reduced from 0.29 +/- 0.15 (SD) microgram/kg/min to 0.15 +/- 0.14 and 0.07 +/- 0.10 microgram/kg/min after the first (at 1.5 hrs, p < .001) and last (at 7.5 hrs, p < .0001) boluses, respectively. These reductions in norepinephrine requirements were maintained at 24, 48, and 72 hrs (p < .01 at all time points). These hemodynamic changes began within 5 mins of starting the diaspirin cross-linked hemoglobin infusion. MAP, heart rate, central venous pressure, pulmonary artery occlusion pressure, mean pulmonary arterial pressure (MPAP), systemic vascular resistance index, and urine output did not demonstrate any significant changes from preinfusion values. Pulmonary vascular resistance index increased at 7.5 hrs despite nonsignificant increases in MPAP. Cardiac index and oxygen delivery index decreased significantly at 7.5 hrs and 24 hrs. Total plasma bilirubin increased significantly from baseline at 24 and 48 hrs, before returning to baseline values within 5 days. Platelet count was significantly reduced at 6 and 24 hrs. No other biochemical or hematologic analyses were altered significantly post diaspirin cross-linked hemoglobin.

CONCLUSIONS

This preliminary study demonstrated that diaspirin cross-linked hemoglobin is a potent vasopressor agent in critically ill patients with septicemic shock or systemic inflammatory response syndrome. This vasopressor characteristic of diaspirin cross-linked hemoglobin may have future clinical applications.

Basic fibroblast growth factor reduces the gut and liver morphologic and functional injuries after ischemia and reperfusion

OBJECTIVE

To explore the possible effects of basic fibroblast growth factor (bFGF) on ischemic gut and liver injuries after trauma.

METHODS

Animal models of superior mesenteric artery occlusion (45 minutes) and reperfusion (3 days) were used in this study. Seventy-two Wistar rats were divided into three groups of 24 rats each. The animals in bFGF-treated group were injected with 4 microg bFGF/rat in 0.15 mL normal saline solution containing heparin 0.1% (w/v) through the jugular vein at the onset of reperfusion. In the normal saline control group, all rats received the same vehicle, but without bFGF. Group 3 (sham-operated) underwent the same laparotomy procedure, but without superior mesenteric artery occlusion. Liver function parameters, the levels of serum tumor necrosis factor alpha, nitric oxide, superoxide dismutase, malondialdehyde (MDA), tissue bacterial examination, and pathologic study were used to evaluate the results.

RESULTS

In bFGF-treated rats, the amounts of serum alanine transaminase and aspartate aminotransferase and serum tumor necrosis factor-alpha were reduced significantly at 6, 24, and 48 hours when compared with normal saline-treated rats. However, the changes in nitric oxide, superoxide dismutase, and MDA varied from each other as a function of time after injury. The amounts of nitric oxide were increased significantly at 6 hours in intestine in normal saline-treated rats and in liver in bFGF-treated rats (p < 0.05). At 6 hours after reperfusion, the activity of superoxide dismutase in normal saline-treated rats were much lower in liver than those in bFGF-treated and sham-operated rats (p < 0.05), but the levels of MDA were increased in intestine in bFGF-treated rats and in liver in normal saline-treated rats when compared with sham-operated rats (p < 0.05). At 24 hours, the levels of MDA in normal saline-treated rats were much higher than those in both bFGF and sham-operated rats (p < 0.05). Bacterial examination revealed that the ratio and the amounts of bacterial translocation from gut to liver, spleen, and mesenteric lymph nodes in bFGF-treated rats were much lower than those in normal saline-treated rats. The results of pathologic study support the assumption that bFGF provided protective effects against reperfusion injury.

CONCLUSIONS

Intravenous administration of bFGF may benefit in reducing gut and liver injuries after ischemia and reperfusion. The mechanisms of those effects may involve mitogenic and nonmitogenic effects of bFGF.

Use of tissue oxygen tension measurements during resuscitation from hemorrhagic shock

BACKGROUND

Tissue oxygen tension can be measured directly in selected organ beds, and these measurements may be more sensitive in assessing the adequacy of resuscitation than global physiologic parameters. We hypothesized that heart tissue oxygen tension would be an important marker for the severity of ischemic insult to the heart during hemorrhagic shock. We further hypothesized that gut oxygen tension measured in the jejunum would prove to be a better measure of splanchnic hypoperfusion than intramucosal pH (pHi).

METHODS

Tissue oxygen probes were inserted directly into the myocardium of the left ventricle and into the lumen of the proximal jejunum in 10 anesthetized swine. A pHi catheter was introduced into the stomach. The animals were subjected to a controlled hemorrhage of 50% of estimated blood volume. Gut and cardiac oxygen were monitored continuously during hemorrhage and resuscitation, which was performed with shed blood and crystalloid.

RESULTS

While gut O2 and pHi trended together, we were unable to establish a correlation between changes in these two variables during hemorrhage and resuscitation. Heart PO2 decreased significantly during hemorrhage, but surpassed baseline values after resuscitation, a finding not seen in gut PO2. No standard physiologic variables reliably predicted changes in heart PO2 during these experiments.

CONCLUSIONS

Tissue oxygen tensions measurements are highly responsive to changes induced during graded hemorrhagic shock and resuscitation. Gut PO2 and pHi appear to be measuring different physiologic processes in the gastrointestinal tract. The compensatory ability of the heart far exceeds that of the gut after ischemic insult. This hemorrhagic shock model appears feasible for the study of various methods of resuscitation.

Cellular responses to surgical trauma, hemorrhage, and resuscitation with diaspirin cross-linked hemoglobin in rats

BACKGROUND

Resuscitation with acellular oxygen carrier solutions offers the potential advantage of improved oxygen delivery compared with crystalloid solutions, but the detailed consequences of improved resuscitation have not been fully evaluated. This study evaluated local and systemic cellular effects of trauma, hemorrhage, and resuscitation in a model of hemorrhage and surgical trauma.

METHODS

Rats with a 10 cm full-thickness incisional wound and a 15 mL/kg hemorrhage were either not resuscitated or resuscitated with blood or diaspirin cross-linked hemoglobin (DCLHb). Cellular proliferative responses were evaluated at 1.5, 6, 24, and 48 hours after wounding by labeling in vivo with 5-bromo-2'-deoxyuridine. Plasma levels of interleukin-6, tumor necrosis factor-alpha, and interferon-gamma were measured by bioassay or enzyme-linked immunosorbent assay (ELISA). Bacterial translocation was measured by culturing liver homogenates.

RESULTS

Trauma inhibited keratinocyte and hepatocyte proliferation at 1.5 and 6 hours, and stimulated subsequent proliferation of keratinocytes and liver nonparenchymal cells. DCLHb stimulated wound keratinocyte proliferation, attenuated the inhibition of hepatocyte proliferation, eliminated bacterial translocation to the liver, protected the intestine from ischemic damage, and induced a rapid increase of interleukin-6 during the early phase of injury.

CONCLUSIONS

Surgical trauma alone, or in combination with hemorrhage, modulated cell proliferation both in the wound and in the remote organs of intestine and liver. DCLHb enhanced wound healing and cell proliferation as well as, or better than, freshly drawn blood, which may be beneficial for trauma care.

Phase I study of the safety and pharmacologic effects of diaspirin cross-linked hemoglobin solution

OBJECTIVE

To evaluate the safety, pharmacokinetics, and pharmacodynamics of diaspirin cross-linked hemoglobin solution (DCLHb) in normal, healthy volunteers.

DESIGN

Randomized, double-blind, controlled, crossover study.

SETTING

Phase I research facility of a contract research organization.

PATIENTS

Twenty-four healthy adult volunteers.

INTERVENTIONS

Diaspirin cross-linked hemoglobin solution (25, 50, or 100 mg/kg) or equal volume of lactated Ringer's solution was infused on day 1; the alternate solution was infused 6 days later. Laboratory analyses, electrocardiograms, and Holter and telemetry monitoring were performed to assess organ function, pharmacokinetics, and potential toxicity. Vital signs, pulse oximetry, laser Doppler flowmetry, and toe temperature were measured to evaluate diaspirin cross-linked hemoglobin solution's pharmacodynamic effects.

MEASUREMENTS AND MAIN RESULTS

There were no serious adverse events associated with diaspirin cross-linked hemoglobin solution infusion. Abdominal pain occurred in three subjects after control infusion and in six subjects after diaspirin cross-linked hemoglobin solution infusion; no treatment was required. A dose-related increase in lactic dehydrogenase (LDH)-5 isoenzyme concentrations was observed in 12 subjects after diaspirin cross-linked hemoglobin solution infusion. There were no associated increases in the circulating concentrations of total LDH, aspartate aminotransferase, alanine aminotransferase, or alkaline phosphatase. Total serum creatine kinase concentrations increased significantly after infusion of 100 mg/kg of diaspirin cross-linked hemoglobin solution; the isoenzyme creatine kinase-myocardial band (CK-MB) was not increased, nor were there any abnormal electrocardiogram findings. There were no differences in laser Doppler, pulse oximetry, or toe temperature measurements during or after either infusion. The half-life of diaspirin cross-linked hemoglobin solution was 2.5 hrs for the 25- and 50-mg/kg doses and 3.3 hrs for the 100-mg/kg dose. A dose-related increase in blood pressure occurred with diaspirin cross-linked hemoglobin solution.

CONCLUSIONS

Diaspirin cross-linked hemoglobin solution doses of 25, 50, and 100 mg/kg are well tolerated, without evidence of organ dysfunction or toxicity. Diaspirin cross-linked hemoglobin solution's pressor effect is without evidence of decreased peripheral perfusion. Further investigations of its use in certain patient populations are warranted.

Subcutaneous tissue oxygen pressure: a reliable index of peripheral perfusion in humans after injury

The usual initial life-threatening effect of injury is hypovolemic shock. In the hierarchical physiologic response to hypovolemia, perfusion of peripheral tissues is sacrificed early and restored late. But the usual hemodynamic and metabolic measurements of blood pressure, urine output, and base deficit are not reliable indices of peripheral perfusion. Although the Clark electrode can quantitate tissue oxygen pressure and thereby serve as an index of perfusion, its use is compromised by several technical deficiencies. Recently, an optical method (optode) using fluorescent technology has been developed for measurement of oxygen tension in subcutaneous tissue (P sgO2). Our studies compared this device with the Clark electrode in the laboratory and tested its value in both animal and clinical studies of hypovolemic shock. The results of these several studies demonstrated that: (1) the new oximeter tracked a rapid fall or rapid rise of oxygen tension between room air (150 mm Hg) and 0 mm Hg ( a glucose oxidase/catalase solution) as well as the Clark electrode without encountering its technical problems; (2) with an acute hemorrhage to 20% of base line, the PsgO2 was found to decline rapidly in parallel with the decline of mean arterial pressure (MAP). Although the MAP rapidly returned to normal after immediate complete return of all shed blood, the PsgO2 did not reach normal levels for at least 2 hours, suggesting persistent peripheral vasoconstriction. (3) Studies in progress suggest that between 35 and 78% of trauma patients (n = 18) adequately resuscitated for hypovolemia b customary criteria have a decreased level of PsgO2 for as long as 60 hours after resuscitation for injury. If care is taken to prevent other causes of catecholamine induced vasoconstriction such as pain, fear, cold, and arterial hypoxia, these several results suggest that a certain number of injured patients are inadequately resuscitated despite the return to normal of conventional hemodynamic measurements. The serial analysis of PsgO2 may assist in managing patients and promote better understanding of the responses to injury.