Plasma volume expansion with solutions of hemoglobin, albumin, and Ringer lactate in sheep

Tracking Research on Hemoglobin-Based Oxygen Carriers: A Scientometric Analysis and In-Depth Review

Numerous studies on the formulation and clinical applications of novel hemoglobin-based oxygen carriers (HBOCs) are reported in the scientific literature. However, there are fewer scientometric analysis related to HBOCs. Here, we illustrate recent studies on HBOCs using both a scientometric analysis approach and a scope review method. We used the former to investigate research on HBOCs from 1991 to 2022, exploring the current hotspots and research trends, and then we comprehensively analyzed the relationship between concepts based on the keyword analysis. The evolution of research fields, knowledge structures, and research topics in which HBOCs located are revealed by scientometric analysis. The elucidation of type, acting mechanism, potential clinical practice, and adverse effects of HBOCs helps to clarify the prospects of this biological agent. Scientometrics analyzed 1034 publications in this research field, and these findings provide a promising roadmap for further study.

Variable responses of regional renal oxygenation and perfusion to vasoactive agents in awake sheep

Vasoactive agents are used in critical care to optimize circulatory function, but their effects on renal tissue oxygenation in the absence of anesthesia remain largely unknown. Therefore, we assessed the effects of multiple vasoactive agents on regional kidney oxygenation in awake sheep. Sheep were surgically instrumented with pulmonary and renal artery flow probes, and combination fiber-optic probes, in the renal cortex and medulla, comprising a fluorescence optode to measure tissue Po2 and a laser-Doppler probe to assess tissue perfusion. Carotid arterial and renal venous cannulas enabled measurement of arterial pressure and total renal oxygen delivery and consumption. Norepinephrine (0.1 or 0.8 μg·kg−1·min−1) dose-dependently reduced cortical and medullary laser Doppler flux (LDF) and Po2 without significantly altering renal blood flow (RBF), or renal oxygen delivery or consumption. Angiotensin II (9.8 ± 2.1 μg/h) reduced RBF by 21%, renal oxygen delivery by 28%, oxygen consumption by 18%, and medullary Po2 by 38%, but did not significantly alter cortical Po2 or cortical or medullary LDF. Arginine vasopressin (3.3 ± 0.5 μg/h) caused similar decreases in RBF and renal oxygen delivery, but did not significantly alter renal oxygen consumption or cortical or medullary LDF or Po2. Captopril had no observable effects on cortical or medullary LDF or Po2, at a dose that increased renal oxygen delivery by 24%, but did not significantly alter renal oxygen consumption. We conclude that vasoactive agents have diverse effects on regional kidney oxygenation in awake sheep that are not predictable from their effects on LDF, RBF, or total renal oxygen delivery and consumption.

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

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

Adverse effects of hemorrhagic shock resuscitation with stored blood are ameliorated by inhaled nitric oxide in lambs*

OBJECTIVES

Transfusion of stored RBCs is associated with increased morbidity and mortality in trauma patients. Plasma hemoglobin scavenges nitric oxide, which can cause vasoconstriction, induce inflammation, and activate platelets. We hypothesized that transfusion of RBCs stored for prolonged periods would induce adverse effects (pulmonary vasoconstriction, tissue injury, inflammation, and platelet activation) in lambs subjected to severe hemorrhagic shock and that concurrent inhalation of nitric oxide would prevent these adverse effects.

DESIGN

Animal study.

SETTING

Research laboratory at the Massachusetts General Hospital, Boston, MA.

SUBJECTS

Seventeen awake Polypay-breed lambs.

INTERVENTIONS

Lambs were subjected to 2 hours of hemorrhagic shock by acutely withdrawing 50% of their blood volume. Lambs were resuscitated with autologous RBCs stored for 2 hours or less (fresh) or 39 ± 2 (mean ± SD) days (stored). Stored RBCs were administered with or without breathing nitric oxide (80 ppm) during resuscitation and for 21 hours thereafter.

MEASUREMENTS AND MAIN RESULTS

We measured hemodynamic and oxygenation variables, markers of tissue injury and inflammation, plasma hemoglobin concentrations, and platelet activation. Peak pulmonary arterial pressure was higher after resuscitation with stored than with fresh RBCs (24 ± 4 vs 14 ± 2 mm Hg, p < 0.001) and correlated with peak plasma hemoglobin concentrations (R = 0.56, p = 0.003). At 21 hours after resuscitation, pulmonary myeloperoxidase activity was higher in lambs resuscitated with stored than with fresh RBCs (11 ± 2 vs 4 ± 1 U/g, p = 0.007). Furthermore, transfusion of stored RBCs increased plasma markers of tissue injury and sensitized platelets to adenosine diphosphate activation. Breathing nitric oxide prevented the pulmonary hypertension and attenuated the pulmonary myeloperoxidase activity, as well as tissue injury and sensitization of platelets to adenosine diphosphate.

CONCLUSIONS

Our data suggest that resuscitation of lambs from hemorrhagic shock with autologous stored RBCs induces pulmonary hypertension and inflammation, which can be ameliorated by breathing nitric oxide.

Perioperative fluid and volume management: physiological basis, tools and strategies

Fluid and volume therapy is an important cornerstone of treating critically ill patients in the intensive care unit and in the operating room. New findings concerning the vascular barrier, its physiological functions, and its role regarding vascular leakage have lead to a new view of fluid and volume administration. Avoiding hypervolemia, as well as hypovolemia, plays a pivotal role when treating patients both perioperatively and in the intensive care unit. The various studies comparing restrictive vs. liberal fluid and volume management are not directly comparable, do not differ (in most instances) between colloid and crystalloid administration, and mostly do not refer to the vascular barrier's physiologic basis. In addition, very few studies have analyzed the use of advanced hemodynamic monitoring for volume management.

This article summarizes the current literature on the relevant physiology of the endothelial surface layer, discusses fluid shifting, reviews available research on fluid management strategies and the commonly used fluids, and identifies suitable variables for hemodynamic monitoring and their goal-directed use.

Reduced systolic torsion in chronic "pure" mitral regurgitation

BACKGROUND

Global left ventricular (LV) torsion declines with chronic ischemic mitral regurgitation (MR), which may accelerate the LV remodeling spiral toward global cardiomyopathy; however, it has not been definitively established whether this torsional decline is attributable to the infarct, the MR, or their combined effect. We tested the hypothesis that chronic "pure" MR alone reduces global LV torsion.

METHODS AND RESULTS

Chronic "pure" MR was created in 13 sheep by surgically punching a 3.5- to 4.8-mm hole (HOLE) in the mitral valve posterior leaflet. Nine control (CNTL) sheep were operated on concurrently. At 1 (WK-01) and 12 weeks (WK-12) postoperatively, the 4D motion of implanted radiopaque markers was used to calculate global LV torsion. MR-grade in HOLE was greater than CNTL at WK-01 and WK-12 (2.5+/-1.1 versus 0.6+/-0.5, P<0.001 at WK-12). HOLE LV mass index was larger at WK-12 compared with CNTL (195+/-14 versus 170+/-17 g/m(2), P<0.01), indicating LV remodeling. Global LV systolic torsion decreased in HOLE from WK-01 to WK-12 (4.1+/-2.8 degrees versus 1.7+/-1.7 degrees , P<0.01), but did not change in CNTL (5.5+/-1.8 degrees versus 4.2+/-2.7 degrees , P=NS). Global LV torsion was lower in HOLE relative to CNTL at WK-12 (P<0.05) but not at WK-01 (P=NS).

CONCLUSIONS

Twelve weeks of chronic "pure" MR resulting in mild global LV remodeling is associated with significantly increased LV mass index and reduced global LV systolic torsion, but no other significant changes in hemodynamics. MR alone is a major component of torsional deterioration in "pure" MR and may be an important factor in chronic ischemic mitral regurgitation.

Effects of isovolemic resuscitation with hemoglobin-based oxygen carrier Hemoglobin glutamer-200 (bovine) on systemic and mesenteric perfusion and oxygenation in a canine model of hemorrhagic shock: a comparison with 6% hetastarch solution and shed blood

OBJECTIVE

To study Hemoglobin glutamer-200 bovine (Hb-200), 6% hetastarch (HES) and shed whole blood (WB) resuscitation in canine hemorrhagic shock.

STUDY DESIGN

Prospective laboratory investigation. Animals Twelve adult dogs [29 +/- 1 kg (mean +/- SD)].

METHODS

Anesthetized dogs were instrumented for recording systemic and mesenteric hemodynamic parameters and withdrawal of arterial, mixed and mesenteric venous blood, in which hematological, oxygenation, blood gas and acid-bases variables were determined. Recordings were made before [baseline (BL)], after 1 hour of hypovolemia and immediately and 3 hours post-resuscitation with 30 mL kg(-1) of either Hb-200, HES, or WB.

RESULTS

Blood withdrawal (average 34 +/- 2 mL kg(-1)) caused significant hemodynamic changes, metabolic acidosis and hyperlactatemia characteristic for hemorrhagic shock. Only WB transfusion restored all variables. Hemoglobin glutamer-200 bovine infusion returned most hemodynamic parameters including cardiac output and mesenteric arterial blood flow to BL but increased mean arterial pressure above BL (p < 0.05). However, Hb-200 failed to restore total Hb and arterial oxygen content (CaO2), leaving systemic (DO2I) and mesenteric O2 delivery (DO2Im) below BL (p < 0.05). Nevertheless, acid-base variables recovered completely after Hb-200 resuscitation, and met-hemoglobin (Met-Hb) levels increased (p < 0.05). Hetastarch resuscitation returned hemodynamic variables to or above BL but further decreased total Hb and CaO2, preventing recovery of sDO2I and mDO2I (p < 0.05). Thus, systemic and mesenteric O2 extraction stayed above BL (p < 0.05) while acid-base variables recovered to BL, although slower than in Hb-200 and WB groups (p < 0.05).

CONCLUSIONS AND CLINICAL RELEVANCE

Resuscitation with Hb-200 seemed to resolve metabolic acidosis and lactatemia more rapidly than HES, but not WB; yet it is not superior to HES in improving DO2I and DO2Im. The hyperoncotic property of solutions like Hb-200 that results in rapid volume expansion with more homogenous microvascular perfusion and the ability to facilitate diffusive O2 transfer accelerating metabolic recovery may be the key mechanisms underlying their beneficial effects as resuscitants.

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.

Hemoglobin-Based Oxygen Carrier Distribution Inside Vascular Wall and Arterial Pressure Evolution: Is There a Relationship?

The hemoglobin-based oxygen carriers (HBOC), like dextran-benzene-tetracarboxylate-hemoglobin (Dex-BTC-Hb), which are present at high concentrations in plasma disturb arterial pressure and induce hypertension. To study if the increase of mean arterial pressure (MAP) is due to the presence of cell-free hemoglobin (Hb) inside abdominal aortic wall, we followed on a model of 50% isovolemic exchange transfusion (IET) in anesthetized guinea pigs, the kinetic of Dex-BTC-Hb distribution inside abdominal aortic wall and we investigated the relationship between arterial pressure modifications and modified Hb distribution. The administration of Dex-BTC-Hb induced instantaneously an increase of MAP that reached its maximum (53% of hypertension from baseline) at 17 min after the end of the IET and was maintained maximally up to 30 min. A significantly decrease of MAP (45% of hypertension from baseline) was observed after 60 min and the baseline level was recovered at 180 min. The investigation of tissue at 17 min by confocal microscopy showed the presence of free Hb in or upon endothelial cells (EC) in intima and in vasa vasorum. At 180 min, the free Hb was found in or upon EC and inside all abdominal aortic wall meanwhile MAP recovered its basal value. These results suggest for the first time that Hb in intima seems to induce the hypertension observed upon IET but can not sustain it even if Hb stayed present in intima and in abdominal aortic wall.

Hemodynamic response and oxygen transport in pigs resuscitated with maleimide-polyethylene glycol-modified hemoglobin (MP4)

Cell-free Hb increases systemic and pulmonary pressure and resistance and reduces cardiac output and heart rate in animals and humans, effects that have limited their clinical development as “blood substitutes.” The primary aim of this study was to evaluate the hemodynamic response to infusion of several formulations of a new polyethylene glycol (PEG)-modified human Hb [maleimide PEG Hb (MalPEGHb)] in swine, an animal known to be sensitive to Hb-induced vasoconstriction. Anesthetized animals underwent controlled hemorrhage (50% of blood volume), followed by resuscitation (70% of shed volume) with 10% pentastarch (PS), 4% MalPEG-Hb in lactated Ringer (MP4), 4% MalPEG-Hb in pentastarch (HS4), 2% MalPEG-Hb in pentastarch (HS2), or 4% stroma-free Hb in lactated Ringer solution (SFH). Compared with baseline, restoration of blood volume after resuscitation was similar and not significantly different for the PS (103%), HS2 (99%), HS4 (106%), and MP4 (87%) animals but significantly less for the SFH animals (66%) ( P < 0.05). All solutions that contained MalPEG-Hb restored mean arterial and pulmonary pressure and cardiac output. Systemic vascular resistance was unchanged, and pulmonary arterial pressure and resistance were increased slightly. Both systemic and pulmonary vascular resistance increased significantly in animals that received SFH, despite less adequate blood volume restoration. Oxygen consumption was maintained in all animals that received MalPEG-Hb, but not PS. Base excess improved only with MalPEG-Hb and PS, but not SFH. Red blood cell O2extraction was significantly increased in animals that received Hb, regardless of formulation. These data demonstrate resuscitation with MalPEG-human Hb without increasing systemic vascular resistance and support our previous observations in animals suggesting that the efficacy of low concentrations of PEG-Hb in the plasma results from reduced vasoconstriction.

[Exact measurement of the volume effect of 6% hydoxyethyl starch 130/0.4 (Voluven) during acute preoperative normovolemic hemodilution]

BACKGROUND

What is the effect of preoperative acute normovolemic hemodilution (ANH) with 6% hydroxyethyl starch (HES) 130/0.4 (Voluven) on blood volume?

METHODS

In 10 patients undergoing radical hysterectomy, ANH was performed to a hematocrit of 21% using 6% HES 130/0.4 (Voluven) whereby a replacement of blood with 115% of colloid was planned. Plasma volume (indocyanine green dilution technique) and hematocrit were determined before, 30 and 60 min after ANH. Red cell volume (labelling erythrocytes with fluorescein) was determined before and 30 min after ANH.

RESULTS

After removal of 1,431+/-388 ml of blood and simultaneous replacement with 1,686+/-437 ml of colloid, blood volumes were 218+/-174 ml higher than before (at 105+/-4%). The volume effect was 98+/-12%, 30 min after ANH. Even 60 min after ANH, mean blood volumes were with 4,228+/-986 ml slightly higher than before ANH (102+/-5%). The hematocrit decreased disproportionally in relation to the residual intravascular volume. Consequently, estimating the volume effect from the changes in hematocrit led to an overestimation (about +30%).

CONCLUSION

Double label measurements of blood volume demonstrated that the volume effect of 6% HES 130/0.4 (Voluven) is about 100% in the course of ANH. The reason for the disproportionally large decrease in hematocrits could be the mobilization of a fraction of the plasma volume which was retained within the endothelial glycocalyx.

Arterial oxygenation and oxygen delivery after hemoglobin-based oxygen carrier infusion in canine hypovolemic shock: a dose-response study

OBJECTIVE

To compare effects of 6% hetastarch (Hextend) and hemoglobin-based oxygen carrier hemoglobin glutamer-200 (Hb-200) (bovine; Oxyglobin) on hemodynamics, arterial oxygen content, and systemic oxygen delivery in a canine hemorrhagic shock model.

DESIGN

Randomized laboratory investigation.

SETTING

University surgical research facility.

SUBJECTS

Twenty-four anesthetized healthy, adult, mongrel dogs (28 +/- 1 kg; 7 female, 17 male).

INTERVENTIONS

Dogs were instrumented for determinations of heart rate, arterial, central venous, pulmonary arterial, and pulmonary arterial occlusion pressures, and cardiac index. Total solids, colloid oncotic pressure, arterial oxygen content, Hb, lactate, pH, and blood gases were analyzed in blood samples. Recordings were made before, after 1 hr of hemorrhagic shock, and immediately and 3 hrs after infusion of either 30 mL/kg hetastarch (group 1), 10 mL/kg Hb-200 + 20 mL/kg hetastarch (group 2), 20 mL/kg Hb-200 + 10 mL/kg hetastarch (group 3), or 30 mL/kg Hb-200 (group 4).

MEASUREMENTS AND MAIN RESULTS

Hemorrhage (35 +/- 1 mL/kg) reduced mean arterial pressure to 50 mm Hg and caused significant decreases in total Hb, mean pulmonary arterial pressure, cardiac index and systemic oxygen delivery, increases in heart rate and systemic vascular resistance, and lactic acidosis. In group 1, hetastarch infusion was accompanied by increases of pulmonary arterial pressure, cardiac index, and blood oxygen extraction above baseline, and decreases of systemic vascular resistance, total Hb, total solids, arterial oxygen content, and systemic oxygen delivery below baseline (p <.05). Other data returned to baseline. In groups 2 to 4, hemodynamic functions (except pulmonary arterial pressure) recovered, yet neither total Hb (i.e., plasma and red blood cell Hb) nor arterial oxygen content increased despite increases in plasma Hb of 2 to 5 g/dL and proportionate increases in total solids. Systemic oxygen delivery improved dose-dependently with Hb-200 but did not return to baseline (p <.05), reaching values comparable to hetastarch group only at 30 mL/kg Hb-200. In all groups, oxygen extraction remained above baseline. Metabolic acidosis and lactatemia resolved significantly faster in groups 2 to 4, and colloid oncotic pressure after resuscitation was greater in groups 2 to 4 than in controls (p <.05).

CONCLUSIONS

In hemorrhagic shock, Hb-200 infusion may not improve oxygen delivery more than hetastarch, likely due to hemodilution caused by its high colloid oncotic pressure, but may facilitate diffusive oxygen transport to tissues.

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.

Hemodilution mediates hemodynamic changes during acute expansion in unanesthetized rats

Studies were carried out to determine the relative importance of volume and hemodilution on hemodynamic adjustments to acute volume expansion. Systemic and renal hemodynamics were monitored in unanesthetized and unrestrained rats during progressive and equivalent blood volume expansion with saline (Sal; 1, 2, and 4% body wt), 7% BSA solution (0.35, 0.7, and 1.4% body wt), and reconstituted whole blood from donor rats (WBL; 0.35, 0.7, and 1.4% body wt). Mean arterial pressure remained unchanged in Sal and BSA but increased progressively in WBL-expanded rats (from 92 to 106 mmHg after maximal expansion). In Sal and BSA-expanded rats, cardiac output (CO) and renal blood flow (RBF) increased (CO: Sal from 19 to 20, 22, and 25; BSA from 21 to 23, 27, and 31; RBF: Sal from 1.6 to 1.8, 2.2, and 2.5; BSA from 2 to 2.4, 2.7, and 3.1 ml. min(-1). 100 g body wt(-1)), whereas total peripheral (TPR) and renal vascular (RVR) resistance decreased in parallel with the expansions. After expansion with WBL, CO increased progressively but less extensively than in cell-free expanded rats (21 to 22, 24, and 26 ml. min(-1). 100 g body wt(-1)), whereas TPR and RVR remained unchanged. Systemic hematocrit (Hct) decreased approximately the same after expansion with Sal or BSA solutions but remained unchanged after expansion with WBL. Isovolemic hemodilution to Hct levels comparable to those seen after maximal expansion with cell-free solutions also reduced SVR and RVR, although less extensively. These findings suggest that in unanesthetized rats hemodilution plays a major role in the systemic and renal hemodynamics during expansion.