Improvement of impaired microcirculation and tissue oxygenation by hemodilution with hydroxyethyl starch plus cell-free hemoglobin in acute porcine pancreatitis

A Nationwide Analysis of Fluid Resuscitation Outcomes in Patients With Acute Pancreatitis

BACKGROUND

Traditionally, fluid resuscitation has been the foundation of effective acute pancreatitis (AP) treatment. Experts advocate for aggressive intravenous fluid (IVF) resuscitation, especially within the first 24 hours. Research suggests limited efficacy of this approach; in fact, some studies show there may be a risk of increased complications. The aim of this study was to assess outcomes of aggressive IVF resuscitation in patients with AP.

METHODS

We queried the TriNetX Research Network (Cambridge, Massachusetts, United States) for patients admitted between January 1, 2010, and December 31, 2020, with a diagnosis of AP and who had received IVF on admission for at least 24 hours. We compared two cohorts; cohort 1 consisted of patients receiving aggressive IVF resuscitation (>3 ml/kg/hr), and cohort 2 was comprised of patients receiving non-aggressive (≤1.5 ml/kg/hr) IVF resuscitation. We compared mortality during index hospitalization, hospital length of stay (HLS), mechanical ventilation rates, acute kidney injury (AKI), and severe sepsis between the cohorts with propensity scoring matched (PSM) pairs of patients. A sub-analysis of patients with severe AP was performed.

RESULTS

After comparing the two well-matched PSM cohorts (3,680/3,680), we found no significant differences in mortality, HLS, mechanical ventilation rates, AKI, or severe sepsis. We found similar results after conducting the sub-analysis of patients with severe pancreatitis.

CONCLUSIONS

We found no significant differences in mortality and HLS when comparing rates of IVF resuscitation.

Repetitive Cerulein-Induced Chronic Pancreatitis in Growing Pigs-A Pilot Study

Chronic pancreatitis (CP) is an irreversible and progressive inflammatory disease. Knowledge on the development and progression of CP is limited. The goal of the study was to define the serum profile of pro-inflammatory cytokines and the cell antioxidant defense system (superoxidase dismutase-SOD, and reduced glutathione-GSH) over time in a cerulein-induced CP model and explore the impact of these changes on selected cytokines in the intestinal mucosa and pancreatic tissue, as well as on selected serum biochemical parameters. The mRNA expression of CLDN1 and CDH1 genes, and levels of Claudin-1 and E-cadherin, proteins of gut barrier, in the intestinal mucosa were determined via western blot analysis. The study showed moderate pathomorphological changes in the pigs' pancreas 43 days after the last cerulein injection. Blood serum levels of interleukin (IL)-1-beta, IL-6, tumor necrosis factor alpha (TNF-alpha), C-reactive protein (CRP), lactate dehydrogenase (LDH), gamma-glutamyl transpeptidase (GGTP), SOD and GSH were increased following cerulein injections. IL-1-beta, IL-6, TNF-alpha and GSH were also increased in jejunal mucosa and pancreatic tissue. In duodenum, decreased mRNA expression of CDH1 and level of E-cadherin and increased D-lactate, an indicator of leaky gut, indicating an inflammatory state, were observed. Based on the current results, we can conclude that repetitive cerulein injections in growing pigs not only led to CP over time, but also induced inflammation in the intestine. As a result of the inflammation, the intestinal barrier was impaired.

Characteristics of New Oxygen-Carrying Plasma and Its Application Prospects in the Treatment of Severe Acute Pancreatitis

ABSTRACT

Oxygen-carrying plasma, a new type of colloid substitute, is composed of hydroxyethyl starch and acellular hemoglobin-based oxygen carriers. It can supplement colloidal osmotic pressure and rapidly improve the body's oxygen supply. The resuscitation effect of the new oxygen-carrying plasma in animal shock models is better than that of hydroxyethyl starch or hemoglobin-based oxygen carriers alone. It can reduce the histopathological damage and mortality associated with severe acute pancreatitis, and it is expected to become an interesting treatment method for severe acute pancreatitis. This article reviews the characteristics of the new oxygen-carrying plasma, its role in fluid resuscitation, and its application prospects in the treatment of severe acute pancreatitis.

Abdominal Compartment Syndrome in Acute Pancreatitis: A Narrative Review

Abdominal compartment syndrome (ACS) represents a severe complication of acute pancreatitis (AP), resulting from an acute and sustained increase in abdominal pressure >20 mmHg, in association with new organ dysfunction. The harmful effect of high intra-abdominal pressure on regional and global perfusion results in significant multiple organ failure and is associated with increased morbidity and mortality. There are several deleterious consequences of elevated intra-abdominal pressure on end-organ function, including respiratory, cardiovascular, gastrointestinal, neurologic, and renal effects. It is estimated that about 15% of patients with severe AP develop intra-abdominal hypertension or ACS, with a mortality rate around 50%. The treatment of abdominal compartment syndrome in acute pancreatitis begins with medical intervention and percutaneous drainage, where possible. Abdominal compartment syndrome unresponsive to conservatory treatment requires immediate surgical decompression, along with vacuum-assisted closure therapy techniques, followed by early abdominal fascia closure.

Cholecystokinin-8 treatment reduces acinar necrosis and edema of pigs with induced pancreatitis

BACKGROUND

Acute pancreatitis is an inflammatory process of the pancreas and a leading cause of hospitalization amongst gastrointestinal disorders. Previously, cholecystokinin (CCK) has been described to play a role in regeneration of pancreas. The aim of this study was to analyse the function of cholecystokinin octapeptide (CCK-8) during induced pancreatitis in an animal model.

METHODS

Overall acute pancreatitis was induced in 38 pigs. After the induction of acute pancreatitis, half of the animals were treated with CCK-8. Intraoperative clinical data, postoperative blood parameters, 'Porcine Well-being' (PWB) and fitness score and post-mortal histopathological data were analysed.

RESULTS

At baseline, physiologically parameters of the pigs of both groups were comparable. No differences were observed regarding the overall survival of animals (p = 0.97). Postoperative PWB score were significantly enhanced in animals treated with CCK-8 as compared to the control group (p = 0.029). Moreover, histopathological analysis of the pancreatic tissue revealed that acinar necrosis and edema were significant reduced in the CCK-8 group in comparison to the control group (p = 0.016 and p = 0.019).

CONCLUSIONS

In conclusion, we found that CCK-8 treatment reduces acinar necrosis and edema of pancreatic tissue after induction of an acute pancreatitis in pigs.

Melatonin treatment of pigs with acute pancreatitis reduces inflammatory reaction of pancreatic tissue and enhances fitness score of pigs: experimental research

Background

Severe acute pancreatitis is associated with high morbidity and mortality. Melatonin is known as the activator of antioxidant enzymes. The main purpose of this study was to evaluate the clinical effect of melatonin treatment in a pig model with induced acute pancreatitis.

Methods

In this study, acute pancreatitis was induced in 38 German domestic pigs (German Hybrid). After induction of acute pancreatitis, 18 animals were treated with melatonin. Intraoperative clinical data, postoperative blood parameters, fitness, and Porcine Well-being (PWB) score, and post-mortal histopathological data were analyzed in both study groups.

Results

The matching procedure created two groups (melatonin group and control group) which were very similar. The fitness and PWB score were postoperative significantly enhanced in the melatonin group as compared to the control group (p = 0.005 and p = 0.003). Additionally, histological analysis revealed that acinar necrosis, fat tissue necrosis, and edema were significantly reduced in the melatonin group as compared to the non-melatonin group (p = 0.025, p = 0.003, and p = 0.028).

Conclusions

Pigs, which were treated with melatonin, were characterized by higher fitness and PWB scores than those of the control group. Moreover, melatonin treatment reduces the acinar necrosis, fat tissue necrosis, and edema of pancreatic tissue. Thus, melatonin might be a useful therapeutic option in severe acute pancreatitis.

Hydroxyethyl starch resuscitation downregulate pro-inflammatory cytokines in the early phase of severe acute pancreatitis: A retrospective study

In the present study, we investigated the effects of hydroxyethyl starch (HES) 130/0.4 on serum pro-inflammatory variables, immunologic variables, fluid balance (FB)-negative(−) rate and renal function in severe acute pancreatitis (SAP) patients. From October, 2007 to November, 2008, a total of 120 SAP patients were enrolled in this retrospective study. Fifty-nine patients in the HES group received 6% HES 130/0.4 combined with crystalloid solution for fluid resuscitation (HES group). In the control group, 61 patients received only crystalloid solution after admission. Interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor (TNF)-α levels in serum were measured on days 1, 2, 4 and 8. The peripheral blood CD4⁺CD8⁺ T lymphocyte rates, serum BUN and Cr values were also measured on days 1, 4 and 8. Patients with FB(−) rates were recorded from day 1 to 8. Interaction term analysis (hospital stay and fluid resuscitation methods) based on mixed-effects regression model revealed significantly lower levels of IL-1 and TNF-α in the HES group compared with the control group. The difference in curve's risk ratio was not significant for IL-6, CD4⁺CD8⁺ T lymphocyte rate, BUN and Cr values (P>0.05). In the HES group, we detected a significantly higher rate of patients with FB(−) from day 4 to 8 (P<0.05). Thus, HES 130/0.4 resuscitation could decrease the IL-1 and IL-8 levels, shorten the duration of positive FB, and preserve the patient's immune status as well as renal function during the early phase of SAP.

The Effects of Pancreatic Microcirculatory Disturbances on Histopathologic Tissue Damage and the Outcome in Severe Acute Pancreatitis

OBJECTIVES

Severe acute pancreatitis is an inflammatory disease of the pancreas with a high morbidity and mortality. To date, no causal treatment is known. The aim of the present study was to analyze the impact of pancreatic microcirculatory disturbances in severe acute pancreatitis and to correlate the effects with histopathologic tissue damage and outcome.

METHODS

Severe acute pancreatitis was induced in 129 pigs by injection of glycodeoxycholic acid into the pancreatic duct. Pancreatic microcirculation, pancreatic tissue oxygenation, histopathologic tissue damage, and survival were measured and analyzed.

RESULTS

Our study demonstrates a strong correlation between pancreatic microcirculatory disturbances and histopathologic tissue damage (r = 0.728; P < 0.001). Furthermore, we showed a strong correlation between tissue oxygenation and the severity of the pancreatitis according to an established porcine pancreatitis score (r = 0.694; P < 0.001). In addition, disturbances of the pancreatic microcirculation were shown to be associated with an increased mortality rate in severe acute pancreatitis.

CONCLUSIONS

We found that pancreatic microcirculatory disturbances have significant effects on histopathologic tissue damage and the outcome of severe acute pancreatitis. For a better survival of severe acute pancreatitis, the treatment should focus on an improvement of pancreatic microcirculation.

Protective effects of polyenoylphosphatidylcholine in rats with severe acute pancreatitis

OBJECTIVE

The aim of this study was to investigate the protective effect of polyenoylphosphatidylcholine (PPC) in rats with severe acute pancreatitis (SAP) and its mechanism.

METHODS

Seventy-two clean, conventional Sprague-Dawley rats were randomly divided into 4 groups (SAP; sham operation [SO], SAP + PPC, and SO + PPC; n = 18 per group). The SAP model was induced by injecting 4% sodium taurocholate (1 mL/kg) into the biliopancreatic duct. Animals in the SO groups underwent laparotomy and biliopancreatic duct puncture without fluid injection. Polyenoylphosphatidylcholine (50 mg/kg) was injected through the penis dorsal vein. Pancreatic acinar cell membrane fluidity and pancreatic tissue calcium pump activity were measured through fluorescence polarization and quantization of phosphonium ions, whereas pancreatic tissue superoxide dismutase and malondialdehyde were detected through xanthine oxidase method and thiobarbituric acid colorimetric analysis method, respectively.

RESULTS

The SAP + PPC group had significantly improved pathologic pancreas; increased in pancreatic acinar cell membrane fluidity, pancreatic tissue Ca-Mg-ATPase activity, and superoxide dismutase; as well as decreased in malondialdehyde, ascites volume, and serum amylase compared with the SAP group.

CONCLUSIONS

Polyenoylphosphatidylcholine could reduce the damage to the pancreas through increasing pancreatic acinar cell membrane fluidity and pancreatic tissue calcium pump activity. Polyenoylphosphatidylcholine also scavenges oxygen free radicals and reduces lipid peroxide levels.

Individualized early goal-directed therapy in systemic inflammation: is full utilization of preload reserve the optimal strategy?

OBJECTIVES

In severe acute pancreatitis, the administration of fluids in the presence of positive fluid responsiveness is associated with better outcome when compared to guiding therapy on central venous pressure. We compared the effects of such consequent maximization of stroke volume index with a regime using individual values of stroke volume index assessed prior to severe acute pancreatitis induction as therapeutic hemodynamic goals.

DESIGN

Prospective, randomized animal study.

SETTING

University animal research laboratory.

SUBJECTS

Thirty domestic pigs.

INTERVENTIONS

After randomization, fluid resuscitation was started 2 hours after severe acute pancreatitis induction and continued for 6 hours according to the respective treatment algorithms. In the control group, fluid therapy was directed by maximizing stroke volume index, and in the study group, stroke volume index assessed prior to severe acute pancreatitis served as primary hemodynamic goal.

MEASUREMENTS AND MAIN RESULTS

Within the first 6 hours of severe acute pancreatitis, the study group received a total of 1,935.8 ± 540.7 mL of fluids compared with 3,462.8 ± 828.2 mL in the control group (p < 0.001). Pancreatic tissue oxygenation did not differ significantly between both groups. Vascular endothelial function, measured by flow-mediated vasodilation before and 6 hours after severe acute pancreatitis induction, revealed less impairment in the study group after treatment interval (-90.76% [study group] vs -130.89% [control group]; p = 0.046). Further, lower levels of heparan sulfate (3.41 ± 5.6 pg/mL [study group] vs 43.67 ± 46.61 pg/mL [control group]; p = 0.032) and interleukin 6 (32.18 ± 8.81 pg/mL [study group] vs 77.76 ± 56.86 pg/mL [control group]; p = 0.021) were found in the study group compared with control group. Histopathological examination of the pancreatic head and corpus at day 7 revealed less edema for the study group compared with the control group (1.82 ± 0.87 [study group] vs 2.89 ± 0.33 [control group, pancreatic head]; p = 0.03; 2.2 ± 0.92 [study group] vs 2.91 ± 0.3 [control group, pancreatic corpus]; p = 0.025).

CONCLUSIONS

Individualized optimization of intravascular fluid status during the early course of severe acute pancreatitis, compared with a treatment strategy of maximizing stroke volume by fluid loading, leads to less vascular endothelial damage, pancreatic edema, and inflammatory response.

Fluid resuscitation in acute pancreatitis

Acute pancreatitis remains a clinical challenge, despite an exponential increase in our knowledge of its complex pathophysiological changes. Early fluid therapy is the cornerstone of treatment and is universally recommended; however, there is a lack of consensus regarding the type, rate, amount and end points of fluid replacement. Further confusion is added with the newer studies reporting better results with controlled fluid therapy. This review focuses on the pathophysiology of fluid depletion in acute pancreatitis, as well as the rationale for fluid replacement, the type, optimal amount, rate of infusion and monitoring of such patients. The basic goal of fluid epletion should be to prevent or minimize the systemic response to inflammatory markers. For this review, various studies and reviews were critically evaluated, along with authors’ recommendations, for predicted severe or severe pancreatitis based on the available evidence.

Effects of hydroxyethyl starch and cell-free hemoglobin on microcirculation, tissue oxygenation, and survival in severe acute porcine pancreatitis: results of a randomized experimental trial

OBJECTIVE

Severe acute pancreatitis is a life-threatening disease with a high mortality; so far, no causal treatment is known. The aim of this study was to evaluate the therapeutic potential of hydroxyethyl starch (HES) and cell-free hemoglobin in an experimental model.

METHODS

Thirty-nine pigs were randomly assigned into 3 groups. Severe acute pancreatitis was induced by intraductal injection of glycodeoxycholic acid in combination with intravenous administration of cerulein. All animals were kept in isovolemic conditions by application of Ringer solution, 10% HES, or cell-free hemoglobin. The pancreatic microcirculation was evaluated over 8 hours. Thereafter, the animals were observed for 6 days followed by killing of the animals and histopathologic examination.

RESULTS

The administration of HES and cell-free hemoglobin led to improved microcirculation and tissue oxygenation compared with the Ringer's group. Consequently, the histopathologic damage was reduced (5.5 [3-8.5] vs 9.5 [7.5-11]; P < 0.001). In addition, the mean survival was significantly longer at 121 hours (95% confidence interval, 102-139) versus the Ringer group's 57 hours (95% confidence interval, 32-82; P < 0.001).

CONCLUSIONS

The administration of HES and cell-free hemoglobin can improve microcirculation in severe acute porcine pancreatitis, with consequent reduction in histopathologic damage and mortality. Therefore, this might represent an interesting therapeutic option in the treatment of severe acute pancreatitis.

The role of thoracic epidural anesthesia in severe acute pancreatitis

In animal studies of severe acute pancreatitis, thoracic epidural anesthesia appears to enhance the splanchnic circulation, improve end-organ perfusion, and favorably influence mortality. The application of thoracic epidurals in the critically ill human patient is less clear. Methodological difficulties in reliably assessing mesenteric flow have hampered progress, and clinical concerns surrounding this potentially attractive therapeutic modality remain unanswered. Future research needs to focus on the impact of epidural anesthesia on basic human physiological pmeters to help direct further randomized studies in human disease.

Effects of thoracic epidural anesthesia on survival and microcirculation in severe acute pancreatitis: a randomized experimental trial

Introduction

Severe acute pancreatitis is still a potentially life threatening disease with high mortality. The aim of this study was to evaluate the therapeutic effect of thoracic epidural anaesthesia (TEA) on survival, microcirculation, tissue oxygenation and histopathologic damage in an experimental animal model of severe acute pancreatitis in a prospective animal study.

Methods

In this study, 34 pigs were randomly assigned into 2 treatment groups. After severe acute pancreatitis was induced by intraductal injection of glycodesoxycholic acid in Group 1 (n = 17) bupivacaine (0.5%; bolus injection 2 ml, continuous infusion 4 ml/h) was applied via TEA. In Group 2 (n = 17) no TEA was applied. During a period of 6 hours after induction, tissue oxygen tension (tpO₂) in the pancreas and pancreatic microcirculation was assessed. Thereafter animals were observed for 7 days followed by sacrification and histopathologic examination.

Results

Survival rate after 7 days was 82% in Group 1 (TEA) versus 29% in Group 2: (Control) (P <0.05). Group 1 (TEA) also showed a significantly superior microcirculation (1,608 ± 374 AU versus 1,121 ± 510 AU; P <0.05) and tissue oxygenation (215 ± 64 mmHg versus 138 ± 90 mmHG; P <0.05) as compared to Group 2 (Control). Consecutively, tissue damage in Group 1 was reduced in the histopathologic scoring (5.5 (3 to 8) versus 8 (5.5 to 10); P <0.05).

Conclusions

TEA led to improved survival, enhanced microcirculatory perfusion and tissue oxygenation and resulted in less histopathologic tissue-damage in an experimental animal model of severe acute pancreatitis.

Effects of different resuscitation fluid on severe acute pancreatitis

AIM: To compare effects of different resuscitation fluid on microcirculation, inflammation, intestinal barrier and clinical results in severe acute pancreatitis (SAP).

METHODS: One hundred and twenty patients with SAP were enrolled at the Pancreatic Disease Institute between January 2007 and March 2010. The patients were randomly treated with normal saline (NS group), combination of normal saline and hydroxyethyl starch (HES) (SH group), combination of normal saline, hydroxyethyl starch and glutamine (SHG group) in resuscitation. The ratio of normal saline to HES in the SH and SHG groups was 3:1. The glutamine (20% glutamine dipeptide, 100 mL/d) was supplemented into the resuscitation liquid in the SHG group. Complications and outcomes including respiratory and abdominal infection, sepsis, abdominal hemorrhage, intra-abdominal hypertension, abdominal compartment syndrome (ACS), renal failure, acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome (MODS), operation intervention, length of intensive care unit stay, length of hospital stay, and mortality at 60 d were compared. Moreover, blood oxygen saturation (SpO₂), gastric intramucosal pH value (pHi), intra-abdominal pressure (IAP), inflammation cytokines, urine lactulose/mannitol (L/M) ratio, and serum endotoxin were investigated to evaluate the inflammatory reaction and gut barrier.

RESULTS: Compared to the NS group, patients in the SH and SHG groups accessed the endpoint more quickly (3.9 ± 0.23 d and 4.1 ± 0.21 d vs 5.8 ± 0.25 d, P < 0.05) with less fluid volume (67.26 ± 28.53 mL/kg/d, 61.79 ± 27.61 mL/kg per day vs 85.23 ± 21.27 mL/kg per day, P < 0.05). Compared to the NS group, incidence of renal dysfunction, ARDS, MODS and ACS in the SH and SHG groups was obviously lower. Furthermore, incidence of respiratory and abdominal infection was significantly decreased in the SH and SHG groups, while no significant difference in sepsis was seen. Moreover, less operation time was needed in the SH and SHG group than the NS group, but the difference was not significant. The mortality did not differ significantly among these groups. Blood SpO₂ and gastric mucosal pHi in the SH and SHG groups increased more quickly than in the NS group, while IAP was significantly decreased in the SH and SHG group. Moreover, the serum tumor necrosis factor-α, interleukin-8 and C-reactive protein levels in the SH and SHG groups were obviously lower than in the NS group at each time point. Furthermore, urine L/M ratio and serum endotoxin were significantly lower in the SH group and further decreased in the SHG group.

CONCLUSION: Results indicated that combination of normal saline, HES and glutamine are more efficient in resuscitation of SAP by relieving inflammation and sustaining the intestinal barrier.

The impact of early goal-directed fluid management on survival in an experimental model of severe acute pancreatitis

PURPOSE

Severe acute pancreatitis (SAP) remains a life-threatening disease with classic etiology of systemic inflammatory response and mortality between 30 and 50 %. The aim of the present study is to compare two different treatment strategies of goal-directed hemodynamic management and evaluate their impact on survival, microcirculation, tissue oxygenation, and histopathologic damage in acute pancreatitis in a prospective animal study.

METHODS

Thirty-four domestic pigs were randomly assigned to two different treatment groups. After induction of acute pancreatitis, in group 1 volume administration was guided by central venous pressure (CVP >12 mmHg) and mean arterial pressure (MAP). In group 2, hemodynamic management was guided primarily by left-ventricular stroke volume variation (SVV <10 %), MAP, and cardiac output (CO). Treatment according to randomization was performed for 6 h, and tissue oxygen tension in the pancreas and pancreatic microcirculation were evaluated. Thereafter, animals were observed for 7 days and then sacrificed. Standardized tissue specimens were taken post mortem, and histopathologic scoring was performed.

RESULTS

Survival after 7 days was 29.4 % in group 2 versus 11.8 % in group 1 (p < 0.05). Pancreatic oxygen tension (138.0 ± 89.5 mmHg versus 71.1 ± 35.3 mmHg; p < 0.05) and pancreatic microcirculation (1,209.9 ± 630 AU versus 732 ± 315 AU; p < 0.05) were significantly higher in group 2. Significantly less histopathologic damage within the pancreas could be analyzed post mortem in group 2.

CONCLUSIONS

Goal-directed hemodynamic management guided by stroke volume variation led to improved survival, tissue oxygenation, and microcirculatory perfusion, as well as less histopathologic damage in an animal model of severe acute pancreatitis.

Could hydroxyethyl starch be a therapeutic option in management of acute aluminum phosphide toxicity?

Acute aluminum phosphide poisoning is a serious toxicity and results in high mortality rate despite the progress of critical care. After ingestion, phosphine gas is released and absorbed quickly, causing systemic poisoning and cell hypoxia. Excessive thirst, severe hypotension, arrhythmias, tachypnea, and severe metabolic acidosis are the common clinical manifestations. We think acute metabolic response which characteristically occurs in severe injury also happens in aluminum phosphide poisoning. Necropsy examinations indicate congestion in almost all vital organs because of leakage of fluids from intravascular to extravascular space. The most favorable type of fluid for intravascular volume resuscitation persists and is disputed. Colloids remain in the intravascular space rather than crystalloids, and provide more rapid hemodynamic stabilization. Furthermore, hydroxyethyl starch solution may have other benefits e.g. it can reduce the extra vascular leak of albumin and fluids from an endothelial injury site. As refractory hypotension and cardiovascular collapse, because leakage of fluids from intravascular to extravascular space are common cause of death in this toxicity, we propose that hydroxyethyl starch can dominate this refractory hypotension and consequently acute metabolic response.

Hemoglobin encapsulation in vesicles retards NO and CO binding and O2 release when perfused through narrow gas-permeable tubes

Intravenous administration of cell-free Hb induces vasoconstriction and circulatory disorders, presumably because of the intrinsic affinities to endogenous nitric oxide (NO) and carbon monoxide (CO) as vasorelaxation factors and because of the facilitated O2 release that might induce autoregulatory vasoconstriction. We examined these gas reactions when Hb-containing solutions of four kinds were perfused through artificial narrow tubes at a practical Hb concentration (10 g/dl). Purified Hb solution, polymerized bovine Hb (PolyBHb), encapsulated Hb [Hb-vesicles (HbV), 279 nm], and red blood cells (RBCs) were perfused through a gas-permeable narrow tube (25 μm inner diameter) at 1 mm/s centerline velocity. The level of reactions was determined microscopically based on the visible-light absorption spectrum of Hb. When the tube was immersed in NO and CO atmospheres, both NO binding and CO binding of deoxygenated Hb (deoxy-Hb) and PolyBHb in the tube was faster than those of HbV and RBCs, and HbV and RBCs showed almost identical binding rates. When the tube was immersed in a N2 atmosphere, oxygenated Hb and PolyBHb showed much faster O2 release than did HbV and RBCs. PolyBHb showed a faster reaction than Hb because of the lower O2 affinity of PolyBHb than Hb. The diffusion process of the particles was simulated using Navier-Stokes and Maxwell-Stefan equations. Results clarified that small Hb (6 nm) diffuses laterally and mixes rapidly. However, the large-dimension HbV shows no such rapid diffusion. The purely physicochemical differences in diffusivity of the particles and the resulting reactivity with gas molecules are one factor inducing biological vasoconstriction of Hb-based oxygen carriers.

Effects of hemodilution with a hemoglobin-based oxygen carrier (HBOC-201) on ischemia/reperfusion injury in a model of partial warm liver ischemia of the rat

BACKGROUND

Ischemia/reperfusion injury is an unavoidable complication in liver surgery and transplantation. Hemodilution with colloids can reduce postischemic injury but limits oxygen transport. Hemoglobin-based oxygen carriers have been evaluated as blood substitute and provide a plasma-derived oxygen transport. It was the aim of our study to evaluate the combined benefits of hemodilution with a better oxygen supply to reperfused liver tissue by the use of HBOC-201 (Hemopure).

MATERIAL AND METHODS

A model of partial warm liver ischemia in the rat was used. One group served as untreated control, the other groups were hemodiluted either with Ringer's lactate, Dextran-70, HBOC-201 or a mixture of Dextran and HBOC-201. After reperfusion, intravital microscopy studies were done and tissue pO(2) levels and transaminases measured. Statistical analysis was done by one- and two-way ANOVA, followed by pairwise comparison.

RESULTS

Hemodilution with Ringer's lactate did not show any improvement compared to the control group. Dextran and HBOC group were superior to the Ringer and control animals in all parameters studied. Leucocyte adherence in postsinusoidal venules improved from 569.03+/-171.87 and 364.52+/-167.32 in control and Ringer group to 131.68+/-58.34 and 68.44+/-20.31/mm(2) endothelium in Dextran and HBOC group (p<0.001). Concerning tissue pO(2) levels, HBOC (23.4+/-5.0 mmHg) proved to be superior to Dextran (7.9+/-4.4 mmHg; p=0.007).

CONCLUSION

HBOC was equivalent to Dextran in reducing I/R injury in the liver, but improved oxygenation of postreperfusion liver tissue.

Therapeutic small-volume resuscitation preserves pancreatic microcirculation in acute experimental pancreatitis of graded severity in rats

BACKGROUND

Microcirculatory disorders play a major part in the pathogenesis of acute pancreatitis. Improvement of microcirculation is hypothesized to open a therapeutic window. The aim of this study was to evaluate the effects of small-volume resuscitation in acute pancreatitis.

METHODS

In rats, acute pancreatitis of graded severity was induced and pancreatic microcirculation was observed in vivo with an epiluminescent microscope. Primary outcome measures were microcirculation, leukocyte adherence, concentration of trypsinogen-activating peptide, amylase activity and histopathologic tissue damage.

RESULTS

In necrotizing pancreatitis patients receiving prophylactic intervention with 7.5% hypertonic saline the functional capillary density was 76%. Postcapillary venular leukocyte adherence was 45% of vein cross-section. The median histopathologic damage scored 8 points. In controls, a complete microcirculatory breakdown was observed, and in the group with therapeutic intervention no significant difference was detected. In intermediate pancreatitis, the number of perfused capillaries remained 55.0 versus 23.3% in controls. Leukocyte adherence was 40.0 versus 51.7%. The histopathologic damage scored 6.0 versus 9.0 points. Trypsinogen-activating peptide concentration was reduced to 164 versus 402 nM in controls. In cerulein pancreatitis, the number of perfused capillaries was equally preserved in both groups.

CONCLUSION

Small-volume resuscitation preserves capillary microcirculation and prevents pancreatic injury in intermediate necrotizing pancreatitis.

Early changes in blood urea nitrogen predict mortality in acute pancreatitis

BACKGROUND & AIMS

Routine laboratory tests that reflect intravascular volume status can play an important role in the early assessment of acute pancreatitis (AP). The objective of this study was to evaluate accuracy of serial blood urea nitrogen (BUN) versus serial hemoglobin (Hgb) measurement for prediction of in-hospital mortality in AP.

METHODS

We performed an observational cohort study on data from 69 US hospitals from January 2003 to December 2006. Repeated measures analysis was used to examine the relationship between early trends in BUN and Hgb with respect to mortality. Multivariate logistic regression was used to evaluate the impact of admission BUN, change in BUN, admission Hgb, and change in Hgb on mortality. Time-specific receiver operating characteristic curves and multivariable logistic regression compared accuracy of BUN, Hgb, and additional routine laboratory tests.

RESULTS

BUN levels were persistently higher among nonsurvivors than survivors during the first 48 hours of hospitalization (F-test; P < .0001). No such relationship existed for Hgb (F-test; P = .33). For every 5-mg/dl increase in BUN during the first 24 hours, the age- and gender-adjusted odds ratio for mortality increased by 2.2 (95% confidence limits, 1.8, 2.7). Of the 6 routine laboratory tests examined, BUN yielded the highest area under the concentration-time curve (AUC) for predicting mortality at admission (AUC = 0.79), 24 hours (AUC = 0.89), and 48 hours (AUC = 0.90). Combining admission BUN and change in BUN at 24 hours produced an AUC of 0.91 for mortality.

CONCLUSION

In a large, hospital-based cohort study, we identified serial BUN measurement as the most valuable single routine laboratory test for predicting mortality in AP.

Fluid resuscitation in acute pancreatitis

Acute pancreatitis is a common inflammatory disorder of the pancreas resulting in considerable morbidity and a mortality rate of approximately 5%. Although there are no pharmacologic treatments known to improve important outcomes, aggressive intravenous fluid resuscitation generally is recommended in all patients. However, few human investigations have been performed and several important questions have not been answered. For example, what is the optimal resuscitative fluid? Is there a role for colloid solutions? To what clinical marker should resuscitation be targeted? When is the best time to start such fluids and in which group of patients? This review describes the microcirculation of the pancreas and the pathophysiologic alterations caused by acute pancreatitis. Previous animal experiments are described, as are the limited human studies specifically addressing fluid resuscitation. Finally, current recommendations and goals for further investigation are highlighted. It is our hope that this review will stimulate interest in this often overlooked subject and lead to carefully designed human clinical trials using varying fluid solutions and rates, with an emphasis on patient monitoring and safety, in the near future.

PANCREATIC INJURY AFTER THORACOABDOMINAL AORTIC OCCLUSION IN A PORCINE MODEL

BACKGROUND

The aim of this study was to investigate pancreatic injury after 45 min of thoracoabdominal aortic occlusion in a porcine model.

METHODS

Twenty-four pigs were used. Six pigs underwent sham operation and 18 intravascular balloon thoracoabdominal aortic occlusions for 45 min. The animals were randomly killed at 12, 48 and 120 h after reperfusion. After killing, all pancreata were examined macroscopically for any signs of acute pancreatitis, whereas gland specimens were harvested for histological study to evaluate pancreatic injury (haematoxylin and eosin staining) and acinar cell apoptosis (Terminal deoxynucleotidyl transferase mediated dUTP Nick-End Labelling staining).

RESULTS

Pancreatic injury severity score was mildly increased in terms of oedematous features at 12 h after reperfusion, but normalized to sham levels by the second day and thereafter. Necrotic injury was not statistically significant at any time point. Acinar cell apoptotic index was mildly increased at 12 and 48 h, but showed a tendency to decrease towards sham levels by the fifth day. One animal developed acute pancreatitis.

CONCLUSION

Acute pancreatitis is unlikely to occur after 45 min of thoracoabdominal aortic occlusion. However, an early, mild oedematous and apoptotic injury that occurs subclinically seems to be a constant event. This injury might have clinical significance when combined with pre-existent pancreatic pathologies.

Pathophysiological role of platelets in acute experimental pancreatitis: influence of endothelin A receptor blockade

The potential pathophysiological role of platelet-endothelium interactions was investigated during ischemia/reperfusion (I/R), and the effect of a selective endothelin(A) receptor antagonist (ET(A)-RA) was evaluated in an acute pancreatitis model. Acute pancreatitis was induced by warm ischemia (60 min) in Wistar rats, and its effects with and without antagonist treatment were investigated. Equivalent sham-operated animals were also studied. Microcirculatory changes were assessed by in vivo microscopy, and serum levels for lipase/amylase and histological specimens were investigated. Capillary constriction to 83.7 +/- 6.7% of sham-operated diameters was observed after 60 min of ischemia. A capillary density of 56.8 +/- 9.3% of the sham-operated group (396.3 +/- 15.8 mm(-1)) was measured after reperfusion. Stagnant leukocytes (329.5 +/- 30.4%) and platelets (337.5 +/- 32.3%) increased in postcapillary venules (P < 0.05). Administration of the ET(A)-RA significantly reduced I/R injury. Capillary diameters were maintained (101.4 +/- 4.5%), and capillary density was improved to 73.3 +/- 7.6% of sham-operated animals (P < 0.05). Stagnant leukocytes (152.3 +/- 10.6%) and platelets (207.1 +/- 19.8%) in sinusoids and postcapillary venules were reduced (P < 0.05). The extent of acute pancreatitis was reduced in the therapy group as indicated by serum lipase/amylase values and histological tissue damage (P < 0.05). Thus, ET(A)-RA therapy was effective in reducing I/R-induced pancreatitis in this experimental model.