Isovolemic hemodilution with dextran prevents contrast medium induced impairment of pancreatic microcirculation in necrotizing pancreatitis of the rat

Early Changes in Blood Urea Nitrogen (BUN) Can Predict Mortality in Acute Pancreatitis: Comparative Study between BISAP Score, APACHE-II, and Other Laboratory Markers-A Prospective Observational Study

BACKGROUND

Changes in BUN have been proposed as a risk factor for complications in acute pancreatitis (AP). Our study aimed to compare changes in BUN versus the Bedside Index for Severity in Acute Pancreatitis (BISAP) score and the Acute Physiology and Chronic Health Evaluation-II score (APACHE-II), as well as other laboratory tests such as haematocrit and its variations over 24 h and C-reactive protein, in order to determine the most accurate test for predicting mortality and severity outcomes in AP.

METHODS

Clinical data of 410 AP patients, prospectively enrolled for study at our institution, were analyzed. We define AP according to Atlanta classification (AC) 2012. The laboratory test's predictive accuracy was measured using area-under-the-curve receiver-operating characteristics (AUC) analysis and sensitivity and specificity tests.

RESULTS

Rise in BUN was the only score related to mortality on the multivariate analysis (p=0.000, OR: 12.7; CI 95%: 4.2-16.6). On the comparative analysis of AUC, the rise in BUN was an accurate test in predicting mortality (AUC: 0.842) and persisting multiorgan failure (AUC: 0.828), similar to the BISAP score (AUC: 0.836 and 0.850) and APACHE-II (AUC: 0.756 and 0.741). The BISAP score outperformed both APACHE-II and rise in BUN at 24 hours in predicting severe AP (AUC: 0.873 vs. 0.761 and 0.756, respectively).

CONCLUSION

Rise in BUN at 24 hours is a quick and reliable test in predicting mortality and persisting multiorgan failure in AP patients.

Microcirculation-guided protection strategy in hemodynamic therapy

Microcirculatory shock is a condition defined by the presence of tissue hypoperfusion despite the normalization of systemic and regional blood flow. Currently, more evidence shows that intrinsic septic shock is microcirculatory shock, which results in septic shock that is difficult to resuscitate. At present, treatments are aimed at recovering macro-circulation functions and include fluid resuscitation, vasoactive drugs, positive inotropic drugs, de-obstruction, and even mechanical assistance to improve oxygen delivery. However, the application of these treatments to more accurately improve microcirculation or avoid further microcirculatory damage is more important in clinics. In this article, we discuss the need for microcirculation protection and microcirculation-guided protection strategies in hemodynamic therapies.

Colloids and the Microcirculation

Colloid solutions have been advocated for use in treating hypovolemia due to their expected effect on improving intravascular retention compared with crystalloid solutions. Because the ultimate desired effect of fluid resuscitation is the improvement of microcirculatory perfusion and tissue oxygenation, it is of interest to study the effects of colloids and crystalloids at the level of microcirculation under conditions of shock and fluid resuscitation, and to explore the potential benefits of using colloids in terms of recruiting the microcirculation under conditions of hypovolemia. This article reviews the physiochemical properties of the various types of colloid solutions (eg, gelatin, dextrans, hydroxyethyl starches, and albumin) and the effects that they have under various conditions of hypovolemia in experimental and clinical scenarios.

Translational Research for Acute Pancreatitis - Which Results Have Really Influenced Our Therapy?

Acute pancreatitis is a common disease characterized by acinar cell destruction and acute inflammatory changes of the pancreas that lead to a systemic inflammatory response. A major research effort has been undertaken to unravel the underlying pathophysiology and to identify possible therapeutic targets. Still, only very few findings have influenced our clinical practice in the treatment of acute pancreatitis. Pancreatic microcirculation and capillary blood flow have long been suspected to play a major role in the course of the disease. It therefore seemed tempting to speculate that manipulation of the vasoconstrictor endothelin or its antagonist nitrogen monoxide could positively influence the outcome. We had to acknowledge, however, that these mechanisms take place very early in the disease course and that only prophylactic applications show an effect; this is useful in the setting of pancreas transplantation and endoscopic retrograde cholangiopancreatography but not applicable for clinical use in the therapy of acute pancreatitis. Research then focused on later pathophysiological stages of the disease, mainly on the process of adhesion and extravasation of leukocytes into the pancreatic tissue. Here, integrins and adhesion molecules like the intercellular adhesion molecule-1 (ICAM-1) were investigated in detail. A monoclonal antibody to ICAM-1 showed promising results in experimental models but was never further evaluated in the clinical setting. Hemodilution and fluid resuscitation was recognized to be an important therapeutic tool in acute pancreatitis. Here, initial experimental studies favored colloid solutions, and especially dextrans for isovolemic fluid resuscitation. It was recognized only later that colloid solutions are not effective and may even increase mortality in critically ill patients. Therefore, goal-directed infusion of Ringer's lactate solution at a moderate infusion rate to optimize volume status and hemoconcentration in acute pancreatitis is now advocated. In summary, out of the numerous experimental and translational studies, only very few have really influenced our daily clinical practice. Further research is therefore needed to find more specific and effective therapeutic agents for the treatment of acute pancreatitis.

Hydroxyethyl starch resuscitation reduces the risk of intra-abdominal hypertension in severe acute pancreatitis

OBJECTIVES

This study aimed to address whether hydroxyethyl starch (HES) is beneficial for intra-abdominal pressure (IAP) in severe acute pancreatitis (SAP) in early stages.

METHODS

Forty-one patients with SAP were randomized to HES group (n = 20) and the Ringer's lactate (RL) group (n = 21). The groups received 6% HES 130/0.4 for 8 days and RL solution without colloid, respectively. The primary end point was the IAP. The secondary end points were fluid balance, major organ complications, the Acute Physiology and Chronic Heath Evaluation II score, and the serum levels of C-reactive protein, interleukin-6, and interleukin-8.

RESULTS

The characteristics of baseline data were similar in the 2 groups. In the HES group, the IAP was significantly lower in 2 to 7 days, and fewer patients received mechanical ventilation (15.0% vs 47.6%). A negative fluid balance was observed earlier in the HES group than in the RL group (2.5 ± 2.2 vs 4.0 ± 2.5 days).

CONCLUSIONS

Fluid resuscitation with HES in the early stages of SAP can decrease the risk of intra-abdominal hypertension and reduce the use of mechanical ventilation.

Fluid resuscitation with human albumin or hydroxyethyl starch--are there differences in the healing of experimental intestinal anastomoses?

OBJECTIVES

Restoration of the macro- and microcirculation is important for the healing of gastrointestinal anastomoses. Colloids and crystalloids are widely used for blood volume therapy. We evaluated the effects of human albumin, hydroxyethyl starch (HES) 130/0.4 and saline on the microcirculation and on wound healing in colon anastomoses in rats.

MATERIAL AND METHODS

Male Wistar rats received a colonic end-to-end anastomosis. The animals were randomized into three groups and a single 3-ml dose of either 20% human albumin, 6% HES 130/0.4 or 0.9% saline was applied intravenously. Six, 24, 48, 96 h and 2 weeks after the procedure, 10 animals per group were reanesthetized. Measurements of capillary blood flow, vessel permeability and anastomosis bursting pressure were performed. The amounts of vascular endothelial growth factor (VEGF) and IL-6 in the plasma were determined by enzyme-linked immunosorbent assays, and the mRNA levels of VEGF and collagen types I and III were measured by real-time polymerase chain reaction.

RESULTS

No significant differences were found between albumin, HES 130/0.4 and saline in capillary blood flow, vessel permeability and anastomotic bursting pressure in this rat model. Concentrations of collagen I and III mRNA were significantly elevated after 96 h in animals that had received HES 130/0.4 or albumin. RNA and protein levels of VEGF and interleukin-6 were unaffected by therapy.

CONCLUSIONS

Human albumin, which is still widely used in the clinical setting, had no advantage over HES 130/0.4 and saline with regard to anastomotic healing in this animal model. Nevertheless, we prefer HES 130/0.4 because it is more effective for volume therapy than saline and has a better availability and is less expensive than human albumin.

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.

Risk assessment in acute pancreatitis

BACKGROUND

Acute pancreatitis has a variable natural history and in a proportion of patients is associated with severe complications and a significant risk of death. The various tools available for risk assessment in acute pancreatitis are reviewed.

METHODS

Relevant medical literature from PubMed, Ovid, Embase, Web of Science and The Cochrane Library websites to May 2008 was reviewed.

RESULTS AND CONCLUSION

Over the past 30 years several scoring systems have been developed to predict the severity of acute pancreatitis in the first 48-72 h. Biochemical and immunological markers, imaging modalities and novel predictive models may help identify patients at high risk of complications or death. Recently, there has been a recognition of the importance of the systemic inflammatory response syndrome and organ dysfunction.

Acute pancreatitis: etiology, clinical presentation, diagnosis, and therapy

Acute pancreatitis is a relatively common disease that affects about 300,000 patients per annum in America with a mortality of about 7%. About 75% of pancreatitis is caused by gallstones or alcohol. Other important causes include hypertriglyceridemia, medication toxicity, trauma from endoscopic retrograde cholangiopancreatography, hypercalcemia, abdominal trauma, various infections, autoimmune, ischemia, and hereditary causes. In about 15% of cases the cause remains unknown after thorough investigation. This article discusses the causes, diagnosis, imaging findings, therapy, and complications of acute pancreatitis.

Intravital microscopic characterization of suramin effects in an orthotopic immunocompetent rat model of pancreatic cancer

OBJECTIVES

We investigated the effect of suramin on tumor growth and spread in an immunocompetent, orthotopic rat model of pancreatic cancer and analyzed the tumor vasculature by intravital microscopy.

METHODS AND METHODS

In vitro, rat ductal pancreatic cancer cells (DSL-6A) were incubated with suramin (10-800 microg/ml), and cell proliferation was assessed. In vivo, DSL-6A tumors were induced in the pancreas of Lewis rats. Animals received suramin (60 mg/kg, weekly i.p.) or the vehicle (controls). Treatment started after 3 days. Intravital microscopy after 1, 4, and 8 weeks quantified diameter, density, and permeability of tumor vessels. Primary tumor volume, local infiltration, and metastatic spread were determined at autopsy. Microvessel density was analyzed by immunohistochemistry.

RESULTS

In vitro, proliferation was inhibited by suramin up to 95%. In vivo, all controls developed extensive tumor growth and spread. No tumor was detectable in half of the suramin-treated animals after 8 weeks; tumor dissemination was almost completely depressed. Suramin therapy resulted in a complete regression of tumor macrovessels and a significant reduction of microvessel density.

CONCLUSION

Suramin significantly reduces primary tumor growth and dissemination in a clinically relevant rat model of pancreatic cancer and seems to play an important role for the inhibition of tumor angiogenesis.

Oxygen radical formation does not have an impact in the treatment of severe acute experimental pancreatitis using free cellular hemoglobin

AIM: Microcirculatory dysfunction and free oxygen radicals are important factors in the pathogenesis of severe acute pancreatitis. Additional oxygen delivery might enhance lipid peroxidation but may also improve pancreatic microcirculation. This study assesses the effect of free cellular bovine hemoglobin on the formation of oxygen radicals and microcirculation in a rodent model of severe acute pancreatitis.

METHODS: Fifteen minutes after induction of acute pancreatitis Wistar rats received either 0.8 mL bovine hemoglobin (HBOC-200), hydroxyethyl starch (HES) or 2.4 mL of normal saline to ensure normovolemic substitution. After 6 h of examination the pancreas was excised and rapidly processed for indirect measurement of lipid peroxidation products malondialdehyde (MDA) and reduced glutathione (GSH) in pancreatic tissue.

RESULTS: The single application of HBOC-200 improved pancreatic microcirculation and reduced histopathological tissue damage significantly. Tissue concentration of MDA did not differ between the groups. Also no differences in GSH levels were detected.

CONCLUSION: Though the single application of HBOC-200 and HES improve pancreatic microcirculation, no differences in lipid peroxidation products were detected. The beneficial effect of additional oxygen supply (HBOC-200) does not lead to enhanced lipid peroxidation.

Contrast-enhanced computed tomography in acute pancreatitis: does contrast medium worsen its course due to impaired microcirculation?

BACKGROUND

An early and accurate diagnosis of severe acute (necrotizing) pancreatitis is important to allow timely institution of therapy to limit the extra-pancreatic sequelae of this necrotizing process and to minimize the incidence of super-infection of the necrosis (i.e., progression to infected necrosis). Contrast-enhanced computed tomography (CECT) has become the cornerstone of diagnosis by confirming the clinical diagnosis of severe acute pancreatitis based on the various clinical scoring criteria. Moreover, CECT serves as an anatomic roadmap for guiding radiological and surgical interventions. However, still-controversial experimental studies in animals in the mid-1990s suggested that the use of intravenous radiographic contrast media early in the course of the disease might exacerbate the necrotizing process by further impairing the already compromised pancreatic microcirculation. A series of experimental and clinical studies followed that have both refuted and supported this claim; unfortunately, none is conclusive, and the topic remains, as yet, unresolved.

AIMS

Our objective was to review objectively the available literature found by a Medline search on this subject.

METHODS

Meta-analysis and review.

RESULTS AND CONCLUSION

Our conclusion, after analysis of these studies, is that there are no well-substantiated data that could resolve the controversy. However, several caveats will be offered.

Can fluid resuscitation prevent pancreatic necrosis in severe acute pancreatitis?

BACKGROUND/AIMS

In previous studies, we have demonstrated that hemoconcentration was an early marker for necrotizing pancreatitis. The aim of the present study was to determine whether fluid resuscitation could prevent pancreatic necrosis among patients with hemoconcentration at the time of admission.

METHODS

Data was pooled from the prior two studies of all patients with necrotizing pancreatitis and interstitial pancreatitis with a hematocrit of > or = 44 on admission. Hematocrit values in necrotizing pancreatitis and interstitial pancreatitis were compared at admission and at 24 h. Statistical analyses were performed using the Wilcoxon rank-sum test.

RESULTS

A total of 39 patients satisfied our inclusion criteria, 28 with necrotizing pancreatitis and 11 with interstitial pancreatitis. Patients with necrotizing pancreatitis presented earlier than patients with interstitial pancreatitis (median 18 vs. 38 h, respectively) (p = 0.005). There was no significant difference between the intergroup median hematocrits on admission and at 24 h. All patients with hematocrits that failed to decrease at 24 h developed necrotizing pancreatitis (12/28 with necrotizing pancreatitis vs. 0/11 with interstitial pancreatitis) (p = 0.009). There was no significant difference at 24 h in rehydration among the three groups: 4.0 liters among the 12 patients with necrotizing pancreatitis whose hematocrits increased and 4.5 liters among the 16 whose hematocrits decreased at 24 h, and 4.1 liters among the 11 patients with interstitial pancreatitis (p = 0.81).

CONCLUSION

Patients who presented early were more likely to have necrotizing pancreatitis than interstitial pancreatitis. While fluid resuscitation was not shown to prevent pancreatic necrosis, all patients with inadequate fluid resuscitation as evidenced by persistence of hemoconcentration at 24 h developed necrotizing pancreatitis.

Influencing factors of pancreatic microcirculatory impairment in acute panceatitis

Pancreatic microcirculatory disturbance plays an important role in the pathogenesis of acute pancreatitis, and it involves a series of changes including vasoconstriction, ischaemia, increased vascular permeability, impairment of nutritive tissue perfusion, ischaemia/reperfusion, leukocyte adherence, hemorrheological changes and impaired lymphatic drainage. Ischaemia possibly acts as an initiating factor of pancreatic microcirculatory injury in acute pancreatitis, or as an aggravating/continuing mechanism. The end-artery feature of the intralobular arterioles suggests that the pancreatic microcirculation is highly susceptible to ischaemia. Various vasoactive mediators, as bradykinin, platelet activating factor, endothelin and nitric oxide participate in the development of microcirculatory failure.

Endothelin receptor blockade in severe acute pancreatitis leads to systemic enhancement of microcirculation, stabilization of capillary permeability, and improved survival rates

BACKGROUND

We previously demonstrated that therapy with a new endothelin A receptor antagonist (ET-RA) significantly reduced mortality rates in severe acute pancreatitis (AP) in the rat without attenuating local signs of disease severity (intrapancreatic protease activation, acinar cell necrosis). This raised the question as to why ET-RA was so effective. The purpose of this study was to assess the effect of ET-RA on microcirculation (particularly capillary permeability) within and outside of the pancreas on intravascular fluid loss and extravascular fluid sequestration and on distant organ function.

METHODS

Severe AP was induced in rats by standardized intraductal bile acid infusion and cerulein hyper-stimulation. Starting 6 hours (n = 24 rats) and 12 hours (n = 30 rats) after the onset of AP, animals randomly received either the ET-RA (LU-135252) or saline solution with fluid resuscitation (6 mL/kg/h Ringer's lactate). At 24 hours, animals were relaparotomized for intravital microscopic determination of capillary blood flow, leukocyte rolling, and capillary permeability in the pancreas and colon. Further monitoring included cardiorespiratory and renal parameters, hematocrit levels and quantification of ascites and pleural effusions, and acinar cell necrosis at autopsy. Groups of sham-operated healthy animals (n = 6 animals each) that had been treated according to the same protocol served as control animals.

RESULTS

ET-RA treatment that was started 6 hours after AP-induction significantly decreased hematocrit levels (38% +/- 1% vs 45% +/- 2% with saline solution treatment), reduced ascites and pleural effusions (6.7 +/- 1.3 mL vs 11.9 +/- 1.3 mL), and improved urine production (4.8 +/- 0.5 mL vs 2.9 +/- 0.6 mL) and respiratory parameters. Moreover, all microcirculatory parameters were improved; in particular, capillary permeability was stabilized (158% +/- 9% vs 248% +/- 8% in the colon). These beneficial effects were also seen when therapy was delayed until 12 hours after AP induction. Pancreatic necrosis was not significantly reduced. The overall mortality rate was 12% in ET-RA-treated animals and 42% in saline solution-treated control animals (P <.05). In healthy animals ET-RA did not significantly alter the target parameters, except for a reduction of capillary permeability in the pancreas.

CONCLUSIONS

Improved microcirculation and stabilized capillary permeability in ET-RA-treated animals together with reduced intravascular fluid loss and extravascular fluid sequestration and improved renal and pulmonary function (1) may explain improved survival in this model, (2) support the hypothesis that systemic disease sequelae significantly contribute to outcome in AP, and (3) suggest that ET-RA may be a promising therapeutic tool in AP because it counteracts microcirculatory disorders that contribute to pancreatitis-associated organ dysfunction even when therapy is delayed to a point at which pancreatic injury may no longer be influenced.

Therapy for microcirculatory disorders in severe acute pancreatitis: comparison of delayed therapy with ICAM-1 antibodies and a specific endothelin A receptor antagonist

Many of the complications in severe acute pancreatitis result from the amplifying effects of microcirculatory disruption. The pathogenesis of these microcirculatory disorders is multifactorial and involves various vasoactive mediators. Thus questions arise as to which vasoactive mediators are most important and how long after the onset of disease vasoactive mediator blockade may be effective. The present study compares the effect of delayed therapy with two vasoactive mediator antagonists, previously tested with promising results in other studies in a well-established rodent model of severe acute pancreatitis. Twelve hours after induction of acute pancreatitis, rats were randomized to therapy with intracellular adhesion molecule-1 (ICAM-1) antibody (2 mg/kg IA-29), endothelin A receptor antagonist (ET-RA) (40 mg/kg LU 135252), or saline solution (volume equivalent). After 12 hours of fluid resuscitation, animals underwent repeat laparotomy for intravital microscopic determination of capillary blood flow, leukocyte rolling, and capillary permeability in the pancreas and colon. Other measurements included cardiorespiratory parameters, hematocrit, pleural effusions, ascites, urine production, and survival. Compared to saline treatment, both ICAM antibody and ET-RA significantly enhanced capillary blood flow in the pancreas and colon, reduced leukocyte rolling, and stabilized capillary permeability. These beneficial effects on microcirculation were associated with decreased fluid loss into the third space and improved renal function and survival. Although both antagonists likewise enhanced capillary blood flow and reduced leukocyte rolling, ET-RA was significantly more effective than ICAM antibody in counteracting capillary leakage, thereby further reducing fluid sequestration. The present study confirms the beneficial effects of endothelin and ICAM antagonists in severe acute pancreatitis, even with delayed therapy, suggesting that both compounds are candidates for further clinical testing. Selective endothelin A receptor blockade appears to be especially attractive for clinical use not only because it was superior to ICAM antibody in the present study but also because of its favorable pharmacologic properties and (preliminary) positive results in clinical phase 2 studies currently underway for other diseases.

Hemoconcentration is an early marker for organ failure and necrotizing pancreatitis

In a previous retrospective case-control study, hemoconcentration was associated with the development of pancreatic necrosis. The aim of the present study was to determine in a cohort study whether hemoconcentration is a marker for both organ failure and necrotizing pancreatitis. A cohort study was performed on patients admitted with acute pancreatitis from February 1996 to April 1997. Pancreatic necrosis was defined by findings on dynamic contrast-enhanced computed tomography scan or magnetic resonance imaging. Of 128 total patients with acute pancreatitis, 53 underwent computed tomography or magnetic resonance imaging. Eighteen of 53 had necrotizing pancreatitis. Logistic regression identified an admission hematocrit > or = 44% and a failure of admission hematocrit to decrease at 24 hours as the best binary predictors of necrotizing pancreatitis and organ failure. By 24 hours, 17 of 18 patients with necrotizing pancreatitis versus 11 of 35 with interstitial pancreatitis met one or the other criterion for necrosis (p < 0.001). By 24 hours, 13 of 15 with organ failure versus 36 of 104 without organ failure met one or the other criterion (p < 0.001). The negative predictive value by 24 hours was 96% for necrotizing pancreatitis and 97% for organ failure. Hemoconcentration with an admission hematocrit > or = 44% and/or failure of admission hematocrit to decrease at approximately 24 hours was associated with the development of necrotizing pancreatitis and organ failure. Patients who did not experience hemoconcentration were very unlikely to develop pancreatic necrosis or organ failure.

Therapy for microcirculatory disorders in severe acute pancreatitis: effectiveness of platelet-activating factor receptor blockade vs. endothelin receptor blockade

Many of the complications of severe acute pancreatitis are the result of the amplifying effects of microcirculatory disruption. The factors causing microcirculatory disorders in acute pancreatitis involve vasoactive mediators such as platelet-activating factor (PAF) and endothelin-1 (ET) activated during the inflammatory response to pancreatic injury. To further evaluate the potential therapeutic role of specific receptor antagonists (RA) to these mediators, the present study compares the effect of PAF and ET receptor blockade on microcirculation and organ function in a well-established rodent model of severe acute pancreatitis. Six hours after acute pancreatitis induction, rats were randomized to therapy with ET-RA (50 mg/kg LU-135252), PAF-RA (82 microg/kg WEB-2170), or NaCl 0.9% (volume equivalent). After 18 hours of fluid resuscitation, animals were relaparotomized for intravital microscopic determination of capillary blood flow, leukocyte rolling, and capillary permeability in the pancreas and colon. Other measurements included cardiorespiratory parameters, hematocrit, pleural effusions, ascites, urine production, and survival. Compared to saline treatment both ET-RA and PAF-RA significantly improved capillary blood flow in the pancreas and colon, reduced leukocyte rolling, and stabilized capillary permeability. The beneficial effects of receptor antagonist treatment on microcirculation were associated with decreased fluid loss into the third space, improved renal and respiratory function, and survival. Although both receptor antagonists likewise improved capillary blood flow, ET-RA was significantly more effective in counteracting leukocyte rolling and capillary leakage, thereby further reducing fluid sequestration. The present study confirms the beneficial effects of PAf and ET receptor blockade on microcirculation inside and outside the pancreas, organ function, and survival when given at the early stage of severe pancreatitis. Because ET-RA was more effective in stabilizing capillary permeability and avoiding subsequent fluid loss into the third space, we propose that ET-RA should be tested in a clinical trial (either in comparison or in addition to PAF-RA).

Endothelin receptor blockade improves fluid sequestration, pancreatic capillary blood flow, and survival in severe experimental pancreatitis

OBJECTIVE

To evaluate the effect of a new endothelin receptor antagonist (ET-RA) on the course of severe experimental pancreatitis.

BACKGROUND

Endothelin-1 has been shown to reduce regional blood flow in various organs, including the pancreas, and to aggravate cerulein-induced mild pancreatitis.

METHODS

Acute necrotizing pancreatitis (ANP) was induced in rats by standardized intraductal bile acid infusion and cerulein hyperstimulation. Serum trypsinogen activation peptides (TAP) were measured to verify comparable disease severity. Starting 6 hours after the onset of ANP, animals randomly received either saline or the new ET-RA LU-135252. Monitoring included cardiorespiratory parameters, urine output, hematocrit, and TAP levels. After 24 hours, animals were relaparotomized to determine pancreatic capillary blood flow and to assess the amount of free intraabdominal fluid and acinar cell necrosis. Survival was determined in a second set of experiments on 24 animals observed for 48 hours after pancreatitis induction and treatment with either normal saline or ET-RA.

RESULTS

Comparable TAP increases confirmed equally severe ANP in both groups before treatment. Treatment with ET-RA significantly reduced the mortality rate, from 50% in untreated animals to 8%. Improved survival was associated with significantly decreased hematocrit, improved urinary output, decreased ascites, and increased pancreatic capillary blood flow. There were no significant differences in plasma TAP and acinar cell injury in the surviving animals of the two treatment groups.

CONCLUSION

Therapy with the new ET-RA reduces the early mortality rate in experimental ANP, probably by reducing fluid sequestration and improving microcirculation.

Hemoconcentration as an early risk factor for necrotizing pancreatitis

OBJECTIVE

The aim of our study was to determine whether measurement of serum hematocrit during the first 24 h helps in distinguishing necrotizing from mild pancreatitis.

METHODS

From May 1992 to June 1996, a case-control study was performed with cases of patients with necrotizing pancreatitis. We selected as a control the next patient admitted with mild pancreatitis.

RESULTS

There were 32 patients in each group. Logistic regression identified an admission hematocrit of > or = 47% and a failure of admission hematocrit to decrease at 24 h as the best binary risk factors for necrotizing pancreatitis. At admission, more patients with necrotizing pancreatitis than with mild pancreatitis had a hematocrit > or = 47% (11/32 vs 3/32; p = 0.03). At 24 h, 15 additional patients with necrotizing pancreatitis versus only one with mild pancreatitis showed no decrease in admission hematocrit (p < 0.01). Thus, by 24 h, 26 of 32 patients with necrotizing pancreatitis versus only four of 32 patients with mild pancreatitis met one or the other criterion (p < 0.01). The sensitivity and specificity at admission were 34% and 91%; at 24 h, 81% and 88%.

CONCLUSIONS

Hemoconcentration with an admission hematocrit > or = 47% or failure of admission hematocrit to decrease at approximately 24 h were strong risk factors for the development of pancreatic necrosis.

Endothelin-1 mediates the alcohol-induced reduction of pancreatic capillary blood flow

Increased plasma endothelin-1 (ET-1) levels in rats after alcohol administration and increased endothelin receptor expression in the pancreas in chronic alcoholic pancreatitis have led to the hypothesis that ET-1 may play a critical role in the pathogenesis of ethanol-induced pancreatic injury through impairment of perfusion. To further test the hypothesis that ET-1 mediates an alcohol-induced reduction of pancreatic perfusion, the present study compares the effect of intravenous alcohol and ET-1 on pancreatic capillary blood flow (PCBF) and investigates whether endothelin receptor blockade prevents the alcohol-induced reduction in PCBF. Anesthetized rats were randomly assigned to receive one of the following: a 1-hour infusion of 2 g/kg alcohol or the volume equivalent of saline solution plus ET-1 (1.25 microgram/kg), a specific endothelin-A receptor antagonist (50 mg/kg), or saline solution (volume equivalent). The pancreas was exposed for intravital microscopy; PCBF was determined at the same location before the test solutions were given, after the infusion, and 1 hour thereafter. Alcohol and ET-1 significantly decreased PCBF from 2.0 nl/min/cap to 1.7 nl/min/cap. The reduction in PCBF was even more pronounced when alcohol and ET-1 were combined (1.5 nl/min/cap), whereas the ET receptor antagonist increased PCBF in saline-treated rats to 2.2 nl/min cap and maintained stable PCBF in alcohol-treated animals. The observation that PCBF is reduced by both alcohol and ET-1 and that the alcohol-induced reduction of PCBF can be aggravated by ET-1 and prevented by a specific endothelin-1 antagonist supports the hypothesis that ET-1 is the mediator of the alcohol-associated reduction of pancreatic perfusion.