New therapies in sepsis

Application of LC-MS-based metabolomics method in differentiating septic survivors from non-survivors

Septic shock is the most severe form of sepsis, which is still one of the leading causes of death in the intensive care unit (ICU). Even though early prognosis and diagnosis are known to be indispensable for reaching an optimistic outcome, pathogenic complexities and the lack of specific treatment make it difficult to predict the outcome individually. In the present study, serum samples from surviving and non-surviving septic shock patients were drawn before clinical intervention at admission. Metabolic profiles of all the samples were analyzed by liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. One thousand four hundred nineteen peaks in positive mode and 1878 peaks in negative mode were retained with their relative standard deviation (RSD) below 30 %, in which 187 metabolites were initially identified by retention time and database in the light of the exact molecular mass. Differences between samples from the survivors and the non-survivors were investigated using multivariate and univariate analysis. Finally, 43 significantly varied metabolites were found in the comparison between survivors and non-survivors. Concretely, metabolites in the tricarboxylic acid (TCA) cycle, amino acids, and several energy metabolism-related metabolites were up-regulated in the non-survivors, whereas those in the urea cycle and fatty acids were generally down-regulated. Metabolites such as lysine, alanine, and methionine did not present significant changes in the comparison. Six metabolites were further defined as primary discriminators differentiating the survivors from the non-survivors at the early stage of septic shock. Our findings reveal that LC-MS-based metabolomics is a useful tool for studying septic shock. Graphical abstract ᅟ.

Polyclonal intravenous immunoglobulin for the prophylaxis and treatment of infection in critically ill adults

Infection is a major cause of morbidity and mortality in critically ill patients. Despite advances in technology, its mortality rate has changed minimally over the past two decades, and new therapies are needed. Polyclonal intravenous immunoglobulin (IVIG) has been investigated both as a preventive and a treatment modality for sepsis and septic shock in critically ill adult patients. Prophylaxis with IVIG has been shown to reduce significantly the incidence of infection, particularly pneumonia, in selected postsurgical intensive care patients. However, it does not reduce mortality. The risk-benefit and cost effectiveness of this therapeutic intervention have not been determined, and its routine use is therefore not recommended. Treatment with IVIG has been shown in a number of small trials and a meta-analysis to reduce dramatically sepsis and septic shock mortality. However, a large, unpublished randomized trial has apparently shown no mortality benefit with this therapy. Despite limited evidence, IVIG has become the standard of care for the management of group A streptococcal toxic shock syndrome. At present, clinical equipoise exists for the use of IVIG in the treatment of sepsis and septic shock, and further study is needed.

The reduction of tumor necrosis factor-alpha release and tissue damage by pentobarbital in the experimental endotoxemia model

Sepsis is the leading cause of death for intensive care patients. Lipopolysaccharide (LPS) administration to animals under anesthesia is a strategy for the study of uncontrolled release of proinflammatory cytokines. Anesthetics have been indicated that they can specially affect immune responses, such as the inflammatory response. Pentobarbital is an anesthetic used mainly in animal studies. Thus, the effect of pentobarbital on tumor necrosis factor-alpha (TNF-alpha) release was determined. The results revealed that pentobarbital suppressed the expression of TNF-alpha mRNA and its proteins, which may result from the decrease in the activities of nuclear factor-kappaB and activator protein 1 and the reduction of the expression of p38 mitogen-activated protein kinase by pentobarbital. After the inhibitory activity of the pentobarbital for TNF-alpha release was proven in vivo, the cytotoxic effects of LPS were examined in vivo with or without pentobarbital treatments. In vivo results indicated that plasma levels of alanine aminotransferase, aspartate aminotransferase, lactic dehydrogenase, creatine kinase, serum urea nitrogen, and amylase decreased dramatically in the anesthetic group with pentobarbital administration. Finally, the effect of pentobarbital on TNF-alpha-related cell death was monitored in vitro, and the results indicated the pentobarbital could directly enhance the viabilities of cells under the treatment of TNF-alpha and protected cells from apoptosis induced by deferoxamine mesylate-induced hypoxia. These results suggest that pentobarbital significantly influences the LPS-induced inflammatory response and protects cells from death directly and indirectly induced by TNF-alpha. The information provides a perspective to re-evaluate the results of the experiments in which animals were anesthetized with pentobarbital. The anti-inflammatory effects of the drugs may have been caused by the synergistic effect of pentobarbital.

New evaluation therapies for sepsis

This article presents an analysis of the literature of the last 2 years on the treatment of sepsis and septic shock. It appears that most of the antimediator therapies applied in phase II or III clinical trials yielded disappointing results. But, many other therapeutic approaches are proposed or are ongoing, and many papers report critical analysis of the reasons for the lack of success of past clinical trials.

Ozone Therapy in Induced Endotoxemic Shock. II. The Effect of Ozone Therapy Upon Selected Histochemical Reactions in Organs of Rats in Endotoxemic Shock

Mitochondria and lysosomes were evaluated by assessment of changes in activity of selected enzymes: lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), adenosinetriphosphatase (ATPase), acid phosphatase (AcPase) and beta-glucuronidase (BG) in rats under profound hypoxia induced by endotoxemic shock. The study was conducted on adult male Wistar rats. The animals formed the following four groups of 15 rats each: control animals (C);-rats receiving intraperitonally O(2)/O(3) (CO), rats receiving of Escherichia coli toxin (LPS) (CL); rats receiving LPS plus oxygen-ozone mixture (OL). Histoenzymatic examinations of liver, kidney, lungs, and heart muscle were performed. Lipopolysaccharide suppressed activities of all the enzymes except for LDH, the activity of which as high as a fourfold increase. The results demonstrated potent, stabilizing and regenerative effects of ozone therapy on body enzymatic processes in course of induced endotoxemic shock in rats, which might prove to be of clinical significance.

Procalcitonin in the diagnosis of inflammation in intensive care units

OBJECTIVES

To assess the effectiveness of different procalcitonin cutoff values to distinguish non-infected (negative+SIRS) from infected (sepsis+severe sepsis+septic shock) medical and surgical patients.

DESIGN AND METHODS

PCT plasma concentration was measured using an automated chemiluminescence analyzer in 1013 samples collected in 103 patients within 24 h of admission in ICU and daily during the ICU stay. We compared PCT levels in medical and surgical patients. We also compared PCT plasma levels in non-infected versus infected patients and in SIRS versus infected patients both in medical and in surgical groups.

RESULTS

Median values of PCT plasma concentrations were significantly higher in infected than in non-infected groups, both in medical (3.18 vs. 0.45 microg/L) (p<0.0001) and in surgical (10.45 vs. 3.89 microg/L; p<0.0001) patients. At the cutoff of 1 microg/L, the LR+ was 4.78, at the cutoff of 6 microg/L was 12.53, and at the cutoff of 10 microg/L was 18.4.

CONCLUSIONS

This study highlights the need of different PCT cutoff values in medical and surgical critically ill patients, not only at the ICU admission but also in the entire ICU stay.

Effects of ozone oxidative preconditioning on TNF-alpha release and antioxidant-prooxidant intracellular balance in mice during endotoxic shock

Ozone oxidative preconditioning is a prophylactic approach, which favors the antioxidant-prooxidant balance for preservation of cell redox state by the increase of antioxidant endogenous systems in both in vivo and in vitro experimental models. Our aim is to analyze the effect of ozone oxidative preconditioning on serum TNF-α levels and as a modulator of oxidative stress on hepatic tissue in endotoxic shock model (mice treated with lipopolysaccharide (LPS)). Ozone/oxygen gaseous mixture which was administered intraperitoneally (0.2, 0.4, and 1.2 mg/kg) once daily for five days before LPS (0.1 mg/kg, intraperitoneal). TNF-α was measured by cytotoxicity on L-929 cells. Biochemical parameters such as thiobarbituric acid reactive substances (TBARS), enzymatic activity of catalase, glutathione peroxidase, and glutathione-S transferase were measured in hepatic tissue. One hour after LPS injection there was a significant increase in TNF-α levels in mouse serum. Ozone/oxygen gaseous mixture reduced serum TNF-α levels in a dose-dependent manner. Statistically significant decreases in TNF-α levels after LPS injection were observed in mice pretreated with ozone intraperitoneal applications at 0.2 (78%), 0.4 (98%), and 1.2 (99%). Also a significant increase in TBARS content was observed in the hepatic tissue of LPS-treated mice, whereas enzymatic activity of glutathion-S transferase and glutathione peroxidase was decreased. However in ozone-treated animals a significant decrease in TBARS content was appreciated as well as an increase in the activity of antioxidant enzymes. These results indicate that ozone oxidative preconditioning exerts inhibitory effects on TNF-α production and on the other hand it exerts influence on the antioxidant-prooxidant balance for preservation of cell redox state by the increase of endogenous antioxidant systems.

Effect of pentoxifylline on endotoxin-induced haemostatic disturbances in rabbits

Pentoxifylline (PTX, a methylxanthine derivative) has been found to interrupt early gene activation for tumour necrosis factor, interleukin-1, interleukin-6 and tissue factor production and to improve survival from experimental sepsis. During endotoxaemia, lipopolysaccharide (LPS, endotoxin) and proinflammatory cytokines trigger the development of disseminated intravascular coagulation (DIC) via the tissue factor-dependent pathway of coagulation. The present study was undertaken to determine whether pentoxifylline could prevent coagulation disturbances in LPS-treated rabbits. Endotoxaemia was induced with E. coli lipopolysaccharide in New Zealand White rabbits. Forty rabbits were used and divided into four equal groups. Group 1 served as a control group; Group 2: lipopolysaccharide was injected intravenously, Group 3: pentoxifylline was injected intraperitoneally, Group 4: lipopolysaccharide and pentoxifylline were injected simultaneously. Blood samples were collected 6 h after the treatments. In rabbits with endotoxin-induced DIC, platelet count, leukocyte count, percentage of differential leukocyte values, fibrinogen level, antithrombin III (AT-III) and protein C (PC) activity were decreased. Moreover, activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged when compared to the control group. In conclusion, haemostatic disturbances associated with endotoxin-induced DIC were moderately suppressed by the administration of PTX.

Protective effect of β-glucan on lung injury after cecal ligation and puncture in rats

OBJECTIVE

Understanding the biological mediators involved in the complex inflammatory response of sepsis and acute lung injury offers the possibility of future investigations targeting treatment based on these mediators. This study investigated whether macrophage activator beta-glucan has a protective effect on acute lung injury in an experimental model of sepsis.

DESIGN AND SETTING

Experimental study in an experimental research center.

MATERIALS

30 rats randomized into three groups (sham, sepsis, and beta-glucan).

INTERVENTIONS

Cecal ligation and puncture were performed in the beta-glucan and sepsis groups. The beta-glucan group was given a single intraperitoneal dose of beta-glucan (4 mg/kg) following cecal ligation.

MEASUREMENTS AND RESULTS

Rats treated with beta-glucan had fewer circulating neutrophils, more blood monocytes, and higher serum interleukin 6 levels than septic animals. The percentages of neutrophils and lymphocytes from the bronchoalveolar lavage fluid and the myeloperoxidase activity measured in the lung tissue were lower in the beta-glucan group than in the sepsis group. Less alveolar hemorrhage and neutrophil infiltration were observed in lungs from animals in the beta-glucan group in the septic groups.

CONCLUSIONS

In this rat model of intra-abdominal sepsis beta-glucan treatment partially protected against secondary lung injury, decreased lung hemorrhages, and lung neutrophilia. These results suggest that beta-glucan protects against sepsis-associated lung damage.

Comparison of procalcitonin and C-reactive protein as markers of sepsis

OBJECTIVE

To compare the clinical informative value of procalcitonin (PCT) and C-reactive protein (CRP) plasma concentrations in the detection of infection and sepsis and in the assessment of severity of sepsis.

DESIGN

Prospective study.

SETTING

Medicosurgical intensive care unit.

PATIENTS

Seventy consecutive adult patients who were admitted to the intensive care unit for an expected stay >24 hrs.

INTERVENTIONS

None.

MEASUREMENTS

PCT and CRP plasma concentrations were measured daily during the intensive care unit stay. Each patient was examined daily for signs and symptoms of infection and was classified daily in one of the following four categories according to the American College of Chest Physicians/Society of Critical Care Medicine criteria: negative, systemic inflammatory response syndrome, localized infection, and sepsis group (sepsis, severe sepsis, or septic shock). The severity of sepsis-related organ failure was assessed by the sepsis-related organ failure assessment score.

MAIN RESULTS

A total of 800 patient days were classified into the four categories. The median plasma PCT concentrations in noninfected (systemic inflammatory response syndrome) and localized-infection patient days were 0.4 and 1.4 ng/mL (p <.0001), respectively; the median CRP plasma concentrations were 79.9 and 85.3 mg/L (p =.08), respectively. The area under the receiver operating characteristic curve was 0.756 for PCT (95% confidence interval [CI], 0.675-0.836), compared with 0.580 for CRP (95% CI, 0.488-0.672) (p <.01). The median plasma PCT concentrations in nonseptic (systemic inflammatory response syndrome) and septic (sepsis, severe sepsis, or septic shock) patient days were 0.4 and 3.65 ng/mL (p <.0001), respectively, whereas those for CRP were 79.9 and 115.6 mg/L (p <.0001), respectively. The area under the receiver operating characteristic curve was 0.925 for PCT (95% CI, 0.899-0.952), compared with 0.677 for CRP (95% CI, 0.622-0.733) (p <.0001). The linear correlation between PCT plasma concentrations and the four categories was much stronger than in the case of CRP (Spearman's rho, 0.73 vs. 0.41; p <.05). A rise in sepsis-related organ failure assessment score was related to a higher median value of PCT but not CRP.

CONCLUSION

PCT is a better marker of sepsis than CRP. The course of PCT shows a closer correlation than that of CRP with the severity of infection and organ dysfunction.

Randomized, controlled clinical trials in sepsis: has methodological quality improved over time?

OBJECTIVE

To systematically evaluate the methodological quality of randomized clinical trials and to determine whether randomized clinical trials of sepsis improved in methodological quality over time.

DATA SOURCES

Computerized MEDLINE search of articles published in any language from 1966 to 1998 combined with a manual search of bibliographies of published articles and communication with known experts in the field.

STUDY SELECTION

All randomized clinical trials of sepsis, severe sepsis, and septic shock performed in adults and published as full articles.

DATA EXTRACTION

Abstracts of all retrieved records were reviewed and the inclusion criteria were applied. All selected articles were classified into (a) trials designed to detect differences in mortality as the primary end point, or (b) trials focusing on surrogate outcome measures (i.e., physiological or biochemical parameters). All retrieved trials were then graded for methodological quality using an objective grading scheme developed specifically for this study. The data selection and extraction process was carried out independently by two of the authors; any disagreement was resolved by discussion.

DATA SYNTHESIS

Seventy-four randomized clinical trials involving septic patients qualified for inclusion in this study (40 reporting mortality outcomes, 34 reporting other surrogate outcomes). Trials reporting mortality as the primary outcome had significantly higher quality scores compared with trials reporting surrogate outcome measures (29.6 +/- 1.0 vs. 24.3 +/- 0.8, p =.0006). From 1976 to 1998, trial methodology improved significantly over time (an average of 0.36 points per year, p =.021). Mortality outcome trials improved an average of 0.58 points per year (p =.0011) whereas surrogate outcome trials did not demonstrate an improvement in methodological quality over time (p =.249).

CONCLUSION

The methodological limitations identified in this article can help to target further improvement in trial design to enhance the validity of findings from future randomized clinical trials of sepsis.

The effect of aging on circulating levels of proinflammatory cytokines during septic shock. Norasept II Study Investigators

BACKGROUND

As the proportion of the population that is older continues to rise, infection in older people has become an important healthcare problem. Although aging is associated with multiple abnormalities in immune function, the effect of aging on the production of proinflammatory cytokines has not been well studied under conditions of clinical stress.

OBJECTIVES

The aim of this study was to examine the effect of aging on circulating levels of the proinflammatory cytokines in a large cohort of septic shock patients. We hypothesized that aging would be associated with a diminished proinflammatory cytokine response to sepsis.

DESIGN

Patients with septic shock who were enrolled in the placebo limb of the North American Sepsis Trial (NORASEPT II) study were analyzed.

SETTING

The intensive care units of 105 hospitals in the United States and Canada.

PARTICIPANTS

Nine hundred and thirty patients presenting to hospital within 12 hours of the onset of septic shock.

MEASUREMENTS

Interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble tumor necrosis factor-receptor-55 (sTNF-R55), and soluble tumor necrosis factor-receptor-75 (sTNF-R75) concentrations were measured at enrollment. The study population was broken down into five age groups as follows: less than 50 years (group one), 50 to 64 years (group two), 65 to 74 years (group three), 75 to 84 years (group four), and 85 or older (group five). Clinical, demographic, and cytokine data were extracted to describe each age group.

RESULTS

Data were available for 930 patients. The patients' mean age (+/- SD) was 59 +/- 17 years (range, 18 to 102). There were 280 patients in group one, 242 in group two, 210 in group three, 150 in group four, and 48 in group five. The primary diagnoses; clinical characteristics; and IL-6, sTNF-R55, and sTNF-R75 levels were similar among the five age groups. The TNF-alpha levels were significantly higher, however, in the oldest group of patients (group five). The 28-day survival was 49% in patients over the age of 75 and 58% in those under 75 years (P = .03). There was no gender difference in survival or cytokine levels.

CONCLUSIONS

Contrary to our expectations, we found that aging was not associated with a decline in the circulating levels of proinflammatory cytokines.

Coagulation inhibitor replacement in sepsis is a potentially useful clinical approach

In sepsis, levels of the endogenous coagulation inhibitors antithrombin III and protein C are lowered as a result of complex formation with multiple activated clotting factors. In addition, their activity can further be curtailed by proteolytic inactivation. Loss of antithrombin III and protein C activity blocks the endogenous control mechanism for thrombin generation resulting in a state of systemic activation of coagulation and inflammatory processes. Levels of tissue factor pathway inhibitor, a third endogenous coagulation inhibitor, are increased in sepsis rather than decreased, probably reflecting a depletion of the endothelial cell bound tissue factor pathway inhibitor pool with loss of its endothelial protective function. Administration of any of these three inhibitors in various animal species and sepsis models reduces morbidity and mortality. In addition to their anticoagulant effects, these inhibitors also have various anti-inflammatory activities that may contribute to their protective effects. Phase II studies in patients with severe sepsis using coagulation inhibitors have indicated that this therapeutic approach may be useful. Large-scale phase III trials will ultimately decide whether adjunctive coagulation inhibitor replacement will have a place in the treatment of patients with severe sepsis.

Severe sepsis and septic shock. Definitions, epidemiology, and clinical manifestations

Severe sepsis and septic shock are frequently encountered conditions in today's hospital environment. The incidence appears to be increasing despite our growing armamentarium of antibiotics and our enhanced knowledge of the pathophysiologic processes at play. The clinical presentation may take a variety of forms, especially in patients at the extremes of age and in the immunocompromised population. A high index of suspicion and prompt institution of appropriate antimicrobial treatment is mandatory for a successful outcome. It is hoped that adoption of uniform definitions will aid in research and in effective communication concerning sepsis and its adverse sequelae.

The important role of the gut in initiating the hyperdynamic response during early sepsis

BACKGROUND

Although the initial response to sepsis includes a hyperdynamic phase and although the increased hepatic perfusion in early sepsis is due solely to the increased portal blood flow, it remains unknown whether the gut plays an important role in producing such a response.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats underwent a complete enterectomy (ER) before being subjected to sepsis by cecal ligation and puncture (CLP; the cecum was excised from the removed gut and stitched to the posterior peritoneum in ER groups) or sham operation. At 2 h after CLP (i.e., the early, hyperdynamic phase of sepsis), cardiac output and heart performance (+/-dP/dt(max)), as well as hepatic and renal blood flow, were measured. Systemic and regional oxygen delivery (DO(2)) and oxygen consumption (VO(2)) were also determined.

RESULTS

Cardiac output, heart performance, organ blood flow, as well as DO(2) and VO(2), increased significantly 2 h after CLP. ER prior to the onset of sepsis, however, prevented the elevation of those parameters. ER in sham animals did not alter the measured parameters with the exception that portal blood flow decreased by 85% and hepatic arterial blood flow increased by 368%, resulting in no significant reduction in hepatic DO(2) and VO(2). There were no changes in circulating blood volume among groups, indicating that the effect of ER on hemodynamics after CLP was not due to alterations in blood volume.

CONCLUSION

Since ER immediately before the onset of sepsis prevents the increase in cardiac output and regional hemodynamics, the gut appears to play an important role in producing the hyperdynamic response during the early stage of polymicrobial sepsis.

Differential alterations in systemic and regional oxygen delivery and consumption during the early and late stages of sepsis

BACKGROUND

Studies have indicated that regional changes in oxygen utilization during sepsis cannot be predicted from the changes in the whole body oxygen delivery (DO2) and consumption (VO2). The aim of this study, therefore, was to determine whether differential alterations in systemic and regional DO2 and VO2 occur during the early and late stages of sepsis.

METHODS

Adult male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 hours (i.e., the early, hyperdynamic phase of sepsis) or 20 hours (i.e., the late, hypodynamic phase) after CLP, cardiac output, and organ blood flow were measured by radioactive microspheres. Systemic and regional DO2 and VO2 were determined and plasma levels of lactate were measured.

RESULTS

Cardiac output and blood flow to the liver, small intestine, and kidneys increased at 5 hours and decreased at 20 hours after CLP. Although both systemic DO2 and VO2 increased at 5 hours after CLP, systemic DO2 but not VO2 decreased at 20 hours. At 5 hours after CLP, intestinal and renal DO2 increased. However, DO2 in all the tested organs decreased at 20 hours after CLP. VO2 increased in the liver, small intestine, and kidneys at 5 hours after CLP but decreased only in the liver and small intestine at 20 hours after the onset of sepsis. Moreover, plasma lactate levels increased at the late stage of sepsis.

CONCLUSION

Because hepatic and intestinal VO2 but not systemic and renal VO2 decreased at 20 hours after CLP, the liver and small intestine seem to be more vulnerable to the hypoxic insult during the hypodynamic stage of polymicrobial sepsis.

Adjunctive Therapies for Sepsis and Septic Shock

The inflammatory cascade that ensues after an infectious insult is protean in its manifestations, resulting in mild self-limited illness in some patients, while progressing to fulminant sepsis and multisystem organ failure in others. Research into the pathophysiology of this cascade has been intense, but advances in the treatment of sepsis have been few and far between. Although mortality rates have been impacted slightly in patients with sepsis--with improved survival in certain patient subgroups--overall survival still reaches only 55% to 60%. In this paper we will review some of the most recent advances in the therapy of the sepsis syndrome, specifically the roles of cytokine modifiers, supranormal delivery of oxygen, granulocyte colony-stimulating factor administration in leukopenic patients, and parenteral nutrition. Hopefully, these modalities represent additional steps in the path towards a meaningful improvement in survival from this catastrophic condition.

New criteria for selecting the proper antimicrobial chemotherapy for severe sepsis and septic shock

The mortality rate resulting from severe bacterial sepsis, particularly that associated with shock, still approaches 50% in spite of appropriate antimicrobial therapy and optimum supportive care. Bacterial endotoxins that are part of the cell wall are one of the cofactors in the pathogenesis of sepsis and septic shock and are often induced by antimicrobial chemotherapy even if it is administered rationally. Not all antimicrobial agents are equally capable of inducing septic shock; this is dependant on their mechanism of action rather than on the causative pathogen species. The quantity of endotoxin released depends on the drug dose and whether filaments or spheroplast formation predominates. Some antibiotics such as carbapenems, ceftriaxone, cefepime, glycopeptides, aminoglycosides and quinolones do not have the propensity to provoke septic shock because their rapid bactericidal activity induces mainly spheroplast or fragile spheroplast-like bacterial forms.

Reduction in vascular responsiveness to adrenomedullin during sepsis

BACKGROUND

Although sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase, the mechanism responsible for the transition from the hyperdynamic to the hypodynamic state remains unknown. Since recent studies have shown that adrenomedullin (ADM), a novel potent vasodilatory peptide, is upregulated during sepsis, the aim of this study was to determine whether the reduced vascular responsiveness to ADM is associated with the transition from the hyperdynamic phase to the hypodynamic phase of sepsis.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 and 10 h (i.e., the hyperdynamic phase of sepsis) or 20 h (the hypodynamic phase) after CLP, the thoracic aorta or small intestine was harvested and preconstricted with norepinephrine. Adrenomedullin (10(-7) M) was applied and the percentage of ADM-induced vascular relaxation in the aortic ring and isolated small intestine was determined.

RESULTS

The responsiveness to ADM in the thoracic aorta was not altered at 5-10 h, but decreased significantly at 20 h after CLP. Although ADM-induced relaxation in resistance blood vessels of the small intestine did not change at 5 h, it decreased markedly at 10 and 20 h after the onset of sepsis.

CONCLUSIONS

Since the transition from hyperdynamic to hypodynamic sepsis takes place between 10 and 20 h after CLP, it is likely that reduced vascular responsiveness to ADM may be responsible for such an event during the course of polymicrobial sepsis. In view of this, maintenance of vascular ADM responsiveness by pharmacologic agents appears to be a novel approach for preventing or delaying the occurrence of hypodynamic sepsis and septic shock.