Cardiac dysfunction in sepsis: new theories and clinical implications

Integrated analysis of multi-omics data reveals T cell exhaustion in sepsis

Background

Sepsis is a heterogeneous disease, therefore the single-gene-based biomarker is not sufficient to fully understand the disease. Higher-level biomarkers need to be explored to identify important pathways related to sepsis and evaluate their clinical significance.

Methods

Gene Set Enrichment Analysis (GSEA) was used to analyze the sepsis transcriptome to obtain the pathway-level expression. Limma was used to identify differentially expressed pathways. Tumor IMmune Estimation Resource (TIMER) was applied to estimate immune cell abundance. The Spearman correlation coefficient was used to find the relationships between pathways and immune cell abundance. Methylation and single-cell transcriptome data were also employed to identify important pathway genes. Log-rank test was performed to test the prognostic significance of pathways for patient survival probability. DSigDB was used to mine candidate drugs based on pathways. PyMol was used for 3-D structure visualization. LigPlot was used to plot the 2-D pose view for receptor-ligand interaction.

Results

Eighty-four KEGG pathways were differentially expressed in sepsis patients compared to healthy controls. Of those, 10 pathways were associated with 28-day survival. Some pathways were significantly correlated with immune cell abundance and five pathways could be used to distinguish between systemic inflammatory response syndrome (SIRS), bacterial sepsis, and viral sepsis with Area Under the Curve (AUC) above 0.80. Seven related drugs were screened using survival-related pathways.

Conclusion

Sepsis-related pathways can be utilized for disease subtyping, diagnosis, prognosis, and drug screening.

Prognostic tools for elderly patients with sepsis: in search of new predictive models

As a tool to support clinical decision-making, Mortality Prediction Models (MPM) can help clinicians stratify and predict patient risk. There are numerous scoring systems for patients with sepsis that predict sepsis-related mortality and the severity of sepsis. But there are currently no MPMs for adults with sepsis who meet the criteria of "good." Clinicians are unlikely to use complex MPMs that require extensive or expensive data collection to impede workflow. Machine learning applied to minimal medical records of patients diagnosed with sepsis can be a useful tool. Progress is needed in the development and validation of clinical decision support tools that can assist in patient risk stratification, prognosis, discussion of patient outcomes, and shared decision making.

Exercise alters cardiac function independent of acute systemic inflammation in healthy men

Acute elevations in inflammatory cytokines have been demonstrated to increase aortic and left ventricular stiffness and reduce endothelial function in healthy subjects. As vascular and cardiac functions are often transiently reduced following prolonged exercise, it is possible that cytokines released during exercise may contribute to these alterations. The a priori aims of this study were to determine whether vaccine-induced increases in inflammatory cytokines would reduce vascular and left ventricular function, whether vascular alterations would drive cardiac impairments, and whether this would be potentiated by moderate exercise. In a randomized crossover fashion, 16 male participants were tested under control (CON) and inflammatory (INF) conditions, wherein INF testing occurred 8 h following administration of an influenza vaccine. On both days, participants underwent measures of echocardiography performed during light cycling (stress-echocardiography), carotid-femoral pulse wave velocity (cf-PWV), and superficial femoral flow-mediated dilation (FMD) before and after cycling for 90 min at ∼85% of their first ventilatory threshold. IL-6 increased significantly (Δ1.9 ± 1.3 pg/mL, P < 0.001), whereas TNFα was nonsignificantly augmented (Δ0.05 ± 0.11 pg/mL, P = 0.09), 8 h following vaccination. Vascular function was unaltered following cycling or inflammation (all P > 0.05). The use of echocardiography during light cycling revealed cardiac alterations traditionally expected to occur only with greater exercise loads, with reduced systolic (e.g., longitudinal strain CON: Δ3.3 ± 4.4%, INF: Δ1.7 ± 2.7%, P = 0.002) and diastolic function (e.g., E/A ratio CON: Δ-0.32 ± 0.34 a.u., INF:Δ-0.25 ± 0.27 a.u., P = 0.002) following cycling, independent of inflammation. The vaccine reduced stroke volume (SV) (main effect of condition P = 0.009) before-and-after cycling. These findings indicate that reduced cardiac function following exercise occurs largely independent of additional inflammatory load.NEW & NOTEWORHTHY This experimental investigation sought to determine the role of inflammation on the occurrence of cardiovascular alterations following exercise. Despite successfully stimulating systemic inflammation via vaccination, vascular and cardiac functions were largely unaltered. Prolonged exercise itself reduced cardiac function assessed via echocardiography performed during light exercise stress. This demonstrates a potential advantage to using stress-echocardiography for measuring exercise-induced cardiac fatigue, as typical resting measures following similar exercise exposures commonly suggest no effect.

Stress cardiomyopathy of the critically ill: Spectrum of secondary, global, probable and subclinical forms

Stress cardiomyopathy (SC) typically presents as potential acute coronary syndrome (ACS) in previously healthy people. While there may be physical or mental stressors, the initial symptom is usually chest pain. This form conforms to the published Mayo diagnostic criteria, is well reported and as the presentation is initially cardiac, is considered primary SC. Increasingly we see SC develop several days into the hospitalization secondary to medical or surgical critical illness. This condition is more complex, presents atypically, is not easy to recognize and carries a much worse prognosis. Label of Secondary SC is appropriate as it manifests in sicker hospitalized patients with numerous comorbidities. We review the limited but provocative literature pertinent to SC in the critically ill and describe important clues to identify global, subclinical and probable forms of SC. We illustrate the several unique clinical features, demographic differences and propose a diagnostic algorithm to optimize cardiac care in the critically ill.

Role of TFEB Mediated Autophagy, Oxidative Stress, Inflammation, and Cell Death in Endotoxin Induced Myocardial Toxicity of Young and Aged Mice

Elderly patients are susceptible to sepsis. LPS induced myocardial injury is a widely used animal model to assess sepsis induced cardiac dysfunction. The age dependent mechanisms behind sepsis susceptibility were not studied. We analyzed age associated changes to cardiac function, cell death, inflammation, oxidative stress, and autophagy in LPS induced myocardial injury. Both young and aged C57BL/6 mice were used for LPS administration. The results demonstrated that LPS induced more cardiac injury (creatine kinase, lactate dehydrogenase, troponin I, and cardiac myosin-light chains 1), cardiac dysfunction (left ventricular inner dimension, LVID, and ejection fraction (EF)), cell death, inflammation, and oxidative stress in aged mice compared to young mice. However, a significant age dependent decline in autophagy was observed. Translocation of Transcription Factor EB (TFEB) to nucleus and formation of LC3-II were significantly reduced in LPS administered aged mice compared to young ones. In addition to that, downstream effector of TFEB, LAMP-1, was induced in response to LPS challenge in young mice. The present study newly demonstrates that TFEB mediated autophagy is crucial for protection against LPS induced myocardial injury particularly in aging senescent heart. Targeting this autophagy-oxidative stress-inflammation-cell death axis may provide a novel therapeutic strategy for cardioprotection in the elderly.

Hyperdynamic left ventricular ejection fraction in the intensive care unit

Introduction

Limited information exists on the etiology, prevalence, and significance of hyperdynamic left ventricular ejection fraction (HDLVEF) in the intensive care unit (ICU). Our aim in the present study was to compare characteristics and outcomes of patients with HDLVEF with those of patients with normal left ventricular ejection fraction in the ICU using a large, public, deidentified critical care database.

Methods

We conducted a longitudinal, single-center, retrospective cohort study of adult patients who underwent echocardiography during a medical or surgical ICU admission at the Beth Israel Deaconess Medical Center using the Multiparameter Intelligent Monitoring in Intensive Care II database. The final cohort had 2867 patients, of whom 324 had HDLVEF, defined as an ejection fraction >70 %. Patients with an ejection fraction <55 % were excluded.

Results

Compared with critically ill patients with normal left ventricular ejection fraction, the finding of HDLVEF in critically ill patients was associated with female sex, increased age, and the diagnoses of hypertension and cancer. Patients with HDLVEF had increased 28-day mortality compared with those with normal ejection fraction in multivariate logistic regression analysis adjusted for age, sex, Sequential Organ Failure Assessment score, Elixhauser score for comorbidities, vasopressor use, and mechanical ventilation use (odds ratio 1.38, 95 % confidence interval 1.039–1.842, p =0.02).

Conclusions

The presence of HDLVEF portended increased 28-day mortality, and may be helpful as a gravity marker for prognosis in patients admitted to the ICU. Further research is warranted to gain a better understanding of how these patients respond to common interventions in the ICU and to determine if pharmacologic modulation of HDLVEF improves outcomes.

Preventing intensive care admissions for sepsis in tropical Africa (PICASTA): an extension of the international pediatric global sepsis initiative: an African perspective

BACKGROUND

The Global Sepsis Initiative recommends prevention of sepsis through immunizations, vitamins, breast feeding, and other important interventions. In our study, we consider a second set of proposals for preventing intensive care admissions for sepsis in tropical Africa, which have been specifically designed to further prevent ICU admissions for sepsis in the group A nation hospital setting.

OBJECTIVES

To reduce admissions with severe sepsis in an ICU of a group A nation through the identification of challenges leading to preventable, foreseeable, or nosocomial sepsis specific to our setting.

METHODS

Malawi is one of the poorest countries in the world. Lacking the ability to comply with standard sepsis treatment, we conducted over 4 years several studies, audits, and surveys to identify challenges leading to preventable pediatric sepsis in our setting. We developed a method to identify malnourished children through a "gatekeeper" in the theaters without any equipment, tried to implement the World Health Organization's Safe Surgery Campaign checklist, evaluated our educational courses for the districts to improve the quality of referrals, looked into the extreme fasting times discovered in our hospital, trained different cadres in the districts to deal with peripartal and posttraumatic sepsis, and identified the needs in human resources to deal with pediatric sepsis in our setting.

RESULTS

Six foci were identified as promising to work on in future. Focus 1: Preventing elective operations and procedures in malnourished children in the hospital and in the district: 134 of 145 nurses (92.4%) and even 25 of 31 African laymen (80.6%) were able to identify malnourished children with their own fingers. Focus 2: Preventing sepsis-related problems in emergencies through the implementation of the Safe Surgery Campaign checklist: only 100 of 689 forms (14.5%) were filled in due to challenges in ownership, communication responsibility, and time constraints. Focus 3: Preventing sepsis through the reduction of unwise referrals: our courses toward this topic reached 82-100% satisfaction of the 391 participants for relevance, presentation applicability, content, and teaching technique. Focus 4: Preventing sepsis-related problems through reduction of excessive fasting times in our hospital: necessity for action was documented by a mean fasting time of 10.2 hours (SD, 4.4 hr). Focus 5: Concentration on two extremely sepsis-relevant health challenges for children in Malawian districts, trauma and peripartal complications: numbers after our courses in the trained two districts showed a reduction in the maternal mortality rate (from 150.3 to 55 and 234.2 to 75.2), an inconclusive result for posttraumatic deaths and the identification of 44 future instructors. Focus 6: Implementation of a Master in Medicine (anesthesia and intensive care) and improvement of training in anesthesia for all cadres resulted in the first five anesthetic registrars in training and enhanced numbers in all other cadres in anesthesia dealing in own responsibility with pediatric sepsis.

CONCLUSIONS

Every hospital can try to improve sepsis prevention on a local level by the Preventing Intensive Care Admissions for Sepsis in Tropical Africa approach. This will help support the promotion of the regionally adjusted Global Sepsis Initiative guidelines and the future global implementation of feasible bundles as a gold standard for resource-poor countries.

Prognostic value of troponins in sepsis: a meta-analysis

RATIONALE

The role of biomarkers such as troponin in risk stratification of sepsis is still debated. The aim of this meta-analysis is to assess the relation between troponin elevation in sepsis and mortality.

METHODS

All observational studies from Embase, Medline and those manually searched up to September 2010 were included. Studies identified were those which reported on patients with a diagnosis of sepsis and if a 2 × 2 table could be constructed based on troponins and death. We pooled the relative risk (RR) and odds-ratio (OR) using the inverse variance method in studies that conducted univariate and multivariable (adjusted) analysis.

MAIN RESULTS

Thirteen studies encompassing 1,227 patients were included. The prevalence of elevated troponin was 61 % ([95 %] CI 58-64 %). Elevated troponin was significantly associated with all-cause mortality (RR 1.91; CI 1.63-2.24), with homogeneity across studies. In adjusted analysis (four studies comprising 791 patients) according to prognostic scores, elevated troponin was associated with an increased risk of death (OR 1.92; CI 1.35-2.74). The area under the ROC curve was 0.68 (CI 0.63-0.71). Pooled sensitivity and specificity were 77 % (CI 61-88) and 47 % (CI 30-64) with heterogeneity across studies. It corresponded to positive and negative likelihood ratios of 1.50 (95 % CI: 1.20-1.90) and 0.49 (CI 0.38-0.64), respectively.

CONCLUSIONS

Elevated troponin identifies a subset of patients with sepsis at higher risk of death. Further studies are needed to define the precise role of troponins and their optimal cut-offs.

Sepsis-induced cardiomyopathy: a review of pathophysiologic mechanisms

Cardiac dysfunction is a well-recognized complication of severe sepsis and septic shock. Cardiac dysfunction in sepsis is characterized by ventricular dilatation, reduction in ejection fraction and reduced contractility. Initially, cardiac dysfunction was considered to occur only during the "hypodynamic" phase of shock. But we now know that it occurs very early in sepsis even during the "hyperdynamic" phase of septic shock. Circulating blood-borne factors were suspected to be involved in the evolution of sepsis induced cardiomyopathy, but it is not until recently that the cellular and molecular events are being targeted by researchers in a quest to understand this enigmatic process. Septic cardiomyopathy has been the subject of investigation for nearly half a century now and yet controversies exist in understanding it's pathophysiology. Here, we discuss our understanding of the pathogenesis of septic cardiomyopathy and the complex roles played by nitric oxide, mitochondrial dysfunction, complements and cytokines.

Phospholemman: a novel cardiac stress protein

Phospholemman (PLM), a member of the FXYD family of regulators of ion transport, is a major sarcolemmal substrate for protein kinases A and C in cardiac and skeletal muscle. In the heart, PLM co-localizes and co-immunoprecipitates with Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and L-type Ca(2+) channel. Functionally, when phosphorylated at serine(68), PLM stimulates Na(+)-K(+)-ATPase but inhibits Na(+)/Ca(2+) exchanger in cardiac myocytes. In heterologous expression systems, PLM modulates the gating of cardiac L-type Ca(2+) channel. Therefore, PLM occupies a key modulatory role in intracellular Na(+) and Ca(2+) homeostasis and is intimately involved in regulation of excitation-contraction (EC) coupling. Genetic ablation of PLM results in a slight increase in baseline cardiac contractility and prolongation of action potential duration. When hearts are subjected to catecholamine stress, PLM minimizes the risks of arrhythmogenesis by reducing Na(+) overload and simultaneously preserves inotropy by inhibiting Na(+)/Ca(2+) exchanger. In heart failure, both expression and phosphorylation state of PLM are altered and may partly account for abnormalities in EC coupling. The unique role of PLM in regulation of Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and potentially L-type Ca(2+) channel in the heart, together with the changes in its expression and phosphorylation in heart failure, make PLM a rational and novel target for development of drugs in our armamentarium against heart failure. Clin Trans Sci 2010; Volume 3: 189-196.

Protective role of peroxisome proliferator-activated receptor-β/δ in septic shock

RATIONALE

Peroxisome proliferator-activated receptor (PPAR)-β/δ is a transcription factor that belongs to the PPAR nuclear hormone receptor family, but the role of PPAR-β/δ in sepsis is unknown.

OBJECTIVES

We investigated the role of PPAR-β/δ in murine models of LPS-induced organ injury and dysfunction and cecal ligation and puncture (CLP)-induced polymicrobial sepsis.

METHODS

Wild-type (WT) and PPAR-β/δ knockout (KO) mice and C57BL/6 mice were subjected to LPS for 16 hours. C57BL/6 mice received the PPAR-β/δ agonist GW0742 (0.03 mg/kg intravenously, 1 h after LPS) or GW0742 plus the PPAR-β/δ antagonist GSK0660 (0.1 mg/kg intravenously, 30 min before LPS). CD-1 mice subjected to CLP received GW0742 or GW0742 plus GSK0660.

MEASUREMENTS AND MAIN RESULTS

In PPAR-β/δ KO mice, endotoxemia exacerbated organ injury and dysfunction (cardiac, renal, and hepatic) and inflammation (lung) compared with WT mice. In C57BL/6 mice subjected to endotoxemia, GW0742 significantly (1) attenuated organ (cardiac and renal) dysfunction and inflammation (lung); (2) increased the phosphorylation of Akt and glycogen synthase kinase (GSK)-3β; (3) attenuated the increase in extracellular signal-regulated kinase (ERK)1/2 and signal transducer and activator of transcription (STAT)-3 phosphorylation; and (4) attenuated the activation of nuclear factor (NF)-κB and the expression of inducible nitric oxide synthase (iNOS). In CD-1 mice subjected to CLP, GW0742 improved 10-day survival. All the observed beneficial effects of GW0742 were attenuated by the PPAR-β/δ antagonist GSK0660.

CONCLUSIONS

PPAR-β/δ protects against multiple organ injury and dysfunction, and inflammation caused by endotoxic shock and improves survival in polymicrobial sepsis by a mechanism that may involve activation of Akt and inhibition of GSK-3β and NF-κB.

Mood, Th-1/Th-2 cytokine profile, and autonomic activity in older adults with acute/decompensated heart failure: preliminary observations

In order to assess the relationships among mood, peripheral autonomic output and circulating immunoinflammatory mediators in older individuals with decompensated heart failure (CHF), 20 consecutive patients (78+/-7 years, 35% women) admitted to the coronary care unit with a clinical diagnosis of acute/decompensated CHF of coronary origin were examined. Mood was evaluated by the 21-item Hamilton Depression Scale (HAM-D). Four patients met the criteria for major depression. Heart rate variability (HRV) analysis and the levels of tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-2, IL-4, IL-6 and IL-10 were measured within 24-72 h of admission. A significant positive relationship between score in HAM-D and serum IL-6 levels was detected with a similar trend as far as IL-2 levels. Circulating IL-2 levels were strongly associated with the HRV L/H quotient, an index of increased sympathetic and/or decreased parasympathetic thoracic activity. A negative correlation between vagal activity (as assessed by HRV) and IL-4 occurred. Neither TNF-alpha nor IL-10 were detectable in this group of elderly patients. The results add to the concept that mood and autonomic unbalance are associated with increased systemic inflammation in old patients with decompensated CHF, a potential mechanism for mood-related worsened prognosis of heart failure at an advanced age.

Pharmacokinetic issues for antibiotics in the critically ill patient

OBJECTIVE

To discuss the altered pharmacokinetic properties of selected antibiotics in critically ill patients and to develop basic dose adjustment principles for this patient population.

DATA SOURCES

PubMed, EMBASE, and the Cochrane-Controlled Trial Register.

STUDY SELECTION

Relevant papers that reported pharmacokinetics of selected antibiotic classes in critically ill patients and antibiotic pharmacodynamic properties were reviewed. Antibiotics and/or antibiotic classes reviewed included aminoglycosides, beta-lactams (including carbapenems), glycopeptides, fluoroquinolones, tigecycline, linezolid, lincosamides, and colistin.

DATA SYNTHESIS

Antibiotics can be broadly categorized according to their solubility characteristics which can, in turn, help describe possible altered pharmacokinetics that can be caused by the pathophysiological changes common to critical illness. Hydrophilic antibiotics (e.g., aminoglycosides, beta-lactams, glycopeptides, and colistin) are mostly affected with the pathphysiological changes observed in critically ill patients with increased volumes of distribution and altered drug clearance (related to changes in creatinine clearance). Lipophilic antibiotics (e.g., fluoroquinolones, macrolides, tigecycline, and lincosamides) have lesser volume of distribution alterations, but may develop altered drug clearances. Using antibiotic pharmacodynamic bacterial kill characteristics, altered dosing regimens can be devised that also account for such pharmacokinetic changes.

CONCLUSIONS

Knowledge of antibiotic pharmacodynamic properties and the potential altered antibiotic pharmacokinetics in critically ill patients can allow the intensivist to develop individualized dosing regimens. Specifically, for renally cleared drugs, measured creatinine clearance can be used to drive many dose adjustments. Maximizing clinical outcomes and minimizing antibiotic resistance using individualized doses may be best achieved with therapeutic drug monitoring.

Protein phosphatase 2A contributes to the cardiac dysfunction induced by endotoxemia

Aims

Sepsis-associated cardiac dysfunction represents an intrinsic impairment of cardiomyocyte function due in part to a decrease in myofilament Ca²⁺ sensitivity associated with a sustained increase in cardiac troponin I (cTnI) phosphorylation at Ser23/24. Dephosphorylation of cTnI is under regulatory control. Thus, muscarinic and adenosine A₁-receptor agonists antagonize β-adrenergic stimulation via activation of protein phosphatase 2A (PP2A). The aim of this study was to determine whether modulation of PP2A and thus cTnI phosphorylation could improve sepsis-induced contractile dysfunction.

Methods and results

Cardiomyocytes were isolated from control or septic mice 16–18 h after an injection of vehicle or lipopolysaccharide (LPS; 9 mg/kg ip) respectively. Protein expression and phosphatase activity were determined in homogenates of control and septic hearts. Our data showed that LPS significantly increased cTnI phosphorylation at Ser23/24 in cardiomyocytes and reduced contraction amplitude without affecting Ca²⁺-transients. Treatment of cardiomyocytes with the A₁ agonist cyclopentyladenosine (CPA) or the protein kinase A inhibitor H89 significantly attenuated the LPS-induced contractile dysfunction without effect on Ca²⁺-transients. Co-treatment with CPA and H89 completely reversed the contractile dysfunction. Increased cTnI phosphorylation in septic hearts was associated with a significant reduction in the protein expression of both the catalytic and regulatory subunits (B56α) of PP2A and a decrease in PP2A activity. CPA treatment of septic hearts increased PP2A activity. An increase in the protein expression of demethylated PP2A and a decrease in the PP2A-methyltransferase (PPMT; the methyltransferase that catalyses this reaction) were also observed.

Conclusion

These data support the hypothesis that sustained cTnI phosphorylation underlies the contractile dysfunction seen in sepsis.

Phospholemman: its role in normal cardiac physiology and potential as a druggable target in disease

Phospholemman (PLM) is a member of the FXYD ('fix-it') family of proteins many of which have now been identified as tissue-specific regulators of the Na/K ATPase. PLM (FXYD1) is the primary sarcolemmal substrate for PKC and PKA in the heart. We have recently identified PLM as a novel accessory protein that forms part of the cardiac Na/K ATPase pump complex. PLM regulates Na/K pump activity in a way analogous to the regulation of SERCA by phospholamban-that is un-phosphorylated PLM exerts a tonic inhibition on the Na/K pump, while phosphorylated PLM relieves this inhibition and stimulates pump activity. This process is likely to be fundamentally important in the normal physiological regulation of the cell particularly at high heart rates and, as briefly reviewed in this article, is also likely to offer novel therapeutic targets for the treatment of diseases such as cardiac hypertrophy and heart failure.

Neurotensin increases mortality and mast cells reduce neurotensin levels in a mouse model of sepsis

Sepsis is a complex, incompletely understood and often fatal disorder, typically accompanied by hypotension, that is considered to represent a dysregulated host response to infection. Neurotensin (NT) is a 13-amino-acid peptide that, among its multiple effects, induces hypotension. We find that intraperitoneal and plasma concentrations of NT are increased in mice after severe cecal ligation and puncture (CLP), a model of sepsis, and that mice treated with a pharmacological antagonist of NT, or NT-deficient mice, show reduced mortality during severe CLP. In mice, mast cells can degrade NT and reduce NT-induced hypotension and CLP-associated mortality, and optimal expression of these effects requires mast cell expression of neurotensin receptor 1 and neurolysin. These findings show that NT contributes to sepsis-related mortality in mice during severe CLP and that mast cells can lower NT concentrations, and suggest that mast cell-dependent reduction in NT levels contributes to the ability of mast cells to enhance survival after CLP.

Cardiac morphological and functional changes during early septic shock: a transesophageal echocardiographic study

OBJECTIVE

The objective was to prospectively evaluate cardiac morphological and functional changes using transesophageal echocardiography (TEE) during early septic shock.

DESIGN

Prospective, observational study.

SETTING

Medical-surgical intensive care unit of a teaching hospital.

PATIENTS AND PARTICIPANTS

Ventilated patients with septic shock, sinus rhythm and no cardiac disease underwent TEE within 12h of admission (Day0), after stabilization of hemodynamics by fluid loading (median volume: 4.9l [lower and upper quartiles: 3.7-9.6l]) and vasopressor therapy, and after vasopressors were stopped (Dayn).

MEASUREMENTS AND RESULTS

Thirty-five patients were studied (median age: 60 years [range 44-68]; SAPS II: 53 [46-62]; SOFA score: 9 [8-11]) and 9 of them (26%) died while on vasopressors. None of the patients exhibited TEE findings of cardiac preload dependence. Between Day0 and Dayn (7 days [range 6-9]), mean left ventricular (LV) ejection fraction (EF) increased (47 +/- 20 vs. 57 +/- 14%: p < 0.05), whereas mean LV end-diastolic volume decreased (97 +/- 25 vs. 75 +/- 20ml: p < 0.0001). Out of 16 patients (46%) with LV systolic dysfunction on Day0, 12 had normal LVEF on Dayn and 4 patients fully recovered by Day28. Only 4 women had LV dilatation (range, LV end-diastolic volume: 110-148ml) on Day0, but none on Dayn. Doppler tissue imaging identified an LV diastolic dysfunction in 7 patients (20%) on Day0 (3 with normal LVEF), which resolved on Dayn.

CONCLUSIONS

This study confirms that LV systolic and diastolic dysfunctions are frequent, but LV dilatation is uncommon in fluid-loaded septic patients on vasopressors. All abnormalities regressed in survivors, regardless of their severity.

DESCRIPTORS

Shock: clinical studies (38), Cardiovascular monitoring (34).

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.

Recruitment of functionally active heart beta2-adrenoceptors in the initial phase of endotoxic shock in pithed rats

A supersensitivity of the beta-adrenoceptor-mediated chronotropic response has been demonstrated in atria isolated from rats subjected to septic shock. Our study was undertaken to investigate whether bacterial endotoxin/LPS affects the increase in heart rate induced by beta-adrenoceptor agonists in the rat also in vivo. In pithed and vagotomized rats, the nonselective beta-adrenoceptor agonist isoprenaline (0.05-0.15 nmol/kg) and agonists at the high- and low-affinity state of beta1-adrenoceptors, that is, prenalterol (0.3-3 nmol/kg) and (+/-)-4-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,3-dihydro-2H-benzimidazole-2-one (CGP 12177; 3-6 nmol/kg), respectively, and at beta2-adrenoceptors, that is, fenoterol (1-5 nmol/kg), increased heart rate by 50 to 60 beats/min. Administration of LPS (0.4, 1, and 1.5 mg/kg), under continuous infusion of vasopressin, dose-dependently amplified the chronotropic response to isoprenaline, prenalterol, and fenoterol (by 80%, 50%, and 100%, respectively) but not to CGP 12177. The beta2-adrenoceptor antagonist erythro-(+/-)-1-(7-methylindan-4-yloxy)-3-isopropylaminobutan-2-ol (ICI 118551 0.1 mumol/kg) did not affect the chronotropic responses of isoprenaline, fenoterol, and prenalterol under non-endotoxic conditions, but abolished the potentiation of tachycardia produced by LPS (1.5 mg/kg). The beta1-adrenoceptor antagonist (+/-)-2-hydroxy-5-[2-[[2-hydroxy-3-[4-[1-methyl-4-(trifluoromethyl)-1H-imidazol-2-yl]-phenoxy]propyl]-amino]ethoxy]-benzamide CGP 20712A; 0.1 mumol/kg almost completely reduced the chronotropic effects of isoprenaline, fenoterol, and prenalterol both in control rats and in animals exposed to LPS (1.5 mg/kg). We conclude that LPS sensitizes cardiac beta-adrenoceptors by recruiting functionally active beta2-adrenoceptors, but the amplification of tachycardia occurs only when both beta1- and beta2-adrenoceptors are concomitantly activated. The pithed rat may serve as a model to examine the beta-adrenoceptor supersensitivity in vivo.

Propofol infusion syndrome

In this article, we present the case of a previously well 31-year-old man who sustained a mild closed-head injury following a motor vehicle incident and was admitted to the intensive care unit of a major teaching hospital. The man was sedated using propofol combined with midazolam and morphine as the main sedating agent. The propofol was started and continued at high dose for 8 days, over which time the patient deteriorated with metabolic acidosis, rhabdomyolysis, renal impairment, and cardiovascular collapse and then died. A forensic autopsy was performed. The only positive autopsy finding was a cardiac perivascular and interstitial infiltrate of mononuclear cells. The clinical and pathological features in the case presented were consistent with propofol infusion syndrome. No other cause for the above features was found and the cause of death was given as death related to propofol infusion syndrome.Propofol infusion syndrome is characterized by metabolic acidosis, rhadbomyolysis, and myocardial failure, sometimes with renal failure and hyperkalemia occurring in the setting of high-dose propofol treatment. The syndrome has become increasingly recognized in recent years. The syndrome is of importance to forensic pathologists who may see cases referred to their practice because of the unexplained deterioration of a patient in the intensive care unit and the association with head-injured patients and the pediatric population. Death associated with propofol infusion has not been described in the forensic literature.

[Role of adrenomedullin in the pathogenesis and treatment of cardiovascular dysfunctions and sepsis]

Adrenomedullin (AM) is an endogenous vasodilatory peptide hormone, which plays a key role in the regulation and preservation of cardiovascular and pulmonary functions. Clinical and experimental studies have demonstrated that AM represents an alternative therapeutic option in the treatment of pulmonary hypertension. In addition, AM proved to be useful in the treatment of cardiovascular dysfunctions, such as arterial hypertension and congestive heart failure following myocardial infarction. Recent research has also shown that AM plays a pivotal role in the development of sepsis-associated hemodynamic and microcirculatory disorders. Experimental studies also suggest that infusion of exogenous AM might be a rational approach to prevent and treat hypodynamic septic shock. The objectives of this review article are to characterize the regulative properties of AM and to discuss clinical and experimental studies which allow to judge the role of AM in the setting of cardiovascular dysfunction and sepsis.

NADPH oxidases in cardiovascular health and disease

Increased oxidative stress plays an important role in the pathophysiology of cardiovascular diseases such as hypertension, atherosclerosis, diabetes, cardiac hypertrophy, heart failure, and ischemia-reperfusion. Although several sources of reactive oxygen species (ROS) may be involved, a family of NADPH oxidases appears to be especially important for redox signaling and may be amenable to specific therapeutic targeting. These include the prototypic Nox2 isoform-based NADPH oxidase, which was first characterized in neutrophils, as well as other NADPH oxidases such as Nox1 and Nox4. These Nox isoforms are expressed in a cell- and tissue-specific fashion, are subject to independent activation and regulation, and may subserve distinct functions. This article reviews the potential roles of NADPH oxidases in both cardiovascular physiological processes (such as the regulation of vascular tone and oxygen sensing) and pathophysiological processes such as endothelial dysfunction, inflammation, hypertrophy, apoptosis, migration, angiogenesis, and vascular and cardiac remodeling. The complexity of regulation of NADPH oxidases in these conditions may provide the possibility of targeted therapeutic manipulation in a cell-, tissue- and/or pathway-specific manner at appropriate points in the disease process.

Glucose-insulin and potassium infusions in septic shock

Glucose-insulin and potassium (GIK) infusions are beneficial in treating ischemic myocardial depression. Myocardial depression is also an important feature in septic shock. We describe two cases of pressor-resistant hypodynamic septic shock that responded to high-dose GIK infusions. In each case, hemodynamic profiles improved sufficiently to allow withdrawal of vasopressor agents. Further assessment of GIK in patients with hypodynamic septic shock is necessary to confirm efficacy and prognostic significance.

Takotsubo Cardiomyopathy (Acute Left Ventricular Apical Ballooning Syndrome) Occurring in the Intensive Care Unit

OBJECTIVE

Diagnosis of Takotsubo cardiomyopathy (also known as stress cardiomyopathy or acute left ventricular apical ballooning syndrome) can be challenging in patients who are being treated for other diseases in the intensive care unit, because symptoms could erroneously be attributed to the underlying disease or patients may not experience symptoms due to analgesia and sedation. The aim of our study was to assess clinical features of Takotsubo cardiomyopathy occurring in the intensive care unit.

DESIGN

Prospective observational study.

SETTING

University hospital.

PATIENTS

Six consecutive patients diagnosed with Takotsubo cardiomyopathy who were being treated for other diseases in the intensive care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Sudden hemodynamic deterioration (i.e., sudden hypotension, tachycardia or drop in monitored stroke volume) requiring vasopressor support was the presenting symptom in five of the six patients. Only one patient was able to report angina-like chest pain, all others were unable to experience symptoms due to analgesia and sedation. The electrocardiogram was abnormal in all patients upon diagnosis, demonstrating either ST-segment elevation (n=2) and/or T-wave inversion (n=5). Mild elevation of cardiac enzymes disproportionate to the extent of wall motion abnormalities on left ventriculography was present in all patients. All patients survived their acute event.

CONCLUSIONS

Sudden hemodynamic deterioration requiring vasopressor support and/or ECG abnormalities consisting of ST-segment elevation, ST-segment depression or T-wave inversion may be the presenting symptom of Takotsubo cardiomyopathy in the intensive care unit and should be included in the diagnostic algorithm.

Antibacterial Dosing in Intensive Care

Treatment of sepsis remains a significant challenge with persisting high mortality and morbidity. Early and appropriate antibacterial therapy remains an important intervention for such patients. To optimise antibacterial therapy, the clinician must possess knowledge of the pharmacokinetic and pharmacodynamic properties of commonly used antibacterials and how these parameters may be affected by the constellation of pathophysiological changes occurring during sepsis. Sepsis, and the treatment thereof, increases renal preload and, via capillary permeability, leads to 'third-spacing', both resulting in higher antibacterial clearances. Alternatively, sepsis can induce multiple organ dysfunction, including renal and/or hepatic dysfunction, causing a decrease in antibacterial clearance. Aminoglycosides are concentration-dependent antibacterials and they display an increased volume of distribution (V(d)) in sepsis, resulting in decreased peak serum concentrations. Reduced clearance from renal dysfunction would increase the likelihood of toxicity. Individualised dosing using extended interval dosing, which maximises the peak serum drug concentration (C(max))/minimum inhibitory concentration ratio is recommended. Beta-lactams and carbapenems are time-dependent antibacterials. An increase in V(d) and renal clearance will require increased dosing or administration by continuous infusion. If renal impairment occurs a corresponding dose reduction may be required. Vancomycin displays predominantly time-dependent pharmacodynamic properties and probably requires higher than conventionally recommended doses because of an increased V(d) and clearance during sepsis without organ dysfunction. However, optimal dosing regimens remain unresolved. The poor penetration of vancomycin into solid organs may require alternative therapies when sepsis involves solid organs (e.g. lung). Ciprofloxacin displays largely concentration-dependent kill characteristics, but also exerts some time-dependent effects. The V(d) of ciprofloxacin is not altered with fluid shifts or over time, and thus no alterations of standard doses are required unless renal dysfunction occurs. In order to optimise antibacterial regimens in patients with sepsis, the pathophysiological effects of systemic inflammatory response syndrome need consideration, in conjunction with knowledge of the different kill characteristics of the various antibacterial classes. In conclusion, certain antibacterials can have a very high V(d), therefore leading to a low C(max) and if a high peak is needed, then this would lead to underdosing. The V(d) of certain antibacterials, namely aminoglycosides and vancomycin, changes over time, which means dosing may need to be altered over time. Some patients with serum creatinine values within the normal range can have very high drug clearances, thereby producing low serum drug levels and again leading to underdosing.

Roles of MMP-2/-9 in cardiac dysfunction during early multiple organ failure in an ovine animal model

Biventricular dilation and severe cardiac dysfunction are observed during septic shock. However, when endotoxemia and vasoconstrictor-masked hypovolemia work in concert in the pathogenesis of shock, the clinical scenario is more adverse compared to one of the insults acting alone. Matrix metalloproteinases (MMPs) are involved in chronic and acute heart failure by degrading the mechanical scaffold of the heart and several intracellular proteins. Therefore, the roles of MMP-2, MMP-9, MT1-MMP, focal adhesion kinase (FAK), and Paxillin in hearts of early multiple organ failure induced by norfenefrine-masked hypovolemia and endotoxemia were investigated in an ovine model. Experimental groups included (1) norfenefrine-masked hypovolemia plus endotoxemia (NMH+ENDO) (n=6), (2) norfenefrine-masked hypovolemia without endotoxemia (NMH) (n=6), (3) recurrent endotoxemia during normovolemia (ENDO) (n=6), and (4) healthy untreated controls (CON) (n=3). Apoptosis was determined by TUNEL-staining. Gel zymography revealed significantly increased MMP-2 activity in NMH+ENDO compared to ENDO and controls. MMP-9 activity was significantly elevated in all experimental groups. MMP-2 was significantly increased at the protein level, while MMP-9 was unaltered. MT1-MMP was not significantly changed in any group. Increased MMP activities were associated with cardiac deterioration. MMP-2/-9 activity and phosphorylated Paxillin (p-Paxillin) expression correlated positively with cardiomyocyte apoptosis. This study underscores the pivotal roles of MMP in acute cardiac dysfunction during early multiple organ failure in combined vasoconstrictor-masked hypovolemic and endotoxemia shock.

Left ventricular apical ballooning due to severe physical stress in patients admitted to the medical ICU

PURPOSES

We sought to assess the frequency and clinical implications of left ventricular apical ballooning (LVAB) in patients who had been admitted to the medical ICU for noncardiac physical illnesses.

METHODS

Ninety-two consecutive patients who were admitted to the medical ICU from March to May 2003 were prospectively enrolled. Patients underwent echocardiography on the day of ICU admission, and on the third and seventh days in the hospital. LVAB was defined as symmetric severe hypokinesia or akinesia of the left ventricular wall, except for the basal part of the left ventricle, with a < 50% ejection fraction.

RESULTS

Of the 92 patients, 65 (71%) were men, and they had a mean (+/- SD) age of 63 +/- 11 years. LVAB was observed in 26 patients (28%), with a mean lowest ejection fraction of 33 +/- 8% (range, 19 to 46%). Compared with the 66 patients (72%) without LVAB, those with LVAB had a higher frequency of sepsis (62% vs 14%, respectively; p < 0.001), a higher prevalence of hypotension on ICU admission, more frequent use of inotropic agents, and a higher frequency of cardiomegaly and pulmonary edema (p < 0.005 for each). Sepsis was the only variable associated with the development of LVAB (odds ratio, 9.2; 95% confidence interval, 2.4 to 35.8; p < 0.001). The development of Q-wave or ST-segment displacement was associated with LVAB, but the sensitivities were 12% and 19%, respectively. Serum creatine kinase level was elevated in 12 of 26 patients (46%) with LVAB. The normalization of this condition occurred in 20 of 26 patients (77%) a mean duration of 7.4 +/- 5.6 days later (range, 2 to 25 days). The mean 2-month survival rate was lower in patients with LVAB than in those without (71 +/- 6% vs 52 +/- 10%, respectively; p = 0.047).

CONCLUSION

LVAB develops in a considerable number of patients who are admitted to the medical ICU, and echocardiography is useful in detecting this phenomenon.

The petrified heart in sepsis

We report the case of a 33-year-old transsexual man who developed severe sepsis after an accidental intravenous injection of urine (3-5 ml) instead of methadone. He died unexpectedly 28 days after the onset of sepsis. On postmortem examination, the outstanding findings were restricted to the heart with an unusual macroscopic presentation. On histological examination extensive calcifications of the heart muscle, particularly of the left ventricle were found. The pattern of calcifications on the right ventricle was also striking. In contrast, the entire cardial conduction system was unaffected. Furthermore, there were no calcium deposits in other organs and tissues. The advanced widespread cardial calcifications in the present case can be attributed to endotoxin-related myocarditis in severe long-term sepsis. The only treatment would have been an urgent heart transplantation. Without prior knowledge of such a condition, it is impossible for clinicians to correctly recognize, diagnose and treat or prevent in due time such a complication.

Lactate concentration gradient from right atrium to pulmonary artery: a commentary

Inadequate myocardial performance is a common complication of severe sepsis. Studies in humans strongly argue against a decrease in coronary blood flow in the pathogenesis of this sepsis-induced cardiac injury. Moreover, regional myocardial ischemia may well be present in sepsis patients with coexistent coronary artery disease. Nevertheless, the diagnosis of myocardial ischemia remains difficult in patients with sepsis, since elevation of troponin in these patients can be the result of a variety of conditions other than acute myocardial ischemia. The use of the right atrium to pulmonary artery lactate gradient could perhaps help the clinician in detecting myocardial ischemia in patients with sepsis.

Protection against endotoxemia-induced contractile dysfunction in mice with cardiac-specific expression of slow skeletal troponin I

Gram negative endotoxemia is associated with an intrinsic impairment of cardiomyocyte contraction, in part due to a reduction in myofilament Ca2+ responsiveness. Endotoxemic rat hearts show increased cardiac troponin I (cTnI) phosphorylation at serines 23 and 24, residues required for the protein kinase A (PKA)-dependent reduction of myofilament Ca2+ sensitivity after beta-adrenoceptor stimulation. To investigate the functional significance of increased TnI phosphorylation in endotoxemia, we studied the contractile effects of systemic bacterial lipopolysaccharide (LPS) treatment in transgenic mice (TG) with cardiac-specific replacement of cTnI by slow skeletal TnI (ssTnI, which lacks the PKA phosphorylation sites) and matched nontransgenic littermates (NTG) on a CD1 background. In wild-type CD1 mice treated with LPS (6 mg/kg ip), after 16-18 h there was a significant reduction in the maximum rates of left ventricular pressure development and pressure decline in isolated Langendorff-perfused hearts compared with saline-treated controls and a decrease in isolated myocyte unloaded sarcomere shortening from 6.1 +/- 0.2 to 3.9 +/- 0.2% (1 Hz, 32 degrees C, P<0.05). Similarly, in NTG myocytes, endotoxemia reduced myocyte shortening by 42% from 6.7 +/- 0.2 to 3.9 +/- 0.1% (P<0.05) with no change in intracellular Ca2+ transients. However, in the TG group, LPS reduced myocyte shortening by only 13% from 7.5 +/- 0.2 to 6.5 +/- 0.2% (P<0.05). LPS treatment significantly reduced the positive inotropic effect of isoproterenol in NTG myocytes but not in TG myocytes, even though isoproterenol-induced increases in Ca2+ transient amplitude were similar in both groups. Only LPS-treated NTG hearts showed a significant increase in cTnI phosphorylation. Investigation of the sarcomere shortening-Ca2+ relationship in Triton-skinned cardiomyocytes revealed a significant reduction in myofilament Ca2+ sensitivity after LPS treatment in NTG myocytes, an effect that was substantially attenuated in TG myocytes. In conclusion, the replacement of cTnI with ssTnI in the heart provides significant protection against endotoxemia-induced cardiac contractile dysfunction, most probably by preserving myofilament Ca2+ responsiveness due to prevention of phosphorylation of TnI at PKA-sensitive sites.

B-type natriuretic peptide and the prediction of outcome in patients admitted to intensive care

B-type natriuretic peptide is known to predict outcome in congestive cardiac failure and myocardial infarction. We aimed to determine whether measurement of B-type natriuretic peptide would predict hospital mortality in patients admitted to an intensive care unit. We conducted a prospective observational cohort study in 78 consecutive patients. Demographics, clinical details and clinical outcomes were recorded. Admission and 24 h B-type natriuretic peptide and cardiac troponin I levels were measured. B-type natriuretic peptide and cardiac troponin I levels taken on intensive care admission and 24 h after admission did not accurately predict hospital mortality for all patients, including patients with severe sepsis or septic shock (all p > 0.05). B-type natriuretic peptide levels were higher in patients with severe sepsis and septic shock (p = 0.02), in patients > or = 65 years (p = 0.04) and in patients with raised creatinine > or = 110 micromol.l(-1) (p = 0.02). We concluded that B-type natriuretic peptide, measured soon after admission to intensive care, does not usefully predict outcome after intensive care.

Cardiac troponin I predicts myocardial dysfunction and adverse outcome in septic shock

OBJECTIVE

The objectives of this study were to determine myocardial injury in patients with septic shock by measuring serum cardiac troponin I (cTnI), to evaluate relationship between elevated cTnI and myocardial dysfunction and to determine if cTnI is a predictor of outcome in these patients.

METHODS

Thirty-seven consecutive patients with septic shock were included in the study. Serum cTnI was measured at study entry and after 24 and 48 h. Transthoracic echocardiogram, electrocardiogram and regular biochemical and hemodynamic assessments were performed.

RESULTS

Sixteen (43%) patients had elevated serum cTnI. These patients had higher need for inotropic/vasopressor support (94% vs. 53%, p=0.018), higher APACHE II score (28 vs. 20, p=0.004), higher incidence of regional wall motion abnormalities on echocardiography (56% vs. 6%, p=0.002), lower ejection fraction (46% vs. 62%, p=0.04) and higher mortality (56% vs. 24%, p=0.04) compared to normal cTnI patients. By multiple logistic regression analysis, serum cTnI and APACHE II score were independent predictor of death and length of stay in intensive care unit. Serum cTnI, APACHE II score, anion gap and serum lactate were independent predictor of need for inotropic/vasopressor support. Receiver-operating characteristics of serum cTnI as a predictor of death in septic shock were significant. The elevated serum level of cTnI correlated with the lower left ventricular ejection fraction (p<0.001).

CONCLUSIONS

Myocardial injury can be determined in patients with septic shock by serum cTnI. Serum cTnI concentration correlates with myocardial dysfunction in septic shock. High serum cTnI predicts increased severity of sepsis and higher mortality. A close monitoring of patients with septic shock and elevated levels cTnI is warranted.

Emergency care in pediatric septic shock

Septic shock causes more deaths in children than cancer. However, studies have shown that mortality can be significantly reduced by adhering to the American College of Critical Care Medicine/Pediatric Advanced Life Support guidelines. This article reviews the definitions, pathophysiology, and emergency management of children with septic shock, including the controversial role of steroids.

Peroxynitrite decomposition catalysts prevent myocardial dysfunction and inflammation in endotoxemic rats

OBJECTIVES

The aim of this study was to test whether peroxynitrite neutralizers would reduce peroxynitrite accumulation and improve myocardial contractile dysfunction and inflammation in endotoxin-treated rats.

BACKGROUND

Release of endogenous proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha in response to endotoxin is responsible for the production of large amounts of nitric oxide (NO), which may exert detrimental effects on the myocardium in animal models, isolated hearts, and isolated cardiac myocytes. Recent studies have indicated that many of the deleterious effects of NO are mediated by peroxynitrite, a powerful oxidant generated from a fast diffusion-limited reaction of NO and superoxide anion.

METHODS

We studied the effects of peroxynitrite neutralizers, such as mercaptoethylguanidine (MEG) sodium succinate (10 mg/kg) and 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrinato iron (III) (FeTPPS) (30 mg/kg) on peroxynitrite accumulation, in vivo endothelial cell-leukocyte activation on the mesenteric venule, and myocardial contractile dysfunction and inflammation in a model of sepsis induced by injection of endotoxin (10 mg/kg) in rats.

RESULTS

Mercaptoethylguanidine sodium succinate and FeTPPS largely prevented the accumulation of peroxynitrite as measured by plasma rhodamine fluorescence and heart nitrotyrosine staining. Interestingly, MEG sodium succinate and FeTPPS improved endotoxin-induced myocardial contractile dysfunction, which was associated with reduced degradation of nuclear factor kappa B inhibitory protein I-kappa-B, plasma TNF-alpha levels, and microvascular endothelial cell-leukocyte activation.

CONCLUSIONS

These observations suggest that the beneficial effects of MEG and FeTPPS on endotoxin-induced myocardial contractile dysfunction could be related to the unique effects of these compounds on cardiovascular inflammation processes.

CALPAIN INHIBITORS IMPROVE MYOCARDIAL DYSFUNCTION AND INFLAMMATION INDUCED BY ENDOTOXIN IN RATS

Excessive activation of calpains has been implicated in the pathophysiology of inflammation, trauma, and ischemia reperfusion injury. Here, we investigated the effects of calpain inhibition on myocardial dysfunction and inflammation induced by endotoxin in rats. Rats were treated i.v. with endotoxin (10 mg/kg) or endotoxin plus calpain inhibitors and were then prepared after 4 h for myocardial contractility assessment, detection of endothelium leukocyte interactions, and plasma TNF-alpha, nitrite/nitrate, and endocan levels. Compared with vehicle-treated rats, hearts from endotoxin-treated rats had reduced systolic performance that was partially prevented by calpain inhibitors, i.e., acetyl-leucyl-leucyl-arginal (leupeptin), carbobenzoxy-valyl-phenylalanial (calpain inhibitor III), and N-acetyl-leucinyl-leucinyl-norleucinal (ALLN). Leupeptin and calpain inhibitor III reduced plasma TNF-alpha levels in endotoxin-treated rats. ALLN reduced plasma TNF-alpha and nitrite/nitrate levels in endotoxin-treated rats. Endotoxin treatment increased mesenteric venule leukocyte rolling (10 +/- 3 leukocytes/min vs. 44 +/- 10 leukocytes/min; P < 0.01) and adhesion (2 +/- 2 leukocytes/min vs. 15 +/- 3 leukocytes/min; P < 0.01), which was reduced by calpain inhibitors. Attenuation of leukocyte endothelium interactions observed in calpain inhibitor-treated rats with sepsis was associated with increases in plasma anti-adhesion molecule endocan. In conclusion, calpain inhibitors improved endotoxin-induced cardiac dysfunction, which may be attributed to the modulation of endothelium leukocyte interactions in the inflamed vasculature.

Endotoxin-induced myocardial dysfunction: evidence for a role of sphingosine production

OBJECTIVE

To determine whether sphingomyelinase pathway activation would participate in myocardial depression induced by endotoxin.

DESIGN

Randomized, controlled trial.

SETTING

Experimental laboratory.

SUBJECTS

Male Sprague-Dawley rats, isolated rat heart, and cardiac myocytes.

INTERVENTIONS

Cardiovascular function was evaluated in rats injected with saline, endotoxin (10 mg/kg, intravenously), and N-oleoylethanolamine (NOE; 10 mg/kg, intravenously). In ex vivo experiments, isolated rat hearts were perfused with endotoxin (5 microg/mL). For pharmacologic intervention, NOE (1 micromol/L) was admixed to the perfusate 20 mins before endotoxin. In in vitro experiments, ventricular myocytes were incubated with sphingosine (20 microM). Myocyte cell shortening and calcium transient were measured. Mitochondrial membrane potential was measured using the cationic dye tetramethylrhodamine methylester fluorescence technique.

MEASUREMENTS AND MAIN RESULTS

Endotoxin treatment at 4 hrs did not alter mean arterial pressure and abdominal blood flow compared with control rats. Left ventricle developed pressure (LVDP) and its first derivatives (i.e., maximal and minimal change in pressure over time [dP/dtmax and dP/dtmin]) were decreased after 4 hrs in endotoxin-treated rats compared with control rats. NOE (10 mg/kg) treatment largely prevented left ventricular systolic function alterations of endotoxin-treated hearts (n = 6 in each group). In isolated rat heart, endotoxin (5 microg/mL) caused increases in tumor necrosis factor-alpha perfusate concentration and delayed depression of LVDP, dP/dtmax, and dP/dtmin after 60 mins, which was partially abrogated in the presence of the ceramidase inhibitor NOE (1 micromol/L). Sphingosine (20 microM) caused decreases in cell fractional shortening, calcium transient, and mitochondrial membrane potential of cardiac myocytes.

CONCLUSION

These observations suggest that the sphingomyelinase pathway participates in endotoxin-induced myocardial depression.

E. Coli Sepsis Induces Profound Mechanoenergetic Inefficiency in the Porcine Left Ventricle

Myocardial dysfunction is believed to be a central part of septic multiorgan manifestations. The aim of the present study was to assess whether E. coli sepsis in an in vivo model would induce a dysfunction in the relationship between mechanical work and energy consumption in the left ventricle (LV). Accordingly, we measured hemodynamics, left ventricular pressure-volume area (PVA), and myocardial oxygen consumption (MVo2) in deeply anesthetized pigs. Eight pigs received 2.0 +/- 0.5 x 10(9) E. coli bacteria intravenously, and seven served as controls. Compared with baseline and the control group, no alternations were observed in LV diastolic function or indices of contractility in the septic group. The MVo2-PVA relationship was highly linear in both groups (all r2 = 0.96-0.99). At 5 h, the y-axis intercept of the MVo2-PVA relationship (nonmechanical MVo2) had increased in the sepsis group by 70% compared with baseline (P = 0.004) and by 60% compared with the control group (P = 0.003). Contractile efficiency (the inverse of the MVo2-PVA slope) remained unchanged over time and between groups. The study demonstrates a profound increase in nonmechanical oxygen consumption during E. coli sepsis in the LV.

Systemic inflammatory response syndrome in surgical patients with sepsis

Systemic inflammatory response syndrome and sepsis are common in surgically treated patients. Systemic inflammatory response syndrome represents a major factor of morbidity and mortality in these patients. The pathogenesis of these syndromes has been increasingly clarified. The objective of this review is to present an overview of our current understanding of the physiology underlying these conditions. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href=http://dx.doi.org/10.2298/SARH1206269U>10.2298/SARH1206269U</a><u></b></font>

Identification, characterization, and gene expression profiling of endotoxin-induced myocarditis

In septic shock, reversible cardiac dysfunction starts within 24 h. Myocardial depressant factors are thought to cause myocyte dysfunction, resulting in alterations of intrinsic cardiac function. Nitric oxide is a myocardial depressant factor candidate. Here we identify endotoxin-induced myocarditis (EIM) a previously uncharacterized pathophysiological entity. Features of EIM include differential patterns of inducible NO synthase (NOS2) mRNA induction in the left (LV) and right (RV) ventricles during the systemic response inflammatory syndrome (SIRS) and the presence of myocarditis with focal areas of aseptic necrosis in the RV 24 h after SIRS induction. Even though clinical data lead to the presumption of myocardial injury in sepsis, the underlying pathophysiological mechanisms have not been previously elucidated. Gene expression profiling was used to test the hypothesis of differential LV and RV responses in EIM, and revealed novel patterns of qualitative and quantitative expansion of transcription. Those genes are novel targets for drug development in SIRS and sepsis. Our results demonstrate spatial and temporal heterogeneity of myocardial responses in EIM. These findings justify the design of treatments to ameliorate tissue injury in the RV. Because the complexity of the inflammatory response increases substantially as time elapses, we suggest a stepwise and multitarget therapeutic approach for SIRS and sepsis. Our findings can help identify innate immune pathways that could become targets for immunotherapy in the treatment of disease caused by potential bioterrorism agents.

The pathophysiology of propofol infusion syndrome: a simple name for a complex syndrome

Propofol infusion syndrome (PRIS) is a rare and often fatal syndrome described in critically ill children undergoing long-term propofol infusion at high doses. Recently several cases have been reported in adults, too. The main features of the syndrome consist of cardiac failure, rhabdomyolysis, severe metabolic acidosis and renal failure. To date 21 paediatric cases and 14 adult cases have been described. These latter were mostly patients with acute neurological illnesses or acute inflammatory diseases complicated by severe infections or even sepsis, and receiving catecholamines and/or steroids in addition to propofol. Central nervous system activation with production of catecholamines and glucocorticoids, and systemic inflammation with cytokine production are priming factors for cardiac and peripheral muscle dysfunction. High-dose propofol, but also supportive treatments with catecholamines and corticosteroids, act as triggering factors. At the subcellular level, propofol impairs free fatty acid utilisation and mitochondrial activity. Imbalance between energy demand and utilisation is a key pathogenetic mechanism, which may lead to cardiac and peripheral muscle necrosis. Propofol infusion syndrome is multifactorial, and propofol, particularly when combined with catecholamines and/or steroids, acts as a triggering factor. The syndrome can be lethal and we suggest caution when using prolonged (>48 h) propofol sedation at doses higher than 5 mg/kg per h, particularly in patients with acute neurological or inflammatory illnesses. In these cases, alternative sedative agents should be considered. If unsuitable, strict monitoring of signs of myocytolysis is advisable.

Surgical sepsis: dysregulation of immune function and therapeutic implications

Sepsis is defined clinically as the systemic inflammatory response of the host to the documented systemic infection. The pathophysiological disturbance involves both the innate and adaptive immune systems encompassing cellular immunity, humoral components and the complement system. Dendritic cells (antigen-presenting cells) are key cells involved in the regulation of the immune response in sepsis, in particular in activating T cells and especially inducing the production and secretion of specific cytokines. These are the main mediators in establishing prominent disturbances of inflammation in patients with sepsis. The clinical features of the sepsis syndrome may vary from minor clinical disturbances to severe multiple organ failure and death of the host. Appropriate therapeutic strategies for patients with sepsis utilise conventional therapy and new novel forms of treatment, which are showing promise for the future.

Protective effect of 3-deazaadenosine in a rat model of lipopolysaccharide-induced myocardial dysfunction

Severe sepsis is accompanied by a profound depression of myocardial contractility. Leukocyte adhesion with subsequent local excess nitric oxide and reactive oxygen species production play major roles for this deleterious effect. We hypothesized that 3-deazaadenosine (c3Ado), an adenosine analogue with anti-inflammatory properties, prevents endotoxin-induced myocardial dysfunction. Wistar rats (8 per group) were treated with Escherichia coli lipopoly-saccharide (LPS, 1 mg/kg, i.p., strain 0111:B4) +/- c3Ado (10 mg/kg, i.p.) 8 h before their hearts were harvested for isolated perfusion, histochemical analysis, or electrophoretic mobility shift assay. LPS induced a marked depression of left ventricular contractility. Immunohistochemistry revealed an upregulation of the adhesion molecules VCAM-1, ICAM-1, and P-selectin within the postcapillary venules. c3Ado inhibited VCAM-1 and ICAM-1 upregulation, but not P-selectin, and prevented cardiodepression. Electrophoretic mobility shift assay revealed inactivation of the transcription factor nuclear factor-kappaB and immunohistochemical staining for gp91phox, ED1, and CD11b demonstrated that c3Ado prevented local recruitment of monocytes and polymorph nuclear neutrophils to the myocardium. Accordingly, significantly fewer leukocytes producing nitric oxide or reactive oxygen species accumulated within the myocardium. Intravital microscopy of intestinal venules confirmed that LPS-induced adhesion of leukocytes was prevented by c3Ado. Additionally, c3Ado prevented LPS-induced elevation of serum tumor necrosis factor-alpha levels. Our results imply that c3Ado may prove to have clinical relevance for inflammatory disease processes.

Enhanced NO and superoxide generation in dysfunctional hearts from endotoxemic rats

Free radicals have been implicated in the etiology of cardiac dysfunction during sepsis, but the actual species responsible remains unclear. We studied the alterations in myocardial nitric oxide (NO), superoxide, and peroxynitrite generation along with cardiac mechanical function and efficiency in hearts from lipopolysaccharide (LPS)-treated rats. Six hours after LPS (4 mg/kg ip) or saline (control) treatment, hearts were isolated and perfused for 1 h with recirculating Krebs-Henseleit buffer and paced at 300 beats/min. Cardiac work, O(2) consumption, and cardiac efficiency were markedly depressed in LPS hearts compared with controls. Plasma nitrate/nitrite level was elevated in LPS rats, and ventricular NO production was enhanced as measured by electron spin resonance spectroscopy, Ca(2+)-independent NO synthase (NOS) activity, and inducible NOS immunohistochemistry. Ventricular superoxide production was also enhanced in LPS-treated hearts as seen by lucigenin chemiluminescence and xanthine oxidase activity. Increased nitrotyrosine staining (immunohistochemistry) and higher lipid hydroperoxides levels were also detected in LPS-treated hearts, indicating oxygen radical-induced stress. Enhanced generation of both NO and superoxide, and thus peroxynitrite, occur in dysfunctional hearts from endotoxemic rats.

Continuously infused methylene blue modulates the early cardiopulmonary response to endotoxin in awake sheep

BACKGROUND

In endotoxemia and septic shock, enhanced generation of endogenous nitric oxide (NO) contributes to myocardial depression, hypotension, and derangement of gas exchange. We hypothesized that continuous infusion of methylene blue (MB), an inhibitor of the NO pathway, would counteract these effects in endotoxemic sheep.

METHODS

Twenty-one sheep were anesthetized and instrumented for a chronic study with vascular catheters. On the day of the experiment, 18 conscious animals randomly received either an intravenous injection of MB 10 mg x kg(-1) or isotonic saline. Thirty minutes later, sheep received a 20-min intravenous infusion of Escherichia coli endotoxin 1 microg x kg(-1) and either an intravenous infusion of MB 2.5 mg x kg(-1) x h(-1) or isotonic saline, respectively, for 5 h. In addition, 3 animals were exposed to the same dose of MB alone.

RESULTS

MB reduced the early endotoxin-induced declines in stroke volume, left ventricular stroke work and cardiac indices, and prevented mean arterial pressure from falling. Moreover, MB ameliorated the increases in pulmonary arterial pressure and pulmonary vascular resistance index. In addition, MB reduced the increments in venous admixture and AaPO2, decreased the falls in PaO2, SaO2, and oxygen delivery, and maintained oxygen consumption. MB also prevented the rises in body temperature and plasma nitrites and nitrates, and delayed the elevation of plasma lactate. When given alone to healthy sheep, MB transiently reduced plasma lactate and PaO2, and increased AaPO2.

CONCLUSION

In ovine endotoxemia, continuously infused MB counteracts the early myocardial dysfunction and derangement of hemodynamics and gas exchange.

Infusion of methylene blue in human septic shock: a pilot, randomized, controlled study

OBJECTIVE

To evaluate the effects of continuous infusion of methylene blue (MB), an inhibitor of the nitric oxide pathway, on hemodynamics and organ functions in human septic shock.

DESIGN

Prospective, randomized, controlled, open-label, pilot study.

SETTING

Multidisciplinary intensive care unit of a university hospital.

PATIENTS

Twenty patients with septic shock diagnosed <24 hrs before randomization.

INTERVENTIONS

Patients were randomized 1:1 to receive either MB (MB group, n = 10) or isotonic saline (control group, n = 10), adjunctive to conventional treatment. MB was administered as an intravenous bolus injection (2 mg/kg), followed 2 hrs later by infusion at stepwise increasing rates of 0.25, 0.5, 1, and 2 mg/kg/hr that were maintained for 1 hr each. During infusion, mean arterial pressure was maintained between 70 and 90 mm Hg, while attempting to reduce concurrent adrenergic support.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and organ function variables were assessed over a 24-hr period, and the survival rate at day 28 was noted. Infusion of MB prevented the stroke volume and the left-ventricular stroke work indexes from falling and increased mean arterial pressure. Compared with the control group, MB reduced the requirement for norepinephrine, epinephrine, and dopamine by as much as 87%, 81%, and 40%, respectively. Oxygen delivery remained unchanged in the MB group and decreased in the control group. MB also reduced the body temperature and the plasma concentration of nitrates/nitrites. Leukocytes and organ function variables such as bilirubin, alanine aminotransferase, urea, and creatinine were not significantly affected. Platelet count decreased in both groups. Five patients treated with MB survived vs. three patients receiving conventional treatment.

CONCLUSIONS

In human septic shock, continuously infused MB counteracts myocardial depression, maintains oxygen transport, and reduces concurrent adrenergic support. Infusion of MB appears to have no significant adverse effects on the selected organ function variables.