Sepsis and the heart

Ventricular dysfunction and dilation in severe sepsis and septic shock: relation to endothelial function and mortality

PURPOSE

The aim of this study was to evaluate echocardiography-based indices of myocardial function and markers of vascular inflammation and endothelial dysfunction in the early phases of severe sepsis.

MATERIAL AND METHODS

Forty-five adult patients (67% women; age 51 ± 18 years; Acute Physiology and Chronic Health Disease Classification System II score, 23 ± 7) admitted to the intensive care unit up to 24 hours after fulfilling criteria for severe sepsis or septic shock were studied. Clinical, laboratorial (endothelin 1 [ET1], vascular cellular adhesion molecule 1), and echocardiographic data were collected within the first 24 hours and again 72 hours and 7 days after admission.

RESULTS

Intrahospital mortality was 33% (15 deaths). Left ventricular (LV) dysfunction (LV ejection fraction <55%) was identified in 15 (33%) patients, whereas right ventricular (RV) dysfunction (RV tissue Doppler peak systolic velocity [RV-Sm] <12 cm/s) was present in 14 (30%) patients. LogET1 was increased in patients with LV dysfunction (2.3 ± 0.6 vs 1.8 ± 0.4 pg/mL; P = .01) and RV dysfunction (2.5 ± 0.5 vs 1.8 ± 0.4 pg/mL; P < .001) and had negative correlations with LV ejection fraction (r = -0.50; P = .002) and RV-Sm (r = -0.67; P < .001). Left ventricular end-diastolic diameter, RV-Sm, and diastolic dysfunction were able to discriminate survivors from nonsurvivors, and the combination of these parameters identified groups of very low and high risk.

CONCLUSION

Both LV and RV systolic dysfunctions are prevalent in severe sepsis, being directly associated with markers of endothelial dysfunction. Left ventricular nondilation, RV dysfunction, and diastolic dysfunction seem related to poor prognosis in this scenario.

Nitrosative protein oxidation is modulated during early endotoxemia

Formation of nitric oxide and its derivative reactive nitrogen species during endotoxemia has been implicated in the pathogenesis of the associated cardiovascular dysfunction. This stress can promote nitrosative post-translational modifications of proteins that may alter their activity and contribute to dysregulation. We utilized the ascorbate-dependent biotin-switch method to assay protein S-nitrosylation and immunoblotted for tyrosine nitration to monitor changes in nitrosative protein oxidation during endotoxemia. Hearts from lipopolysaccharide (LPS)-treated rats showed no apparent variation in global protein S-nitrosylation, but this may be due to the poor sensitivity of the biotin-switch method. To sensitize our monitoring of protein S-nitrosylation we exposed isolated hearts to the efficient trans-nitrosylating agent nitrosocysteine (which generated a robust biotin-switch signal) and then identified a number of target proteins using mass spectrometry. We were then able to probe for these target proteins in affinity-capture preparations of S-nitrosylated proteins prepared from vehicle- or LPS-treated animals. Unexpectedly this showed a time-dependent loss in S-nitrosylation during sepsis, which we hypothesized, may be due to concomitant superoxide formation that may lower nitric oxide but simultaneously generate the tyrosine-nitrating agent peroxynitrite. Indeed, this was confirmed by immunoblotting for global tyrosine nitration, which increased time-dependently and temporally correlated with a decrease in mean arterial pressure. We assessed if tyrosine nitration was causative in lowering blood pressure using the putative peroxynitrite scavenger FeTPPS. However, FeTPPS was ineffective in reducing global protein nitration and actually exacerbated LPS-induced hypotension.

Levosimendan and mortality after coronary revascularisation: a meta-analysis of randomised controlled trials

INTRODUCTION

Patients undergoing coronary revascularization often require inotropic support that has been associated with an increased risk for death and morbidity. The purpose of this study was to evaluate the effect of levosimendan versus control on survival after coronary revascularization.

METHODS

A systemic review and meta-analysis of the literature was carried out on published randomized controlled clinical trials that investigated the efficacy of levosimendan compared to other therapy in patients having coronary revascularisaion. The databases searched were Pubmed, EMBASE, the Cochrane Registry of Clinical Trials and the metaRegister of Controlled Trials. Studies that compared levosimendan to any other therapy for coronary revascularisation in adult humans and reported at least one outcome of interest were considered for inclusion. Both percutaneous coronary intervention and cardiac surgery were included. Data extraction was performed independently by two reviewers using predefined criteria. Relevant outcomes included mortality, cardiac index, cardiac enzymes, length of stay and post-procedural atrial fibrillation.

RESULTS

The meta-analysis included 729 patients from 17 studies. Levosimendan was associated with a mortality reduction after coronary revascularization, (19/386 in the levosimendan group vs 39/343 in the control arm) odds ratio (OR) 0.40 (95% confidence interval (CI) 0.21 to 0.76, P for overall effect 0.005, P for heterogeneity = 0.33, I2 = 12% with a total of 729 patients. Levosimendan also had a favourable effect on cardiac index (standardised mean difference 1.63, 95% CI 1.43 to 1.83, P for overall effect < 0.00001), length of intensive care stay (random effects model, mean difference - 26.18 hours 95% CI 46.20 to 6.16, P for heterogeneity < 0.00001, I2 = 95%, P for overall effect P = 0.01), reductions in the rate of atrial fibrillation (OR 0.54, 95% CI 0.36 to 0.82, P for effect = 0.004, P for heterogeneity 0.84, I2 = 0% for 465 patients) and troponin I levels group (mean difference -1.59, 95% CI 1.78 to 1.40, P for overall effect < 0.00001, P for heterogeneity < 0.00001, I2 = 95%). Limitations of this analysis are discussed.

CONCLUSIONS

Levosimendan is associated with a significant improvement in mortality after coronary revascularization. There are also improvements in several secondary endpoints. A suitably powered randomised controlled trial is required to confirm these findings and to address the unresolved questions about the timing and dosing of levosimendan.

Vascular complications in patients undergoing femoral cannulation for extracorporeal membrane oxygenation support

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a well-established treatment for severe cardiopulmonary failure. Patients undergoing ECMO support through femoral vessels are prone to vascular complications. The aim of this study was to evaluate such complications to outline basic technical principles for their prevention.

METHODS

From January 2005 to December 2009, 174 patients underwent ECMO support through cannulation of the femoral vessels. The primary outcome was any vascular complication. Secondary outcomes were 30-day mortality and 1-year survival. A logistic regression analysis including ECMO duration, peripheral arterial disease, ECMO access (percutaneous versus open), and diabetes mellitus identified predictors for vascular complications.

RESULTS

The venoarterial mode was used in 143 patients (82%), and venovenous in 31 patients (18%). Of the 17 (10%) observed vascular complications, 15 (88%) occurred in patients with venoarterial access, whereas 2 (12%) occurred after venovenous access (p=0.50) Two patients who had extremity ischemia required limb amputation. Thirty-day mortality and 1-year survival rates were 63% and 26%, respectively. Peripheral arterial disease was the only strong predictor of vascular complications (odds ratio, 6.95; 95% confidence interval, 1.89 to 25.59; p=0.003). Vascular complications were not associated with early or late mortality.

CONCLUSIONS

The incidence of vascular complications in venovenous cannulation was low, whereas in arterial cannulation, it is still considerable. Peripheral arterial disease remains a risk factor, and early involvement of vascular surgeons for open vascular exposure or alternative vascular access sites can be recommended. Vascular complications after ECMO support are not associated with higher mortality rates.

Cardiorenal syndromes and sepsis

The cardiorenal syndrome is a clinical and pathophysiological entity defined as the concomitant presence of renal and cardiovascular dysfunction. In patients with severe sepsis and septic shock, acute cardiovascular, and renal derangements are common, that is, the septic cardiorenal syndrome. The aim of this paper is to describe the pathophysiology and clinical features of septic cardiorenal syndrome in light of the actual clinical and experimental evidence. In particular, the importance of systemic and intrarenal endothelial dysfunction, alterations of kidney perfusion, and myocardial function, organ “crosstalk” and ubiquitous inflammatory injury have been extensively reviewed in light of their role in cardiorenal syndrome etiology. Treatment includes early and targeted optimization of hemodynamics to reverse systemic hypotension and restore urinary output. In case of persistent renal impairment, renal replacement therapy may be used to remove cytokines and restore renal function.

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.

Cymbopogon citratus as source of new and safe anti-inflammatory drugs: bio-guided assay using lipopolysaccharide-stimulated macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Aqueous extracts of Cymbopogon citratus (Cy) leaves are used in traditional medicine for the treatment of inflammatory conditions, however, little is known about their mechanism of action.

AIM OF THE STUDY

The aim of this study is to explore the anti-inflammatory properties of Cymbopogon citratus leaves and their polyphenol-rich fractions (PFs), as well its mechanism of action in murine macrophages.

MATERIALS AND METHODS

A lipid- and essential oil-free infusion of Cy leaves was prepared (Cy extract) and fractionated by column chromatography. Anti-inflammatory properties of Cy extract (1.115 mg/ml) and its PFs, namely phenolic acids (530 μg/ml), flavonoids (97.5 μg/ml) and tannins (78 μg/ml), were investigated using lipopolysaccharide (LPS)-stimulated Raw 264.7 macrophages as in vitro model. As inflammatory parameters, nitric oxide (NO) production was evaluated by Griess reaction, as well as effects on cyclooxygenase-2 (COX-2), inducible NO synthase (iNOS) expression and on intracellular signaling pathways activation, which were analyzed by Western blot using specific antibodies.

RESULTS

Cy extract inhibited iNOS expression, NO production and various LPS-induced pathways like p38 mitogen-activated protein kinase (MAPK), c-jun NH(2)-terminal kinase (JNK) 1/2 and the transcription nuclear factor (NF)-κB. The extracellular signal-regulated kinase (ERK) 1/2 and the phosphatidylinositol-3-kinase (PI3K)/Akt activation were not affected by Cy extract. Both phenolic acid- and tannin-rich fractions significantly inhibited NF-κB activation, iNOS expression and NO production but none of the PFs modulated MAPKs or PI3K/Akt activation. Neither Cy extract nor PFs affected LPS-induced COX-2 expression but LPS-induced PGE(2) production is inhibited by Cy extract and by phenolic acid-rich fraction.

CONCLUSIONS

Our data provide evidence that support the usage of Cymbopogon citratus leaves extract in traditional medicine, and suggest that Cy, in particular its polyphenolic compounds, could constitute a natural source of a new and safe anti-inflammatory drug.

Year in review 2009: Critical Care--shock

The research papers on shock that have been published in Critical Care throughout 2009 are related to four major subjects: first, alterations of heart function and, second, the role of the sympathetic central nervous system during sepsis; third, the impact of hemodynamic support using vasopressin or its synthetic analog terlipressin, and different types of fluid resuscitation; as well as, fourth, experimental studies on the treatment of acute respiratory distress syndrome. The present review summarizes the key results of these studies together with a brief discussion in the context of the relevant scientific and clinical background published both in this and other journals.

Myocardial dysfunction in fetuses exposed to intraamniotic infection: new insights from tissue Doppler and strain imaging

OBJECTIVE

The purpose of this study was to assess myocardial function of fetuses who were exposed to intraamniotic infection compared with fetuses of uncomplicated pregnancies by the application of tissue Doppler and strain rate (SR) imaging.

STUDY DESIGN

We evaluated the right ventricular function of fetuses with preterm premature rupture of membranes and proven intraamniotic infection (n = 12 fetuses) and healthy fetuses (n = 27). Tissue Doppler velocities during early diastolic relaxation (E(m)) and atrial contraction (A(m)) and early diastolic SR were measured as indices of diastolic function, whereas the peak systolic strain and SR were used as parameters of systolic function.

RESULTS

Fetuses with intraamniotic infection exhibit impairment in both diastolic and systolic performance, which was characterized by increased diastolic compliance (increased E(m)/A(m) ratio, increased early diastolic SR compared with the control fetuses), decreased systolic contractile function (reduced systolic strain and SR), and longitudinal myocardial dyskinesia.

CONCLUSION

New echocardiographic tools suggest that fetal heart is a target organ in the context of intraamniotic infection.

Anaesthetic management of patients with severe sepsis

Severe sepsis, a syndrome characterized by systemic inflammation and acute organ dysfunction in response to infection, is a major healthcare problem affecting all age groups throughout the world. Anaesthetists play a central role in the multidisciplinary management of patients with severe sepsis from their initial deterioration at ward level, transfer to the diagnostic imaging suite, and intraoperative management for emergency surgery. The timely administration of appropriate i.v. antimicrobial therapy is a crucial step in the care of patients with severe sepsis who may require surgery to control the source of sepsis. Preoperative resuscitation, aimed at optimizing major organ perfusion, is based on judicious use of fluids, vasopressors, and inotropes. Intraoperative anaesthesia management requires careful induction and maintenance of anaesthesia, optimizing intravascular volume status, avoidance of lung injury during mechanical ventilation, and ongoing monitoring of arterial blood gases, lactate concentration, haematological and renal indices, and electrolyte levels. Postoperative care overlaps with ongoing management of the severe sepsis syndrome patient in the intensive care unit. These patients are by definition, high risk, already requiring multiple supports, and require experienced and skilful decision-making to optimize their chances of a favourable outcome. Similar to acute myocardial infarction, stroke, or acute trauma, the initial hours (golden hours) of clinical management of severe sepsis represent an important opportunity to reduce morbidity and mortality. Rapid clinical assessment, resuscitation and surgical management by a focused multidisciplinary team, and early effective antimicrobial therapy are the key components to improved patient outcome.

Endothelin-mediated gut microcirculatory dysfunction during porcine endotoxaemia

BACKGROUND

The potent vasoconstrictor endothelin-1 has been implicated in the pathogenesis of the microcirculatory dysfunction seen in sepsis. The mixed endothelin receptor antagonist tezosentan and the selective endothelin A-receptor antagonist TBC3711 were used to investigate the importance of the different endothelin receptors in modulating splanchnic regional blood flow and microvascular blood flow in endotoxaemia.

METHODS

Eighteen anaesthetized pigs were i.v. infused with endotoxin (Escherichia coli lipopolysaccharide, serotype 0111:b4) for 300 min. After 120 min, six animals received tezosentan and six animals received TBC3711. Six animals served as endotoxin-treated controls. Laser Doppler flowmetry was used to measure microcirculatory blood flow in the liver and ileum. Superior mesenteric artery flow (SMA(FI)) and portal vein flow (PV(FI)) were measured with ultrasonic flow probes, and air tonometry was used to measure Pco₂ in the ileal mucosa.

RESULTS

TBC3711 did not improve splanchnic regional blood flow or splanchnic microvascular blood flow compared with endotoxin-treated controls. Tezosentan increased PV(FI) (P<0.05), but SMA(FI) was not improved compared with the other groups. In the tezosentan group, microvascular blood flow in the ileal mucosa (MCQ(muc)) improved and mucosal-arterial Pco₂ gap decreased (P<0.05 for both) compared with endotoxin-treated controls and the TBC3711 group.

CONCLUSIONS

Tezosentan improved MCQ(muc) without any concomitant increase in SMA(FI), implying a direct positive effect on the microcirculation. TBC3711 was not effective in improving regional splanchnic blood flow or splanchnic microvascular blood flow. Dual endothelin receptor antagonism was necessary to improve MCQ(muc), indicating a role for the endothelin B-receptor in mediating the microcirculatory failure in the ileal mucosa.

Endotoxin impairs cardiac hemodynamics by affecting loading conditions but not by reducing cardiac inotropism

Acute myocardial dysfunction is a typical manifestation of septic shock. Experimentally, the administration of endotoxin [lipopolysacharride (LPS)] to laboratory animals is frequently used to study such dysfunction. However, a majority of studies used load-dependent indexes of cardiac function [including ejection fraction (EF) and maximal systolic pressure increment (dP/dt(max))], which do not directly explore cardiac inotropism. Therefore, we evaluated the direct effects of LPS on myocardial contractility, using left ventricular (LV) pressure-volume catheters in mice. Male BALB/c mice received an intraperitoneal injection of E. coli LPS (1, 5, 10, or 20 mg/kg). After 2, 6, or 20 h, cardiac function was analyzed in anesthetized, mechanically ventilated mice. All doses of LPS induced a significant drop in LV stroke volume and a trend toward reduced cardiac output after 6 h. Concomitantly, there was a significant decrease of LV preload (LV end-diastolic volume), with no apparent change in LV afterload (evaluated by effective arterial elastance and systemic vascular resistance). Load-dependent indexes of LV function were markedly reduced at 6 h, including EF, stroke work, and dP/dt(max). In contrast, there was no reduction of load-independent indexes of LV contractility, including end-systolic elastance (ejection phase measure of contractility) and the ratio dP/dt(max)/end-diastolic volume (isovolumic phase measure of contractility), the latter showing instead a significant increase after 6 h. All changes were transient, returning to baseline values after 20 h. Therefore, the alterations of cardiac function induced by LPS are entirely due to altered loading conditions, but not to reduced contractility, which may instead be slightly increased.