The haemodynamics of human septic shock

Risk factors for life-threatening complications of head and neck space infections: A systematic review and meta-analysis

OBJECTIVE

The present systematic review was performed to identify risk factors associated with life-threatening complications of head and neck space infections (LCHNSI) within the included studies and assess the magnitude of their impact on patients.

METHODS

We systematically searched PubMed, Web of Science, EmBase, Scopus and CNKI for articles that reported risk factors associated with life-threatening complications of head and neck space infections from inception to 14 December 2023. Only factors reported in at least three papers were considered in the meta-analysis. Pooled odds ratio (OR) and 95 % confidence interval (CI) were calculated using fixed effects model and random effects model. The between-study heterogeneity of effect size was quantified using the Q statistic and I2. In addition, subgroup analysis stratified by study characteristics and sensitivity analysis were performed to explore the potential sources of heterogeneity and the stability of the results.

RESULTS

The review included a total of 29 studies. The results revealed that the risk factors which associated with LCHNSI were included diabetes mellitus (OR = 3.31, 95 % CI: 2.49-4.40), total leukocyte count(≥15 × 109/L) (OR = 1.21, 95 %CI: 1.04-1.42), multiple space involvement (OR = 4.32, 95 %CI: 3.47-5.38), combined systemic diseases (OR = 9.94, 95 %CI: 6.30-15.67), advanced age(≥60) (OR = 3.90, 95 %CI: 2.80-5.44), dyspnoea (OR = 23.39, 95 %CI: 12.41-44.10), high temperature(≥39°C) (OR = 3.23, 95 %CI: 2.02-5.17), retropharyngeal space involvement (OR = 3.62, 95 %CI: 2.06-6.35), parapharyngeal space involvement (OR = 4.62, 95 %CI: 2.27-9.42).

CONCLUSIONS

According to the current analysis, diabetes mellitus, total leukocyte count(≥15 × 109/L), combined systemic diseases, multiple space involvement, advanced age(≥60), dyspnoea, high temperature (≥39 °C), retropharyngeal space involvement, parapharyngeal space involvement were the risk factors for LCHNSI. To mitigate the incidence of LCHNSI, clinical staff should carefully manage these risk factors, ensure prompt diagnosis, and implement timely preventive measures.

Towards Improved Management of Tuberculous Bloodstream Infections: Pharmacokinetic Considerations with Suggestions for Better Treatment Outcomes

Mycobacterium tuberculosis is the leading cause of sepsis among HIV-infected adults, yet effective treatment remains a challenge. Efficacy of antituberculous drugs is optimized by high Area Under Curve to Minimum Inhibitory Concentration (AUC/MIC) ratios, suggesting that both the drug concentration at the disease site and time above MIC are critical to treatment outcomes. We elaborate on sepsis pathophysiology and show how it adversely affects antituberculous drug kinetics. Expanding distribution volumes secondary to an increased vascular permeability prevents the attainment of target Cmax concentrations for nearly all drugs. Furthermore, sepsis-induced metabolic acidosis promotes protonation, which increases renal clearance of basic drugs such as isoniazid and ethambutol, and hence AUCs are substantially reduced. Compared with the treatment of non-sepsis TB disease, these distorted kinetics underlie the poor treatment outcomes observed with bloodstream infections. In addition to aggressive hemodynamic management, an increase in both the dose and frequency of drug administration are warranted, at least in the early phase of treatment.

Cell-Free Hemoglobin Is Associated With Increased Vascular Resistance and Reduced Peripheral Perfusion in Severe Malaria

BACKGROUND

In severe falciparum malaria, unlike sepsis, hypotension on admission is uncommon. We hypothesized that low nitric oxide bioavailability due to the presence of cell-free hemoglobin (CFH) increases vascular tone in severe malaria.

METHODS

Patients with severe malaria (n = 119), uncomplicated malaria (n = 91), or suspected bacterial sepsis (n = 56), as well as healthy participants (n = 50), were recruited. The systemic vascular resistance index (SVRI) was estimated from the echocardiographic cardiac index and the mean arterial pressure.

RESULTS

SVRI and hematocrit levels were lower and plasma CFH and asymmetric dimethylarginine levels were higher in patients with malaria, compared with healthy participants. In multivariate linear regression models for mean arterial pressure or SVRI in patients with severe malaria, hematocrit and CFH but not asymmetric dimethylarginine were significant predictors. The SVRI was lower in patients with suspected bacterial sepsis than in those with severe malaria, after adjustment for hematocrit and age. Plasma CFH levels correlated positively with the core-peripheral temperature gradient and plasma lactate levels and inversely with the perfusion index. Impaired peripheral perfusion, as reflected by a low perfusion index or a high core-peripheral temperature gradient, predicted mortality in patients with severe malaria.

CONCLUSIONS

CFH is associated with mean arterial pressure, SVRI, and peripheral perfusion in patients with severe malaria. This may be mediated through the nitric oxide scavenging potency of CFH, increasing basal vascular tone and impairing tissue perfusion.

Endovascular Perfusion Augmentation for Critical Care: Partial Aortic Occlusion for Treatment of Severe Ischemia-Reperfusion Shock

BACKGROUND

The resuscitation of patients in shock is materially intensive and many patients are refractory to maximal therapy. We hypothesized that partial inflation of an intra-aortic balloon, termed Endovascular Perfusion Augmentation for Critical Care (EPACC), would minimize material requirements while improving physiologic metrics.

METHODS

Swine underwent a 25% controlled bleed and 45 min of complete aortic occlusion to create a severe ischemia-reperfusion shock state. Animals received either standardized critical care (SCC) composed of IV fluids and norepinephrine delivered through an algorithmically controlled platform or EPACC in addition to SCC. Physiologic parameters were collected, and blood was sampled for analysis. Primary outcomes were total IV fluids and average MAP during the critical care phase. Differences (P < 0.05) were measured with t test (continuous data) and Wilcoxon rank-sum test (ordinal data).

RESULTS

There were no differences in baseline characteristics. There were no differences in the maximum lactate; however, animals in the EPACC group had a higher average MAP (EPACC 65 mmHg, 95% confidence interval [CI], 65-66; SCC 60 mmHg, 95% CI, 57-63; P < 0.01) and remained within goal MAP for a greater period of time (EPACC 95.3%, 95% CI, 93.2-97.4; SCC 51.0%, 95% CI, 29.5-72.6; P < 0.01). EPACC animals required less IV fluids when compared with the SCC group (EPACC 21 mL/kg, 95% CI, 0-42; SCC 96 mL/kg, 95% CI, 76-117; P < 0.01). There were no differences in final lactate. Animals in the EPACC group had a higher final creatinine (EPACC 2.3 mg/dL, 95% CI, 2.1-2.5; SCC 1.7 mg/dL, 95% CI, 1.4-2.0; P < 0.01), but there were no differences in renal cellular damage on histology (P = 0.16).

CONCLUSION

Using a swine model of severe shock, the addition of EPACC to SCC significantly reduced fluid resuscitation requirements and improved blood pressure. This is the first description of a new therapy for patients in refractory shock or in resource-limited settings.

Cytokine adsorption as a promising option for septic shock and multiple organ failure due to Candida infection and decompensated type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) represents one of the most common chronic diseases in childhood. It is associated with high morbidity and mortality rates due to metabolic dysregulation, immunosuppressive effects, and a predisposition to fungal infections. Candidiasis is a severe infection and its prevalence has increased throughout the last decades. We report the case of a 19-year-old female patient admitted to our intensive care unit with T1DM and Candida infection associated with severe metabolic acidosis. In the absence of response to high dose catecholamine cardiovascular therapy and the presence of severe metabolic acidosis, a CytoSorb cartridge was implemented into the extracorporeal dialysis circuit resulting in a stabilization of hemodynamics accompanied by a tremendous decrease in vasopressor requirements, control of the hyperinflammatory response, as well as a resolution of metabolic acidosis and regeneration of renal function. Treatment with CytoSorb was safe and feasible without technical problems. Notably, this is the first case description reporting on the effects of CytoSorb in a patient with Candida infection as part of T1DM.

Impact of Cytokine Adsorption Treatment in Liver Failure

Sepsis causes life-threatening organ dysfunction and is the leading cause of morbidity and mortality in critically ill patients worldwide. Mortality rate of sepsis is close to 30% to 50% despite better understanding of the pathophysiology of sepsis, and advances in antimicrobial therapy, resuscitation strategies, and mechanical ventilation. Liver failure is characterized by accumulation of potentially toxic substances in the systemic circulation of the patient. Toxic effects of these molecules can induce cellular injuries leading to multiorgan dysfunction. Hydrophobic unconjugated bilirubin and bile acids, hydrophilic conjugated bilirubin, and ammonium are the main toxins accumulated in liver failure. We carried out cytokine adsorbtion (CytoSorb) procedure with continuous venovenous hemodialysis in 12-hour sessions. The biochemical values of the patients before and after the use of the filter were recorded. The parameters compared were as follows: total bilirubin, direct bilirubin, C-reactive protein, leukocyte, neutrophil, alanine aminotransferase, aspartate aminotransferase, creatinine, colloid oncotic pressure, ammonia, gamma-glutamyl transferase, alkaline phosphatase, procalcitonin, hematocrit, hemoglobin, pH, albumin, international normalized ratio, fibrinogen, lactate dehydrogenase, platelet, temperature, changes in vasoactive medication requirement, temperature. According to these results, cytokine adsorption systems can be considered as an option to lower bilirubin levels in cases of liver failure. Its inability to lower ammonia level is considered a disadvantage compared with other bilirubin-lowering methods. Although further studies are needed to compare different methods, cytokine adsorption systems may be considered in treatment planning as it contributes to the treatment of sepsis and hyperbilirubinemia in liver failure patients with sepsis.

Hemoadsorption by CytoSorb in septic patients: a case series

Background

Septic shock, defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, is a highly lethal condition that causes substantial morbidity and mortality among critically ill patients. One of the hallmarks of sepsis is the excessive release of cytokines and other inflammatory mediators causing refractory hypotension, tissue damage, metabolic acidosis and ultimately multiple organ failure. In this context, cytokine reduction by hemoadsorption represents a new concept for blood purification, developed to attenuate the overwhelming systemic levels of pro-inflammatory and anti-inflammatory mediators released in the early phase of sepsis.

Methods

In the present case series, we evaluated the impact of a new hemoadsorption device (CytoSorb) used as adjunctive therapy, on hemodynamics and clinically relevant outcome parameters in 26 critically ill patients with septic shock and in need of renal replacement therapy.

Results

We found that treatment of these patients with septic shock was associated with hemodynamic stabilization and a reduction in blood lactate levels. Actual mortality in the overall patient population was lower than mortality predicted by acute physiology and chronic health evaluation II (APACHE II). These effects seem to be more pronounced in patients in whom therapy started within 24 h of sepsis diagnosis, whereas a delay in the start of therapy was associated with a poor response to therapy in terms of reduction of catecholamine demand and survival. Moreover, from our patient population, medical patients seemed to benefit more than post-surgical patients in terms of survival. Treatment using the CytoSorb device was safe and well-tolerated with no device-related adverse events during or after the treatment sessions.

Conclusion

Hemoadsorption using CytoSorb resulted in rapid hemodynamic stabilization and increased survival, particularly in patients in whom therapy was started early. Given the positive clinical experience of this case series, randomized controlled trials are urgently needed to define the potential benefits of this new treatment option.

Complement and sepsis-induced heart dysfunction

It is well known that cardiac dysfunction develops during sepsis in both humans and in rodents (rats, mice). These defects appear to be reversible, since after "recovery" from sepsis, cardiac dysfunction disappears and the heart returns to its function that was present before the onset of sepsis. Our studies, using in vivo and in vitro models, have demonstrated that C5a and its receptors (C5aR1 and C5aR2) play key roles in cardiac dysfunction developing during sepsis. Use of a neutralizing antibody to C5a largely attenuates cardiac dysfunction and other adverse events developing during sepsis. The molecular basis for cardiac dysfunctions is linked to generation of C5a and its interaction with C5a receptors present on surfaces of cardiomyocytes (CMs). It is established that C5a interactions with C5a receptors leads to significant reductions involving faulty contractility and relaxation in CMs. In addition, C5a interactions with C5a receptors on CMs results in reductions in Na⁺/K⁺-ATPase in CMs. This ATPase is essential for intact action potentials in CMs. The enzymatic activity and protein for this ATPase were strikingly reduced in CMs during sepsis by unknown mechanisms. In addition, C5a interactions with C5aRs also caused reductions in CM homeostatic proteins that regulate cytosolic [Ca²⁺]i in CMs: sarco/endoplasmic reticulum Ca²⁺-ATPase2 (SERCA2) and Na⁺/Ca²⁺ exchanger (NCX). In the absence of C5a receptors, defects in SERCA2 and NCX in CMs after sepsis are strikingly attenuated. These observations suggest new strategies to protect the heart from dysfunction developing during sepsis.

Day 3 versus Day 1 Disseminated Intravascular Coagulation Score among Sepsis Patients: A Prospective Observational Study

The role of disseminated intravascular coagulation (DIC) has not been extensively studied in patients with sepsis. A prospective study was performed in a single university hospital. The incidences of DIC at day 1 (<24 hours post-sepsis diagnosis) and day 3 (48 to 72 hours) were investigated among patients with sepsis. The International Society of Thrombosis and Haemostasis criteria for DIC were used. Among 381 patients initially screened, 219 were enrolled in this study and the incidences of overt DIC were 27.9% and 30.1% on day 1 and day 3, respectively. Patients with pneumonia had a lower incidence of DIC on day 1, but a higher hospital mortality rate compared to those with non-pneumonia sepsis. In multivariate models, although day 1 and day 3 DIC scores were not associated with hospital mortality after adjusting for existing severity scores, the change in DIC scores (odds ratio 1.862; 95% confidence interval 1.061 to 3.266) exhibited a significant association. Day 3 DIC scores were more accurate in predicting hospital mortality than day 1 DIC scores ( P <0.001), especially in patients with non-pneumonia sepsis. However, DIC scores did not give additional discriminative power to the existing prognostic scores in predicting mortality of patients with sepsis. In conclusion, the change in DIC score was significantly associated with hospital mortality. Patients with pneumonia sepsis had a lower incidence of DIC on day 1, despite their higher disease severity and mortality rate, compared to those with other sources of sepsis.

Sepsis pathophysiology and anesthetic consideration

Sepsis remains to be a significant health care issue associated with high mortality and healthcare cost, despite the extensive effort to better understand the pathophysiology of the sepsis. Recently updated clinical guideline for severe sepsis and septic shock, "Surviving Sepsis Campaign 2012", emphasizes the importance of early goal-directed therapy, which can be implemented in intraoperative management of sepsis patients. Herein, we review the updates of current guideline and discuss its application to anesthesic management. Furthermore, we review the recent advance in knowledge of sepsis pathophysiology, focusing on immune modulation, which may lead to new clinical therapeutic approach to sepsis.

The conserved nhaAR operon is drastically divergent between B2 and non-B2 Escherichia coli and is involved in extra-intestinal virulence

The Escherichia coli species is divided in phylogenetic groups that differ in their virulence and commensal distribution. Strains belonging to the B2 group are involved in extra-intestinal pathologies but also appear to be more prevalent as commensals among human occidental populations. To investigate the genetic specificities of B2 sub-group, we used 128 sequenced genomes and identified genes of the core genome that showed marked difference between B2 and non-B2 genomes. We focused on the gene and its surrounding region with the strongest divergence between B2 and non-B2, the antiporter gene nhaA. This gene is part of the nhaAR operon, which is in the core genome but flanked by mobile regions, and is involved in growth at high pH and high sodium concentrations. Consistently, we found that a panel of non-B2 strains grew faster than B2 at high pH and high sodium concentrations. However, we could not identify differences in expression of the nhaAR operon using fluorescence reporter plasmids. Furthermore, the operon deletion had no differential impact between B2 and non-B2 strains, and did not result in a fitness modification in a murine model of gut colonization. Nevertheless, sequence analysis and experiments in a murine model of septicemia revealed that recombination in nhaA among B2 strains was observed in strains with low virulence. Finally, nhaA and nhaAR operon deletions drastically decreased virulence in one B2 strain. This effect of nhaAR deletion appeared to be stronger than deletion of all pathogenicity islands. Thus, a population genetic approach allowed us to identify an operon in the core genome without strong effect in commensalism but with an important role in extra-intestinal virulence, a landmark of the B2 strains.

Sepsis Associated Encephalopathy

Sepsis associated encephalopathy (SAE) is a common but poorly understood neurological complication of sepsis. It is characterized by diffuse brain dysfunction secondary to infection elsewhere in the body without overt CNS infection. The pathophysiology of SAE is complex and multifactorial including a number of intertwined mechanisms such as vascular damage, endothelial activation, breakdown of the blood brain barrier, altered brain signaling, brain inflammation, and apoptosis. Clinical presentation of SAE may range from mild symptoms such as malaise and concentration deficits to deep coma. The evaluation of cognitive dysfunction is made difficult by the absence of any specific investigations or biomarkers and the common use of sedation in critically ill patients. SAE thus remains diagnosis of exclusion which can only be made after ruling out other causes of altered mentation in a febrile, critically ill patient by appropriate investigations. In spite of high mortality rate, management of SAE is limited to treatment of the underlying infection and symptomatic treatment for delirium and seizures. It is important to be aware of this condition because SAE may present in early stages of sepsis, even before the diagnostic criteria for sepsis can be met. This review discusses the diagnostic approach to patients with SAE along with its epidemiology, pathophysiology, clinical presentation, and differential diagnosis.

Sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction that occurs secondary to infection in the body without overt CNS infection. SAE is frequently encountered in critically ill patients in intensive care units, and in up to 70% of patients with severe systemic infection. The severity of SAE can range from mild delirium to deep coma. Seizures and myoclonus are infrequent and cranial nerves are almost always spared, but most severe cases have an associated critical illness neuromyopathy. Development of SAE probably involves a number of mechanisms that are not mutually exclusive and vary from patient to patient. Substantial neurological and psychological morbidities often occur in survivors. Mortality is almost always due to multiorgan failure rather than neurological complications, and is almost 70% in patients with severe SAE. Further research into the pathophysiology, management and prevention of SAE is needed. This Review discusses the epidemiology and clinical presentation of SAE. Recent evidence for SAE pathophysiology is outlined and a diagnostic approach to patients with this syndrome is presented. Lastly, prognosis and management of SAE is discussed.

Patterns of unexpected in-hospital deaths: a root cause analysis

BACKGROUND

Respiratory alarm monitoring and rapid response team alerts on hospital general floors are based on detection of simple numeric threshold breaches. Although some uncontrolled observation trials in select patient populations have been encouraging, randomized controlled trials suggest that this simplistic approach may not reduce the unexpected death rate in this complex environment. The purpose of this review is to examine the history and scientific basis for threshold alarms and to compare thresholds with the actual pathophysiologic patterns of evolving death which must be timely detected.

METHODS

The Pubmed database was searched for articles relating to methods for triggering rapid response teams and respiratory alarms and these were contrasted with the fundamental timed pathophysiologic patterns of death which evolve due to sepsis, congestive heart failure, pulmonary embolism, hypoventilation, narcotic overdose, and sleep apnea.

RESULTS

In contrast to the simplicity of the numeric threshold breach method of generating alerts, the actual patterns of evolving death are complex and do not share common features until near death. On hospital general floors, unexpected clinical instability leading to death often progresses along three distinct patterns which can be designated as Types I, II and III. Type I is a pattern comprised of hyperventilation compensated respiratory failure typical of congestive heart failure and sepsis. Here, early hyperventilation and respiratory alkalosis can conceal the onset of instability. Type II is the pattern of classic CO2 narcosis. Type III occurs only during sleep and is a pattern of ventilation and SPO2 cycling caused by instability of ventilation and/or upper airway control followed by precipitous and fatal oxygen desaturation if arousal failure is induced by narcotics and/or sedation.

CONCLUSION

The traditional threshold breach method of detecting instability on hospital wards was not scientifically derived; explaining the failure of threshold based monitoring and rapid response team activation in randomized trials. Furthermore, the thresholds themselves are arbitrary and capricious. There are three common fundamental pathophysiologic patterns of unexpected hospital death. These patterns are too complex for early detection by any unifying numeric threshold. New methods and technologies which detect and identify the actual patterns of evolving death should be investigated.

The evolution of the understanding of sepsis, infection, and the host response: a brief history

An appreciation for the problem of sepsis starts at the very beginning of recorded time. Early writings from the Middle East, China, and Greece indicate that waves of epidemics and sudden death in previously healthy people were noted as having special significance long before the germ theory of disease was first postulated. This article focuses on the evolution of understanding about the fundamental nature of infection and the host response that leads to sepsis.

The history and evolution of circulatory shock

This article reviews the development of early ideas regarding the origins and pathogenesis of shock. The early history of shock is related primarily to traumatic shock. More recent history centers on differentiation of clinical syndromes and individual characteristics. Definitions, classification systems, pathogenic theories, and treatments have evolved. Progress has been aided by constant development of improved assessment technologies. Today, shock is not a single syndrome and the definition of shock no longer is descriptive in nature. The most accepted current definition involves an oxygen supply/demand imbalance that can have various causes-hypovolemia, cardiac dysfunction, vascular failure, or obstructive processes.

Cardiac assessment of patients for haematopoietic stem cell transplantation

The expanding role of haematopoietic stem-cell transplantation (HSCT) renders the previous policy of avoiding transplantation in high-risk cardiac patients obsolete. Patients with amyloid, autoimmune conditions, sickle-cell disease, or thalassaemia, and patients over the age of 60 years are increasingly being offered HSCT. It is evident that the policy of avoiding transplantation in patients with impaired systolic function fails to identify all high-risk patients in such groups, and will deprive some patients of the benefits of HSCT unnecessarily. The development of an appropriate algorithm for cardiac pre-assessment and peri-transplant management is hampered by an inadequate understanding of the predictive value of various tests of cardiovascular function, the rapid evolution of advanced management strategies for cardiac dysfunction, and the development of non-cardiotoxic conditioning regimens. To meet this need we propose that an algorithm based on evidence from other clinical situations - already been found to be successful in the management of HSCT in patients with systemic sclerosis - should be used uniformly, and registry studies should be undertaken to distinguish those aspects of the algorithm that positively help to expand the remit of HSCT from those that add little of value.

Ischemia reperfusion injury, preconditioning and critical illness

The purpose of this review is to describe in more detail ischemia reperfusion injury and preconditioning, and to speculate on the potential role of preconditioning in the care of critically ill patients. Current hemodynamic treatment of hypotension and hypoperfusion in critically ill patients is directed at ensuring essential organ perfusion by maintaining intravascular volume and cardiac output, and ensuring adequate oxygen delivery by maintaining arterial oxygen partial pressure and hemoglobin levels. However, morbidity and mortality remain high and new approaches to critically ill patients are required. Treatments are needed that can protect against organ ischemia during periods of low blood flow. In recent years, there has been a growing appreciation of the importance of ischemia reperfusion injury. Ischemia associated with reperfusion may result in greater injury than ischemia alone. Ischemic preconditioning is used to describe the protective effect of short periods of ischemia to an organ or tissue against longer periods of ischemia. Although first described in the myocardium, there is now evidence that this phenomenon occurs in a wide variety of organs and tissues, including the brain and other nervous tissue such as the retina and spinal cord, liver, stomach, intestines, kidney, and the lungs. Preconditioning therapy may offer a new avenue of treatment in critically ill patients. Both traditional preconditioning methods and pharmacologic agents that mimic or induce such preconditioning may be used in the future. Clinical trials of pharmacologic agents are underway in patients with coronary artery disease. Further trials of such methods and agents are needed in critically ill patients suffering from sepsis or multiorgan system failure.

High-volume hemofiltration as salvage therapy in severe hyperdynamic septic shock

OBJECTIVES

To evaluate the effect of short-term (12-h) high-volume hemofiltration (HVHF) in reversing progressive refractory hypotension and hypoperfusion in patients with severe hyperdynamic septic shock. To evaluate feasibility and tolerance and to compare observed vs. expected hospital mortality.

DESIGN AND SETTING

Prospective, interventional, nonrandomized study in the surgical-medical intensive care unit of an academic tertiary center.

PATIENTS

Twenty patients with severe septic shock, previously unresponsive to a multi-intervention approach within a goal-directed, norepinephrine-based algorithm, with increasing norepinephrine (NE) requirements (>0.3 microg kg(-1) min(-1)) and lactic acidosis.

INTERVENTIONS

Single session of 12-h HVHF.

MEASUREMENTS AND RESULTS

We measured changes in NE requirements and perfusion parameters every 4h during HVHF and 6h thereafter. Eleven patients showed decreased NE requirements and lactate levels (responders). Nine patients did not fulfill these criteria (nonresponders). The NE dose, lactate levels, and heart rates decreased and arterial pH increased significantly in responders. Hospital mortality (40%) was significantly lower than predicted (60%): 67% (6/9) in nonresponders vs. 18% (2/11) in responders. Of 12 survivors 7 required only a single 12-h HVHF session. On logistic regression analysis the only statistically significant predictor of survival was theresponse to HVHF (odds ratio 9).

CONCLUSIONS

A single session of HVHF as salvage therapy in the setting of a goal-directed hemodynamic management algorithm may be beneficial in severe refractory hyperdynamic septic-shock patients. This approach may improve hemodynamics and perfusion parameters, acid-base status, and ultimately hospital survival. Moreover, it is feasible, and safe.

Critical care in the emergency department: shock and circulatory support

Effective resuscitation includes the rapid identification and correction of an inadequate circulation. Shock is said to be present when systemic hypoperfusion results in severe dysfunction of the vital organs. The finding of normal haemodynamic parameters, for example blood pressure, does not exclude shock in itself. This paper reviews the pathophysiology, resuscitation, and continuing management of the patient presenting with shock to the emergency department.

Endotoxin releases a precursor to vasodilation from large veins in an NF-κB-dependent manner

INTRODUCTION

Our previous studies have shown that when a segment of rat aorta was placed upstream and in series to a rat cremasteric isolated arteriole, endotoxin (ET) exposure produced significant vasodilatation. Without the aorta, no loss of tone was noted, indicating that a precursor, as of yet unidentified, was washed downstream, thereby inducing vasodilation. Prior treatment of the donor of either the aorta or the arteriole with pyrrolidine dithiocarbamate (PDTC), a potent NF-kappaB inhibitor, prevented the loss of tone. This suggests a role for NF-kappaB in the signaling pathway. The aim of this study was to determine if a large vein was also capable of releasing a similar factor in response to ET.

MATERIALS AND METHODS

This project followed the same experimental design except that the upstream aortic segment was replaced by a segment of vena cava. Male Sprague-Dawley rats were given an intraperitoneal (ip) injection of PDTC (100 mg/kg) or a sham injection of saline. First-order cremasteric arterioles were isolated, cannulated, and pressurized. A segment of inferior vena cava was then placed in series with the microvascular preparation. Arterioles were allowed to equilibrate and achieve spontaneous myogenic tone in a bath of warm physiological buffer over 1 h (t = 0). Internal vessel diameters were measured with video calipers and the response to ET or continued infusion of buffer was measured over 2 h (t = 120). The control group (n = 8) received a sham injection and the vessels were exposed to buffer only. The ET group (n = 7) was exposed to ET only. The PDTC group (n = 5) received PDTC only. The PDTC/ET group (n = 6) received PDTC and was exposed to ET.

RESULTS

After equilibration, spontaneous tone (measured as a percentage of maximal diameter) was similar in the four groups (t = 0). After 2 h (t = 120), the ET group had significantly less tone (30.1 +/- 3.6%; P < 0.05) than the control (44.8 +/- 2.6%), the PDTC group (43.0 +/- 1.3%), and the PDTC/ET group (49.4 +/- 3.0%).

CONCLUSIONS

These results show that the vena cava is capable of releasing a factor leading to vasodilation in response to ET in a manner similar to the aorta. Produced by the veins, it will affect venous capacitance as well as contribute to the total amount in the plasma pool affecting the tone of the resistant arterioles. Thus, it appears that these large conducting vessels, regardless of origin, play a role in the deleterious effects during septic events.

The role of Ca++-sensitizers for the treatment of heart failure

For increasing myocardial contractility in patients with cardiac failure, catecholamines, phosphodiesterase-III (PDE) inhibitors, and calcium sensitizers are available. Improving myocardial performance with catecholamines and PDE inhibitors leads to increased intracellular calcium concentration as an unavoidable side effect. An increase in intracellular calcium can induce harmful arrhythmias and increases the energetic demands of the myocardium. Long-term trials with PDE inhibitors have raised concerns about the safety of positive inotropic treatment for cardiac failure. Calcium sensitizers are a new class of inotropic drugs. They improve myocardial performance by directly acting on contractile proteins without increasing intracellular calcium load. Thus, they avoid the undesired effects of an increased intracellular calcium load. Calcium sensitizers may enhance myocardial performance without increasing myocardial oxygen consumption and without provoking fatal arrhythmias. Two calcium sensitizers are available for the treatment of cardiac failure in men. Pimobendan is a drug with positive inotropic effects that additionally inhibits the production of proinflammatory cytokines. However, it exerts a significant inhibition of PDE at clinically relevant doses. Levosimendan is a calcium sensitizer with no major inhibition of PDE at clinically relevant doses. It opens ATP-dependent potassium channels and thus has vasodilating and cardioprotective effects. The most important studies of the long-term treatment of stable cardiac failure with pimobendan and on the short-term treatment of unstable cardiac failure with levosimendan are presented.

In vivo measurement of nitric oxide production in porcine gut, liver and muscle during hyperdynamic endotoxaemia

1. During prolonged endotoxaemia, an increase in arginine catabolism may result in limiting substrate availability for nitric oxide (NO) production. These effects were quantitated in a chronically instrumented porcine endotoxaemia model. 2. Ten days prior to the beginning of the experiments, pigs were catheterized. On day 0, pigs received a continuous infusion of endotoxin (3 microg kg(-1) h(-1)) over 24 h and were saline resuscitated. Blood was drawn from the catheters at 0 and 24 h during primed-infusion of (15)N(2)-arginine and P-aminohippurate to assess (15)N(2)-arginine to (15)N-citrulline conversion and plasma flow rates, respectively, across the portal-drained viscera, liver and hindquarter. 3. During endotoxin infusion a hyperdynamic circulation with elevated heart rate, cardiac index and decreased mean arterial pressure was achieved, characteristic of the human septic condition. 4. Endotoxin induced NO production by the portal-drained viscera and the liver. The increased NO production was quantitatively matched by an increase in arginine disposal. Nitrite/nitrate levels remained unchanged during endotoxaemia. 5. Despite an increased arginine production from the hindquarter and an increased whole-body arginine appearance rate during endotoxin infusion, the plasma arginine concentration was lower in endotoxin-treated animals than in controls. 6 On a whole-body level, the muscle was found to serve as a major arginine supplier and, considering the lowered arginine plasma levels, seems critical in providing arginine as precursor for NO synthesis in the splanchnic region.