Neutrophils, nitric oxide, and microvascular permeability in severe sepsis

Molecular Targets of Brown Algae Phlorotannins for the Therapy of Inflammatory Processes of Various Origins

Inflammatory reactions are part of a complex biological response that plays a vital role in the appearance of various stimuli resulting from tissue and cell damage, the invasion of pathogenic bacteria, and the formation of the subsequent adaptive immune response. The production of many triggers and mediators of inflammation, which are inducers of pro-inflammatory factors, is controlled by numerous differentiation programs, through which inflammation is resolved and tissue homeostasis is restored. However, prolonged inflammatory responses or dysregulation of pro-inflammatory mechanisms can lead to chronic inflammation. Modern advances in biotechnology have made it possible to characterize the anti-inflammatory activity of phlorotannins, polyphenolic compounds from brown seaweed, and the mechanisms by which they modulate the inflammatory response. The purpose of this review is to analyze and summarize the results of numerous experimental in vitro and in vivo studies, illustrating the regulatory mechanisms of these compounds, which have a wide range of biological effects on the body. The results of these studies and the need for further research are discussed.

The Role of Sphingolipid Signaling in Oxidative Lung Injury and Pathogenesis of Bronchopulmonary Dysplasia

Premature infants are born with developing lungs burdened by surfactant deficiency and a dearth of antioxidant defense systems. Survival rate of such infants has significantly improved due to advances in care involving mechanical ventilation and oxygen supplementation. However, a significant subset of such survivors develops the chronic lung disease, Bronchopulmonary dysplasia (BPD), characterized by enlarged, simplified alveoli and deformed airways. Among a host of factors contributing to the pathogenesis is oxidative damage induced by exposure of the developing lungs to hyperoxia. Recent data indicate that hyperoxia induces aberrant sphingolipid signaling, leading to mitochondrial dysfunction and abnormal reactive oxygen species (ROS) formation (ROS). The role of sphingolipids such as ceramides and sphingosine 1-phosphate (S1P), in the development of BPD emerged in the last decade. Both ceramide and S1P are elevated in tracheal aspirates of premature infants of <32 weeks gestational age developing BPD. This was faithfully reflected in the murine models of hyperoxia and BPD, where there is an increased expression of sphingolipid metabolites both in lung tissue and bronchoalveolar lavage. Treatment of neonatal pups with a sphingosine kinase1 specific inhibitor, PF543, resulted in protection against BPD as neonates, accompanied by improved lung function and reduced airway remodeling as adults. This was accompanied by reduced mitochondrial ROS formation. S1P receptor1 induced by hyperoxia also aggravates BPD, revealing another potential druggable target in this pathway for BPD. In this review we aim to provide a detailed description on the role played by sphingolipid signaling in hyperoxia induced lung injury and BPD.

Characterizing Eckol as a Therapeutic Aid: A Systematic Review

The marine biosphere is a treasure trove of natural bioactive secondary metabolites and the richest source of structurally diverse and unique compounds, such as phlorotannins and halo-compounds, with high therapeutic potential. Eckol is a precursor compound representing the dibenzo-1,4-dioxin class of phlorotannins abundant in the Ecklonia species, which are marine brown algae having a ubiquitous distribution. In search of compounds having biological activity from macro algae during the past three decades, this particular compound has attracted massive attention for its multiple therapeutic properties and health benefits. Although several varieties of marine algae, seaweed, and phlorotannins have already been well scrutinized, eckol deserves a place of its own because of the therapeutic properties it possesses. The relevant information about this particular compound has not yet been collected in one place; therefore, this review focuses on its biological applications, including its potential health benefits and possible applications to restrain diseases leading to good health. The facts compiled in this review could contribute to novel insights into the functions of eckol and potentially enable its use in different uninvestigated fields.

Comparison of bedside assessed arm and leg fluid filtration determined by venous congestion plethysmography in perioperative cancer patients: An observational study investigating agreement

In recent years, pathophysiology and clinical impact of microvascular fluid filtration has regained interest. As the latest data in surgical patients have been published almost 20 years ago, there is need for further research to better understand fluid filtration during the perioperative period. Venous congestion plethysmography (VCP) provides a rapid and noninvasive method, which has been shown suitable for the assessment of fluid filtration in limbs. Fluid filtration assessed by VCP can be obtained from forearm and calf measurement sites, while in many clinical situations a reduced access to the patient often restricts the measurements to patient's forearm. We aimed to investigate if fluid filtration obtained from forearm and calf measurement site is interchangeable in nonsedated perioperative patients.Fluid filtration by VCP was obtained simultaneously from forearm and calf in patients with ovarian cancer at 4 time points during the perioperative course and assessed by the difference of volume changes of the limb between third and sixth minutes (VC6-3min) during venous congestion. VC6-3min obtained from forearm and calf measurement sites was compared with respect to agreement and evaluated regarding the association with the presence of leg edema.A total of 74 paired measurements were analyzed in 29 patients. Forearm VC6-3min was significantly higher than calf VC6-3min (median [25th; 75th quartile], 0.6 (0.4; 0.9) vs 0.4 [0.3; 0.6] %, P = 0.008). Bland-Altman and Polar analysis revealed a poor agreement between forearm and calf VC6-3min at predefined time points and changes of VC6-3min during the perioperative course (bias +0.23%, limits of agreement [LOA] -1.1% to 1.6%; angular bias -2.5°, radial LOA -82° to +77°). Forearm VC6-3min was significantly increased in patients with presence of leg edema (0.7 (0.5; 1.0) vs 0.5 (0.4; 0.6) %, P < 0.001) while calf VC6-3min did not differ in patients with and without edema.This study indicates that forearm and calf measurement sites are not interchangeable when bedside assessing fluid filtration by VCP in nonsedated perioperative patients. Considering that only forearm fluid filtration was related to the presence of edema, forearm measurement site should be chosen as a primary site for assessing fluid filtration.

Direct detection of blood nitric oxide reveals a burn-dependent decrease of nitric oxide in response to Pseudomonas aeruginosa infection

PURPOSE

Burn is associated with severe immune dysfunction, including an anti-inflammatory state that occurs late after burn. While increased nitric oxide (NO) production is associated with severe infection and sepsis, the effect of burn trauma on these levels during a non-lethal infection remains unknown. We hypothesized that in a mouse model, (1) NO levels would be increased after infection without trauma and (2) burn would lead to decreased NO production even during infection.

METHODS

Mice were infected via intra-tracheal inoculation with Pseudomonas aeruginosa 14 d following a 20% total body surface area contact burn. At 48h following infection, blood was drawn to quantify NO concentrations using a microfluidic electrochemical sensor.

SIGNIFICANT FINDINGS

In uninjured mice, infection caused a significant increase in blood NO levels. Increases in NO occurred in a dose-dependent response to the bacterial inoculum. Following burn, an identical infection did not elicit increases in NO.

CONCLUSIONS

While increases in NO are expected over the course of an infection without prior trauma, burn and subsequent immune suppression decreases NO levels even in the presence of infection.

Biomarkers of necrotising soft tissue infections: aspects of the innate immune response and effects of hyperbaric oxygenation-the protocol of the prospective cohort BIONEC study

INTRODUCTION

The mortality and amputation rates are still high in patients with necrotising soft tissue infections (NSTIs). It would be ideal to have a set of biomarkers that enables the clinician to identify high-risk patients with NSTI on admission. The objectives of this study are to evaluate inflammatory and vasoactive biomarkers as prognostic markers of severity and mortality in patients with NSTI and to investigate whether hyperbaric oxygen treatment (HBOT) is able to modulate these biomarkers. The overall hypothesis is that plasma biomarkers can be used as prognostic markers of severity and mortality in patients with NSTI and that HBOT reduces the inflammatory response.

METHODS AND ANALYSIS

This is a prospective, observational study being conducted in a tertiary referral centre. Biomarkers will be measured in 114 patients who have been operatively diagnosed with NSTI. On admission, baseline blood values will be obtained. Following surgery and HBOT, daily blood samples for measuring regular inflammatory and vasoactive biomarkers (pentraxin-3, interleukin-6 and nitrite) will be acquired. Samples will be analysed using validated ELISA assays, chemiluminescence and Griess reaction. Clinical data will be obtained during admission in the intensive care unit for a maximum of 7 days. The primary analysis will focus on pentraxin-3, interleukin-6 and nitrite as early markers of disease severity in patients with NSTI.

ETHICS AND DISSEMINATION

The study has been approved by the Regional Scientific Ethical Committee of Copenhagen (H-2-2014-071) and the Danish Data Protection Agency (J. no. 30-0900 and J. no. 30-1282). Results will be presented at national and international conferences and published in peer-reviewed scientific journals.

TRIAL REGISTRATION

NCT02180906.

S-Nitrosothiol analysis via photolysis and amperometric nitric oxide detection in a microfluidic device

A 530 nm light emitting diode was coupled to a microfluidic sensor to facilitate photolysis of nitrosothiols (i.e., S-nitrosoglutathione, S-nitrosocysteine, and S-nitrosoalbumin) and amperometric detection of the resulting nitric oxide (NO). This configuration allowed for maximum sensitivity and versatility, while limiting potential interference from nitrate decomposition caused by ultraviolet light. Compared to similar measurements of total S-nitrosothiol content in bulk solution, use of the microfluidic platform permitted significantly enhanced analytical performance in both phosphate-buffered saline and plasma (6-20× improvement in sensitivity depending on nitrosothiol type). Additionally, the ability to reduce sample volumes from milliliters to microliters provides increased clinical utility. To demonstrate its potential for biological analysis, this device was used to measure basal nitrosothiol levels from the vasculature of a healthy porcine model.

Anti-inflammatory functions of purpurogallin in LPS-activated human endothelial cells

Enzymatic oxidation of commercially available pyrogallol was efficiently transformed to an oxidative product, purpurogallin. Purpurogallin plays an important role in inhibiting glutathione S-transferase, xanthine oxidase, catechol O-methyltransferase activities and is effective in the cell protection of several cell types. However, the anti-inflammatory functions of purpurogallin are not well studied. Here, we determined the effects of purpurogallin on lipopolysaccharide (LPS)-mediated proinflammatory responses. The results showed that purpurogallin inhibited LPS-mediated barrier hyper-permeability, monocyte adhesion and migration and such inhibitory effects were significantly correlated with the inhibitory functions of purpurogallin on LPS-mediated cell adhesion molecules (vascular cell adhesion molecules, intracellular cell adhesion molecule, E-selectin). Furthermore, LPS-mediated nuclear factor-κB (NF-κB) and tumor necrosis factor-α (TNF-α) releases from HUVECs were inhibited by purpurogallin. Given these results, purpurogallin showed its anti-inflammatory activities and could be a candidate as a therapeutic agent for various systemic inflammatory diseases. [BMB reports 2012; 45(3): 200-205].

Neutrophils from critically ill septic patients mediate profound loss of endothelial barrier integrity

Introduction

Sepsis is characterized by systemic immune activation and neutrophil-mediated endothelial barrier integrity compromise, contributing to end-organ dysfunction. Studies evaluating endothelial barrier dysfunction induced by neutrophils from septic patients are lacking, despite its clinical significance. We hypothesized that septic neutrophils would cause characteristic patterns of endothelial barrier dysfunction, distinct from experimental stimulation of normal neutrophils, and that treatment with the immunomodulatory drug β-glucan would attenuate this effect.

Methods

Blood was obtained from critically ill septic patients. Patients were either general surgery patients (Primary Sepsis (PS)) or those with sepsis following trauma (Secondary Sepsis (SS)). Those with acute respiratory distress syndrome (ARDS) were identified. Healthy volunteers served as controls. Neutrophils were purified and aliquots were untreated, or treated with fMLP or β-glucan. Endothelial cells were grown to confluence and activated with tissue necrosis factor (TNF)-α . Electric Cell-substrate Impedance Sensing (ECIS) was used to determine monolayer resistance after neutrophils were added. Groups were analyzed by two-way analysis of variance (ANOVA).

Results

Neutrophils from all septic patients, as well as fMLP-normal neutrophils, reduced endothelial barrier integrity to a greater extent than untreated normal neutrophils (normalized resistance of cells from septic patients at 30 mins = 0.90 ± 0.04; at 60 mins = 0.73 ± 0.6 and at 180 mins = 0.56 ± 0.05; p < 0.05 vs normal). Compared to untreated PS neutrophils, fMLP-treated PS neutrophils caused further loss of barrier function at all time points; no additive effect was noted in stimulation of SS neutrophils beyond 30 min. Neutrophils from ARDS patients caused greater loss of barrier integrity than those from non-ARDS patients, despite similarities in age, sex, septic source, and neutrophil count. Neutrophils obtained after resolution of sepsis caused less barrier dysfunction at all time points. β-glucan treatment of septic patients’ neutrophils attenuated barrier compromise, rendering the effect similar to that induced by neutrophils obtained once sepsis had resolved.

Conclusions

Neutrophils from septic patients exert dramatic compromise of endothelial barrier integrity. This pattern is mimicked by experimental activation of healthy neutrophils. The effect of septic neutrophils on the endothelium depends upon the initial inflammatory event, correlates with organ dysfunction and resolution of sepsis, and is ameliorated by β-glucan.

Barrier protective activities of curcumin and its derivative

AIM AND OBJECTIVE

Curcumin, a poly-phenolic compound, possesses diverse pharmacologic activities. However, the barrier protective functions of curcumin or its derivative have not yet been studied. The objective of this study was to investigate the barrier protective activities of curcumin and its derivative (bisdemethoxycurcumin, BDMC) on lipopolysaccharide (LPS) barrier disruption in human umbilical vein endothelial cells (HUVECs) were investigated.

METHODS

The barrier protective effects of curcumin and BDMC such as permeability, expression of cell adhesion molecules, monocytes adhesion and migration toward HUVECs were tested.

RESULTS

Curcumin and BDMC inhibited LPS-induced barrier permeability, monocyte adhesion and migration; inhibitory effects were significantly correlated with inhibitory functions of curcumin and BDMC on LPS-induced cell adhesion molecules (vascular cell adhesion molecules, intracellular cell adhesion molecule, E-selectin). Furthermore, LPS-induced nuclear factor-κB (NF-κB) activation and tumor necrosis factor-α (TNF-α) release from HUVECs were inhibited by curcumin and BDMC. Surprisingly, the barrier protective activities of BDMC were better than those of curcumin, indicating that the methoxy group in curcumin negatively regulated barrier protection function of curcumin.

CONCLUSION

Given these results, curcumin or its derivative, BDMC, showed barrier protective activities and they could be a therapeutic candidates for various systemic inflammatory diseases.

The role of sphingolipids in respiratory disease

Sphingolipids form a broad class of lipids with diverse functions ranging from membrane constituents to intracellular second messengers and extracellular mediators. They can be rapidly generated or converted into each other and they play pivotal roles in various cellular processes, many of which are broadly associated with inflammation and apoptosis. Among the numerous sphingolipids, ceramide and sphingosine-1-phosphate (S1P) have received the greatest attention. Ceramide is a hydrophobic molecule that is increased in the lungs of patients with cystic fibrosis and chronic obstructive pulmonary disease (COPD). Ceramide is the eponym for ceramide-rich membrane platforms. that need to form as a prerequisite to the uptake of several microorganisms including Pseudomonas aeruginosa, and as a prerequisite to many signaling processes including apoptosis and increased vascular permeability. Accordingly, abnormal amounts of enzymes involved in the synthesis of ceramide, such as neutral or acid sphingomyelinase, are found in emphysematic smokers and in patients with severe sepsis, and are considered as novel pharmacological targets. S1P acts as an extracellular mediator that opposes several actions of ceramide and acts by binding to G-protein coupled S1P receptors (S1P(1)-S1P(5)). Of particular interest are S1P(1) receptors that enhance vascular barrier functions and are antiapoptotic. Therefore, S1P(1)-receptor ligands are suggested as novel drugs for COPD and acute lung injury. S1P is a potent chemotaxin for many leukocytes, it organizes lymphocyte trafficking and is involved in several key symptoms of asthma such as airway hyperresponsiveness and pulmonary eosinophil sequestration. S1P is formed by sphingosine kinases that have been identified as possible drug targets for the treatment of asthma. Based on these findings, several new drugs have recently been developed to specifically target sphingomyelinases, sphingosine kinases and S1P receptors for the treatment of COPD, cystic fibrosis, asthma and acute lung injury.

Endothelial nitric oxide synthase gene polymorphisms associated with susceptibility to high altitude pulmonary edema in Chinese railway construction workers at Qinghai-Tibet over 4 500 meters above sea level

OBJECTIVE

To examine whether the polymorphisms of endothelial nitric oxide synthase (eNOS) gene are associated with the susceptibility to high altitude pulmonary edema (HAPE) in Chinese railway construction workers at Qinghai-Tibet where the altitude is over 4 500 m above sea level.

METHODS

A case-control study was conducted including 149 HAPE patients in the construction workers and 160 healthy controls randomly recruited from their co-workers, matching the patients in ethnicity, age, sex, lifestyle, and working conditions. Three polymorphisms of eNOS gene, T-786C in promoter, 894G/T in exon 7, and 27bp variable number tandem repeat (VNTR) in intron 4, were genotyped using polymerase chain reaction (PCR) and confirmed with DNA sequencing.

RESULTS

The frequencies of 894T allele and heterozygous G/T of the 894G/T variant were significantly higher in HAPE patients group than in the control group (P=0.0028 and P=0.0047, respectively). However, the frequencies of the T-786C in promoter and the 27bp VNTR in intron 4 were not significantly different between the two groups. Haplotypic analysis revealed that the frequencies of two haplotypes (H3,T-T-b, b indicates 5 repeats of 27 bp VNTR; H6, C-G-a, a indicates 4 repeats of 27 bp VNTR) were significantly higher in HAPE patients (both Pü0.0001). On the contrary, the frequencies of H1 (T-G-b) and H2 (T-G-a) were lower in HAPE patients than in healthy controls (both Pü0.001).

CONCLUSIONS

Two haplotypes (T-T-b and C-G-a) may be strongly associated with susceptibility to HAPE. Compared with the individual alleles of eNOS gene, the interaction of multiple genetic markers within a haplotype may be a major determinant for the susceptibility to HAPE.

Intravenous 2-chloroadenosine protects BALB/c mice from Klebsiella pneumoniae B5055-induced sepsis by modulating the pro-inflammatory immune response

Sepsis is a severe inflammatory immune response of the host against an infectious agent or its product i.e. lipopolysaccharide (LPS). Therefore, targeting the immune system during sepsis may lower the morbidity and mortality associated with sepsis. The present study shows the protective immunomodulatory action of 2-chloroadenosine (2-CADO) in K. pneumoniae B5055 induced sepsis in male BALB/c mice. Sepsis was induced by implanting the fibrin-thrombin clot containing known amount (10(2)cfu) of Klebsiella pneumoniae B5055 into the peritoneal cavity of mice. 100% mortality with in the 5 post infection days (PIDs) was observed in control group animals. Intravenous 2-CADO (10 microg/kg/day) treatment increased in survival of animals by 70% without significantly (p>0.05) decreasing the blood bacterial load. But a significant (p<0.05) decrease in the level of inflammatory markers (TNF-alpha, il-1alpha, MDA, NO) responsible for sepsis was observed. However, serum il-10 levels were found to be significantly (p<0.05) increased with 2-CADO treatment.

Ascorbate protects endothelial barrier function during septic insult: Role of protein phosphatase type 2A

Endothelial barrier dysfunction contributes to morbidity in sepsis. We tested the hypothesis that raising the intracellular ascorbate concentration protects the endothelial barrier from septic insult by inhibiting protein phosphatase type 2A. Monolayer cultures of microvascular endothelial cells were incubated with ascorbate, dehydroascorbic acid (DHAA), the NADPH oxidase inhibitors apocynin and diphenyliodonium, or the PP2A inhibitor okadaic acid and then were exposed to septic insult (lipopolysaccharide and interferon-gamma). Under standard culture conditions that depleted intracellular ascorbate, septic insult stimulated oxidant production and PP2A activity, dephosphorylated phosphoserine and phosphothreonine residues in the tight junction-associated protein occludin, decreased the abundance of occludin at cell borders, and increased monolayer permeability to albumin. NADPH oxidase inhibitors prevented PP2A activation and monolayer leak, showing that these changes required reactive oxygen species. Okadaic acid, at a concentration that inhibited PP2A activity and monolayer leak, prevented occludin dephosphorylation and redistribution, implicating PP2A in the response of occludin to septic insult. Incubation with ascorbate or DHAA raised intracellular ascorbate concentrations and mitigated the effects of septic insult. In conclusion, ascorbate acts within microvascular endothelial cells to inhibit septic stimulation of oxidant production by NADPH oxidase and thereby prevents PP2A activation, PP2A-dependent dephosphorylation and redistribution of occludin, and disruption of the endothelial barrier.

Non-invasive Assessment of the Microcirculation in Critically Ill Patients

Sepsis is associated with abnormalities of muscle tissue oxygenation and of microvascular function. We investigated whether the technique of near-infrared spectroscopy can evaluate such abnormalities in critically ill patients and compared near-infrared spectroscopy-derived indices of critically ill patients with those of healthy volunteers.

We studied 41 patients (mean age 58±22 years) and 15 healthy volunteers (mean age 49±13 years). Patients were classified into one of three groups: systemic inflammatory response syndrome (SIRS) (n=21), severe sepsis (n=8) and septic shock (n=12). Near-infrared spectroscopy was used to continuously measure thenar muscle oxygen saturation before, during and after a three-minute occlusion of the brachial artery via pneumatic cuff.

Oxygen saturation was significantly lower in patients with SIRS, severe sepsis or septic shock than in healthy volunteers. Oxygen consumption rate during stagnant ischaemia was significantly lower in patients with SIRS (23.9±7.7%/minute, P <0.001), severe sepsis (16.9±3.4%/minute, P <0.001) or septic shock (14.8±6%/minute, P <0.001) than in healthy volunteers (35.5±10.6%/minute). Furthermore, oxygen consumption rate was significantly lower in patients with septic shock than patients with SIRS. Reperfusion rate was significantly lower in patients with SIRS (336±141%/minute, P <0.001), severe sepsis (257±150%/minute, P <0.001) or septic shock (146±101%/minute, P <0.001) than in healthy volunteers (713±223%/minute) and significantly lower in the septic shock than in the SIRS group.

Near-infrared spectroscopy can detect tissue oxygenation deficits and impaired microvascular reactivity in critically ill patients, as well as discriminate among groups with different disease severity.

Nitric oxide, leukocytes and microvascular permeability: causality or bystanders?

Increased microvascular permeability resulting in tissue edema is a hallmark of sepsis-related microcirculatory failure, and leukocyte–endothelium interaction is thought to assume major importance in this context. However, the role of nitric oxide (NO) in the interplay of inflammation, leukocyte–endothelium interaction and increased microcirculatory permeability is still a matter of debate. Hollenberg et al. now report, in the previous issue of Critical Care, that neither genetic deletion nor pharmacologic blockade of the inducible isoform of the NO synthase (iNOS) affected the sepsis-related aggravation of leukocyte rolling and adhesion, whereas iNOS inhibition attenuated microvascular permeability. The authors conclude that excess NO resulting from iNOS activation is important in modulating vascular permeability during sepsis, but that this effect is independent of its action on leukocytes.

Higher blood flow and circulating NO products offset high-altitude hypoxia among Tibetans

The low barometric pressure at high altitude causes lower arterial oxygen content among Tibetan highlanders, who maintain normal levels of oxygen use as indicated by basal and maximal oxygen consumption levels that are consistent with sea level predictions. This study tested the hypothesis that Tibetans resident at 4,200 m offset physiological hypoxia and achieve normal oxygen delivery by means of higher blood flow enabled by higher levels of bioactive forms of NO, the main endothelial factor regulating blood flow and vascular resistance. The natural experimental study design compared Tibetans at 4,200 m and U.S. residents at 206 m. Eighty-eight Tibetan and 50 U.S. resident volunteers (18-56 years of age, healthy, nonsmoking, nonhypertensive, not pregnant, with normal pulmonary function) participated. Forearm blood flow, an indicator of systemic blood flow, was measured noninvasively by using plethysmography at rest, after breathing supplemental oxygen, and after exercise. The Tibetans had more than double the forearm blood flow of low-altitude residents, resulting in greater than sea level oxygen delivery to tissues. In comparison to sea level controls, Tibetans had >10-fold-higher circulating concentrations of bioactive NO products, including plasma and red blood cell nitrate and nitroso proteins and plasma nitrite, but lower concentrations of iron nitrosyl complexes (HbFeIINO) in red blood cells. This suggests that NO production is increased and that metabolic pathways controlling formation of NO products are regulated differently among Tibetans. These findings shift attention from the traditional focus on pulmonary and hematological systems to vascular factors contributing to adaptation to high-altitude hypoxia.

Histochemical Alterations in One Lung Ventilation

BACKGROUND

One lung ventilation is a commonly performed surgical procedure. Although there have been several reports showing that one-lung ventilation can cause pathophysiological alterations such as pulmonary hypoxic vasoconstriction and intrapulmonary shunting, there have been virtually no reports on the effects of one-lung ventilation on lung histology.

MATERIALS AND METHODS

Yorkshire pigs (11-17 kg) were anesthetized, a tracheotomy performed and a tracheal tube inserted. The chest was opened and one lung ventilation (OLV), was induced by clamping of the right main bronchus. OLV was continued for 60 min before the clamp was removed and two lung ventilation (TLV) started. TLV was continued for 30 to 60 min. Blood and lung biopsies were taken immediately before OLV, 30 min and 60 min of OLV and after restoration of TLV.

RESULTS

Histological analyses revealed that the non-ventilated lung was totally collapsed during OLV. On reventilation, there was clear evidence of vascular congestion and alveolar wall thickening at 30 min after TLV. At 60 min of TLV, there was still vascular congestion. Serum nitrite levels (as an index of nitric oxide production) showed steady decline over the course of the experimental period, reaching a significantly low level on reventilation (compared with baseline levels before OLV). Lung MPO activity (marker of neutrophil sequestration) and serum TNFalpha levels were not raised during the entire experimental period.

CONCLUSIONS

These results suggest that there was lung vascular injury after OLV, which was associated with reduced levels of nitric oxide production and not associated with an inflammatory response.

[Microcirculatory monitoring of sepsis]

Microcirculatory dysfunctions play a central role in the pathophysiology of sepsis and shock. Modern methods enable microvascular monitoring in man and offer the possibility to test the effect of novel therapeutical strategies for sepsis. Furthermore, these techniques may be future tools for the monitoring of critically ill patients. In this review, we will describe four microvascular monitoring devices and give an overview of the microcirculatory changes observed during the course of sepsis. Laser Doppler fluxmetry is an easy to use noninvasive technique to measure tissue perfusion enabling monitoring of the effect of different catecholamines on the gastric perfusion during sepsis. Increased microvascular permeability and altered blood flow in septic patients can be quantified by venous congestion plethysmography. Alterations in sublingual microvascular blood flow are detected by intravital microscopy in septic patients and were identified as an outcome predictor. Furthermore, the role of gastrointestinal pCO2-tonometry for microcirculatory monitoring of the perfusion of splanchnic organs during sepsis is discussed. The true clinical value of these techniques has yet to be established and will depend on larger clinical trials showing an impact on diagnostics and patient management.