Evaluation of Home Polysomnography Findings, Quality of Sleep, and Fatigue in Inflammatory Bowel Disease: A Case Series.

STUDY OBJECTIVES: The pathogenesis of inflammatory bowel disease (IBD) is not well understood, and sleep disorders may be potential triggers for IBD. Thus, an evaluation of the sleep characteristics, fatigue symptoms, and cytokine levels was performed in patients with IBD during periods of active disease and remission. METHODS: A total of 20 participants presenting with Crohn's disease or ulcerative colitis, with active disease (n = 7) or in remission (n = 13), underwent home polysomnography (H-PSG). Pittsburgh Sleep Quality Index (PSQI) and Modified Fatigue Impact Scale (MFIS) were applied, in addition to the evaluation of interleukin (IL)-6, IL-10, and tumor necrosis factor alpha (TNF-α) serum levels. Exploratory analysis, t test and Mann-Whitney U test were used. RESULTS: The mean sleep latency in patients with active disease was 133.07 minutes and 106.79 minutes in those in remission. The sleep efficiency and sleep fragmentation in patients with active disease and those in remission were 80.90% and 84.20% (median), and 76.36/min and 69.82/min (mean), respectively, although the H-PSG parameters did not differ between the groups. The PSQI scores indicated poor sleep quality (global score above 5) in all participants with IBD, and the participants with active disease presented more symptoms of fatigue (P = .032). IL-6 and TNF-α average levels were higher in the participants with disease remission, although with a larger dispersion of the data. CONCLUSIONS: No significant difference in the H-PSG characteristics was observed between the patients with IBD with active disease and those in remission; however, the perception of the participants with IBD showed significant effect on the sleep quality and fatigue symptoms.

Identification of novel metabolomic biomarkers in an experimental model of septic acute kidney injury.

The aim of this study is the identification of metabolomic biomarkers of sepsis and sepsis-induced acute kidney injury (AKI) in an experimental model. Pigs were anesthetized and monitored to measure mean arterial pressure (MAP), systemic blood flow (QT), mean pulmonary arterial pressure, renal artery blood flow (QRA), renal cortical blood flow (QRC), and urine output (UO). Sepsis was induced at t = 0 min by the administration of live Escherichia coli ( n = 6) or saline ( n = 8). At t = 300 min, animals were killed. Renal tissue, urine, and serum samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy. Principal component analyses were performed on the processed NMR spectra to highlight kidney injury biomarkers. Sepsis was associated with decreased QT and MAP and decreased QRA, QRC, and UO. Creatinine serum concentration and neutrophil gelatinase-associated lipocalin (NGAL) serum and urine concentrations increased. NMR-based metabolomics analysis found metabolic differences between control and septic animals: 1) in kidney tissue, increased lactate and nicotinuric acid and decreased valine, aspartate, glucose, and threonine; 2) in urine, increased isovaleroglycine, aminoadipic acid, N-acetylglutamine, N-acetylaspartate, and ascorbic acid and decreased myoinositol and phenylacetylglycine; and 3) in serum, increased lactate, alanine, pyruvate, and glutamine and decreased valine, glucose, and betaine concentrations. The concentration of several metabolites altered in renal tissue and urine samples from septic animals showed a significant correlation with markers of AKI (i.e., creatinine and NGAL serum concentrations). NMR-based metabolomics is a potentially useful tool for biomarker identification of sepsis-induced AKI.

Inhibition of Nitro-Oxidative Stress Attenuates Pulmonary and Systemic Injury Induced by High-Tidal Volume Mechanical Ventilation.

Mechanisms contributing to pulmonary and systemic injury induced by high tidal volume (VT) mechanical ventilation are not well known. We tested the hypothesis that increased peroxynitrite formation is involved in organ injury and dysfunction induced by mechanical ventilation. Male Sprague-Dawley rats were subject to low- (VT, 9 mL/kg; positive end-expiratory pressure, 5 cmH2O) or high- (VT, 25 mL/kg; positive end-expiratory pressure, 0 cmH2O) VT mechanical ventilation for 120 min, and received 1 of 3 treatments: 3-aminobenzamide (3-AB, 10 mg/kg, intravenous, a poly adenosine diphosphate ribose polymerase [PARP] inhibitor), or the metalloporphyrin manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP, 5 mg/kg intravenous, a peroxynitrite scavenger), or no treatment (control group), 30 min before starting the mechanical ventilation protocol (n = 8 per group, 6 treatment groups). We measured mean arterial pressure, peak inspiratory airway pressure, blood chemistry, and gas exchange. Oxidation (fluorescence for oxidized dihydroethidium), protein nitration (immunofluorescence and Western blot for 3-nitrotyrosine), PARP protein (Western blot) and gene expression of the nitric oxide (NO) synthase (NOS) isoforms (quantitative real-time reverse transcription polymerase chain reaction) were measured in lung and vascular tissue. Lung injury was quantified by light microscopy. High-VT mechanical ventilation was associated with hypotension, increased peak inspiratory airway pressure, worsened oxygenation; oxidation and protein nitration in lung and aortic tissue; increased PARP protein in lung; up-regulation of NOS isoforms in lung tissue; signs of diffuse alveolar damage at histological examination. Treatment with 3AB or MnTMPyP attenuated the high-VT mechanical ventilation-induced changes in pulmonary and cardiovascular function; down-regulated the expression of NOS1, NOS2, and NOS3; decreased oxidation and nitration in lung and aortic tissue; and attenuated histological changes. Increased peroxynitrite formation is involved in mechanical ventilation-induced pulmonary and vascular dysfunction.

A Metabolomic Approach to the Pathogenesis of Ventilator-induced Lung Injury.

BACKGROUND: Global metabolic profiling using quantitative nuclear magnetic resonance spectroscopy (MRS) and mass spectrometry (MS) is useful for biomarker discovery. The objective of this study was to discover biomarkers of acute lung injury induced by mechanical ventilation (ventilator-induced lung injury [VILI]), by using MRS and MS. METHODS: Male Sprague-Dawley rats were subjected to two ventilatory strategies for 2.5 h: tidal volume 9 ml/kg, positive end-expiratory pressure 5 cm H2O (control, n = 14); and tidal volume 25 ml/kg and positive end-expiratory pressure 0 cm H2O (VILI, n = 10). Lung tissue, bronchoalveolar lavage fluid, and serum spectra were obtained by high-resolution magic angle spinning and H-MRS. Serum spectra were acquired by high-performance liquid chromatography coupled to quadupole-time of flight MS. Principal component and partial least squares analyses were performed. RESULTS: Metabolic profiling discriminated characteristics between control and VILI animals. As compared with the controls, animals with VILI showed by MRS higher concentrations of lactate and lower concentration of glucose and glycine in lung tissue, accompanied by increased levels of glucose, lactate, acetate, 3-hydroxybutyrate, and creatine in bronchoalveolar lavage fluid. In serum, increased levels of phosphatidylcholine, oleamide, sphinganine, hexadecenal and lysine, and decreased levels of lyso-phosphatidylcholine and sphingosine were identified by MS. CONCLUSIONS: This pilot study suggests that VILI is characterized by a particular metabolic profile that can be identified by MRS and MS. The metabolic profile, though preliminary and pending confirmation in larger data sets, suggests alterations in energy and membrane lipids.SUPPLEMENTAL DIGITAL CONTENT IS AVAILABLE IN THE TEXT.

Role of peroxynitrite in sepsis-induced acute kidney injury in an experimental model of sepsis in rats.

The mechanisms involved in sepsis-induced acute kidney injury (AKI) are unknown. We investigated the role of nitrosative stress in sepsis-induced AKI by studying the effects of manganese (III) tetrakis-(1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), a peroxynitrite decomposition catalyst, and aminoguanidine (AG), a selective nitric oxide synthase 2 (NOS2) inhibitor and peroxynitrite scavenger, on kidney function of rats subjected to cecal ligation and puncture (CLP). Sprague-Dawley rats (weighing 350 [SD, 50] g) were treated with MnTMPyP (6 mg/kg i.p.) or AG (50 mg/kg i.p.) at t = 12 and 24 h after CLP or sham procedure. At t = 36 h, mean arterial pressure and aortic blood flow were measured, and blood and urine samples were obtained for biochemical determinations, including creatinine clearance, fractional excretion of sodium, and neutrophil gelatinase-associated lipocalin concentration in the urine. Kidney tissue samples were obtained for (i) light microscopy, (ii) immunofluorescence and Western blot for 3-nitrotyrosine and NOS2, (iii) gene expression (quantitative real-time polymerase chain reaction) studies (NOS1, NOS2, NOS3, and superoxide dismutase 1), and (iv) matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Mean arterial pressure was unchanged and aortic blood flow decreased 25% in CLP animals. The sepsis-induced (i) decreased urine output and creatinine clearance and increased fractional excretion of sodium and urinary neutrophil gelatinase-associated lipocalin concentration, (ii) increased protein nitration and NOS2 protein, and (iii) NOS1 and NOS2 upregulation were all significantly attenuated by treatment with MnTMPyP or AG. Nitrated proteins in renal tissue from CLP animals (matrix-assisted laser desorption ionization time-of-flight mass spectrometry) were glutamate dehydrogenase, methylmalonate-semialdehyde dehydrogenase, and aldehyde dehydrogenase, mitochondrial proteins involved in energy metabolism or antioxidant defense. Nitro-oxidative stress is involved in sepsis-induced AKI, and protein nitration seems to be one mechanism involved.

A metabolomic approach for diagnosis of experimental sepsis.

BACKGROUND: The search for reliable diagnostic biomarkers of sepsis remains necessary. Assessment of global metabolic profiling using quantitative nuclear magnetic resonance (NMR)-based metabolomics offers an attractive modern methodology for fast and comprehensive determination of multiple circulating metabolites and for defining the metabolic phenotype of sepsis. OBJECTIVE: To develop a novel NMR-based metabolomic approach for diagnostic evaluation of sepsis. METHODS: Male Sprague-Dawley rats (weight 325-375 g) underwent cecal ligation and puncture (n = 14, septic group) or sham procedure (n = 14, control group) and 24 h later were euthanized. Lung tissue, bronchoalveolar lavage (BAL) fluid, and serum samples were obtained for (1)H NMR and high-resolution magic-angle spinning analysis. Unsupervised principal components analysis was performed on the processed spectra, and a predictive model for diagnosis of sepsis was constructed using partial least-squares discriminant analysis. RESULTS: NMR-based metabolic profiling discriminated characteristics between control and septic rats. Characteristic metabolites changed markedly in septic rats as compared with control rats: alanine, creatine, phosphoethanolamine, and myoinositol concentrations increased in lung tissue; creatine increased and myoinositol decreased in BAL fluid; and alanine, creatine, phosphoethanolamine, and acetoacetate increased whereas formate decreased in serum. A predictive model for diagnosis of sepsis using these metabolites classified cases with sensitivity and specificity of 100%. CONCLUSIONS: NMR metabolomic analysis is a potentially useful technique for diagnosis of sepsis. The concentrations of metabolites involved in energy metabolism and in the inflammatory response change in this model of sepsis.

Redox balance and cellular inflammation in the diaphragm, limb muscles, and lungs of mechanically ventilated rats.

BACKGROUND: High tidal volume (VT) mechanical ventilation was shown to induce organ injury other than lung injury and systemic inflammation in animal models of ventilator-induced lung injury. The authors aimed to explore whether high VT mechanical ventilation per se induces early oxidative stress and inflammation in the diaphragm, limb muscles, and lungs of healthy rats exposed to ventilator-induced lung injury. METHODS: Protein carbonylation and nitration, antioxidants (immunoblotting), and inflammation (immunohistochemistry) were evaluated in the diaphragm, gastrocnemius, soleus, tibialis anterior, and lungs of mechanically ventilated healthy rats and in nonventilated control animals (n = 8/group) for 1 h, using two different strategies (moderate VT [VT = 9 ml/kg] and high VT [VT = 35 ml/kg]). RESULTS: The main findings are summarized as follows: compared with controls, (1) the diaphragms and gastrocnemius of high-VT rats exhibited a decrease in reactive carbonyls, (2) the soleus and tibialis of high- and moderate-VT rodents showed a reduction in reactive carbonyls and malondialdehyde-protein adducts, (3) the lungs of high-VT rats exhibited a significant rise in malondialdehyde-protein adducts, (4) the soleus and tibialis of both high- and moderate-VT rats showed a reduction in protein nitration, (5) the lungs of high- and moderate-VT rats showed a reduction in antioxidant enzyme levels, but not in the muscles, and (6) the diaphragms and gastrocnemius of all groups exhibited very low inflammatory cell counts, whereas the lungs of high-VT rats exhibited a significant increase in inflammatory infiltrates. CONCLUSIONS: Although oxidative stress and inflammation increased in the lungs of rats exposed to high VT, the diaphragm and limb muscles exhibited a decline in oxidative stress markers and very low levels of cellular inflammation.

Levosimendan increases portal blood flow and attenuates intestinal intramucosal acidosis in experimental septic shock.

It has been proposed that vasodilatory therapy may increase microcirculatory blood flow and improve tissue oxygenation in septic shock. The authors aimed to evaluate the effects of levosimendan in systemic and splanchnic hemodynamics in a porcine model of septic shock in a randomized animal controlled study. This study was performed in an animal research facility in a university hospital. Anesthetized pigs were monitored with a pulmonary artery catheter and an ultrasonic blood flow probe in the portal vein for measurement of systemic and portal blood flows and with a tonometer placed in the small intestine for measurement of the intramucosal-arterial PCO2 gap. Three groups of pigs were studied: nonseptic (n = 7), septic (n = 7), and septic treated with levosimendan (n = 7). Levosimendan was administered i.v. at t = -10 min (200 microg/kg in i.v. bolus followed by 200 microg/kg per h). Sepsis was induced at t = 0 min by the administration of live Escherichia coli. Vascular reactivity was tested by the hemodynamic response to noradrenaline. Levosimendan markedly attenuated the sepsis-induced increase in pulmonary vascular resistance, decrease in portal/systemic blood flow, oliguria, impairment in oxygenation, hyperkalemia, and the widened intramucosal-arterial PCO2 gap. Systemic blood pressure and vascular resistance did not differ as compared with the septic untreated group. Responses to noradrenaline significantly improved in animals treated with levosimendan. Treatment with levosimendan in this animal model of sepsis attenuated pulmonary vasoconstriction and improved portal blood flow, intestinal mucosal oxygenation, pulmonary function, and vascular reactivity.

Role of free radicals in vascular dysfunction induced by high tidal volume ventilation.

OBJECTIVE: To demonstrate that increased formation of reactive oxygen (ROS) and nitrogen species (RNS) is involved in VILI-induced vascular dysfunction. METHODS: Male Sprague-Dawley anesthetized rats were ventilated for 60 min using low V(T) ventilation [V(T) 9 ml/kg, positive end-expiratory pressure (PEEP) 5 cmH(2)O, n = 18], and high V(T) ventilation (V(T) 35 ml/kg, zero PEEP, n = 18). Arterial pressure and respiratory system mechanics were monitored. Blood samples for the determination of arterial blood gases and lactate concentration were drawn. Vascular rings from the thoracic aortae were mounted in organ baths for isometric tension recording. We studied endothelium-dependent relaxation in norepinephrine-precontracted rings (acetylcholine, 10 nM-10 microM) and contraction induced by norepinephrine (1 nM-10 microM) in resting vessels. Vascular rings were preincubated for 30 min with Zn-Mn-SOD (100 u/ml) or tempol (10(-4) M) (extracellular and intracellular superoxide scavengers, respectively) or MnTMPyP (10(-5) M) (a superoxide and peroxynitrite scavenger). The presence of superoxide and nitrotyrosine in aortic rings was evaluated by immunofluorescence. RESULTS: High V(T) ventilation induced hypotension, systemic acidosis, hypoxemia and hyperlactatemia, as well as impairment in acetylcholine and norepinephrine-induced responses in vitro. Responses to acetylcholine were improved by tempol (P = 0.004) and completely corrected (P < 0.001) by MnTMPyP. Responses to norepinephrine were also improved by treatment with tempol (P < 0.001) and MnTMPyP (P < 0.001). However, Zn-Mn-SOD did not improve acetylcholine- or norepinephrine-induced responses. Immunostaining for both superoxide and nitrotyrosine was increased in aortic rings from the high V(T) group. CONCLUSIONS: Our data support a role for intracellular ROS and peroxynitrite in the high V(T) ventilation-induced vascular dysfunction.

High-tidal volume ventilation aggravates sepsis-induced multiorgan dysfunction in a dexamethasone-inhibitable manner.

High-tidal volume (Vt) ventilation induces lung injury and systemic inflammation, and small doses of endotoxin have been shown to increase the susceptibility to ventilation-induced lung injury. We studied whether high-Vt ventilation increases organ injury in a model of bacterial sepsis and whether an anti-inflammatory treatment averts those changes. Anesthetized rats, monitored with an arterial catheter and a blood flow probe in the aorta, were assigned to one of four different groups: nonseptic low-Vt group (Vt = 9 mL/kg, positive end-expiratory pressure = 8 cm H2O, control group), septic low-Vt group, septic overventilated group (Vt = 35 mL/kg, positive end-expiratory pressure = 0), and septic overventilated group pretreated with dexamethasone (6 mg/kg i.p., 30 min before mechanical ventilation). Rats were ventilated for 75 min. Septic rats had undergone cecal ligation and puncture 48 h before mechanical ventilation. We measured hemodynamics, lung mechanics, blood chemistry and gas exchange, liver and heart expression of cyclooxygenase 2 (COX-2) and iNOS (reverse transcriptase-polymerase chain reaction), and lung histopathology. Septic rats showed metabolic acidosis, hyperlactatemia, lung and liver injury, increased liver and heart COX-2, and liver iNOS expression. High-Vt ventilation of septic rats was associated with more marked liver injury and heart COX-2 upregulation, as well as lung inflammation and dysfunction (impaired oxygenation, increased bronchoalveolar lavage fluid protein and IL-6 concentration, decreased thoracic system compliance) and systemic hypotension. All inflammatory changes, as well as pulmonary and vascular dysfunctions, were abrogated by dexamethasone. High-Vt ventilation in bacterial sepsis upregulates the inflammatory response and aggravates the sepsis-induced cardiovascular, pulmonary, and liver dysfunction. Dexamethasone averts mechanical ventilation-induced changes under conditions of bacterial sepsis.

Rats surviving injurious mechanical ventilation show reversible pulmonary, vascular and inflammatory changes.

OBJECTIVE: To describe the time course of the changes in pulmonary and vascular function, and systemic inflammation induced by injurious mechanical ventilation. DESIGN: Experimental study in an animal model of ventilator-induced lung injury. SETTING: Animal research laboratory. METHODS: Anesthetized male adult Sprague-Dawley rats were ventilated with VT 9 ml/kg and PEEP 5 cmH2O, or VT 35 ml/kg and zero PEEP for 1 h, and were killed. Other rats received ventilation for 1 h with high VT, to observe survival (n=36), or to be monitored and killed at different points in time (24, 72 and 168 h; n=7 in each group). Blood samples for measuring biochemical parameters were obtained. Post-mortem, a bronchoalveolar lavage (BAL) was performed, the aorta and pulmonary microvessels were isolated to examine ex-vivo vascular responses and pulmonary slices were examined (light microscopy). MEASUREMENTS AND RESULTS: Mortality in rats ventilated with high VT was 19 of 36 (54%). Mechanical ventilation was associated with hypotension, hypoxaemia and membrane hyaline formation. AST, ALT, IL-6, MIP-2 serum and BAL fluid concentrations, as well as VEGF BAL fluid concentration, were increased in rats ventilated with high VT. Lung injury score was elevated. Aortic vascular responses to acetylcholine and norepinephrine, and microvascular responses to acetylcholine, were impaired. These changes resolved by 24-72 h. CONCLUSIONS: Injurious ventilation is associated with respiratory and vascular dysfunction, accompanied by pulmonary and systemic inflammation. The survival rate was about 50%. In survivors, most induced changes completely normalized by 24-72 h after the insult.

Aging increases the susceptibility to injurious mechanical ventilation.

OBJECTIVE: To test the hypothesis that aging increases the susceptibility to organ dysfunction and systemic inflammation induced by injurious mechanical ventilation. DESIGN AND SETTING: Experimental study in an animal model of ventilator-induced lung injury in the animal research laboratory in a university hospital. METHODS: Young (3-4 months old) and old (22-24 months old) anesthetized Wistar rats were ventilated for 60 min with a protective lung strategy (VT=9 ml/kg and PEEP=5 cm H2O, control) or with an injurious strategy (VT=35 ml/kg and PEEP=0 cm H2O, over-ventilated; n=6 for each group). MEASUREMENTS AND RESULTS: Mean arterial pressure and airway pressures (PAW) were monitored. Arterial blood gases and serum AST, ALT, lactate, and IL-6 were measured. Vascular rings from the thoracic aorta were mounted in organ baths for isometric tension recording. We studied relaxations induced by acetylcholine (10 nM-10 microM) in norepinephrine-precontracted rings, and contractions induced by norepinephrine (1 nM-10 microM) in resting vessels. Lungs were examined by light microscopy. Injurious ventilation in young rats was associated with hypoxemia, lactic metabolic acidosis, increased serum AST, hypotension, impairment in norepinephrine and acetylcholine-induced vascular responses ex vivo and hyaline membrane formation. The high-VT induced hypotension, increase in mean PAW, AST, and IL-6, and the impairment in acetylcholine-induced responses were significantly more marked in aged than in young rats. CONCLUSIONS: Elderly rats showed increased susceptibility to injurious mechanical ventilation-induced pulmonary injury, vascular dysfunction, and systemic inflammation.

An orientation session improves objective sleep quality and mask acceptance during positive airway pressure titration.

The aim of this study was to determine whether an orientation session led by a polysomnography (PSG) technician during the night of positive airway pressure (PAP) titration can improve objective sleep quality and acceptance of nasal mask in patients referred to a sleep laboratory. Consecutive patients (n = 1,481), referred for PAP titration during PSG, were retrospectively evaluated. Patients were distributed in two groups: the control group, patients referred for PAP titration (n = 699) who did not undertake an orientation session led by a PSG technician, and the oriented group, patients referred to PAP titration (n = 782) who followed the orientation session. Demographic data were similar (p > 0.05) between groups (control vs oriented) for: male/female proportion (76:24 vs 75:25%), age (mean +/- SD; 53 +/- 12 vs 52 +/- 12 years), Epworth Sleepiness Scale score (12 +/- 6 vs 12 +/- 6), and body mass index (31 +/- 6 vs 31 +/- 6 kg/m(2)). PSG data were different (p < 0.05) between the groups for: total sleep time (312 +/- 81 vs 326 +/- 85 min), sleep efficiency (74 +/- 17 vs 77 +/- 14%), sleep latency (22 +/- 24 vs 18 +/- 29 min), S1 (8 +/- 8 vs 6 +/- 5%), S3 4 (19 +/- 11 vs 21 +/- 13%), rapid eye movement sleep (17 +/- 9 vs 18 +/- 9%), and wake after sleep onset (106 +/- 68 vs 93 +/- 58 min). After the orientation session, the number of patients who did not accept nasal mask during PSG recording was higher in the control group than the oriented group (80 vs 44; p = 0.001). An orientation session led by a PSG technician can improve objective sleep quality and nasal mask acceptance during the night of PAP titration. Such an addition to PAP titration could be an efficient intervention to improve PAP compliance.

Ventilation-induced lung injury in rats is associated with organ injury and systemic inflammation that is attenuated by dexamethasone.

OBJECTIVE: To determine whether mechanical ventilation using high tidal volume is associated with nonpulmonary organ dysfunction that can be attenuated by dexamethasone. DESIGN: Prospective randomized animal intervention study. SETTING: Animal care facility in a university hospital. SUBJECTS: Sedated and tracheostomized male Sprague-Dawley rats. INTERVENTIONS: Three groups of rats were ventilated with different strategies: tidal volume = 9 mL/kg, positive end-expiratory pressure = 8 cm H(2)O, control group (C); tidal volume = 35 mL/kg, positive end-expiratory pressure = 0 cm H(2)O, overventilated group (OV); and tidal volume = 35 mL/kg, positive end-expiratory pressure = 0 cm H(2)O, plus administration of 6 mg/kg dexamethasone intraperitoneally (OV + dexamethasone). All rats were ventilated for 75 mins with respiratory rate = 70 breaths/min, FIO(2) = 0.35, and plateau time = 0. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure and peak airway pressure were monitored. We measured arterial blood gases, aspartate aminotransferase, alanine aminotransferase, lactate, nitrates and nitrites, tumor necrosis factor-alpha, and interleukin-6 serum concentration. Lung slices were prepared for blind histologic examination. Heart tissue was analyzed for cyclooxygenase-1 and -2 expression (reverse transcription-polymerase chain reaction). Compared with the C group, the OV group showed hypotension; worsened gas exchange; increased aspartate aminotransferase, lactate, nitrates and nitrites, and interleukin-6 serum concentrations; and hyaline membrane formation in the lungs, as well as increased cyclooxygenase-1 and cyclooxygenase-2 expression in the heart. Dexamethasone prevented the pulmonary and cardiovascular injury and attenuated the increase in aspartate aminotransferase, nitrates and nitrites, interleukin-6, and cyclooxygenase-1 and cyclooxygenase-2 expression. CONCLUSIONS: High tidal volume ventilation induces cardiovascular, pulmonary, and liver injury as well as a systemic proinflammatory response. These changes are attenuated by dexamethasone, suggesting that inflammatory rather than purely hemodynamic mechanisms are involved in the changes induced by high tidal volume ventilation.

Large tidal volume mechanical ventilation induces vascular dysfunction in rats.

BACKGROUND: Experimental studies have shown that mechanical ventilation using high tidal volumes (V(T)) damages the lungs, causing pulmonary edema. We tested the hypothesis that high V(T) ventilation in rats induces major vascular dysfunction. METHODS: Healthy Sprague-Dawley rats, weighing (mean +/- SD) 340 +/- 15 g, were ventilated with either V(T) = 9 mL/kg and positive end-expiratory pressure (PEEP) = 8 (n = 8) or V(T) = 35 mL/kg and PEEP = 0 (n = 8). The high V(T) used in the injurious ventilation group is in the V(T) range used in other studies to induce lung damage in a short period of time in rats. Lungs were removed for examination under light microscopy and vascular rings from the thoracic aorta were studied for isometric tension recording. RESULTS: Relaxations to acetylcholine (p < 0.001) and sodium nitroprusside (p < 0.05) and contractions to norepinephrine were markedly decreased (p < 0.001) in the high V(T) group, as compared with the low V(T) group. CONCLUSION: Injurious mechanical ventilation in normal rats is associated with vascular dysfunction characterized by decreased relaxation to an endothelium-dependent vasodilator and to a nitrous oxide donor and by decreased response to norepinephrine.

Interaction between hemoglobin and glutathione in the regulation of blood flow in normal and septic pigs.

BACKGROUND: Hemoglobin (Hb) induces vasoconstriction by heme group binding nitric oxide in an irreversible fashion. Recent in vitro studies indicate that the thiol groups in Hb reversibly bind nitric oxide and participate in trans-nitrosylation reactions with other thiols. Sepsis is a pathophysiologic state characterized by vasodilation mediated, at least in part, by an excessive release of nitric oxide. The role of nitrosothiols (RSNOs) in these changes is unknown. OBJECTIVES: We tested the following in a porcine model of sepsis: (i) whether glutathione (GSH) reverses the hemodynamic effects of Hb; (ii) whether GSH induces an increase in blood flow in sepsis; (iii) whether RSNO plasma concentration increases in sepsis and is related to hypotension. DESIGN: Nonrandomized animal controlled study. SETTING: Animal research facility in a university hospital. SUBJECTS: Anesthetized pigs were monitored with a pulmonary artery catheter and ultrasonic blood flow probes in the mesenteric artery and the portal vein for measurement of systemic, mesenteric, and portal blood flows (Q(TOT), Q(MES), and Q(POR), respectively). Four groups of pigs were studied: nonseptic, septic, nonseptic treated with Hb (stroma-free purified porcine hemoglobin), and septic treated with Hb (n = 6 in each group). INTERVENTIONS: Sepsis was induced at 0 min by the administration of live Escherichia coli. Hb (400 mg/kg/hr) was administered at 240 mins, followed by glutathione (1 g iv). MEASUREMENTS AND MAIN RESULTS: Hb induced a pressor response and a decrease in Q(TOT), Q(MES), and Q(POR). Glutathione reversed the effects of Hb on Q(MES) and Q(POR). In septic pigs not treated with Hb, GSH induced an increase in Q(POR). RSNO plasma concentration increased after the induction of sepsis and correlated significantly with blood pressure. CONCLUSIONS: These results indicate the reversibility of the effects of Hb by GSH, probably by interactions between nitric oxide and the reduced sulfhydryl groups in Hb, and suggest a role of RSNOs in the cardiovascular changes of sepsis.