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Objective: To test the hypothesis whether pure oxygen ventilation is equally safe and beneficial in fully developed fecal peritonitis-induced septic shock as hyperoxia initiated at the induction of sepsis., Design: Prospective, randomized, controlled, experimental study with repeated measures., Setting: Animal research laboratory at a university medical school., Subjects: Twenty anesthetized, mechanically ventilated, and instrumented pigs., Interventions: Twelve hours after induction of fecal peritonitis by inoculation of autologous feces, swine, which were resuscitated with hydroxyethyl starch and norepinephrine to maintain mean arterial pressure at baseline values, were ventilated randomly with an Fio2 required to keep Sao2 >90% (controls: n = 10) or Fio2 1.0 (hyperoxia, n = 10) during the next 12 hrs., Measurements and Main Results: Despite similar hemodynamic support (hydroxyethyl starch and norepinephrine doses), systemic and regional macrocirculatory and oxygen transport parameters, hyperoxia attenuated pulmonary hypertension, improved gut microcirculation (ileal mucosal laser Doppler flowmetry) and portal venous acidosis, prevented the deterioration in creatinine clearance (controls 61 (44;112), hyperoxia: 96 (88;110) mL.min(-1), p = .074), and attenuated the increase in blood tumor necrosis factor-alpha concentrations (p = .045 and p = .112 vs. controls at 18 hrs and 24 hrs, respectively). Lung and liver histology (hematoxyline eosine staining) were comparable in the two groups, but hyperoxia reduced apoptosis (Tunel test) in the liver (4 (3;8) vs. 2 (1;5) apoptotic cells/field, p = .069) and the lung (36 (31;46) vs. 15 (13;17) apoptotic cells/field, p < .001). Parameters of lung function, tissue antioxidant activity, blood oxidative and nitrosative stress (nitrate + nitrite, 8-isoprostane levels; deoxyribonucleic acid (DNA) damage measured using the comet assay) were not further affected during hyperoxia., Conclusions: When compared with the previous report on hyperoxia initiated simultaneously with induction of sepsis, i.e., using a pretreatment approach, pure oxygen ventilation started when porcine fecal peritonitis-induced septic shock was fully developed proved to be equally safe with respect to lung function and oxidative stress, but exerted only moderate beneficial effects.

Purpose: To test the hypothesis whether genetic over-expression of the Cu/Zn-superoxide dismutase (SOD-1) prevents the sepsis-related impairment of myocardial function and norepinephrine responsiveness in a resuscitated murine model of septic shock., Methods: Fifteen hours after cecal ligation and puncture or sham-operation wild type, heterozygous and homozygous SOD-1 over-expressing mice were anesthetized, ventilated and instrumented with central venous and left ventricular pressure-conductance catheters, to assess heart function at 18, 21, and 24 h after CLP or sham-operation. Hydroxyethylstarch and noradrenaline (in the CLP-mice only) were infused to maintain normotensive hemodynamics., Results: Fluid resuscitation and noradrenaline requirements did not differ between the mouse strains. While total myocardial SOD activity was five- and ninefold higher in the heterozygous and homozygous over-expressing animals, respectively, tissue catalase activity was not different. Anesthesia and fluid resuscitation alone caused left ventricular dilatation and a progressive fall in left ventricular end-systolic pressure and maximal systolic contraction (dp/dt (max)), while stroke volume and cardiac output increased. Due to the noradrenaline infusion heart rate, end-systolic pressure as well as dp/dt (max) and dp/dt (max) were significantly higher and relaxation time significantly lower in the CLP-mice, again without difference between the genetic strains., Conclusion: We conclude that neither hetero- nor homozygous SOD-1 over-expression caused a sustained improvement of the sepsis-related impairment of myocardial norepinephrine responsiveness, possibly due to the lacking increase of the tissue catalase and the mitochondrial SOD activity as well as the ongoing i.v. noradrenaline.

Besides excess cytokine and NO production, enhanced oxygen radical formation was referred to contribute to the impaired hepatic gluconeogenesis during sepsis or endotoxemia. Therefore, we tested the hypothesis that genetic overexpression of the Cu/Zn-superoxide dismutase (SOD-1) may restore the sepsis-related lack of the norepinephrine-induced increase in hepatic gluconeogenesis and whole-body glucose oxidation. Anesthetized, ventilated, and instrumented wild-type control, and heterozygous and homozygous SOD-1-overexpressing mice received hydroxyethyl starch and norepinephrine to maintain normotensive hemodynamics measured at 18, 21, and 24 h after cecal ligation and puncture (CLP) or sham operation. Hepatic gluconeogenesis and whole-body glucose oxidation were calculated from liver tissue isotope and expiratory 13CO2 enrichments during continuous i.v. 1,2,3,4,5,6-13C6-glucose. Superior mesenteric artery and portal vein flows (ultrasound flow probes) and hepatic microcirculatory perfusion (Laser Doppler flowmetry) and O2 saturation (remission spectrophotometry) were comparable in the CLP and sham-operated animals, without any difference related to the mouse strain. Despite continuous i.v. norepinephrine necessary in the CLP mice, both glycemia and hepatic gluconeogenesis were similar, irrespective of the presence of sepsis and the genetic strain. Glucose oxidation rate progressively increased in the CLP groups, again without difference between the genetic strains. The surgery- and CLP-induced increase in liver cell oxidative DNA damage (tail moment in the comet assay) was less pronounced in the homozygous mice. Heterozygous nor homozygous SOD-1 overexpression did not improve the sepsis-related impairment of carbohydrate metabolism, possibly because of the lacking increase of the tissue catalase and the mitochondrial SOD activity, and the ongoing i.v. norepinephrine.

Objective: Early goal-directed therapy aims at balancing tissue oxygen delivery and demand. Hyperoxia (i.e., pure oxygen breathing) has not been studied in this context, since sepsis increases oxygen radical production, which is believed to be directly related to the oxygen tension. On the other hand, oxygen breathing improved survival in various shock models. Therefore, we hypothesized that hyperoxia may be beneficial during early septic shock., Design: Laboratory animal experiments., Setting: Animal research laboratory at university medical school., Subjects: Twenty domestic pigs of either gender., Interventions: After induction of fecal peritonitis, anesthetized and instrumented pigs were ventilated with either 100% oxygen or supplemental oxygen as needed to maintain arterial hemoglobin oxygen saturation > or = 90%. Normotensive and hyperdynamic hemodynamics were achieved using hydroxyethyl starch and norepinephrine infusion., Measurements and Main Results: Before and at 12, 18, and 24 hrs of peritonitis, we measured lung compliance; systemic, pulmonary, and hepatosplanchnic hemodynamics; gas exchange; acid-base status; blood isoprostanes; nitrates; DNA strand breaks; and organ function. Gluconeogenesis and glucose oxidation were calculated from blood isotope and expiratory 13CO2 enrichments during continuous intravenous 1,2,3,4,5,6-(13)C6-glucose. Apoptosis in lung and liver was assessed postmortem (TUNEL staining). Hyperoxia did not affect lung mechanics or gas exchange but redistributed cardiac output to the hepatosplanchnic region, attenuated regional venous metabolic acidosis, increased glucose oxidation, improved renal function, and markedly reduced the apoptotic death rate in liver and lung., Conclusions: During early hyperdynamic porcine septic shock, 100% oxygen improved organ function and attenuated tissue apoptosis without affecting lung function and oxidative or nitrosative stress. Therefore, it might be considered as an additional measure in the first phase of early goal-directed therapy.

Objective: To investigate the role of the inducible nitric oxide synthase activation-induced excess nitric oxide formation on the rate of hepatic glucose production during fully resuscitated murine septic shock., Design: Prospective, controlled, randomized animal study., Setting: University animal research laboratory., Subjects: Male C57Bl/6 and B6.129P2-Nos2(tm1Lau)/J (iNOS-/-) mice., Interventions: Fifteen hours after cecal ligation and puncture, anesthetized, mechanically ventilated and instrumented mice (wild-type controls, n = 13; iNOS-/-, n = 12; wild-type mice receiving 5 mg.kg(-1) i.p. of the selective iNOS inhibitor GW274150 immediately after cecal ligation and puncture, n =8) received continuous i.v. hydroxyethylstarch and norepinephrine to achieve normotensive and hyperdynamic hemodynamics., Measurements and Results: Measurements were recorded 18, 21 and 24 h after cecal ligation and puncture. Liver microcirculatory perfusion and capillary hemoglobin O2 saturation (laser Doppler flowmetry and remission spectrophotometry) were well maintained in all groups. Despite significantly lower norepinephrine doses required to achieve the hemodynamic targets, the rate of hepatic glucose production (gas chromatography--mass spectrometry measurements of tissue isotope enrichment during continuous i.v. 1,2,3,4,5,6-13C6-glucose infusion) at 24 h after cecal ligation and puncture was significantly higher in both iNOS-/- and GW274150-treated mice, which was concomitant with a significantly higher hepatic phosphoenolpyruvate carboxykinase activity (spectrophotometry) in these animals., Conclusions: In normotensive, hyperdynamic septic shock, both pharmacologic and genetic deletion of the inducible nitric oxide synthase allowed maintenance of hepatic glucose production, most likely due to maintained activity of the key regulatory enzyme of gluconeogenesis, phosphoenolpyruvate carboxykinase.

Objectives: Excess nitric oxide production is a key mediator of hypotension and catecholamine-resistance in septic shock. Although nitric oxide synthase blockade has been shown to restore hemodynamics, conflicting results on myocardial function were reported. Inducible nitric oxide synthase (iNOS) knockout (iNOS-/-) mice showed improved heart function, but these results were obtained during hypodynamic shock characterized by reduced cardiac output. Therefore, we investigated heart function and catecholamine responsiveness in a clinically relevant, murine model of cecal ligation and puncture (CLP)-induced septic shock., Design: Prospective, controlled, randomized animal study., Setting: University animal research laboratory., Subjects: Male C57Bl/6 wild-type and iNOS-/- mice., Interventions: Fifteen hours after CLP, three groups of mice (wild-type controls, n = 9; iNOS-/-, n = 12; and wild-type mice receiving 5 mg x kg(-1) intraperitoneally of the selective iNOS inhibitor GW274150 immediately after CLP, n = 8) were anesthetized, mechanically ventilated, and instrumented (central venous and left ventricular pressure-conductance catheter). Measurements were recorded 18, 21, and 24 hrs post-CLP. Hydroxyethylstarch and norepinephrine were infused to achieve normotensive and hyperdynamic hemodynamics., Measurements and Main Results: There was no intergroup difference in mean arterial pressure, stroke volume, and left ventricular ejection fraction. Norepinephrine doses required to achieve the hemodynamic targets were lower in GW274150 (p < .001 vs. controls) and even further reduced in iNOS-/- mice (p < .001 vs. controls, p < .001 vs. GW274150). In the control group, the higher norepinephrine doses resulted in significantly higher heart rates and consequently cardiac output, maximal contraction, and relaxation than in the GW274150 and iNOS-/- animals. Left ventricular end-diastolic volume was also significantly higher in the controls than in the GW274150 and iNOS-/- mice, whereas left ventricular end-diastolic pressure did not differ., Conclusions: Our results confirm septic shock-related impaired left ventricular function. Genetic iNOS deletion and pharmacologic iNOS blockade enhanced cardiac norepinephrine responsiveness due to improved systolic function. In contrast, iNOS inhibition seemed to be affiliated with compromised left ventricular relaxation.

Objective: Septic shock-associated organ dysfunction is attributed to derangements of microcirculatory perfusion and/or impaired cellular oxygen utilization. The hepatosplanchnic organs are regarded to play a pivotal role in the pathophysiology of sepsis-related organ failure. In a murine model of septic shock, we tested the hypothesis whether achieving normotensive, hyperdynamic hemodynamics characterized by a sustained increase in cardiac output would allow maintenance of regional microvascular perfusion and oxygenation and, thus, hepatic metabolic capacity., Design: Prospective, controlled, randomized animal study., Setting: University animal research laboratory., Subjects: Male C57Bl/6 mice., Interventions: Fifteen hours after sham operation (n = 11) or cecal ligation and puncture (CLP) (n = 9), mice were anesthetized, mechanically ventilated, and instrumented (central venous and left ventricular pressure-conductance catheter, portal vein and superior mesenteric artery ultrasound flow probes). Animals received continuous intravenous hydroxyethylstarch and norepinephrine to achieve normotensive and hyperdynamic hemodynamics, and glucose was infused to maintain normoglycemia., Measurements and Main Results: Measurements were recorded 18, 21, and 24 hrs post-CLP. In CLP mice, titration of hemodynamic targets were affiliated superior mesenteric artery and portal vein flow. Using a combined laser-Doppler flowmetry and remission spectrophotometry probe, we found well-maintained gut and liver capillary perfusion as well as intestinal microcirculatory hemoglobin oxygen saturation, whereas hepatic microcirculatory hemoglobin oxygen saturation was even increased. At 24 hrs post-CLP, the rate of de novo gluconeogenesis as derived from hepatic C-glucose isotope enrichment after continuous intravenous 1,2,3,4,5,6-C6-glucose infusion (condensation biosynthesis modeling after gas chromatography-mass spectrometry isotope measurements) was similar in the two experimental groups., Conclusions: During murine septic shock achieving normotensive hyperdynamic hemodynamics with fluid resuscitation and norepinephrine, exogenous glucose requirements together with the lack of norepinephrine-induced increase in the rate of gluconeogenesis mirror impaired metabolic capacity of the liver despite well-maintained hepatosplanchnic microvascular perfusion and oxygenation.

The relationship between peaks of G-CSF serum concentrations and respiratory burst activity of polymorphonuclear cells (PMN) was investigated in patients with postoperative or post-traumatic severe sepsis and septic shock. Over a 12 month period, a longitudinal analysis of G-CSF, TNF-alpha and IFN-gamma serum concentrations, burst activity of PMN, and expression of CD64 on the surface of PMN, were performed by ELISA technique and flow cytometric analysis, respectively, in 58 patients admitted to the intensive care unit (ICU) on a daily basis until discharge from the ICU or death. Out of these 58 patients, 27 with proven infections were in septic shock for at least 4 days' duration. Seventeen of these patients survived, whereas ten died. In 15 out of these 27 patients, 26 episodes of G-CSF peaks were observed, which were followed in most patients (13/15) by an increase in PMN burst activity, from 28% up to 540% (median 188%). Following the G-CSF peaks, CD64 expression on PMN remained at an increased level, followed by a marked decline 3 days later. TNF-alpha serum concentrations were elevated in most episodes (22/26), whereas IFN-gamma serum concentrations were below the detection level in 23/26 episodes. Taken together, peaks in G-CSF serum concentrations are followed by enhanced CD64 expression and increased burst activity of PMN in most patients with severe sepsis and septic shock. Thus, endogenous G-CSF increases neutrophil function in patients with severe sepsis and septic shock, necessary for resolution of bacterial infections in these patients., (Copyright 2002 Elsevier Science Ltd. All rights reserved.)

Objective: To clarify the changes in total leukocyte counts, CD64 neutrophil receptor expression and serum granulocyte colony-stimulating factor (G-CSF) concentrations in critically ill patients without infection and sepsis and in patients with septic shock. Design: Prospective study. Setting: Intensive care unit (ICU) and research laboratory of a university hospital. Patients: Eleven critically ill patients without infections and 22 patients with proven infections in septic shock for the first time and of at least 3 days' duration. Measurements and results: Over a 6month period, a longitudinal analysis of expression of the monomeric Fc receptor type I (CD64, FcγRI) on neutrophils was performed by flow cytometric analysis on a daily basis in all postoperative/post-traumatic patients admitted to the ICU until discharge from the ICU or death. Out of 273 patients, 11 patients without sepsis had organ failure and 22 patients with proven infections had septic shock for the first time and of at least 3 days' duration. Ten out of the 22 patients survived, 12 died. CD64 expression was greater in patients with septic shock than in patients without sepsis. Moreover, CD64 expression was only initially and transiently elevated in most survivors (9/10) and non-survivors (8/12) of septic shock. In survivors, G-CSF serum concentrations were markedly decreased in the 2nd week. Conclusions: Decreased neutrophil CD64 expression in an acutely ill population with septic shock may reflect the development of a non-responsive state as well as the early downregulation of neutrophil activation prior to the resolution of an ongoing infection. [ABSTRACT FROM AUTHOR]