ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo test the effect of a continuous infusion of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine(L-NMMA) on survival rate and hemodynamics in a pig model of endogenous peritoneal live bacterial sepsis.DesignProspective, randomized trial.SettingLaboratory at a university medical center.SubjectsThirty-five pigs with an average weight of 26 kg (range 21 to 33).InterventionsAfter surgical preparation, animals (control, n = 6) given anesthesia and fluids were observed for 9 hrs. Fifteen experimental animals received 0.5 g of cecal content/kg of body weight intraperitoneally after surgery. Nine of these animals received standard anesthesia and fluids and were observed for 9 hrs or until death. Six animals received a continuous infusion of L-NMMA (10 mg/kg/hr) 3 hrs after sepsis induction. Starting 3 hrs after surgery, five nonrandomized animals were given anesthesia and fluids and received a 6-hr continuous infusion of L-NMMA (10 mg/kg/hr). An additional nine animals were anesthetized and blood samples were taken to determine plasma nitrate concentrations in nonoperated pigs.Measurements and Main ResultsL-NMMA treatment increased 9-hr survival in septic animals from 11% to 83% (p < .001), prevented a further decrease in mean arterial pressure and restored mean arterial pressure to control levels (p < .00002 vs. nontreated septic animals). Mean pulmonary arterial pressure increased slightly during L-NMMA infusion (p < .0003). Coronary blood flow was preserved during L-NMMA treatment. Cardiac index and urine production reached and maintained control levels during L-NMMA treatment of septic animals. Mean central venous pH did not deteriorate during L-NMMA treatment. Animals treated with L-NMMA had plasma nitrate concentrations similar to nonseptic control animals. The results from the nonseptic control group receiving L-NMMA suggest that a substantial part of the effect of L-NMMA in this model of septic shock may be due to inhibition of the constitutive nitric oxide production.ConclusionsIn this porcine model of peritoneal sepsis, infusion of L-NMMA increased survival rate and maintained mean arterial pressure without worsening tissue oxygenation. Coronary blood flow, cardiac index, systemic vascular resistance, and urine production were well maintained during L-NMMA treatment. (Crit Care Med 1998;26:1490-1499)

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectivesTo determine a mechanism by which nitric oxide alters induction of stress-induced endothelial cell apoptosis in vitro. Apoptosis is a form of cellular suicide that has been implicated in the pathogenesis of multiple organ dysfunction syndrome.DesignProspective, controlled trial.SettingResearch laboratory of a large, academic medical center.SubjectsCultured primary porcine aortic endothelial cells.InterventionsCells were treated with a range of doses of agents that either spontaneously generate nitric oxide (S-nitroso-N-acetyl-D,L-penicillamine [SNAP] or (Z)-1-[2-(2-aminoethyl)-N-(2-ammonloethyl)amino]diazen-1-lum-1,2-diolate [DETA-NO]) or block nitric oxide production (Nomega-methyl-L-arginine[L-NMA]). The ability of these agents to alter the rate of cell death by apoptosis (induced by the sequence stimuli lipopolysaccharide [LPS] followed by sodium arsenite) was measured. Mechanistic studies included examining the ability of: a) nitric oxide "donors" to alter nuclear factor kappa B (NF-kappa B) DNA binding activity and the level of I kappa B alpha accumulation; and b) a stable cyclic guanosine monophosphate (cGMP) analog (8-bromo-cGMP) to mimic the effect of nitric oxide donors.Measurements and Main ResultsThe sequence LPS/sodium arsenite increased the rate of endothelial cell apoptosis (47.4%, p<.05 vs. control), as measured by fluorescent-activated cell scanning using annexin V/propidium iodide staining. DETA-NO generated nitric oxide (as indicated by an increase in the concentration of the stable end-products of nitric oxide metabolism) and decreased the rate of endothelial cell apoptosis (20.6% at a dose of 2 mM, p = .0001, vs. control). DETA-NO also decreased NF-kappa B DNA binding activity and the apparent accumulation of its endogenous inhibitor, I kappa B alpha. The 8-bromo-cGMP did not mimic the effects of nitric oxide donors (DETA-NO) on apoptosis.ConclusionsThese data suggest that exogenous nitric oxide can block stress-induced endothelial cell apoptosis in vitro. The mechanistic studies are consistent with our hypothesis that inhibitors of NF-kappa B DNA binding activity are associated with protection against apoptosis-inducing stimuli. The results do not support a role for cGMP in mediating the protective effect of DETA-NO in our model. (Crit Care Med 1998; 26:1500-1509)

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo determine the fasted and fed gastrointestinal motility characteristics that are possibly responsible for gastric retention in mechanically ventilated patients.DesignProspective, case series.SettingSurgical intensive care unit of a university hospital.PatientsSeven patients who required mechanical ventilation for thoracic or combined thoracic-neurologic injuries and nine healthy volunteers.InterventionsNone.Measurements and Main ResultsAntroduodenal manometry was performed during fasting and gastric feeding with a polymeric diet in patients during mechanical ventilation, weaning, and after detubation. Gastric retention volumes were determined during gastric tube feeding. Motility data were compared with recordings from nine healthy volunteers. During the fasting state, under sedation and morphine, the migrating motor complex in patients was significantly (p < .001) shortened: median 32.0 vs. 101.0 mins in healthy volunteers. During gastric tube feeding, the motility pattern did not convert to a normal postprandial pattern until morphine was discontinued. An interdigestive or mixed interdigestive-postprandial pattern was seen during gastric tube feeding in most patients during morphine administration. Most (94%) of the activity fronts during gastric feeding started in the duodenum. Gastric retention percentages during gastric tube feeding were negatively correlated (r2= .44; p < .01) with antral motor activity.ConclusionsThese data suggest that morphine administration affects antroduodenal motility in mechanically ventilated patients. The gastrointestinal motor pattern involved in impaired gastric emptying in morphine-treated patients is characterized by antral hypomotility and persisting duodenal activity fronts during continuous intragastric feeding. The observed motility patterns suggest that early administration of enteral feeding might be more effective into the duodenum or jejunum than into the stomach of mechanlcally ventilated patients. (Crit Care Med 1998; 26:1510-1517)

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo assess the oxygen cost of breathing with either pressure-support ventilation (PSV) or biphasic intermittent positive airway pressure ventilation (BIPAP).DesignProspective, randomized, crossover study.SettingMedical intensive care unit of a university hospital.PatientsTwenty clinically stable and spontaneously breathing patients after long-term mechanical ventilation.InterventionsPatients were randomized to start on either PSV or BIPAP, and measurements were performed after an adaptation period of 30 mins. Immediately after, the ventilatory mode was changed and after another 30-min adaptation period, the same measurements were performed.Measurements and Main ResultsIndirect calorimetry was performed during each ventilatory mode for a period of 30 mins. Oxygen consumption, energy expenditure, CO2production, and respiratory quotient did not differ significantly between the two ventilatory modes, regardless of the patients' randomization. There were no statistically significant differences with regard to respiratory rate, minute volume, and blood gas analysis. All patients tolerated both ventilatory modes without any signs of discomfort.ConclusionsPressure support ventilation and BIPAP are both used for weaning patients gradually from the ventilator. BIPAP may be advantageous in patients not breathing sufficiently with PSV, since no patient effort is necessary with use of this ventilatory mode. (Crit Care Med 1998; 26:1518-1522)

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectivesAdmission blood lactate is an accurate predictor of injury severity and mortality in trauma patients. The purpose of this study was to evaluate a portable lactate analyzer in a clinical setting by patient care staff.DesignA prospective, single-operator control solution and patient sample study, using two test devices and a reference device.SettingAn urban Level I trauma center.PatientsA convenience sample of 47 trauma patients.InterventionsIntra-assay precision was demonstrated by performance of consecutive analyses of two lactate control solutions (high and low lactate control concentrations) by medical students and physicians. Split sample, simultaneous testing of the portable lactate analyzer was then performed on 66 whole blood specimens from a convenience sample of 47 trauma patients admitted to an urban Level 1 trauma center over 4 mos. Samples were tested simultaneously tested on two portable lactate analyzers and a reference Instrument.Measurements and Main ResultsAcceptable intra-assay precision was achieved. Regression analysis for two test instruments demonstrated a slope of 0.920, an intercept of 0.323, an r2of .982, and an SEM of 0.496. Regression analysis for test instrument "A" vs. the reference instrument showed a slope of 0.861, an intercept of 0.209, an r2of .977, and an SEM of 0.598. Regression analysis for test instrument "B" vs. the reference instrument demonstrated a slope of 0.929, an intercept of -0.095, an r2of .983, and an SEM of 0.506.ConclusionsGood correlation with a low SEM was obtained over a wide range of clinically relevant lactate values. Use of point of care lactate analysis will decrease analytic time, making an important diagnostic parameter immediately available in the critical care setting. (Crit Care Med 1998; 26:1523-1528)

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo obtain optimal protein requirements in critically ill sepsis or trauma patients during the first 2 wks after admission to the intensive care unit.DesignRetrospective study.SettingDepartment of critical care medicine at a teaching hospital.PatientsImmediate posttrauma patients or severely septic patients.InterventionsIn vivo neutron activation analysis was used to measure changes in total body protein over a 10-day perlod which began as soon as the patients were hemodynamically stable. The patients (trauma, n = 18; sepsis, n = 5) were divided into three groups according to the average daily protein intakes. Because the patients were overhydrated ([similar]10 L) and had variable amounts of body fat, the protein intakes were indexed to normally hydrated (corrected) fat-free mass (FFMc): Groups A, B, and C received an average of 1.1, 1.5, and 1.9 g/kg FFMc/day protein, respectively.Measurements and Main ResultsOverall, the average loss of total body protein was 1.2 +/- 0.7 (SD) kg. Changes In total body protein were significantly (p = .011) different between the three groups. The loss of body protein was significantly more in group A compared with groups B (p = .013) and C (p = .023). When the protein intake was increased from 1.1 g/kg FFMc/day to 1.5 g/kg FFMc/day, protein loss was halved. Further increase in protein intake up to 1.9 g/kg FFMc/day resulted in no further improvement. An intake of 1.5 g/kg FFMc/day was equivalent to 1.0 g/day/kg of body weight measured at the begining of the study.ConclusionsCurrent recommended protein requirements of 1.2 to 2.0 g/kg of body weight/day are excessive if they are indexed to the body weight measured soon after the onset of critical illness. Because Individual patients have varying degrees of overhydration early in the illness onset, we suggest that the intensivist should obtain information on preillness body weight and prescribe 1.2 g of protein/kg body weight/day. If information is not available, 1.0 g of protein/day/kg of measured body weight will give a fair approximation to optimal protein requirements. (Crit Care Med 1998; 26:1529-1535)

ISSN:0090-3493    

出版商:OVID    

年代:1998

数据来源: OVID