ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Objectivesa) To determine whether isovolemic exchange transfusion with cell-free, bovine fumaryl beta beta-crosslinked hemoglobin results in a different pattern of regional blood flow distribution than transfusion with a poor oxygen-carrying, colloidal solution. b) Because of potential nitric oxide scavenging by plasma-based hemoglobin, to determine whether blood flow differences are reduced after nitric oxide synthase inhibition.DesignA prospective, randomized design with repeated blood flow measurements within groups.SettingExperimental physiology laboratory in a university medical center.SubjectsPentobarbital-anesthetized female cats.InterventionsThree groups of eight cats were studied: a) a control group with no transfusion (hematocrit of 32%); b) an anemia group in which exchange transfusion with an albumin-containing solution reduced hematocrit to 18% over a 40- to 50-min period; and c) a group in which cell-free hemoglobin was exchanged transfused to reduce hematocrit to 18%, without a proportional reduction in oxygen-carrying capacity. Bovine hemoglobin was covalently crosslinked intramolecularly between the 81-lysine residues on the beta-subunits to stabilize the tetramer. Regional blood flow was measured by the radiolabeled microsphere technique before transfusion and at 10, 100, and 180 mins from the start of transfusion. At 190 mins, Nomega-nitro-L-arginine methyl ester (L-NAME; 10 mg/kg) was infused to inhibit nitric oxide synthase and blood flow was measured 30 mins later.Measurements and Main ResultsMean arterial pressure was unchanged in the control and albumin-transfused groups. However, mean arterial pressure increased rapidly in the hemoglobin-transfused group. With hemoglobin transfusion, there were marked reductions in blood flow to the intestines, kidneys, and adrenal glands. Administration of L-NAME after hemoglobin transfusion failed to increase arterial pressure or cause further reductions in intestinal, renal, or adrenal blood flow. Administration of L-NAME to the control and albumin-transfused groups increased arterial pressure and reduced intestinal, renal, and adrenal blood flows to values attained with hemoglobin transfusion. In contrast, in skeletal muscle and left ventricle, blood flow rates increased in the albumin-transfused group and were greater than those values found in the control group and the hemoglobin-transfused group. The greater flow in the albumin-transfused group persisted after L-NAME administration. There was no difference in renal sodium, potassium, or osmolar excretion, or in urine flow between groups.ConclusionsTransfusion with cell-free, bovine crosslinked hemoglobin in cats can cause selective reductions in blood flow in the intestines, kidneys, and adrenal glands without evidence of renal dysfunction by a mechanism consistent with nitric oxide scavenging. In skeletal and cardiac muscle, the increase in blood flow persisted after nitric oxide inhibition in the albumin group relative to the hemoglobin-transfused group at equivalent hematocrit values. This finding is consistent with compensatory vasoconstriction with hemoglobin transfusion due to improved oxygenation by this oxygen carrier.(Crit Care Med 1996; 24:558-565)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo determine whether activation of pyruvate dehydrogenase with dichloroacetate can reverse sepsis-induced insulin resistance in humans or rats.DesignProspective, controlled study.SettingIntensive care unit (ICU) and laboratory at a university medical center.SubjectsNine patients were admitted to the ICU with Gramnegative sepsis, confirmed by cultures. In addition, chronically instrumented, Sprague-Dawley rats, either controls or with live Escherichia coli-induced sepsis.InterventionsHyperinsulinemic euglycemic clamp, with or without coadministration of dichloroacetate.Measurements and Main ResultsIn humans, a primed, constant infusion of [6,6-sup 2 H2]glucose was used to determine endogenous glucose production and whole-body glucose disposal. Septic humans exhibited impaired maximal insulin-stimulated glucose utilization (39.5 plus minus 2.7 micro mol/kg/min), despite complete suppression of endogenous glucose production. In rats, a primed, constant infusion of [3-sup 3 H]glucose was used to determine endogenous glucose production and whole-body glucose disposal. Tissue glucose uptake in vivo was determined by [sup 14 C]-2-deoxyglucose uptake. Maximal, whole-body, insulin-stimulated glucose utilization was 205 plus minus 11 and 146 plus minus 9 micro mol/kg/min in control and septic rats, respectively. The defect was specific to skeletal muscle and heart. Stimulation of pyruvate dehydrogenase with dichloroacetate caused a 50% decrease in plasma lactate concentration but failed to improve whole-body insulin-stimulated glucose utilization in either the septic human or rat. Dichloroacetate reversed the impairment of insulin-stimulated myocardial glucose uptake in septic rats, but did not influence skeletal muscle glucose uptake either under basal conditions or during insulin stimulation.ConclusionsActivation of pyruvate dehydrogenase with dichloroacetate does not ameliorate the impairment of whole-body, insulin-stimulated glucose uptake in septic humans or rats, or reverse the specific defect in insulin-mediated skeletal muscle glucose uptake by septic rats. Therefore, the decreased pyruvate dehydrogenase activity associated with sepsis does not appear to mediate sepsis-induced insulin resistance during insulin-stimulated glucose uptake at either the whole-body or tissue level.(Crit Care Med 1996; 24:566-574)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo characterize biochemical changes in skeletal muscle in critically ill patients.DesignSurvey of critically ill patients.SettingIntensive care unit (ICU) at a university hospital.PatientsCritically ill patients (n equals 20) subjected to trauma, surgical complications, and/or bacteremia who were treated in the ICU and showed no risk of bleeding complications were included. Reference groups of metabolically healthy volunteers and patients served as the control/reference groups.InterventionsPercutaneous muscle biopsy was obtained from both patients and healthy volunteers.Measurements and Main ResultsTotal free amino acids in skeletal muscle decreased 59% (p less than .001) and skeletal muscle glutamine concentration decreased 72% (p less than .001) in the critically ill patients. Basic amino acids decreased 49% (p less than .001). Branch-chain amino acids increased 39% (p less than .01), and aromatic amino acids increased 88% (p less than .001) in the patients.Adenosine triphosphate (ATP) was reduced by 12% (p less than .01). Total creatine concentration increased by 26% (p less than .001) due to an 80% increase in free creatine (p less than .001). The phosphorylated creatine fraction of total creatine decreased 22% (p less than .001) in the patients.Alkali-soluble protein/DNA decreased 24% (p less than .01) and fat free solid/DNA decreased 21% (p less than .01) in patients sampled on or after ICU day 5 compared with the reference group. Muscle water increased 10% due to a doubling of the extracellular water fraction.ConclusionsAlthough critically ill patients are a very heterogeneous group from a clinical point of view, there is a remarkable homogeneity in many of the biochemical parameters regardless of the severity of illness and the length of the ICU admission. The three most consistent differences were the skeletal muscle low glutamine concentration, the decrease in protein content, and the increase in extracellular water in the patients.(Crit Care Med 1996; 24:575-583)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo determine the prevalence and clinical significance of hypolipidemia found in critically ill patients, and whether the addition of a reconstituted lipoprotein preparation could inhibit the generation of tumor necrosis factor-alpha (TNF-alpha) in acute-phase blood taken from these patients.SettingSurgical intensive care unit (ICU) of a large urban university hospital.DesignProspective case series.PatientsA total of 32 patients with a variety of critical illnesses had lipid and lipoprotein concentrations determined. Six patients and six age- and gender-matched control subjects had whole blood in vitro studies of the effect of lipoprotein on lipopolysaccharide mediated TNF-alpha production.InterventionsBlood samples were drawn on admission to the ICU and over a subsequent 8-day period.Measurements and Main ResultsMean serum lipid and lipoprotein values obtained from patients within 24 hrs of transfer to the surgical ICU were extremely low: mean total cholesterol was 117 mg/dL (3.03 mmol/L), low-density lipoprotein cholesterol 71 mg/dL (1.84 mmol/L), and high-density lipoprotein cholesterol 25 mg/dL (0.65 mmol/L). Only the mean triglyceride concentration of 105 mg/dL (1.19 mmol/L), and the mean lipoprotein(a) concentration of 25 mg/dL (0.25 g/L) were within the normal range. During the first 8 days following surgical ICU admission, there were trends toward increasing lipid and lipoprotein concentrations that were significant for triglycerides and apolipoprotein B. Survival did not correlate with the lipid or lipoprotein concentrations, but patients with infections had significantly lower (p equals .008) high-density lipoprotein cholesterol concentrations compared with noninfected patients. Lipopolysaccharide-stimulated production of TNF-alpha in patient and control blood samples was completely suppressed by the addition of 2 mg/mL of a reconstituted high-density lipoprotein preparation.ConclusionsPatients who are critically ill from a variety of causes have extremely low cholesterol and lipoprotein concentrations. Correction of the hypolipidemia by a reconstituted highdensity lipoprotein preparation offers a new strategy for the prevention and treatment of endotoxemia.(Crit Care Med 1996; 24:584-589)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveThe aim of this study was to examine the effect of dopamine infusion on the thyrotropin (TSH), thyroid hormone, prolactin, and growth hormone responses to thyrotropin-releasing hormone (TRH) in critically ill patients.DesignProspective, randomized, controlled, open-labeled clinical study.SettingThe intensive care unit, University Hospital Gasthuisberg, Leuven, over a 1-month period.Patients and InterventionsIn 15 critically ill patients receiving dopamine treatment (5 micro gram/kg/min) for a mean of 43.3 plus minus 1.2 (SEM) hrs after trauma or cardiac surgery, we studied the TSH, thyroid hormone, prolactin, and growth hormone responses to the administration of two consecutive intravenous TRH boluses of 200 micro gram, with a 6-hr interval. The dopamine infusion was continued in the control group and discontinued in the study group. Serum concentrations of TSH, prolactin, and growth hormone were measured before and 20, 40, 60, and 120 mins after TRH administration. Serum concentrations of thyroxine (T4), triiodothyronine (T3), reverse T3, and thyroid hormone binding globulin were determined before and 120 mins after each TRH injection.Measurements and Main ResultsThere was a more than 100-fold interindividual variation in the baseline TSH concentration and in the TSH peak value after TRH administration. Two consecutive doses of TRH evoked a mean 16% increase in serum T4concentration (p equals .003) and a mean 47% increase in T3(p equals .001), whereas serum reverse T3and thyroid hormone binding globulin values remained unaltered. Each of the TRH boluses increased serum growth hormone concentrations in the continued dopamine and discontinued dopamine groups, by a median of 60% (p equals .001) and 68% (p equals .001), respectively. Three hours after dopamine withdrawal, there was a three-fold increase of the peak TSH response (p equals .001), a higher T3response (p equals .01), and a ten-fold increase of the peak prolactin value (p equals .001) in response to TRH administration.ConclusionsThe TSH response to TRH administration in critical illness presents a striking interindividual variation and is dopamine dependent. Repeated TRH administration results in a repetitive increase of TSH, prolactin, growth hormone, T4, and T3, without increasing reverse T3. These observations point toward a potential for TRH as a strategy for reversing the euthyroid sick syndrome, growth hormone deficiency, and immune dysfunction associated with critical illness.(Crit Care Med 1996; 24:590-595)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo investigate the prognostic value of increased serum concentrations of soluble tumor necrosis factor (TNF) receptors in patients at high risk for sepsis.DesignProspective study.SettingCardiac surgical intensive care unit in a University Hospital.PatientsThose 27 of 870 consecutive postcardiac surgical patients who met a previously validated high-risk criterion for imminent sepsis (Acute Physiology and Chronic Health Evaluation II [APACHE II] score of more than equals 24 on the first postoperative day [day 1]). In this population, systemic inflammatory response syndrome was present in 96% of the patients and the inhospital mortality rate was 30%. In addition, ten postcardiac surgical patients with an uncomplicated course (mortality rate 0%) were studied for comparison.InterventionsBlood sampling for measurements of serum concentrations of TNF and soluble TNF receptors 55 kilodalton (TNF receptor-p55) and 75 kilodalton (TNF receptor-p75) on days 1, 2, 3, and 5.Measurements and Main ResultsCompared with the ten patients with an uncomplicated course (group A), the high-risk patients had significantly higher baseline (day 1) serum concentrations of soluble TNF receptor-p55 (9.2 vs. 4.2 ng/mL) and soluble TNF receptor-p75 (9.2 vs. 5.5 ng/mL). These high-risk patients could be further differentiated into two subgroups: one (B) with a prompt decrease in APACHE II score and a good prognosis (mortality rate 0%) and another (C) with a persisting high risk of sepsis and mortality rate (40%, p less than .05). Although baseline APACHE II score was similar in both high-risk subgroups, soluble TNF receptor-p55 concentrations were significantly higher in subgroup C compared with subgroup B already at baseline (10.7 vs. 4.7 ng/mL). The receiver operating characteristic curve for subgroup classification by soluble TNF receptor-p55 was in a discriminating position with an area (0.773 plus minus 0.096), confirming soluble TNF receptor-p55 as a predictor of mortality. TNF and soluble TNF receptor-p75 concentrations were less predictive at baseline.ConclusionsThis study suggests that increased soluble TNF receptor-p55 concentrations in the serum of postcardiac surgical patients allow earlier prognostication of subsequent hospital course than APACHE II scores alone. This study further suggests that the combination of physiologic scores and cytokine receptor measurements could improve the predictive power of early postoperative risk stratification.(Crit Care Med 1996; 24:596-600)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo determine the role of serum albumin concentration as a predictor of mechanical ventilation dependency.DesignProspective, observational trial.SettingMultidisciplinary intensive care unit (ICU) in a university hospital.PatientsOne hundred forty-five consecutive patients who required mechanical ventilation for more than 72 hrs.InterventionsPatients were classified into five different groups based on the cause of respiratory failure. The following parameters were recorded daily: serum albumin concentration; Acute Physiology and Chronic Health Evaluation II (APACHE II) score; and fluid balance. Using multiple regression, multiple logistic regression analysis, and the Anderson-Gill proportional hazards model, we determined the metabolic factors that could help predict weaning success.Measurements and Main ResultsThe mean length of ICU stay was 12.3 plus minus 1.0 days. The duration of mechanical ventilation dependency was 10.5 plus minus 1.0 days. The initial mean serum albumin concentration was 25.2 plus minus 0.6 g/L. The APACHE II score on the first day of ICU stay was 19.1 plus minus 0.6. Although albumin concentration was significantly lower and the APACHE II score was significantly higher in ICU nonsurvivors than in ICU survivors, albumin concentration on ICU admission was not a predictor of the length of time spent receiving mechanical ventilation. The profile of albumin concentration changes was different between weaned and mechanical ventilation-dependent patients. At the time of weaning patients from the ventilator, the median albumin concentration was higher than in those patients who continued to be supported by mechanical ventilation. This effect of albumin could not be attributed to patient fluid balance or to the severity of illness since each factor had an independent influence in predicting weaning, using the Anderson-Gill proportional hazards model.ConclusionsInitial serum albumin concentration did not necessarily predict weaning success. However, when serum albumin concentration was assessed on a daily basis, its trend was important in determining the relative chance of being successfully weaned from the ventilator. This finding suggests that albumin may be an index of the metabolic status of the patient, which could be important in determining the weanability of the patients who are mechanically ventilated for prolonged periods of time.(Crit Care Med 1996; 24:601-607)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveWe tested the hypothesis that PaCO2would be more tightly controlled if end-tidal CO2monitoring was used during hand ventilation for transport of intubated patients.DesignRandomized, prospective analysis of the no-monitor and monitor-blind groups (the monitor was on the bed during transport but only the investigator was aware of the end-tidal CO2values). Nonrandomized, prospective analysis of the monitor group (ventilation controlled using end-tidal CO2value from monitor).SettingUniversity hospital operating room and intensive care unit (ICU).PatientsFifty intubated patients who were transported from the operating room to the ICU or from the ICU to the neuroradiology suite were assigned randomly to one of two groups: a) no-monitor group (n equals 25); and b) monitor-blind group (n equals 25). An additional group (monitor group, n equals 10) was subsequently added to the study.InterventionsCapnography was instituted in all patients in a blocked fashion.Measurements and Main ResultsArterial blood gases and end-tidal CO2values were measured before and after transport. When comparing overall group data, pre- and post-PaCO2values were similar: monitor 39 plus minus 2 vs. 41 plus minus 2 torr (5.2 plus minus 0.3 vs. 5.5 plus minus 0.3 kPa); monitor-blind 39 plus minus 1 vs. 39 plus minus 2 torr (5.2 plus minus 0.1 vs. 5.2 plus minus 0.3 kPa); no-monitor 39 plus minus 1 vs. 37 plus minus torr (5.2 plus minus 0.1 vs. 5.0 plus minus 0.1 kPa). However, when comparing PaCO2values for individual patients, we found that there was significantly greater variability for PaCO2after transport when end-tidal CO2was not used for control of ventilation during transport.ConclusionsThese data do not support routine monitoring of end-tidal CO2during short transport times in adult patients requiring mechanical ventilation. However, the monitor may prevent morbidity in patients requiring tight control of PaCO2.(Crit Care Med 1996; 24:608-611)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID