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| 3. |
- Berg, Sören, et al.
(author)
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Proinflammatory cytokines increase the rate of glycolysis and adenosine-5'-triphosphate turnover in cultured rat enterocytes
- 2003
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In: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 31:4, s. 1203-1212
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Journal article (peer-reviewed)abstract
- Objective: Measurements of steady-state adenosine-5'-triphosphate (ATP) levels in tissue samples from patients or experimental animals with sepsis or endotoxemia provide little information about the rate of ATP production and consumption in these conditions. Accordingly, we sought to use an in vitro "reductionist" model of sepsis to test the hypothesis that proinflammatory cytokines modulate ATP turnover rate. Design: In vitro "reductionist" model of sepsis. Setting: University laboratory. Subjects: Cultured rat enterocyte-like cells. Interventions: IEC-6 nontransformed rat enterocytes were studied under control conditions or following incubation for 24 or 48 hrs with cytomix, a mixture of tumor necrosis factor-a (10 ng/mL), interleukin-1ß (1 ng/mL), and interferon-? (1000 units/mL). To measure ATP turnover rate, ATP synthesis was acutely blocked by adding to the cells a mixture of 2-deoxyglucose (10 mM), potassium cyanide (8 mM), and antimycin A (1 µM). ATP content was measured at baseline (before metabolic inhibition) and 0.5, 1, 2, 5, and 10 mins later. Log-linear ATP decay curves were generated and the kinetics of ATP utilization thereby calculated. Measurements and Main Results: ATP consumption rate was higher in cytomix-stimulated compared with control cells (3.11 ± 1.39 vs. 1.25 ± 0.66 nmol/min, respectively, p < .01). Similarly, the half-time for ATP disappearance was shorter in cytomix-stimulated compared with control cells (2.63 ± 1.00 vs. 6.21 ± 3.49, p < .05). In contrast to these findings, the rate of ATP disappearance was similar in cytokine-naïve and immunostimulated IEC-6 cells when protein and nucleic acid synthesis were inhibited by adding 50 µg/mL cycloheximide and 5 µg/mL actinomycin D to cultures for 4 hrs. The rates of glucose consumption and lactate production were significantly greater in cytomix-stimulated compared with controls cells. Conclusions: Incubation of IEC-6 cells with cytomix significantly increased ATP turnover. Increased ATP turnover rate was supported by increases in the rate of anaerobic glycolysis. These findings support the view that proinflammatory mediators impose a metabolic demand on visceral cells. In sepsis, cells may be more susceptible to dysfunction on the basis of diminished oxygen delivery and/or mitochondrial dysfunction.
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- Chew, Michelle, et al.
(author)
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Pediatric cardiac output measurement using surface integration of velocity vectors : an in vivo validation study
- 2000
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In: Critical Care Medicine. - : Ovid Technologies (Wolters Kluwer Health). - 0090-3493 .- 1530-0293. ; 28:11, s. 3664-3671
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Journal article (peer-reviewed)abstract
- Objective: To test the accuracy and reproducibility of systemic cardiac output (CO) measurements using surface integration of velocity vectors (SIVV) in a pediatric animal model with hemodynamic instability and to compare SIVV with traditional pulsed-wave Doppler measurements.Design: Prospective, comparative study.Setting: Animal research laboratory at a university medical center.Subjects: Eight piglets weighing 10-15 kg.Interventions: Hemodynamic instability was induced by using inhalation of isoflurane and infusions of colloid and dobutamine.Measurements: SIVV CO was measured at the left ventricular outflow tract, the aortic valve, and ascending aorta. Transit time CO was used as the reference standard.Results: There was good agreement between SIVV and transit time CO. At high frame rates, the mean difference ± 2 sd between the two methods was 0.01 ± 0.27 L/min for measurements at the left ventricular outflow tract, 0.08 ± 0.26 L/min for the ascending aorta, and 0.06 ± 0.25 L/min for the aortic valve. At low frame rates, measurements were 0.06 ± 0.25, 0.19 ± 0.32, and 0.14 ± 0.30 L/min for the left ventricular outflow tract, ascending aorta, and aortic valve, respectively. There were no differences between the three sites at high frame rates. Agreement between pulsed-wave Doppler and transit time CO was poorer, with a mean difference ± 2 sd of 0.09 ± 0.93 L/min. Repeated SIVV measurements taken at a period of relative hemodynamic stability differed by a mean difference ±2 sd of 0.01 ± 0.22 L/min, with a coefficient of variation = 7.6%. Intraobserver coefficients of variation were 5.7%, 4.9%, and 4.1% at the left ventricular outflow tract, ascending aorta, and aortic valve, respectively. Interobserver variability was also small, with a coefficient of variation = 8.5%.Conclusions: SIVV is an accurate and reproducible flow measurement technique. It is a considerable improvement over currently used methods and is applicable to pediatric critical care.
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- Cucchiara, BL, et al.
(author)
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Early impairment in consciousness predicts mortality after hemispheric ischemic stroke
- 2004
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In: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 32:1, s. 241-245
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Journal article (peer-reviewed)abstract
- Objective: Early predictors of poor outcome after acute ischemic stroke may be useful in selecting patients for potentially beneficial but high-risk interventions. Design. Cohort study of patients given placebo in a randomized clinical trial. Setting. Multicenter trial at 139 U.S. and 14 Canadian hospitals. Patients. A cohort of 564 placebo-treated patients with major anterior circulation ischemic stroke enrolled in the Clomethiazole in Acute Stroke Study-Ischemic Stroke (CLASS-I) trial. Patients did not have significant impairment in consciousness at baseline and were enrolled within 12 hrs of symptom onset. Interventions: Prospective data collection of a number of clinical variables including use of a 6-point level of consciousness scale (1 = awake, 6 = no reaction to pain) to measure patients' level of consciousness at enrollment and 12 additional times during the first 24 hrs after enrollment. The ability of level of consciousness score and additional clinical data to predict 30-day mortality was assessed. Measurements and Main Results., At 1 month, 114 of 564 patients (20%) had died. In univariate analysis, factors significantly associated with mortality included older age, white race, higher National Institutes of Health Stroke Scale score, higher serum glucose, atrial fibrillation, and any impairment in level of consciousness (p < .05). After controlling for these factors, increasing level of consciousness score at 3 hrs after enrollment and at all but one subsequent time point was significantly associated with increased mortality (odds ratio, 1.8 per point, 95% confidence interval, 1.2-2.6, p = .003 at 3-hr time point). Maximum level of consciousness score during the initial 24 hrs of monitoring also predicted mortality (odds ratio, 1.9 per point, 95% confidence interval, 1.4-2.5, p < .001). Conclusion: The development of a decreased level of consciousness within the initial hours after stroke onset, as evaluated by a simple six-point scale, is a powerful independent predictor of mortality after major anterior circulation ischemic stroke.
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- Elf, Kristin, et al.
(author)
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Outcome after traumatic brain injury improved by an organized secondary insult program and standardized neurointensive care
- 2002
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In: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 30:9, s. 2129-2134
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To evaluate today's refined neurosurgical intensive care of patients with traumatic brain injury after implementation of an organized secondary insult program focused on the importance of avoiding secondary brain damage together with a standardized treatment protocol system.DESIGN: Clinical observational patient study.PATIENTS: A total of 154 patients 16-79 yrs of age with acute head trauma and pathologic computed tomographic findings treated between 1996 and 1997.SETTING: Neurointensive care unit.INTERVENTIONS: None.MEASUREMENTS AND MAIN RESULTS: Good recovery was obtained in 44% of the patients, moderate disability in 35%, severe disability in 16%, and no patient remained in a vegetative state. Six percent of the patients died, but only two of these patients (1.3%) died as direct result of their head injury. When the results for patients with Glasgow Coma Scale motor scores of >or=4 were compared with the periods 1980-1981 (preneurosurgical intensive care) and 1987-1988 (basic neurosurgical intensive care), mortality had decreased from 40% in the first period to 27% in the second period and to 2.8% in the present series. Favorable outcome in the same group of patients had increased steadily from 40% in the first period, to 68% in the second period, and finally, to 84% in the present series.CONCLUSIONS: The main observation in this hospital series of traumatic brain injury patients was a low rate of death directly caused by head injury and a high rate of favorable outcome. The comparison of patients with Glasgow Coma Scale motor scores of >or=4 with the previously reported results from the same unit indicate that substantial improvement in outcome has been achieved.
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- Gedeborg, Rolf, et al.
(author)
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Adverse effects of high-dose epinephrine on cerebral blood flow during experimental cardiopulmonary resuscitation
- 2000
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In: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 28:5, s. 1423-1430
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Journal article (peer-reviewed)abstract
- OBJECTIVE:To study the effects of high-dose epinephrine, compared with standard-dose epinephrine, on the dynamics of superficial cortical cerebral blood flow as well as global cerebral oxygenation during experimental cardiopulmonary resuscitation. We hypothesized that high-dose epinephrine might be unable to improve cerebral blood flow during cardiopulmonary resuscitation as compared with standard-dose epinephrine.DESIGN:Randomized controlled study.SETTING:University hospital research laboratory.SUBJECTS:A total of 20 male anesthetized piglets.INTERVENTIONS:Ventricular fibrillation was induced. A nonintervention interval of 8 mins was followed by open-chest cardiopulmonary resuscitation. The animals were randomized to receive repeated bolus injections of either 20 microg/kg (standard-dose group, n = 10) or 200 microg/kg (high-dose group, n = 10) of epinephrine.MEASUREMENTS AND MAIN RESULTS:Focal cortical cerebral blood flow was measured continuously by using laser Doppler flowmetry. The duration of blood flow increase was significantly shorter in the high-dose group after the second dose of epinephrine. In the high-dose group there was also a consistent tendency for lower peak levels and shorter duration of flow increase in response to repeated bolus doses of epinephrine. Cerebral oxygen extraction ratio was significantly lower in the high-dose group after administration of epinephrine.CONCLUSIONS:Repeated bolus doses of epinephrine 200 microg/kg, as compared with 20 microg/kg, do not improve superficial cortical cerebral blood flow during experimental open-chest cardiopulmonary resuscitation. High-dose epinephrine appears to induce vasoconstriction of cortical cerebral blood vessels resulting in redistribution of blood flow from superficial cortex. This might be one explanation for the failure of high-dose epinephrine to improve overall outcome in clinical trials.
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| 8. |
- Holbeck, Staffan, et al.
(author)
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Dextran, gelatin, and hydroxyethyl starch do not affect permeability for albumin in cat skeletal muscle
- 2001
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In: Critical Care Medicine. - 1530-0293. ; 29:1, s. 123-128
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To evaluate the effects of the three commercially available colloid solutions, 6% dextran 70, 6% hydroxyethyl starch (HES) 200/0.5, and 3.5% urea-linked gelatin on permeability for human albumin in a skeletal muscle in vivo model by evaluating their effects on the reflection coefficient for albumin. DESIGN: Controlled laboratory study. SETTING: University research laboratory. SUBJECTS: Eighteen adult cats. INTERVENTIONS: The autoperfused and denervated calf muscles of the cat hindlimb were placed in a plethysmograph. The transvascular fluid absorption induced by an increase in the colloid osmotic pressure following a fixed intravenous bolus of human albumin was analyzed, first before start of, and then during an intra-arterial infusion to, the muscle preparation of the synthetic colloid to be analyzed. Capillary filtration coefficient as a measure of microvascular fluid permeability (conductance) was analyzed before and after start of the synthetic colloid. MEASUREMENTS AND MAIN RESULTS: Arterial blood flow, arterial and venous blood pressures, total vascular resistance, tissue volume changes, capillary filtration coefficient, and plasma volume were measured before and during the colloid infusion. According to the Starling fluid equilibrium, the ratio between the reflection coefficients for albumin on two occasions (before and after infusion of the synthetic colloid) can be calculated from the maximum osmotic absorption rates induced by a fixed intravenous bolus infusion of albumin and from the capillary filtration coefficients. Obtained data were adjusted for different plasma volume at the two occasions. We found that none of the three synthetic colloids analyzed had any significant effect on the reflection coefficient for albumin. CONCLUSION: An effect on albumin microvascular permeability of the synthetic colloids dextran 70, HES 200/0.5, and urea-linked gelatin could not be shown by a method analyzing their effect on the reflection coefficient for albumin.
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| 9. |
- Holbeck, Staffan, et al.
(author)
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Effects of hypertonic saline, mannitol, and urea with regard to absorption and rebound filtration in cat skeletal muscle.
- 2002
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In: Critical Care Medicine. - 1530-0293. ; 30:1, s. 212-217
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To study the effects of the hypertonic solutions 15% mannitol, 3% and 7.5% saline, and 30% urea at clinically relevant plasma concentrations with regard to absorption and rebound effects on tissue volume in skeletal muscle. DESIGN: A prospective, experimental study. SETTING: University laboratory. SUBJECTS: Twenty-eight anesthetized cats. INTERVENTIONS: The study was performed on an autoperfused and denervated cat calf muscle placed in a fluid-filled plethysmograph. Muscle volume changes and capillary filtration coefficient (reflecting capillary fluid conductivity) were measured before, during, and after intra-arterial infusion (4 mL/hr) of the hypertonic solutions. Mannitol and 3% saline have the same osmolality and were compared specifically in an attempt to distinguish osmotic effects from those specific to the compound. MEASUREMENTS AND MAIN RESULTS: All solutions reduced muscle volume during the infusion (p < .05). The maximum volume reduction persisted after 2 hrs of infusion for 3% and 7.5% saline, whereas there was a tendency for volume recovery during the urea infusion and a complete recovery back to control for mannitol. After discontinuation of the infusions, the muscle volume increased for all four solutions, stabilizing at the initial control for 3% and 7.5% saline, whereas it increased to levels above control for mannitol and urea (p < .05). Capillary filtration coefficient was increased by hypertonic saline (p < .05) but was unaffected by mannitol and urea. CONCLUSIONS: The effectiveness of a hypertonic solution in reducing tissue volume and its tendency to cause a rebound volume increase depends not only on the osmolality of the solution. Hypertonic saline may in the long run be superior to mannitol and urea to increase plasma volume or decrease tissue volume of an organ, because it lacks rebound effects. Alterations in capillary filtration coefficient (fluid conductivity) may reflect volume changes of the capillary endothelial cell and thereby differences in cell membrane permeability for the hypertonic solutions, also consistent with the obtained differences in tissue volume effects.
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| 10. |
- Holbeck, Staffan, et al.
(author)
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Endotoxin increases both protein and fluid microvascular permeability in cat skeletal muscle
- 2003
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In: Critical Care Medicine. - 1530-0293. ; 31:2, s. 560-565
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Journal article (peer-reviewed)abstract
- Objective: To evaluate effects of lipopolysaccharide (endotoxin) on protein and fluid permeability in a whole organ skeletal muscle preparation. Design: Controlled, prospective laboratory study. Setting: University research laboratory. Subjects: Eleven adult male cats. Interventions: The study was performed on the autoperfused and denervated calf muscles of the cat hindlimb placed in a fluid-filled plethysmograph. The endotoxin-induced change in the osmotic reflection coefficient for albumin was used as a measure of alteration in protein permeability of the microvascular wall, and the simultaneous change in capillary filtration coefficient was used as a measure of alteration in fluid permeability. Endotoxin as a bolus infusion (1 mg/kg iv) was given to six cats, and another five cats given only the vehicle (NaCl) were used as control. Measurements and Main Results: Arterial blood flow, arterial and venous blood pressures, total vascular resistance, and tissue volume changes were measured continuously. The ratio between the osmotic reflection coefficients for albumin on two occasions (before and about 1.5 hr after endotoxin infusion) was calculated from the Starling fluid equilibrium equation. This was performed by measurement of the maximum absorption rate from an iso-volumetric state by an intravenous bolus infusion of 20% human albumin (0.6 g/kg) and the capillary filtration coefficient. Albumin concentrations were measured before and after the albumin infusion to correct for effects of difference in plasma volume on the induced increase in colloid osmotic pressure. We found that the osmotic reflection coefficient for albumin was reduced by 30% (p < .05), and the capillary filtration coefficient was increased by 31% (p < .05) by endotoxin. No changes were seen in the vehicle experiments. Conclusion: Endotoxin causes a significant increase in both protein and fluid microvascular wall permeability. These effects may explain the marked leakage of plasma to the interstitium that is often seen in critically ill patients with sepsis and systemic inflammatory response syndrome.
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