摘要:

ObjectiveTo study the transported L-arginine in rat hepatocytes during different stages of sepsis.DesignA prospective, controlled study.SubjectsThirty-six Sprague-Dawley male rats (250 to 300 g) were anesthetized and studied.InterventionsEarly sepsis was produced 9 hrs after cecal ligation and puncture (CLP) and late sepsis developed 18 hrs after CLP. The control group underwent sham operation. Plasma membrane of rat hepatocytes was prepared by differential centrifugation. The [(3) H] L-arginine uptake of plasma membrane vesicles during sepsis was measured and inhibition studies employing omega-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine were performed.Measurements and Main ResultsL-arginine transport was saturable, increased linearly with plasma membrane protein concentration, and increased with uptake time up to 5 mins. [(3) H] L-arginine uptake increased by 77% to 121% (p < .05) during early sepsis, with no significant changes during late sepsis. Comparing inhibitors of nitric oxide synthase, L-NAME was effective in inhibiting L-arginine transport while aminoguanidine was not.ConclusionsL-arginine transport was enhanced in rat hepatocytes during the early stage of sepsis. The increased uptake of L-arginine could contribute to the increase production of nitric oxide by hepatocyte during sepsis. (Crit Care Med 1999; 27:137-141)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo evaluate aspiration prophylaxis during cardiopulmonary resuscitation (CPR) using transtracheal jet ventilation (TJV) with different pressure-depths of chest compression and chest compression alone without mechanical ventilation.DesignProspective, animal study.SettingAnimal research laboratory, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Taiwan.SubjectsMongrel dogs (n = 10) weighing 8 to 12 kg.InterventionsEight mongrel dogs were anesthetized, paralyzed, and ventilated transtracheally with a jet ventilator at frequencies varied from 600 to 10 cycles/min. The airway pressures below and above the jetting port were measured. The mouth of the dog was filled with barium and chest radiographs were taken 10 mins after chest compression with 20-pound pressure and 5-cm depth in group 1 and 10-pound pressure and 3-cm depth in group 2 at each different jet frequency. Two additional dogs underwent the same procedures but received only chest compression without TJV.Measurements and Main ResultsPulmonary aspiration was not noted in the chest radiographs from either group. The airway pressure changes between groups were not significantly affected by difference in pressures and depths of chest compression at the same jetting frequency. However, pulmonary aspiration occurred in the two dogs that received chest compression alone without TJV.ConclusionsApplication of TJV during chest compression with different pressures and depths caused no pulmonary aspiration in dogs at frequencies between 600 and 10 cycles/min. The protection against aspiration disappeared if the dogs received only chest compression without TJV. The mechanism of preventing pulmonary aspiration in TJV is thought to be due to forceful unidirectional gas outflow through the larynx and higher airway pressure in the carina than in the upper airway. The airway pressures were not affected by different chest compression pressures and depths because the larynx stayed open during TJV and the air outflow could freely move out without increasing the pressure in the airway. (Crit Care Med 1999; 27:142-145)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectivesDuring endotoxemia, there is a marked and intractable decrease in systemic blood pressure, as well as profound vasoconstriction of the renal artery, thereby leading to septic shock and acute renal failure. The purpose of this study was to elucidate the effect of endothelin-1, a potent endothelium-derived vasoconstrictor peptide, on the hemodynamic and renal vascular changes seen in endotoxemia.DesignProspective, comparative, experimental study.SettingLaboratory at a university hospital.SubjectsThirty-two male mongrel dogs (12.1 +/- 0.4 kg) under pentobarbital anesthesia.InterventionsFour groups of animals were studied: a) the lipopolysaccharide (LPS) group (n = 10), which received LPS (250 ng/kg/min for 2 hrs); b) the TAK-044 (a nonselective endothelinA/endothelinBreceptor antagonist) plus LPS group (n = 12), which received a bolus of TAK-044 (5 mg/kg) 0.5 hr before the start of LPS infusion; c) the TAK-044 plus vehicle group (n = 5), which received the same dose of TAK-044 0.5 hr before the start of vehicle infusion; and d) the control group (n = 5), which received only vehicle infusion.Measurements and Main ResultsChanges in systemic and renal hemodynamics, blood gas, and renal function were measured at baseline, and at 0.5, 1, 2, 3, and 4 hrs. Infusion of LPS resulted in significant decreases in mean arterial pressure, arterial pH, PaO2, base excess, urine volume, renal blood flow, creatinine clearance, and urine osmolality. The administration of TAK-044 before LPS infusion did not affect the LPS-induced hypotension. In contrast, the receptor antagonist prevented LPS-induced metabolic acidosis and hypoxemia, and improved LPS-induced decreases in urine volume, renal blood flow, creatinine clearance, and urine osmolality, whereas TAK-044 or vehicle administered alone resulted in no significant hemodynamic or blood gas changes. Plasma endothelin-1 concentrations significantly increased after LPS infusion, with or without TAK-044.ConclusionsThe present study suggests that endothelin-1 plays an important role in the impaired renal hemodynamics and renal function associated with endotoxemia, and that endothelin receptor antagonists may be useful as therapeutic agents for acute renal failure during endotoxemia. (Crit Care Med 1999; 27:146-153)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo determine whether blood lactate, base deficit, or oxygen-derived hemodynamic variables correlate with morbidity and mortality rates in a clinically-relevant LD50model of penetrating trauma.DesignProspective, controlled study.SettingUniversity research laboratory.SubjectsAnesthetized, mechanically-ventilated mongrel pigs (30 +/- 2 kg, n = 29).InterventionsA captive bolt gun delivered a penetrating injury to the thigh, followed immediately by a 40% to 60% hemorrhage. After 1 hr, shed blood and supplemental crystalloid were administered for resuscitation.Measurements and Main ResultsAfter penetrating injury, 50.7 +/- 0.3% hemorrhage (range 50% to 52.5%), and a 1-hr shock period, seven of 14 animals died, compared with six of six animals after 55% to 60% hemorrhage, and 0 of nine animals after <or=to47.5% hemorrhage. Only two of 13 deaths occurred during fluid resuscitation. At the LD50hemorrhage, peak lactate concentration and base deficit were 11.2 +/- 0.8 mM and 9.3 +/- 1.5 mmol/L, respectively, and minimum mixed venous oxygen saturation, systemic oxygen delivery, and systemic oxygen consumption were 33 +/- 5%, 380 +/- 83 mL/min/kg, and 177 +/- 35 mL/min/kg, respectively. For comparison, baseline preinjury values were 1.6 +/- 0.1 mM, -6.7 +/- 0.6 mmol/L, 71 +/- 3%, 2189 +/- 198 mL/min/kg, and 628 +/- 102 mL/min/kg, respectively. Of all the variables, only lactate was significantly related to blood loss before and after fluid resuscitation in the 16 survivors. However, r2values were relatively low (.20 to .50), which indicates that only a small fraction of the hyperlactacidemia was directly related to tissue hypoperfusion. In the whole population of survivors and nonsurvivors, both lactate and base deficit (but none of the oxygen-derived variables) correlated with blood loss.ConclusionsArterial lactate is a stronger index of blood loss after penetrating trauma than base deficit or oxygen-derived hemodynamic variables. The reliability of arterial lactate depends on several factors, such as the time after injury, the proportion of survivors and nonsurvivors in the study population, and on factors other than tissue hypoxia. (Crit Care Med 1998; 26:154-161)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectivesTo investigate the effects of S-ethylisothiourea (S-EITU) on hemodynamics, oxygen transport, and regional blood flow in healthy and septic sheep.DesignProspective, randomized, controlled experimental study with repeated measures.SettingInvestigational intensive care unit at a university medical center.SubjectsEleven healthy, female adult sheep of the Merino breed, divided into a control group (n = 5) and into a group treated with S-EITU (n = 6).InterventionsAll sheep were chronically instrumented. After a 5-day recovery period, they were randomly assigned to either control or S-EITU groups. While control sheep received only saline, S-EITU was administered in increasing doses of 1, 3, and 9 mg/kg/hr over 1 hr each (nonseptic phase). After 2 days of recovery, a continuous infusion of live Pseudomonas aeruginosa (2.5 x 106colony-forming units/min) was started in all sheep and maintained for the remainder of the experiment. After 24 hrs of sepsis, the sheep again received their assigned treatment (septic phase). In both the nonseptic and septic phases, the sheep received colored microspheres through a left atrial catheter to allow analysis of regional blood flows. All animals were autopsied at the end of the experiments, and organ probes were removed for blood flow analyses.Measurements and Main ResultsThe administration of S-EITU caused a dose-dependent vasoconstriction in the nonseptic phase. After 24 hrs of Pseudomonas infusion, all sheep developed a hyperdynamic circulatory state, with increased cardiac indices and reduced arterial pressures and systemic vascular resistances. Oxygen extraction decreased significantly, preventing an increase in oxygen consumption, despite an increased oxygen delivery. The hyperdynamic circulation was dose dependently reversed by S-EITU, causing an increase in arterial pressure by peripheral vasoconstriction. Sheep in the control group showed a continuation of the hyperdynamic circulation. The effects of S-EITU on hemodynamics and regional blood flows were comparable under septic and nonseptic conditions.ConclusionsWith the inducible form of nitric oxide synthase expressed under septic, but not under nonseptic conditions, S-EITU was expected to have vasoconstrictive properties only in the septic phase. It produced a comparable vasoconstriction during the nonseptic phase of the experiment. Thus, either S-EITU does not selectively block the inducible nitric oxide synthase in sheep, or other vasodilators besides nitric oxide play an important role in septic vasodilation. (Crit Care Med 1999; 27:162-167)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectivesWe hypothesized that tumor necrosis factor-alpha (TNF-alpha) acutely alters left ventricular mechanoenergetics in blood-perfused hearts. To test this hypothesis, we examined the relation between left ventricular mechanics and energetics, both before and after infusion of TNF-alpha.DesignProspective, experimental study.SettingResearch laboratory.SubjectsNine isolated, blood-perfused canine hearts.InterventionsRecombinant human TNF-alpha (90 [micro sign]g/min) was infused into the coronary circulation of the isolated hearts for 20 mins.Measurements and Main ResultsIn the isolated, cross-circulated, blood-perfused canine left ventricles, left ventricular contractility was assessed through measurement of end-systolic elastance (Ees). Energetics were examined in terms of the end-systolic pressure-volume area-myocardial oxygen consumption (MVO21000 ng/mL throughout the experiments. Nevertheless, infusion of TNF-alpha barely affected contractility acutely, i.e., there was a minimal decrease during the infusion (8.1 +/- 2.8% at 10 mins, p < .01) and a minimal increase after the infusion (11.2 +/- 2.5% at 10 mins, p < .01). Neither did the TNF-alpha infusion affect the slope of the end-systolic pressure-volume area-MVO (2) relation. This finding indicated that the chemomechanical conversion efficiency remained unchanged. However, TNF-alpha infusion significantly increased the oxygen cost of contractility by 40% (1.25 +/- 0.13 vs. 1.75 +/- 0.24 mL oxygen[center dot]mL/mm Hg/beat, p < .05), indicating that MVO2for the excitation-contraction coupling increased.ConclusionsTNF-alpha minimally alters left ventricular mechanics, but significantly changes energetics. The latter effect may result from changes in intracellular calcium handling. (Crit Care Med 1999;27:168-176)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveSecondary intracranial hypertension has been linked to leukocytosis. We examined our data bank containing physiologic recordings and outcome data of severely head injured patients to investigate the relationship between delayed increases in intracranial pressure (ICP), defined as occurring after a 12-hr period of normal ICP values, and leukocytosis.DesignA retrospective study of observational data.SettingRegional neurosurgical unit and intensive care unit.Patients20 mm Hg. Thirty-five patients fulfilled selection criteria for delayed increases in ICP (group 1). Twenty-nine patients with increased ICP with no preceding or intervening periods of normal ICP were selected as a comparison group (group 2).Measurements and Main ResultsComparison of 12-month outcome revealed that 11% of group 1 patients died, with 49% remaining severely disabled, in contrast to group 2, where 35% of patients died and 14% were left severely disabled (p = .021). The pattern of outcome was independent of monitoring time, or injury severity. Regression modeling was performed for prediction of delayed increase in ICP. Of 46 patients with an initial increase then decrease in leukocyte count in the first 48 hrs, 65% experienced delayed increases in ICP, as compared with 18% of the 11 patients without this pattern (p = .011).ConclusionsPatients with delayed increases have a significantly different pattern of outcome. Change in leukocyte count from admission to day 2 is a significant predictor of such a delayed increase. (Crit Care Med 1999; 27:177-181)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectivesBilateral loss of the cortical somatosensory evoked potentials (SEP) is usually regarded as a strong predictor for a very poor clinical outcome. We present four patients with a favorable recovery from bilaterally absent cortical SEP.DesignCase series.SettingNeurocritical care unit at the University of Heidelberg.PatientsFour patients with viral encephalitis, carbamazepine intoxication, head trauma, and left-side, space-occupying hemispheric infarction, respectively.InterventionsSerial recording of somatosensory and auditory evoked potentials, therapy of increased intracranial pressure, including decompressive surgery, hypothermia, and barbiturate coma.Measurements and Main ResultsThree patients had an excellent outcome (Glasgow Outcome Scale 4 and 5). In those three patients, the SEP became completely normal during the clinical course. In one patient who remained severely disabled, the SEP became detectable again over the contralateral hemisphere, but remained abnormal. Possible influencing factors were sedative and analgetic drugs in all patients, and hypothermia and barbiturate coma in one of the patients.ConclusionsThe absence of cortical SEP does not invariably imply an unfavorable prognosis. Absent cortical SEP indicates a severe neuronal dysfunction, which may be completely reversible if the underlying disease does not lead to permanent structural damage. (Crit Care Med 1999; 27:182-187)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveProspective study of the efficacy of calf lung surfactant extract in pediatric respiratory failure.DesignMulti-institutional, prospective, randomized, controlled, unblinded trial.SettingEight pediatric intensive care units (ICU) of tertiary medical centers.Patientsor=to7.InterventionInstillation of intratracheal surfactant (80 mL/m2).Measurements and Main ResultsVentilator parameters, arterial blood gases, and derived oxygenation and ventilation indices were recorded before and at intervals after surfactant administration. Complications and outcome measures, including mortality, duration of mechanical ventilation, and length of pediatric ICU and hospital stay, were also examined. Patients who received surfactant demonstrated rapid improvement in oxygenation and, on average, were extubated 4.2 days (32%) sooner and spent 5 fewer days (30%) in pediatric intensive care than control patients. There was no difference in mortality or overall hospital stay. Surfactant administration was associated with no serious adverse effects.ConclusionsAdministration of calf lung surfactant extract, calfactant, appears to be safe and is associated with rapid improvement in oxygenation, earlier extubation, and decreased requirement for intensive care in children with acute hypoxemic respiratory failure. Further study is needed, however, before widespread use in pediatric respiratory failure can be recommended. (Crit Care Med 1999; 27:188-195)

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID