摘要:

Objective:To determine the effects of a pressor agent (phenylephrine and L-arginine) on the abnormal cerebral hemodynamics and on neurologic outcome after a severe cortical impact injury in rats.Design:Prospective, randomized study.Setting:University laboratory.Subjects:Male Long-Evans rats, weighing 300 to 400 g, fasted overnight.Interventions:The animals were anesthetized with isoflurane, and a severe cortical impact injury (velocity, 5 m/sec; deformation, 3 mm) was produced in the right parietal cortex. Five minutes after impact injury, one of the following three treatments were infused: 1 mL saline intravenously for 10 mins, 300 mg/kg L-arginine in 1 mL saline intravenously for 10 mins, or 0.3 μg/kg/min phenylephrine intravenously for 3 hrs. Mean arterial pressure, intracranial pressure (ICP), cerebral perfusion pressure (CPP), and laser Doppler flow (LDF) at the impact site and in the contralateral parietal cortex were monitored for 3 hrs after the impact injury. Histologic examination of the brain was performed at 2 wks after injury in a separate group of L-arginine- and saline-treated animals.Measurements and Main Results:The immediate response to the impact injury was an increase in ICP, and a decrease in mean arterial pressure, CPP, and LDF. In the saline-treated animals, LDF decreased to <25% of the baseline values at the impact site and stayed at that level for the entire 3-hr monitoring period. On the contralateral side, LDF decreased initially and recovered gradually to approximately 50% of the preimpact baseline value. Infusion of both phenylephrine and L-arginine increased LDF back to near-baseline levels. However, phenylephrine increased ICP significantly, whereas ICP with L-arginine did not change. L-arginine treatment reduced the contusion volume from a median value of 5.28 mm3to 0.63 mm3.Conclusions:Phenylephrine increased cerebral blood flow (CBF) by increasing CPP. L-arginine, however, increased CBF without changing CPP. The improvement in CBF was accompanied by a decrease in neurologic injury. Although the pressor agents are used currently to increase CBF after traumatic brain injury, other strategies may also increase CBF without the potential adverse effects of induced hypertension.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:We sought to test the hypothesis that ileal mucosal oxygen consumption is impaired in endotoxemic rats.Methods:Male Sprague-Dawley rats were injected intravenously with eitherEscherichia colilipopolysaccharide (5 mg/kg) or a similar volume of vehicle. A segment of ileum was excised 8 hrs later, and the serosal and muscular layers of the bowel were stripped away from the mucosa. A strip of mucosa was mounted in a polarographic chamber containing air-saturated Krebs-Henseleit buffer plus 20 mM glucose, PO2being monitored during a 10-min period. Some rats were injected intraperitoneally with the inducible nitric oxide synthase inhibitor, aminoguanidine (30 mg/kg per dose), or a similar volume of vehicle, at 1, 3 and 6 hrs after injection of lipopolysaccharide.Results:In an initial experiment, the rate of oxygen consumption was significantly lower for mucosal samples from endotoxemic rats as compared with control rats (0.76 ± 0.11 ng-atoms vs. 1.42 ± 0.22 ng-atoms of 0/min per μg dry weight, respectively; n = 8 per group;p< .05). The rate of mucosal oxygen consumption was higher in aminoguanidine-treated as compared with vehicle-treated endotoxemic rats (1.25 ± 0.11 ng-atoms and 0.73 ± 0.07 ng-atoms of 0/min per μg, respectively; n = 7 and n = 6, respectively;p< .05).Conclusion:Endotoxemia is associated with diminished intestinal mucosal oxygen utilization due to an intrinsic acquired derangement in cellular respiration that is caused, at least in part, by an aminoguanidine-inhibitable mechanism.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine the effect of early enhanced enteral nutrition (EN) on clinical outcome of head-injured patients.Design:Prospective, randomized, controlled trial.Setting:Tertiary neurosurgical and trauma center.Patients:Eighty-two patients suffering head injury and requiring mechanical ventilation.Interventions:Patients were randomized to receive standard EN (gradually increased from 15 mL/hr up to estimated energy and nitrogen requirements) or enhanced EN (started at a feeding rate that met estimated energy and nitrogen requirements) from day 1. Good neurologic outcome (Glasgow Outcome Scale score of 4 or 5) was determined at 3 and 6 months after injury, and the incidence of infective and total complications was determined during the hospital stay up to 6 months.Measurements and Main Results:Disease severity assessed by best preintubation Glasgow Coma Scale score, pupillary responses, Injury Severity Score, Acute Physiology and Chronic Health Evaluation II score, computed tomographic scan categorization, and age was similar in both groups. Intervention patients had a higher percentage of energy (p= .0008) and nitrogen (p< .0001) requirements met by EN in the first week after injury. Neurologic outcome at 6 months was similar between groups, but there was a tendency for more intervention patients to have a good neurologic outcome at 3 months than control patients (61% vs. 39%,p= .08). Fewer intervention patients had an infective complication (61% vs. 85%,p= .02) or more than one total complication (37% vs. 61%,p= .046) compared with control patients. Enhanced EN was associated with a reduction in the ratio of serum concentration of C-reactive protein to albumin up to day 6 after injury (p= .004).Conclusions:Enhanced EN appears to accelerate neurologic recovery and reduces both the incidence of major complications and postinjury inflammatory responses.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To describe a method of rapid fluid removal in children with anasarca and the acute respiratory distress syndrome (ARDS) secondary to sepsis or the systemic inflammatory response syndrome.Design:Consecutive case series.Setting:Pediatric Intensive Care Unit of a children's hospital.Patients:Six patients with ARDS secondary to sepsis or systemic inflammatory response syndrome, who had persistent anasarca complicating their respiratory course despite intravenous diuretic therapy.Interventions:Continuous flow peritoneal dialysis (CFPD) was instituted after percutaneously inserting two Tenckhoff dialysis catheters into the peritoneal cavity of each patient and tunneling them through the subcutaneous tissue to exit from opposite lower abdominal quadrants. A dialysis solution with 2.5% dextrose was administered continuously via one of the catheters at a rate ranging from 10-30 mL/kg/hr, and concomitantly drained via the other catheter. The concentration of the dialysis solution and rate of inflow were adjusted as needed to achieve the desired peritoneal outflow rate. CFPD was discontinued when adequate weight loss had occurred and the patient's daily urine output exceeded their daily fluid intake. The patient's overall fluid balance and change in weight were recorded daily. The PaO2/FIO2ratio, alveolar-arterial oxygen gradient, and oxygenation index were also calculated daily.Measurements and Main Results:Six patients with ARDS, mean age 18.7 ± 37.0 months were mechanically ventilated for 8.0 ± 4.0 days before CFPD, during which time average body weight increased to 63% ± 22% above admission body weight, despite the use of intravenous diuretic therapy. They underwent CFPD for 126.7 ± 60.0 hrs, during which time their body weight decreased to 30% ± 12% above admission weight (p< .05). During dialysis, the dialysis outflow rate exceeded the inflow rate by 4.2 ± 0.9 mL/kg/hr. When compared with values calculated immediately before starting CFPD, post-CFPD PaO2/FIO2increased from 97.0 ± 32.0 to 215.0 ± 40.4 mm Hg (12.9 ± 4.3 to 28.7 ± 5.4 kPa) (p< .05), post-CFPD alveolar-arterial oxygen gradient decreased from 390.7 ± 85.8 to 206.7 ± 72.8 mm Hg (52.1 ± 11.4 to 27.6 ± 9.7 kPa) (p< .05), and post-CFPD the oxygenation index decreased from 29.6 ± 9.8 to 11.8 ± 5.6 (p< .05). There were no complications associated with dialysis catheter insertion or CFPD therapy. Four patients survived. Two patients had an irreversible course of infections and septic shock and died.Conclusion:Severe anasarca in the course of ARDS can be effectively treated in pediatric patients with continuous flow peritoneal dialysis, resulting in a significant improvement in respiratory status.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine whether nonbronchoscopic protected specimen brush (PSB) and bronchoalveolar lavage (BAL) are contributive for diagnosing ventilator-associated pneumonia in mechanically ventilated children.Design:Prospective study.Setting:Fifteen-bed pediatric intensive care unit in a university hospital.Patients:A total of 103 mechanically ventilated children, ranging in age from 7 days to 8.8 yrs, most with a high clinical suspicion for bacterial pneumonia.Interventions:All the children underwent nonbronchoscopic PSB and BAL. Nonbronchoscopic PSB was performed with a plugged double-sheathed brush and BAL with a double-lumen plugged catheter. Endotracheal secretions and blood cultures were also collected. Open-lung biopsy was performed for any child who died within 7 days after the inclusion in the study, according to the parental consent.Measurements and Main Results:The PSB specimens were submitted for bacteriologic quantitative culture (positive threshold, 103colony-forming units [cfu]/mL). The BAL samples were processed for microscopic quantification of the polymorphonuclear cells containing intracellular bacteria (positive threshold, 1%) and quantitative culture (positive threshold, 104cfu/mL). According to diagnostic categories based on clinical, biological, radiologic, and pathologic criteria, 29 children had bacterial pneumonia and 64 did not. Ten children were classified as having an uncertain status. Of the 29 children with bacterial pneumonia, 26 (90%) met one of the following three criteria: a) PSB specimen culture, ≥103cfu/mL; b) intracellular bacteria in cells retrieved by BAL, ≥1%; and c) BAL fluid culture, ≥104cfu/mL. In contrast, 56 (88%) of the 64 patients without pneumonia did not.Conclusion:The results of this study indicate the following: a) nonbronchoscopic PSB and BAL were feasible in a large population of mechanically ventilated children; b) nonbronchoscopic techniques were contributive for diagnosing ventilator-associated pneumonia in children; and c) a combined diagnostic approach, using nonbronchoscopic PSB and BAL, was superior to using either test alone.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To review myopathic changes occurring during intensive care treatment in the light of recent information about manifestation, clinical settings, pathophysiology, and histomorphologic changes.Data Sources:The computerized MEDLINE database, bibliography of pertinent articles, and the author's personal files.Study Selection:Studies were selected according to their relevance to myopathic complications in critically ill patients.Data Extraction:All applicable data were extracted.Data Synthesis:Myopathic changes occur frequently in patients treated in the intensive care unit (ICU). Three main types have been identified: critical illness myopathy, myopathy with selective loss of myosin filaments, and acute necrotizing myopathy of intensive care. These histologic types probably represent variable expressions of a toxic effect not yet identified. Candidates for such myotoxic effects are the mediators of the systemic response in sepsis and high-dose administration of corticosteroids and muscle relaxants. The influence of these latter agents appears to be particularly important in the pathogenesis of myosin loss and myonecrosis. Experimental studies suggest that axonal damage attributable to critical illness neuropathy can be an additional factor triggering myopathies in the ICU. Muscle membrane inexcitability was recently identified as an alternative mechanism of severe weakness in ICU patients.Conclusions:Myopathic changes are surprisingly frequent in critically ill patients. The clinical importance of this finding is still unknown, but it is likely that weakness caused by myopathy prolongs ICU stay and rehabilitation. Because corticosteroids and muscle relaxants appear to trigger some types of ICU myopathy, they should be avoided or administered at the lowest doses possible. Sepsis, denervation, and muscle membrane inexcitability may be additional factors. Studies addressing the pathophysiology of myopathy in critically ill patients are urgently needed.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:We conducted a meta-analysis by using summary receiver operating characteristic curves to compare the diagnostic value for bacterial nosocomial pneumonia of the following: a) quantitative culture (colony-forming units per milliliter or CFU/mL) of respiratory secretions collected with a bronchoscopic protected specimen brush (PSB); b) quantitative culture of a bronchoscopic bronchoalveolar lavage (BAL); and c) the percentage of infected cells (IC) in BAL.Data Sources:All studies published in the English or the French language, through January 1, 1995, on the evaluation of PSB or BAL for the diagnosis of pneumonia were considered for analysis. The relevant literature was identified through computer and reference searching and by experts in the field.Study Selection:A study was included if at least two of three independent readers regarded its purpose as the evaluation of CFU-PSB, CFU-BAL, or IC-BAL for the diagnosis in human beings of bacterial nosocomial pneumonia in ventilated adults and if the study was prospective and published in a peer-reviewed journal.Data Extraction:Three readers reviewed all published articles and decided whether to include each study; consensus was defined as agreement by at least two readers. The authors of each original article included in the meta-analysis were asked to complete a questionnaire in which they were asked to check and to correct the data extracted by one of the independent readers.Data Synthesis:Summary receiver operating characteristic curves were used to compare the efficacy of three diagnostic tests. Eighteen studies on CFU-PSB (795 patients) were included, as well as 11 studies on CFU-BAL (435 patients) and 11 on IC-BAL (766 patients). The accuracy of these tests was not different. However, it seems that administration of previous antibiotics markedly decreased accuracy of CFU-PSB (p= .0002) but not the accuracy of CFU-BAL and that of IC-BAL.Conclusion:Both PSB and BAL are reliable to diagnose bacterial nosocomial pneumonia. Because CFU-BAL and IC-BAL seemed more resistant to the effects of antibiotics, we recommend BAL rather than PSB if the patient is already receiving antibiotics.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background:We have previously described a method for the precise delivery of inhaled nitric oxide (iNO) via a conventional, continuous-flow, pressure-limited, time-cycled ventilator. Because of the augmented effect of iNO decreasing pulmonary vascular resistance with high-frequency oscillatory ventilation (HFOV), we developed and bench tested a system that permits easy and accurate iNO delivery during HFOV.Method:The system uses a mass flow controller to deliver fixed volumes of iNO to the HFOV circuit in the range 0 to 20 ppm iNO. The accuracy of the delivery system is based on a comparison of the difference between iNO measured at strategic points in the circuit and the calculated true value.Results:The mean difference between the measured and calculated value for iNO (n = 360) was −0.2 ± 1.74 ppm (2 SD) (range, 0 to 20 ppm, 0 to 15 Hz). The formation of nitrogen dioxide was <1 ppm at the level of the endotracheal tube.Conclusion:The method tests the accuracy of iNO measurements and provides an assessment of the uncertainty over the range of iNO and HFOV settings used clinically.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:To report a case of acute chest syndrome (ACS) of sickle cell disease treated successfully with nitric oxide and to review the physiologic effects of nitric oxide and its potential ability to improve outcome in ACS.Design:Descriptive case report.Setting:Eighteen-bed pediatric intensive care unit in a university children's hospital.Patient:A 15-yr-old black male with sickle cell disease, bilateral pulmonary infiltrates, refractory hypoxemia, and unstable hemodynamics.Intervention:In addition to exchange transfusion, invasive hemodynamic monitoring, and aggressive ventilatory support, inhaled nitric oxide was administered in the gas mixture in a concentration of 20 ppm for 72 hrs.Measurements and Main Results:Cardiac output, pulmonary arterial pressure, pulmonary artery occlusion pressure, systemic vascular resistance, pulmonary vascular resistance, shunt fraction, and alveolar-arterial oxygen gradient were compared with and without inhaled nitric oxide. Marked reductions in pulmonary arterial pressure and pulmonary vascular resistance were noted. Cardiac output improved, and shunt fraction and alveolar-arterial oxygen gradient were markedly reduced. The patient required decreased ventilator and hemodynamic support and rapidly made a complete recovery.Conclusions:Nitric oxide may be beneficial for patients with ACS because of its ability to ameliorate pulmonary hypertension and ventilation/perfusion mismatch. Nitric oxide may confer some protection against polymerization of sickle hemoglobin and exert a reversible antiplatelet effect that may be beneficial in ACS. Further study is necessary to determine the safety and efficacy of inhaled nitric oxide as a treatment for ACS.

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