摘要:

ObjectivesWe determined the response of intracellular cyclic GMP in human arteries and veins and in smooth muscle cells cultured from these vessels to C-type natriuretic peptide in comparison with atrial natriuretic peptide.DesignRepeated-measures analysis of concentration-response curves.SettingAnesthesia research laboratory.SubjectsVascular smooth muscle cells from human blood vessels obtained with Institutional Review Board approval and patient consent.Measurements and Main ResultsSegments of internal mammary artery and saphenous vein were obtained from patients undergoing coronary artery bypass surgery. Smooth muscle cells were cultured from these vessels. Concentration-response curves of intracellular cyclic GMP were determined and analyzed by twoway analysis of variance with repeated measures. In segments of intact saphenous vein, C-type natriuretic peptide was significantly more effective than atrial natriuretic peptide (16-fold increase in cyclic GMP in response to 1 micro Meter of C-type natriuretic peptide vs. six-fold increase in cyclic GMP in response to 1 micro Meter of atrial natriuretic peptide, p less than .05). In rings of intact internal mammary artery, 1 micro Meter of atrial natriuretic peptide (26-fold increase in cyclic GMP over basal value) was more effective than 1 micro Meter of C-type natriuretic peptide (three-fold increase in cyclic GMP over basal value, p less than .05). In cultured cells from these vessels, the pattern of response to C-type natriuretic peptide and atrial natriuretic peptide was the same as in the intact vessels.ConclusionsThese results indicated that human smooth muscle cells in arteries and veins express both forms of natriuretic peptide receptors but that atrial natriuretic peptide acts primarily on the artery and C-type natriuretic peptide acts predominately on the vein. Increased concentrations of C-type natriuretic peptide could contribute to venous pooling in septic shock.(Crit Care Med 1996; 24:306-310)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo review the cerebrovascular pathophysiology of hypertension, and the risks and benefits of antihypertensive therapies in the patient with intracranial ischemic or space-occupying pathology.Data SourcesReview of English language scientific and clinical literature, using MEDLINE search.Study SelectionPertinent literature is referenced, including clinical and laboratory investigations, to demonstrate principles of pathophysiology and controversies regarding the treatment of hypertension in patients with intracranial ischemic or space-occupying pathology.Data ExtractionThe literature was reviewed to summarize the pathophysiology, risks, and benefits of antihypertensive therapies in the patient with intracranial ischemic or space-occupying pathology. Treatment strategies were outlined with a particular emphasis on how antihypertensive agents may affect the brain.Data SynthesisCerebral autoregulation typically occurs over a range of cerebral perfusion pressures between 50 and 150 mm Hg. Chronic hypertension results in adaptive changes that allow cerebral autoregulation to occur over a higher range of pressures. Acute hypertension (rapid increase in perfusion pressure above the autoregulatory limit) may result in cerebral edema, persistent vasodilation, and brain injury. Treatment of a hypertensive emergency must be undertaken conservatively since the chronically hypertensive patient is at risk for ischemic brain injury when perfusion pressure is rapidly decreased beyond autoregulatory limits. In the patient with head injury or primary neurologic injury, acute antihypertensive intervention can result in further brain injury. Selection of appropriate antihypertensive therapy necessitates the careful consideration of agent-specific effects on cerebral blood flow, autoregulation, and intracranial pressure. For example, some vasodilators treat hypertension but also dilate the cerebral vasculature, and increase cerebral blood volume and intracranial pressure while decreasing cerebral perfusion pressure. Pharmacologic blockade of alpha1- or beta1-adrenergic receptors can reduce arterial blood pressure with little or no effect on intracranial pressure within the autoregulatory range. Like the direct peripheral vasodilators, calcium-channel antagonists are limited by cerebral vasodilation and increased intracranial pressure. Angiotensin converting enzyme inhibitors can also be used for mild to moderate hypertension but have the potential to further increase intracranial pressure in patients with intracranial hypertension. Barbiturates offer an alternative antihypertensive therapy since they decrease blood pressure as well as cerebral blood flow and oxygen metabolism.ConclusionsThe treatment of acute hypertension in the patient with intracranial ischemic or space-occupying pathology requires an understanding of the pathophysiology of hypertension and determinants of cerebral perfusion pressure. Individual agents should be selected based on their ability to promptly and reliably decrease blood pressure, while considering effects on cerebral blood flow and intracranial pressure.(Crit Care Med 1996; 24:311-322)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveExtracorporeal membrane oxygenation (ECMO) has been used with increasing frequency in the treatment of acute respiratory failure in pediatric patients. Our objective in this study was to test the hypothesis that ECMO improves outcome in pediatric patients with acute respiratory failure.DesignMulticenter, retrospective cohort analysis.SettingForty one pediatric intensive care units participated in the study under the auspices of the Pediatric Critical Care Study Group.PatientsAll pediatric patients admitted to the participating institutions with acute respiratory failure during 1991 were included. Patients with congenital heart disease, contraindications to ECMO, or incomplete data were excluded, yielding a data set of 331 patients from 32 hospitals.InterventionsConventional mechanical ventilation, high-frequency ventilation, and extracorporeal membrane oxygenation.Measurements and Main ResultsMultivariate logistic regression analysis was used to identify factors associated with survival. In a second analysis, pairs of ECMO and non-ECMO patients, matched by severity of disease and respiratory diagnosis, were compared.The use of ECMO (p equals .0082), but not the use of high-frequency ventilation, was associated with a reduction in mortality. Other factors independently associated with mortality included oxygenation index (p less than .0001), Pediatric Risk of Mortality score (PRISM) (p less than .0001) and the Paco2(p equals .045). In 53 diagnosis- and risk-matched pairs, there was a significantly lower mortality rate (26.4% vs. 47.2%; p less than .01) in the ECMO-treated patients. When all patients were stratified into mortality risk quartiles on the basis of oxygenation index and PRISM score, the proportion of deaths among ECMO-treated patients in the 50% to 75% mortality risk quartile was less than half the proportion in the non-ECMO treated patients (28.6% vs. 71.4%; p less than .05). No effect was seen in the other quartiles.ConclusionsThe use of ECMO was associated with an improved survival in pediatric patients with respiratory failure. The lack of association of outcome with treatment in the ECMO-capable hospital or with another tertiary technology (i.e., highfrequency ventilation) suggests that ECMO itself was responsible for the improved outcome. Further studies of this procedure are warranted but require broad-based multi-institutional participation to provide sufficient statistical power and sensitivity to demonstrate efficacy.(Crit Care Med 1996; 24:323-329)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo describe the use of percutaneous catheter drainage of tension pneumatocele, secondarily infected pneumatocele, and lung abscess in children.DesignRetrospective case series.SettingA 24-bed pediatric intensive care unit.PatientsPatients with tension pneumatocele, secondarily infected pneumatocele, or lung abscess. Tension pneumatocele was defined as an expanding intraparenchymal cyst compressing adjacent areas of the lung. Infected pneumatocele and lung abscess were defined, respectively, as intraparenchymal thin-walled cyst or thick-walled cavity containing an air-fluid level and purulent fluid.InterventionsSeven pneumatoceles/lung abscesses were percutaneously drained in five patients. After computed tomography of the chest was obtained to localize the optimum site for drainage, a modified Seldinger technique was used to insert an 8.5-Fr soft catheter percutaneously into the cyst/cavity. The catheter was left in place until drainage (fluid and air) stopped.Measurements and Main ResultsAll patients had clinical and radiologic improvement and were afebrile within 24 hrs after drainage. Bacterial culture grew aerobic bacteria from three cysts/cavities, anaerobic bacteria from one, and mixed bacteria from three. One patient had three secondarily infected pneumatoceles. Four of five secondarily infected pneumatoceles were under tension in two patients receiving mechanical ventilation. In both patients, the trachea was extubated within 24 hrs of drainage after prolonged mechanical ventilation. The number of days the catheter was in place ranged from 1 to 20 days.ConclusionsPercutaneous catheter drainage of tension pneumatocele, secondarily infected pneumatocele, and lung abscess can be performed safely and effectively in children. Early drainage is helpful, both as a diagnostic and therapeutic procedure. Drainage of tension pneumatocele may assist in weaning from mechanical ventilation. Computed tomography of the chest is helpful in determining the optimum site for percutaneous drainage.(Crit Care Med 1996; 24:330-333)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo describe the philosophy and approach to patient care called evidence based medicine, and to highlight how it can enhance the practice of intensive care.Data SourcesWe searched MEDLINE, reference lists, and our personal files to identify relevant literature.Study SelectionArticles on intensive care practice, critical appraisal, clinical research, and healthcare delivery were selected for discussion.Data SynthesisWe summarize the rationale for evidence based medicine, its applications and future developments, and suggest several methods for intensivists to use evidence based medicine in their practice and teaching.ConclusionsEvidence based medicine can complement other foundation disciplines in intensive care. This is the first article in a series entitled ``Evidence Based Critical Care Medicine'' which will demonstrate how this approach can be used at the bedside.(Crit Care Med 1996; 24:334-337)

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo assess the cost-effectiveness of prophylaxis for stress-related gastrointestinal hemorrhage in patients admitted to the intensive care unit.DesignDecision model of the cost and efficacy of sucralfate and cimetidine, two commonly used drugs for prophylaxis of stress-related hemorrhage. Outcome estimates were based on data from published studies. Cost data were based on cost of medications and costs of treatment protocols at our institution.Measurements and Main ResultsThe marginal cost-effectiveness of prophylaxis, as compared with no prophylaxis, was calculated separately for sucralfate and cimetidine and expressed as cost per bleeding episode averted. An incremental cost-effectiveness analysis was subsequently employed to compare the two agents. Sensitivity analyses of the effects of the major clinical outcomes on the cost per bleeding episode averted were performed.At the base-case assumptions of 6% risk of developing stress-related hemorrhage and 50% risk-reduction due to prophylaxis, the cost of sucralfate was $1,144 per bleeding episode averted. The cost per bleeding episode averted was highly dependent on the risk of hemorrhage and, to a lesser degree, on the efficacy of sucralfate prophylaxis, ranging from a cost per bleeding episode averted of $103,725 for low-risk patients to cost savings for very high-risk patients. The cost per bleeding episode averted increased significantly if the risk of nosocomial pneumonia was included in the analysis. The effect of pneumonia was greater for populations at low risk of hemorrhage. Assuming equal efficacy, the cost per bleeding episode averted of cimetidine was 6.5-fold greater than the cost per bleeding episode averted of sucralfate.ConclusionsThe cost of prophylaxis in patients at low risk of stress-related hemorrhage is substantial, and may be prohibitive. Further research is needed to identify patient populations that are at high risk of developing stress-related hemorrhage, and to determine whether prophylaxis increases the risk of nosocomial pneumonia.(Crit Care Med 1996; 24:338-345)

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

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

ISSN:0090-3493    

出版商:OVID    

年代:1996

数据来源: OVID