ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The autonomic nervous system plays an integral role in homeostasis. Autonomic modulation can frequently be altered in critically ill patients. Assessment of heart rate variability (HRV) is based on analysis of consecutive normal R-R intervals and may provide quantitative information on the modulation of cardiac vagal and sympathetic nerve input. The hypothesis that depressed HRV may occur over a broad range of critical illness and injury and may be inversely correlated with disease severity and outcome has been tested in the last decade. In this article, we review recent literature concerning assessment of HRV in patients with critical illness or injury, as well as the potential clinical implications and limitations of HRV assessment in this area.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The nature of myocardial dysfunction during sepsis and septic shock has been investigated for more than half a century. This review traces the evolution of scientific thought regarding this phenomenon during this period with particular emphasis on the current understanding of both the clinical manifestations and the molecular/cellular basis of septic myocardial dysfunction in critically ill patients. Current data suggest, contrary to older literature, that patients with septic shock develop a hyperdynamic circulatory state after fluid resuscitation and maintain this hyperdynamic circulatory state until death or recovery. Overt myocardial depression, as manifested by decreased cardiac output, is decidedly uncommon, even in the preterminal phase. Nonetheless, myocardial depression, as evidenced by biventricular dilation and depression of the ejection fraction, can be demonstrated in most patients with septic shock by using either radionuclide cineangiography or echocardiography. Depression is reversible over the course of 7 to 10 days in survivors. Available evidence suggests that myocardial hypoperfusion is not responsible for septic myocardial depression, because examination of humans with septic shock demonstrates increased myocardial perfusion, and animal models of septic shock appear to maintain myocardial high-energy phosphates. A circulating factor or factors, including the cytokines tumor necrosis factor &agr; and interleukin-1&bgr;, appear to have a significant role in the phenomenon. In addition, septic myocardial depression appears to be mediated in part through combinations of nitric oxide–dependent and –independent alterations of basal and catecholamine-stimulated cardiac myocyte contractility.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Cardiac complications such as myocardial infarction and congestive heart failure are the primary source of perioperative morbidity and mortality in elderly surgical patients. This is the result of structural and functional age-related changes in the heart and the vasculature and an increasing incidence of cardiovascular disorders. Appropriate perioperative management of the elderly patient should be based on the extent of functional compromise, the type and severity of pre-existing disease, and the invasiveness of the surgical procedure. Current studies suggest that appropriately administered medical therapy, particularly &bgr;-adrenergic blockade, may reduce perioperative cardiovascular morbidity and mortality in these patients. In this article, we review changes in cardiovascular structure and function that occur with advancing age and describe perioperative medical interventions that may improve cardiac outcome in the elderly critically ill patient.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Adrenergic receptors transduce signals through the G proteins to regulate cardiac function. The catecholamines, via &agr;- and &bgr;-adrenergic receptor (&bgr;-AR) stimulation, may play a role in the development of heart failure. Norepinephrine and isoproterenol can induce cardiac myocyte apoptosis.In vitrostudies suggest that &agr;-, &bgr;1-, and &bgr;2-adrenergic pathways differentially regulate cardiac myocyte apoptosis. The stimulation of &bgr;1-AR leads to cyclic AMP–dependent apoptosis, whereas that of the &bgr;2-AR elicits concurrent apoptosis and survival signals in cardiac myocytes coupled to Gsprotein. Overexpression of &agr;1-adrenergic receptors does not induce apoptosis in wild-type mice. In contrast, the heart failure observed in some murine models has to be related to an enhanced &bgr;-AR kinase expression. These recent advances make it possible to understand the beneficial effects of &bgr;-blockers in the treatment of chronic heart failure and provide novel therapeutic modalities through the stimulation of &bgr;2-ARs or the inhibition of &bgr;-AR kinase expression.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Risk stratification has become an essential element in the practice of cardiac surgery. Several studies have identified preoperative risk factors for adverse outcome. However, outcome is mostly defined by 30-day mortality and morbidity. These data reflect poorly the benefit for the patient. Long-term survival, quality of life, and functional status should be included in a more global analysis of the outcome, particularly in patients with complicated ICU stay. By reviewing the recent data reported in the literature, we can identify a number of preoperative predictive factors for complicated ICU stay, including advanced age, chronic obstructive pulmonary disease, preoperative low ejection fraction, previous myocardial infarction, reoperation, renal failure, combined surgery (coronary artery bypass grafting plus valve surgery), low hematocrit, and neurologic impairment. Short- and long-term outcomes are dependent on the type of postoperative complication. Unfortunately, data regarding the long-term outcome in these situations are very scarce.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Heat shock protein (HSP) synthesis arises transiently as a tool to protect cellular homeostasis after exposure to heat and a wide spectrum of stressful and potentially deleterious stimuli. HSPs are “molecular chaperones” that recognize and form a complex with incorrectly folded or denatured proteins, which ultimately leads to correct folding, compartmentalization, or degradation. Accumulating evidence has implicated HSPs as mediators of myocardial protection, particularly in experimental models of ischemia and reperfusion injury. Impaired myocardial performance, which results from many factors, including hypoxia, is one of the main mechanisms responsible for heart failure in the critically ill patient. In this setting, different protective functions have been attributed to HSPs, which include repairing ion channels, restoring redox balance, interacting with nitric oxide–induced protection, inhibiting proinflammatory cytokines, and preventing apoptosis pathway activation. On this basis, novel therapeutic strategies by means of promising pharmacologic interventions and/or gene transfection techniques are being investigated for their potential to enhance HSP expression by myocardial cells, with the goal of improving the outcome of the critically ill patient.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The heart plays a pivotal role in determining the oxygen supply to the body. As a result of its high oxygen extraction ratio, the myocardium must function efficiently to supply itself with oxygen. In the context of the ICU, the efficient functioning of the myocardium is confounded by a number of pathologic processes that may interfere with its oxygen supply or increase its oxygen demand. Conventional drug treatment of acute myocardial decompensation tends to increase myocardial oxygen demand. The myocardium may potentially be “protected” by treatment modalities that favorably alter the oxygen supply to demand ratio. Newer methods of protecting the heart may involve improving the coordination of myocardial contraction, using novel inotropic agents, supporting the myocardium metabolically, administrating blood products more conservatively, favorably altering the immune response, and using mechanical support devices. Myocardial protection may be improved by better use and understanding of monitors of myocardial performance.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Nosocomial pneumonia is a dynamic disease with multiple etiologic agents and a changing natural history. The highest attack rates and mortality occur in patients with ventilator-associated pneumonia. Diagnosis of nosocomial pneumonia is often made by clinical criteria that are sensitive but lack specificity. The use of quantitative endotracheal aspirates or bronchoscopy with bronchoalveolar lavage and protected specimen brush clearly improve diagnostic specificity and outcome in patients who are mechanically ventilated. The rapid spread of multidrug-resistantStreptococcus pneumoniae,Pseudomonas aeruginosa,Acinetobacterspp, andStaphylococcus aureushas made initial empiric therapy more difficult. Management principles include the use of techniques for more accurate diagnosis and early antimicrobial therapy with appropriate agents along with careful analysis of culture results, clinical response, and potential complications of pneumonia and therapy. Strategies for prophylaxis are of critical importance for risk reduction, improvement in patient outcome, and reduction of hospital costs.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The increase in antibiotic resistance over the past 10 years can be traced to several factors. This includes exogenous transmission of bacteria, usually by hospital personnel. The use of potent antibiotics also can select for resistant bacteria initially present in low quantities. Strategies to reduce antibiotic resistance can be tailored to specific outbreaks in a given ICU. General strategies for reducing antibiotic resistance, on the other hand, include varying the agents used in the ICU over time. Reduction of the duration of therapy may prove to be another method of reducing antibiotic resistance.

ISSN:1070-5295    

出版商:OVID    

年代:2002

数据来源: OVID