Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Oct 2002
Pneumonia complicating the acute respiratory distress syndrome.
Ventilator-associated pneumonia (VAP) complicating the course of acute respiratory distress syndrome (ARDS) is one of the most challenging diagnostic and treatment dilemmas in critical care medicine. The VAP incidence rate ranges from 37 to 60% in ARDS patients, significantly greater than for other causes of respiratory failure. Although the normal risk factors for VAP are the same in ARDS patients, multiple aspects of the underlying disease and its management increase the risk compared with non-ARDS patients. ⋯ The multilobar but predominantly lower lobe pattern of pneumonia in ARDS makes use of quantitative cultures of lower respiratory secretions (sampled by various techniques) very accurate to confirm the presence of pneumonia. VAP in ARDS patients is usually late-onset and therefore caused by highly antibiotic-resistant microorganisms. Somewhat surprisingly, the mortality of ARDS patients with VAP is not significantly greater than that of ARDS patients without VAP, although subsequent duration of mechanical ventilation is consistently prolonged in patients with VAP.
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Semin Respir Crit Care Med · Oct 2002
Strategies for prevention of hospital-acquired pneumonia: oral and selective decontamination of the gastrointestinal tract.
The use of antimicrobial prophylaxis is the most extensively studied, though probably also the most controversial, method to prevent the development of ventilator-associated pneumonia (VAP). Selective decontamination of the digestive tract (SDD) includes the application of topical nonabsorbable antibiotics in the oropharynx, stomach, and intestines in combination with systemic antibiotics during the first days of ventilation. ⋯ Moreover, the significant reductions in incidences of VAP have, so far, not resulted in reductions of duration of ventilation and ICU-stay, and reductions in ICU-mortality were found only in meta-analysis. Selection of resistant bacteria is the most important drawback of antimicrobial prophylaxis, and the demonstrated benefits of antimicrobial prophylaxis should be carefully balanced with this potential risk.
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Airway remodeling is a summary term for the pathological changes that occur in airway structure in allergic or suppurative airway diseases. Characteristic changes of airway remodeling in asthma include goblet cell hyperplasia, deposition of collagens in the basement membrane zone, increased size and number of microvessels in the submucosa, hyperplasia and hypertrophy of airway smooth muscle, and hypertrophy of submucosal glands. Some of these changes, such as goblet cell hyperplasia and subepithelial collagen deposition, are present even in mild asthma; other changes such as increases in airway smooth muscle and gland volume appear to be more characteristic of severe asthma. ⋯ For this reason relatively little is known about the effects of current asthma treatments on airway remodeling. As mechanisms of airway remodeling are developed, it is hoped that novel therapeutic targets will be identified. Treatments specifically targeting mediators of remodeling hold promise as treatments that could modify disease progression in asthma.
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Semin Respir Crit Care Med · Jun 2002
Respiratory complications of rapidly progressive neuromuscular syndromes: Guillain-Barré syndrome and myasthenia gravis.
Neuromuscular respiratory failure is a common complication of both the Guillain-Barré syndrome and myasthenia gravis. Several key pathophysiological mechanisms contribute to the spiral of respiratory insufficiency in these diseases, including inspiratory, expiratory, and bulbar muscle weakness. It is important to identify patients with impending respiratory failure early to avoid emergency intubations. ⋯ Intravenous immunoglobulin and plasmapheresis are the cornerstones of specific therapy for both illnesses when complicated by respiratory failure. Mortality and morbidity are dramatically increased by respiratory failure and are mainly due to associated medical complications. Optimal outcomes depend on avoidance of these and prompt implementation of immunomodulatory therapy.
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Traumatic brain injury (TBI) is a serious health issue in the United States, killing 100,000 people a year and serving as a source of long-term disability for many more. It is the leading cause of death in patients under the age of 45 years. ⋯ Key skills in the care of brain-injured patients include adequately gauging the severity of injury, recognizing the primacy of sufficient blood flow and oxygen delivery to the injured brain, and being able to detect and correct when possible local and global physiological abnormalities that frequently put the injured brain at ongoing risk within the intensive care unit. This article discusses these issues, including invasive hemodynamic and intracranial monitoring, useful methods for reducing intracranial pressure, and management of complications arising from acute head injury.