Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Feb 2005
ReviewSleep in restrictive and neuromuscular respiratory disorders.
Thoracic restrictive disorders (i.e., chest wall deformities or neuromuscular diseases), may predispose to sleep-disordered breathing, poor sleep quality, and nocturnal hypoventilation. These disorders intensify the effects of reductions in both respiratory center output and central chemosensitivity and increases in upper airway resistance that occur with the onset of sleep. Normally, rapid eye movement (REM) sleep suppresses the activity of nondiaphragmatic breathing muscles, further reducing ventilation. ⋯ Although some patients may respond to continuous positive airway pressure (CPAP) alone, noninvasive positive pressure ventilation (NPPV) is a more important part of disease management for patients with restrictive thoracic disorders. This technique improves nocturnal ventilation and sleep quality but may also contribute to sleep fragmentation in some patients. If the patient is an unsuitable candidate for or fails NPPV, tracheostomy mechanical ventilation should be considered.
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Despite advances in positive pressure therapy for obstructive sleep apnea, compliance continues to be a problem for many patients. Sleep apnea surgery is a viable option for patients who are intolerant of positive pressure therapy. This review presents the current state of the art in sleep apnea surgery, including airway evaluation with fiberoptic nasopharyngoscopy and lateral cephalometric radiography, formulation of a surgical plan with selection of procedures to address specific sites of obstruction, as well as discussion of published surgical outcomes.
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Cardiogenic shock has long been a difficult problem for clinicians. The most common cause is left ventricular pump failure after myocardial infarction, but other important causes include mechanical complications of infarction, right ventricular dysfunction, prolonged cardiopulmonary bypass, valvular disease, and cardiomyopathy. Cardiogenic shock is the leading cause of in-hospital death after myocardial infarction. ⋯ Improved understanding of the pathophysiology of cardiogenic shock has led to renewed emphasis on the notion that stunned or hibernating myocardium may recover function with hemodynamic support and restoration of flow. This concept has underscored the importance of expeditious initiation of supportive measures to maintain blood pressure and cardiac output, including both medications and intraaortic balloon counterpulsation. Finally, the theory that coronary revascularization would be beneficial by reversing the vicious cycle in which ischemia causes myocardial dysfunction, which in turn worsens ischemia, which had been supported by an extensive body of observational and registry studies, has now been strongly buttressed by the results of two randomized, controlled trials, both of which show improved mortality with early revascularization for cardiogenic shock in the setting of acute infarction.
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Semin Respir Crit Care Med · Dec 2004
Corticosteroid therapy in patients with severe sepsis and septic shock.
Corticosteroids have been considered for decades for the treatment of severe sepsis and septic shock, based on their pivotal role in the stress response and their hemodynamic and antiinflammatory effects. Whereas short-term therapy with high doses of corticosteroids (up to 42 g hydrocortisone equivalent for 1-2 days) has been ineffective or potentially harmful, prolonged therapy with lower doses (200-300 mg hydrocortisone for 5-7 days or longer) in septic shock has recently revealed beneficial effects in several randomized, controlled trials. Assuming relative adrenal insufficiency (RAI) and peripheral cortisol resistance, treatment with low-dose hydrocortisone improved shock reversal, reduced inflammation, and improved outcome. ⋯ In addition the role of fludrocortisone is uncertain. Nevertheless, based on current data, low-dose hydrocortisone therapy should definitely be considered in vasopressor-dependent septic shock. This review will address some critical points.
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Vasopressin is a hormone that is essential for both osmotic and cardiovascular homeostasis. A deficiency of vasopressin exists in some shock states and replacement of physiological levels of vasopressin can restore vascular tone. ⋯ We then highlight the areas of uncertainty in using vasopressin for septic shock and summarize the reasons for clinical equipoise. We close by suggesting that further randomized controlled trials of vasopressin in septic shock are required before vasopressin is used routinely for management of septic shock.