Seminars in respiratory infections
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Respiratory failure is one of the most important causes of death in patients with acute pneumococcal pneumonia. There are two forms that may or may not coexist: ventilatory failure and hypoxemic respiratory failure. Ventilatory failure is principally caused by mechanical changes in the lungs resulting from pneumonia. ⋯ Factors that tend to increase flow to consolidated lung and worsen shunt include endogenous vasodilator mediators, exogenous systemically administered vasodilator drugs, positioning the patient with the affected lung dependent, and increasing positive airway pressure. Factors that tend to reduce shunt include effective HPV, inhaled locally acting vasodilators that act primarily on ventilated lung, and positioning the patient with the affected lung up. Although thoughtful application of what is known about the pathophysiology of the lung in pneumococcal pneumonia can help the clinician deploy most effectively the available technologies of respiratory support in these patients, even the best intensive supportive measures are frequently inadequate, and mortality rates for patients requiring such support remain unacceptably high.