Critically ill patients have an increased risk for aspirating oropharyngeal secretions and regurgitated gastric contents. For those who are tube-fed, aspiration of gastric contents is of greater concern. While witnessed large-volume aspirations occur occasionally, small-volume clinically silent aspirations are far more common. For example, a laboratory study identified frequent microaspirations in approximately half of a large population of critically ill, mechanically ventilated patients who were receiving tube feedings. In the same study, risk for pneumonia was about 4 times greater in patients identified as frequent aspirators. Because no bedside tests are currently available to detect microaspirations, efforts to prevent or minimize aspiration take on added importance.

There is evidence that a sustained supine position (0° head-of-bed elevation) increases gastroesophageal reflux and the probability for aspiration; for example, using a radioactive-labeled formula, endobronchial counts were higher when patients were lying flat in bed...

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