With few exceptions, always assume that elderly patients presenting to the ED with an acute illness are very dehydrated. Here are a few reasons why the elderly patient, even on a normal day, may be mildly dehydrated: 1. The elderly have been shown to have decreased total body water. 2. The elderly have a decreased thirst response. 3. The elderly have a decreased renal vasopressin response.
Given these issues, when an elderly patient develops a systemic illness (especially pulmonary process), they lose even more fluid via insensible losses. By the time they arrive in the ED, unless they are presenting because of overt pulmonary edema, they almost always will benefit from generous IV fluid administration.
