The main causes for this include anorexia, chronic nausea and emesis, bowel obstruction, dysphagia and delirium. Traditional hospital-based medicine provides intravenous hydration to all these patients. The main rationale for such an approach is the simple fact of the reduced oral intake and dehydration.
Parenteral hydration can support patients until they are able to resume appropriate oral intake.
The administration of intravenous fluids can be uncomfortable and expensive and can force the patients to remain as hospital inpatients unless they have access to expensive and complicated home health services. The arguments put forward against hydration have included the fact that fluids might prolong the dying process. Decreased urine output means less need for bedpan, commode or catheterization, the potential for decreased gastrointestinal and pulmonary secretions, and minimization of edema and ascites. In addition, the fact that decreased fluid levels and electrolyte imbalance act as a natural anesthetic for the central nervous system with decreased levels of consciousness and reduced suffering is part of the rationale. The main issue in decision making on hydration in advanced cancer patients is how the discomfort associated with progressive dehydration can be improved by parenteral hydration and how this potential improvement balances out against the discomfort associated with the maintenance of hydration by the parenteral route.