MODEL RELEASED. Intravenous drip being adjusted by a doctor. The device at left is a reservoir in which a set amount of fluid can be measured. The valve in the doctor's other hand can be used to regulate the speed at which fluid is passed down from the main bag (off top, not seen). A drip is used to administer fluids through these tubes to a patient (not seen). The fluid may be saline, which is used to replace body fluids in dehydrated patients, or the fluid may contains drugs.