Dextrose saline infusion is used to provide water and calories for hydration, treat dehydration and sodium depletion, serve as a source of energy in certain medical conditions, dilute or deliver concentrated intravenous (IV) drugs, and as part of preoperative and postoperative care to initiate renal function. It is also used in situations like hyperemesis gravidarum, where rehydration and nutritional support are needed.