Phases of Oral Rehydration Therapy
ORT encompasses two phases of treatment
- Rehydration phase: Water and electrolytes are administered as oral rehydration solution (ORS) to replace existing losses (the deficit is replaced quickly over 3-4 hours)
- Maintenance phase: This includes both replacement of ongoing fluid and electrolyte losses and adequate dietary intake.
During both phases, fluid losses from vomiting and diarrhea are replaced in an ongoing manner. An age-appropriate, unrestricted diet should also be instituted after the dehydration is corrected. If the patient is breastfed, breastfeeding should continue during this phase as well as during the maintenance phase. Formula-fed infants should continue their usual formula immediately upon rehydration. Lactose-free or lactose-reduced formulas usually are unnecessary. The BRAT (banana-rice-applesauce-toast) diet is unnecessarily restrictive and can provide suboptimal nutrition.
How to Administer Oral Rehydration Therapy
ORS is administered in frequent, small amounts of fluid by spoon or syringe. A nasogastric tube can be used in the child who refuses to drink. Nasogastric (NG) feeding allows continuous administration of ORS at a slow, steady rate for patients with persistent vomiting. For those with vomiting, the majority can be rehydrated successfully with oral fluids if limited volumes of ORS (5 mL) are administered every 5 minutes, with a gradual increase in the amount consumed
Mild to moderate dehydration:
Rehydration phase:The dose is 50-100 ml/kg over 3-4 hours.
During both phases, ongoing losses from diarrhea and vomiting are replaced with ORS. If the losses can be measured accurately, 1 mL of ORS should be administered for each gram of diarrheal stool. Alternatively, 10 mL/kg of body weight of ORS should be administered for each watery or loose stool, and 2 mL/kg of body weight for each episode of emesis.
Severe dehydration is a medical emergency, and requires emergent IV therapy with rapid infusion of 20 mL/kg of isotonic saline. As the patient's condition improves, therapy can be later changed to ORT.
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Reference: Managing Acute Gastroenteritis among Children: Oral Rehydration, Maintenance, and Nutritional Therapy. https://www.cdc.gov/mmwr/PDF/RR/RR5216.pdf