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# Rehydration plans by weight (AIEPI/WHO Plan B and Plan C): worked examples

- Calculation

AIEPI sets the rehydration volume from the child's weight: oral solution in plan B, intravenous fluid in two parts in plan C. The team orders it.

Updated Nov 13, 2026

## Key points

- Educational example, not a clinical order.
- Educational content only, not an order for a real patient. Volumes are set by the treating team per local guidance.
- Plan B: ORS ≈ weight (kg) × 75 mL in the first 4 hours (range 50–100 mL/kg); if the child wants more, give more.
- Plan C: Ringer's lactate 100 mL/kg IV, first 30 mL/kg, then 70 mL/kg: 1 h + 5 h under 12 months; 30 min + 2½ h over 12 months.
- Reassess every hour in plan B and every half hour in plan C; at the end the team reclassifies and chooses plan A, B or C.

## What it is

In AIEPI the volume used to correct dehydration is worked out from the child's weight. In plan B (some dehydration) the child drinks oral rehydration solution (ORS) in the clinic: about 75 mL per kilogram in the first 4 hours, within a range of 50 to 100 mL/kg, and more if the child wants more. In plan C (severe dehydration) the child receives Ringer's lactate intravenously, 100 mL/kg split into a first part of 30 mL/kg and a second part of 70 mL/kg, given faster in children over 12 months than in infants. The nurse uses this arithmetic to check the order, set the pump and know what the child should have received at each reassessment; the treating team chooses the plan and the volume.

## Formulas

- Plan B volume for the first 4 hours = weight (kg) × 75 mL; the chart's range is weight × 50 to weight × 100 mL.
- Plan B average per hour = plan B volume ÷ 4; it is a guide for the hourly check, because the child drinks small amounts often.
- Use age only when the weight is unknown: the chart gives approximate volumes by age and weight band (for example 400–600 mL for 5–7.9 kg).
- Plan C total = weight (kg) × 100 mL of Ringer's lactate; first part = weight × 30 mL, second part = weight × 70 mL.
- Plan C times: infants under 12 months, 1 h then 5 h (6 h in all); children over 12 months, 30 min then 2½ h (3 h in all). Rate (mL/h) = volume ÷ hours.
- If IV treatment is not possible and no facility is within 30 minutes, the chart gives ORS by nasogastric tube, or by mouth if the child can drink, at 20 mL/kg/h for 6 hours (120 mL/kg in all).

## How to calculate it

- Confirm the classification and the plan the team wrote — the plan sets which formula applies.
- Weigh the child, or take today's weight from the record — every volume is per kilogram.
- Plan B: multiply the weight by 75 and check the result lies between weight × 50 and weight × 100 — this is the approximate ORS for the first 4 hours.
- Plan B: divide by 4 to know about how much the child should take each hour — it helps judge progress at the hourly check.
- Plan C: work out the first part (weight × 30) and the second (weight × 70), and check they add up to weight × 100 — an error in one part changes the whole plan.
- Plan C: divide each part by its time to get the pump rate in mL/h — under 12 months 1 h and 5 h; over 12 months 30 min and 2½ h.
- Ask a second person to repeat the calculation and compare it with the order before starting — it is a high-risk calculation in a small patient.
- Reassess as the protocol says (hourly in plan B, every half hour in plan C) and record intake, stools and vomiting — the plan changes with the child's state.
- At the end (4 h in plan B; 6 h or 3 h in plan C) the team reassesses and chooses plan A, B or C — the volume is not repeated automatically.

## Worked examples

| Example (invented child) | Plan and formula | Calculation | Result | Check |
| --- | --- | --- | --- | --- |
| 1. Boy, 6 months, 6 kg, some dehydration | Plan B: 75 mL/kg in 4 h | 6 × 75 = 450 mL; 450 ÷ 4 = 112.5 mL per hour on average | About 450 mL of ORS in the first 4 h | 450 ÷ 6 = 75 mL/kg; chart band 5–7.9 kg: 400–600 mL, so it fits |
| 2. Girl, 14 months, 9 kg, some dehydration | Plan B: 75 mL/kg in 4 h (range 50–100) | 9 × 75 = 675 mL; range 9 × 50 = 450 to 9 × 100 = 900 mL; 675 ÷ 4 ≈ 169 mL per hour | About 675 mL of ORS in the first 4 h | 675 ÷ 9 = 75 mL/kg; chart band 8–10.9 kg: 600–800 mL, so it fits |
| 3. Boy, 3 years, 14 kg, some dehydration | Plan B: 75 mL/kg in 4 h | 14 × 75 = 1050 mL; 1050 ÷ 4 = 262.5 mL per hour on average | About 1050 mL of ORS in the first 4 h | 1050 ÷ 14 = 75 mL/kg; chart band 11–15.9 kg: 800–1200 mL, so it fits |
| 4. Infant, 8 months, 7 kg, severe dehydration | Plan C under 12 months: 30 mL/kg in 1 h, then 70 mL/kg in 5 h | 7 × 30 = 210 mL in 1 h = 210 mL/h; 7 × 70 = 490 mL in 5 h: 490 ÷ 5 = 98 mL/h | 700 mL of Ringer's lactate in 6 h | 210 + 490 = 700 = 7 × 100; 98 × 5 = 490 |
| 5. Girl, 2 years, 12 kg, severe dehydration | Plan C over 12 months: 30 mL/kg in 30 min, then 70 mL/kg in 2½ h | 12 × 30 = 360 mL in 30 min = 720 mL/h; 12 × 70 = 840 mL in 2.5 h: 840 ÷ 2.5 = 336 mL/h | 1200 mL of Ringer's lactate in 3 h | 360 + 840 = 1200 = 12 × 100; 720 × 0.5 = 360 and 336 × 2.5 = 840 |

## Common mistakes

- Swapping the two parts of plan C (70 first, 30 second) or using the wrong factor.
- Using the infant times for a child over 12 months, or the reverse.
- Using an old or estimated weight without saying so in the record.
- Holding ORS at the calculated volume when the child still wants more, although the chart says to give more.
- Abdominal distension during nasogastric rehydration: the chart says to give the solution more slowly.

## Double-checking

- Signs of severe dehydration during plan B: call the nurse in charge and the doctor at once; the chart moves the child to plan C.
- In plan C, hydration that does not improve or a weak pulse: report at once; the team decides whether to speed up or repeat a load.
- Vomiting that prevents ORS, or frequent large watery stools in a child who drinks poorly: report for a change of plan.
- Record the volume taken or infused at each reassessment and say it at handover.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the approximate plan B volume for a child who weighs 10 kg?

10 × 75 = 750 mL of ORS in the first 4 hours, within a range of 10 × 50 = 500 to 10 × 100 = 1000 mL.

## How is plan C split in an infant under 12 months?

30 mL/kg in 1 hour, then 70 mL/kg in 5 hours: 100 mL/kg in 6 hours.

## How is plan C split in a child over 12 months?

30 mL/kg in 30 minutes, then 70 mL/kg in 2½ hours: 100 mL/kg in 3 hours.

## How often is the child reassessed during plan C?

Every half hour; after 6 hours (infants) or 3 hours (older children) the team reassesses and chooses plan A, B or C.

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## Connections

## Related 3

- [Oral rehydration at home and in the clinic: plans A and B, continued feeding and warning signs](https://durgical.com/en/nursing/oral-rehydration-at-home-and-in-the-clinic-plans-a-and-b-continued-feeding-and-w/)
- [Assessing dehydration in a child with diarrhoea or vomiting, including intake and output](https://durgical.com/en/nursing/assessing-dehydration-in-a-child-with-diarrhoea-or-vomiting-including-intake-and/)
- [Fluid balance: recording intake and output](https://durgical.com/en/nursing/fluid-balance-recording-intake-and-output/)

## Related conditions 3

- [Dehydration in children (acute diarrhoeal disease)](https://durgical.com/en/conditions/dehydration-in-children/)
- [Acute (viral) gastroenteritis](https://durgical.com/en/conditions/acute-gastroenteritis/)
- [Cholera](https://durgical.com/en/conditions/cholera/)

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Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: [Cuadro de procedimientos AIEPI (Atención Integrada a las Enfermedades Prevalentes de la Infancia)](https://www.minsalud.gov.co/sites/rid/Lists/BibliotecaDigital/RIDE/VS/PP/cuadro-procedimientos-atencion-integrada-enfermedades-prevalentes-infancia.pdf) (Ministerio de Salud y Protección Social de Colombia, 2016); [Diarrhoeal disease (fact sheet)](https://www.who.int/news-room/fact-sheets/detail/diarrhoeal-disease) (World Health Organization, 2024).

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Representative model, for educational purposes only.

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