Maintenance fluids
Maintenance fluids are prescribed using the Holliday-Segar formula:
Option 1 – 4:2:1 rule for the hourly requirement
4 ml/kg/hr for the first 10 kg, then 2 ml/kg/hr for the second 10 kg, then 1 ml/kg/hr for each subsequent kg
For example a 22kg child – (4 x 10) + (2 x 10) + (1 x 2) = 62 ml/hr
Option 2 – 100:50:20 rule for the daily requirement
100 ml/kg/hr for the first 10 kg, then 50 ml/kg/hr for the second 10kg, then 20 ml/kg/hr for each subsequent kg
For example a 22kg child – (100 x 10) + (50 x 10) + (20 x 2) = 1540 ml/day = 64ml/h
Rehydration fluids
Assessment of dehydration
The Clinical Dehydration Scale utilises four key examination findings:
• presence or absence of tears
• mucous membranes
• whether the eyes are sunken or not
• the general appearance of the child.
Combined items give this scale a sensitivity of around 68%.
Fluids to treat dehydration:
% dehydration x weight x 10g
For example a 22kg child who is 5% dehydrated: 5 x 22 x 10 = 1100 ml
Then calculate the hourly rate. Replace over either 24 hours (if the child became dehydrated very rapidly) or over 48 hours (most children).
For the 22kg child who is 5% dehydrated: 1100 ÷ 48 = 22.9 ml/hr
Add the dehydration fluids to the hourly maintenance fluids
For the 22kg child: 62 ml/h + 22.9 ml/h = 84.9 ml/h
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*The reason dehydration fluids are multiplied by a factor of 10 is to do with percentages and converting litres to millilitres. Percentages are divided by 100. We need to convert weight from kilograms to grams (to do the equivalent litres to millilitres) by multiplying by 1000. Rather than dividing the percentage by 100 and multiplying the whole amount by 1000, we just multiply up by a factor of 10 (1000 ÷ 100 = 10).
| Characteristic | 0 | 1 | 2 |
|---|---|---|---|
| General appearance | Normal | Thirsty, restless, or lethargic, but irritable when touched | Drowsy, limp, cold, sweaty, and/or comatose |
| Eyes | Normal | Slightly sunken | Very sunken |
| Mucous membranes | Moist | 'Sticky' | Dry |
| Tears | Tears | Decreased tears | Absent tears |
