Rapid Intervention
- Oxygen
- IVI 10-20 mL / kg bolus Normal Saline over 30-50 min
- IVI 40-80 mL / kg infusion Normal Saline over 2-4 hours
- IVI 5% Dextrose maintenance
Considered Approach
Degree of Dehydration (deficit) based on clinical signs and documented recent weight loss (cf. prior 2 weeks). Note: dehydration involves both water and electrolyte loss.
I. Calculate Maintenance Fluid Requirements and rehydrate at a rate according to the child’s condition, adjusted according to ongoing assessment, with the following as your guide:
- GE: rapid
- DKA/meningitis: slower
- Hypernatremia: much slower
Maintenance fluids involve replacing insensible losses (breath, sweat, stool) plus allowing for the excretion of an excess solute load (urea, creatinine, electrolytes) in a volume of urine that is of an osmolarity similar to plasma. Fluid volume is usually calculated by the 4-2-1 rule of thumb, but only 2/3rds that volume given where the child is very unwell because of a sustained SIADH (and in meningitis/CNS disease, in which case occasionally further fluid restriction still is necessitated).
II. Calculate the Deficit: % dehydration x weight and replace with Normal Saline.
III. Measure Ongoing Losses: vomiting, diarrhoea, drain losses, ileostomies, etc. and replace with Normal Saline.
∴ Daily volume needed = Maintenance + Deficit + Ongoing Losses (- boluses given)
If in doubt, and the child is clearly severely dehydrated, give 10-20 mL/kg bolus of 0.9% Normal saline intravenously (may be repeated if minimal response).
Clinical signs of dehydration will afford only an approximation of the deficit:
Mild, (< 4%) dehydration in children:
- may show no signs or only manifest as increased thirst
Moderate dehydration, the child has lost 4-6% body weight:
- tachypnoea with
- delayed capillary refill: > 2 seconds
- increased respiratory rate
- mild reduction in tissue turgor is moderate dehydration, the child having
Severe dehydration: ≥ 7% total body weight loss) will have:
- deep acidotic breathing
- very delayed capillary refill: > 3 seconds
- mottled skin with decreased tissue turgor
- other signs of shock: tachycardia, irritable, reduced level of consciousness, decreased BP
Note: sunken eyes, lethargy, dry mucous membranes have not been validated and are less reliable.
Replacement — Intravenous Fluids (IVF)
When there is severe dehydration/shock and fluids are required for intravascular depletion:
- 10-20 ml/kg 0.9% NaCl solution as a bolus
- this may be repeated
Hourly rate = daily volume ÷ 24 (or correct 1/2 deficit in first 8 hours and the remainder in the next 16 hours)
Then calculate:
- Maintenance: 4–2–1 rule
- 4 ml/kg for first 10 kg of body weight
- 2 ml/kg for second 10 kg of body weight
- 1 ml/kg for every subsequent 10 kg of body weight
- Established Deficit: % dehydration x weight
- Ongoing losses: V, D, drain, ileostomy, etc. (may need to factor in KCl replacement for these)
Note: if the child is very unwell, especially if meningitis or other CNS disease, give only 2/3 of normal maintenance requirements because of effect of stress-response ADH release (ADH is a potent conserver of water).
Using hypotonic solutions is no longer considered safe practice.
Note: TBW = body weight x 0.6
Mild: 5% body weight loss ⇒ push oral fluids
- thirsty
- alert or restless
Moderate: 6-9% body weight loss ⇒ urgent oral rehydration therapy (ORT)
- thirsty, restless or lethargic but irritable
- tachycardia (normal BP)
- reduced urine output
- sunken eyes / fontanelle
- dry mucous membranes, absent tears
- pinched skin retracts slowly (1-2 seconds)
Severe: 10% body weight loss ⇒ require intravenous fluid replacement
- lethargic, drowsy, limp, clammy or dry, mottled or cool limbs (infants)
- apprehensive
- rapid feeble pulse, low blood pressure, poor capillary return, cold extremities
- sunken eyes and fontanelle
- very dry mucous membranes
- pinched skin retracts very slowly (> 2 seconds)
- no urine output
Acute fluid losses of > 14% body weight are potentially lethal. Most losses are isotonic, such that serum electrolytes remain normal, disguising the amount of solute loss.
About 5-10% of cases are a hypertonic dehydration (Type 1 DM, gastroenteritis, sun stroke), where fluid losses exceed electrolyte losses. Especially in neonates and small infants, because of a high surface area to volume ratio and a reduced renal concentrating capacity, rehydrate slowly over 24-48 hours otherwise risk convulsions and brain injury.
Rarely, cases of hypotonic dehydration occur. Hypotonic dehydration is seen in children with an ileostomy, foregoing colonic sodium reabsorption. In these children, replace sodium vigorously because of the risk of mortality. A similar scenario of hypotonic dehydration is seen with cholera infection.
See Dehydration, Royal Childrens’ Hospital, Melbourne
