In our last exam tips post, we looked at the use of routine intravenous (IV) maintenance fluids in children. In this article, we will move on to look at the management of dehydration and shock in children.
Dehydration and shock are critical medical conditions that can have severe consequences, especially in the vulnerable population of children. While dehydration itself does not cause death, shock does. Understanding the signs, causes, and appropriate management strategies for dehydration and shock is crucial for healthcare professionals who work with children to ensure prompt and effective interventions.
Assessment of volume status
To determine how best to proceed with IV fluid management, it is essential to assess the volume status of the child.
Generally speaking, a child with clinical signs of dehydration but no evidence of shock can be assumed to be 5% dehydrated. If shock is also present, then 10% dehydration or greater can be assumed to have occurred. 5% dehydration implies that the body has lost 5 g per 100 g body weight, i.e. 50 ml/kg of fluid. 10% dehydration, therefore, implies that the body has lost 100 ml/kg of fluid.
Children possess a large physiological reserve, allowing them to compensate for changes in their health until they become very unwell, at which stage their condition may deteriorate very rapidly.
The symptoms and signs of dehydration and shock are outlined in the latest NICE guidelines for IV fluid prescription in children and young adults.
| No clinically detectable dehydration | Clinical dehydration (5% dehydration) | Clinical shock (10% dehydration) |
|---|---|---|
| Appears well | Appears to be ‘unwell’* | Pale, lethargic or mottled |
| Normal breathing pattern | Normal or tachypnoea* | Tachypnoea |
| Normal heart rate | Normal or tachycardia* | Tachycardia |
| Normal peripheral pulses | Normal peripheral pulses | Weak peripheral pulses |
| Normal capillary refill time | Normal or mildly prolonged capillary refill time | Prolonged capillary refill time |
| Normal blood pressure | Normal blood pressure | Hypotension |
| Normal skin turgor | Reduced skin turgor* | |
| Normal urine output | Decreased urine output | Decreased urine output |
| Alert and responsive | Altered responsiveness* (e.g. irritable, lethargic) | Decreased level of consciousness |
| Eyes not sunken | Sunken eyes* Depressed fontanelle | |
| Moist mucous membranes | Dry mucous membranes | |
| Warm extremities | Warm extremities | Cold extremities |
*These features are red flags, the presence of which may predict a higher risk of progression to shock.
It should be noted that the presence of hypotension is an indication of decompensated shock, signalling that the child is in a critically unwell state.
Fluid replacement therapy
IV fluid replacement therapy is needed for patients with dehydration without clinical features of shock (approximately 5% dehydration or greater) when the oral or nasogastric route is impractical or contraindicated.
The current NICE guidelines recommend adjusting the IV fluid prescription to account for existing fluid and/or electrolyte deficits or excesses, ongoing losses or abnormal distribution. Isotonic crystalloids (e.g. 0.9% saline) should be considered for redistribution. If there are ongoing losses, 0.9% sodium containing potassium should be used. Subsequent fluid composition should be based on plasma electrolyte concentrations and blood glucose measurements. The U&Es and plasma glucose should be monitored at least every 24 hours or more frequently if there are electrolyte abnormalities.
Weight is the most accurate way to assess fluid balance over time, but in most circumstances, initial fluid therapy must be based on a clinical assessment of hydration because pre-sickness weight is usually not available.
The current APLS guidelines recommend using the following rough guide to estimate the percentage dehydration, the fluid deficit and, therefore, the replacement fluids required:
5% dehydration = loss of 5 ml fluid per 100 g body weight, or 50 ml/kg
10% dehydration = loss of 10 ml fluid per 100 g body weight, or 100 ml/kg
If pre-sickness weights are available and the % dehydration can be assessed more accurately, the following formula can be used:
Fluid deficit (ml) = % dehydration x weight (kg) x 10
Replacement fluids are given alongside routine maintenance fluids (link to previous article 2) over a 24-hour period, and the total fluid requirement can, therefore, be calculated using the following formula:
Total fluid requirement (ml) = replacement fluids (ml) + maintenance fluids (ml)
Fluid resuscitation
Fluid resuscitation is the rapid administration of crystalloid in the treatment of hypovolaemic shock secondary to intravascular fluid loss (10% dehydration or greater).
The current NICE guidelines recommend the use of glucose-free crystalloids that contain sodium in the range of 131-154 mmol/l (e.g. 0.9% sodium chloride). The starting volume is 10 ml/kg over less than 10 minutes via intravenous (IV) or intraosseous (IO) access (if IV access is not possible).
The current APLS guidelines state that this 10 ml/kg bolus can be repeated if there is inadequate clinical response and no evidence of fluid overload. However, If the patient is still shocked despite an initial fluid bolus, urgent senior advice (e.g. the paediatric intensive care team) should be sought.
There are some circumstances in which smaller boluses may be needed. These include:
- Neonatal period (<28 days of age)
- Sepsis
- Diabetic ketoacidosis
- Trauma
- Cardiac pathology (e.g. heart failure)
Maintenance fluids after resuscitation
If a resuscitation fluid bolus adequately reverses shock, then the next stage of treatment is to assess the IV fluid replacement requirement. Both the current NICE and APLS guidelines advise that after shock has been treated, the 24-hour replacement fluids should be calculated in the same way as for any other child who was not shocked. There is no need to subtract the resuscitation boluses from the total 24-hour fluid requirements.
This child is shocked and should, therefore, receive a 20 ml/kg fluid bolus. The initial volume of fluid to administer should, therefore, be 20 x 8 ml = 160 ml.
Worked example 1:
A 25 kg child presents with clinical signs of shock and 10% dehydration as a consequence of gastroenteritis. Calculate the initial fluid bolus that should be administered to this child.
Answer:
The starting volume for a fluid bolus is 10 ml/kg over less than 10 minutes:
10 x 25 ml = 250 ml
Worked example 2:
The same 25 kg child who presented above had a good response to the initial fluid bolus, and the signs of shock have now been reversed. How much fluid should be administered over the next 24 hours following this?
Answer:
Following the initial fluid bolus, this child requires:
100 ml/kg replacement for the 10% dehydration = 100 x 25 = 2500 ml
1st 10 kg = 100 ml/kg for daily maintenance fluid = 100 x 10 = 1000 ml
2nd 10 kg = 50 ml/kg for daily maintenance fluid = 50 x 10 = 500 ml
Subsequent kg = 20 ml/kg for daily maintenance fluid = 20 x 5 = 100 ml
Rehydration + maintenance = 2500 + 1600 = 4100 ml over next 24 hours
References:
NICE Guideline: Intravenous fluid therapy in children and young people in hospital
Advanced Paediatric Life Support: A Practical Approach to Emergencies (7th Edition): Appendix B
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Thank you to the joint editorial team of www.mrcemexamprep.net for this ‘Exam Tips’ blog post.
