[29] Dehydration Flashcards
1
Q
What is dehydration?
A
When the body loses more fluid than it takes in
2
Q
Is dehydration serious?
A
It can be if it is untreated
3
Q
What % of an infants body weight is made up of water?
A
As much as 80%
4
Q
What happens to the proportion of body water by 3 years?
A
It falls to about 65%
5
Q
How is body water distributed?
A
Between the cells (intra-cellular) and the extracellular compartments
6
Q
What can the extracellular compartment be further divided into?
A
- Intravascular space
- Extravascular (interstitial) space
7
Q
What separates the intravascular and extravascular space?
A
Capillary endothelium
8
Q
Depletion of what compartment can lead to dehydration?
A
Any
9
Q
What may acute loss of fluid from the intravascular compartment be associated with?
A
Shock
10
Q
What do the clinical signs of dehydration depend on?
A
The concentration of electrolytes in the intracellular and extracellular compartments
11
Q
What are the major ions within the extracellular compartment?
A
- Sodium
- Bicarbonate
12
Q
What is the major ion within the intracellular compartment?
A
- Potassium
13
Q
What is balanced in normal body fluids?
A
Intake and output
14
Q
What does normal fluid balance depend on?
A
- Fluid intake
- Urine volume
- Stool volume
- Sweating
- Insensible loss
15
Q
When does dehydration occur, with regard to fluid balance?
A
When losses exceed input
16
Q
Why do infants have a higher risk of dehydration?
A
- Higher SA to weight ratio than older children, leading to greater insensible water losses
- Higher basal fluid requirements
- Immature renal tubular reabsorption
- Inability to obtain fluids for themselves when thirsty
17
Q
What are the causes of dehydration in children?
A
- Diabetes
- Vomiting and diarrhoea, e.g. gastroenteritis
- Heatstroke
- Fever
- Conditions that make it hard to swallow fluids, e.g. sore throat
18
Q
What are the risk factors for dehydration?
A
- Infants
- Children that have passed 6 or more diarrhoeal stools in the previous 24 hours
- Children that have had vomiting 3 or more times in the previous 24 hours
- Children that have been unable to tolerate, or not offered, oral fluids
- Children with malnutrition
19
Q
What infants in particular are at risk of dehydration?
A
- Under 6 months of age
- Low birthweight
20
Q
What are the symptoms of dehydration?
A
- Feeling thirsty
- Dark yellow and strong-smelling urine
- Feeling dizzy or lightheaded
- Feeling tired
- Reduced urine output
- Few or no tears when crying
21
Q
What needs to be determined in the history in dehydration?
A
- Cause of dehydration
- Severity of dehydration
22
Q
What are the signs of dehydration?
A
- Sunken eyes
- Soft spot on head sinks inwards
- Cold and blotchy-looking hands and feet
- Dry mouth, lips, and eyes
23
Q
What do you need to assess/obtain on physical examination in dehydration?
A
- Weight
- Severity of dehydration
- Signs of cause of dehydration
24
Q
What is the importance of measuring the weight in dehydration?
A
Acute water loss can be estimated from the difference between actual weight and a recent weight made before dehydration occurred, and so regular weighing will allow accurate measurement of fluid replacement
25
How can the cause of dehydration be assessed on examination?
Should perform a thorough examination to identify the foci of infection
26
What should be included on thorough examination to identify the cause of dehydration?
- Ears
- Throat
- Chest
- Abdomen
27
What physical things etc signs should be assessed when determining the severity of dehydration?
- Mental state
- Skin turgor
- Dryness of mucous membranes
- Fontanelle
- Eye turgor
- Skin perfusion
- Pulse rate and character
28
What are the signs of mild dehydration?
Only physical sign may be dry mouth
29
What are the physical signs of moderate dehydration?
- Lethargy
- Inelastic skin
- Sunken fontanelle
- Sunken eyes
- Pulse may be fast, but of normal volume
- Slow refilling of skin when blanched
30
What are the signs of severe dehydration?
- Very confused, only semi-conscious
- Mottled skin
- No refilling of skin when blanched
- Fontanelle and eyes deeply sunken
- Poor eye turgor
- Thready and fast pulse
31
Why is it important to assess how severe dehydration is?
So you can calculate how much fluid replacement is required
32
What investigations should be done in dehydration?
- U&s
| - Urine assessment
33
What findings may be present on U&Es in dehydration?
- Hyper or hyponatraemia
| - Low bicarbonate
34
Why can hyper or hyponatraemia occur in dehydration?
Due to differential loss of sodium
35
What is the importance of identifying hyper or hyponatraemia in dehydration?
It will change your management
36
When might you get low bicarbonate in dehydration?
As a result of diarrhoea
37
What does low bicarbonate due to diarrhoea cause?
Metabolic acidosis
38
What metabolic abnormality may occur if there has been excessive vomiting?
Excessive loss of hydrogen ions, which may cause an initial metabolic alkalosis
39
What urine assessments should be done in dehydration?
Assess urine for specific gravity or osmolality, and consider measuring urine electrolytes
40
Should an assessment of urinary volume over a known period be done in dehydration?
It is helpful, but difficult to collect, and treatment should not be delayed to measure urine output
41
What are the different types of dehydration?
- Isotonic
- Hyponatraemic
- Hypernatraemia
42
What is the most common type of dehydration?
Isotonic
43
What is isotonic dehydration?
When there are equal losses of sodium and water
44
Will the seurm sodium be high, normal, or low in isotonic dehydration?
Normal
45
How do the physical signs of dehydration correlate to the fluid loss in isotonic dehydration?
The physical signs will be proportional to the degree of fluid loss
46
Define clinically hyponatraemic dehydration?
Dehydration with serum sodium <130mmol/L
47
Physiologically, when does hyponatraemic dehydration occur?
Generally, when fluid losses have been replaced with hypotonic solutions such as water
48
How does hyponatraemic dehydration present?
The child will be lethargic, and skin dry and inelastic
49
What is hypernatraemic dehydration clinically defined as?
Dehydration when serum sodium is >150mmol/L
50
When is hyponatraemic dehydration more likely?
- Acute and severe water loss
- Common in breast-fed baby in first 2 weeks of life
- Concentrated formula feeds
51
Why might hyponatraemic dehydration occur in a breastfed baby in the first two weeks of life?
If there is difficulty establishing feeds
52
What might lead to a parent giving a baby concentrated formula feeds?
The parent incorrectly measuring scoops of powdered milk
53
How does hypernatraemic dehydration present?
Infant appears very hungry, but has fewer clinical signs of dehydration. The skin feels doughy.
Metabolic acidosis is a common feature
54
What % dehydration is considered to be mild?
5%
55
How can a child with mild dehydration be treated?
May be treated at home using oral hydration therapy
56
When is oral rehydration likely to be successful in dehydration?
When vomiting is not a major feature
57
What should be used in oral rehydration therapy?
Oral rehydration solutions such as Dioralyte
58
In what forms can oral rehydration solutions such as Dioralyte be dispensed?
- Oral solution
| - Effervescent tablets or powders
59
Should breast feeding be maintained when using oral rehydration solutions?
Yes
60
When can normal milk feed be resumed in dehydration if the baby is bottle fed?
Once diarrhoea has settled
61
When do you need to pay closer attention to the fluid balance in dehydration?
In a child with more significant dehydration, particularly if there is vomiting
62
What do you do in assessment of the fluid balance in a significantly dehydrated child involve?
- Maintaining an accurate input-output chart
- Weighing the child twice daily
- Frequent measurement of serum electrolytes
63
What principles do the calculations of rehydration require?
- Estimate or acute fluid loss
- Estimate of maintenance fluid requirements
- Estimate of on-going losses
64
How is an estimate of acute fluid loss made?
Difference between actual weight and recent normal weight
65
What should be done if recent normal weight is unknown when estimating acute fluid loss?
Rely on clinical assessment of dehydration
66
What is the estimated maintenance fluid requirement for a 0-6 month old?
150mL/kg/24 hours
67
What is the estimated maintenance fluid requirement for a 6-12 month old?
120mL/kg/24 hours
68
What is the estimated maintenance fluid requirement for a 12-24 month old?
100mL/kg/24 hours
69
What is the estimated maintenance fluid requirement for a >24 month old?
80mL/kg/24 hours
70
How are on-going losses estimated in dehydration?
If possible, they should be measured carefully on an hourly basis, and added to the fluid regimen every 4 hours
71
What does the rate of rehydration depend on?
The type of dehydration
72
How should rehydration be given if the patient is shocked?
Circulation must be restored by boluses of colloid
73
How should rehydration be given if hypernatraemia dehydration?
Must correct more slowly over 48 hours
74
Why is it important to correct hypernatraemic dehydration slowly?
To avoid rapid shifts of water within the brain resulting in cerebral oedema
75
What are the complications of dehydration?
- Shock
- Severe metabolic acidosis
- Death
