Fluid and Electrolyte Management Flashcards
What percentage of a child’s body weight is water, compared to an adult?
WATER
PERCENTAGE BODY WEIGHT
At birth = 80%
Falls gradually with age
In adulthood = 60%
What comparments is body water distributed over? What forces affect this?
WATER
COMPARTMENTS OF THE BODY
- Intravascular
- Interstitial
- Intracellular
Affected by pressure and osmotic gradients.
How do you work out the fluid requirement for well normal children?
FLUID REQUIREMENT
NORMAL, WELL CHILDREN
First 10 kg 100 ml/kg/ day
Second 10 kg 50 ml/ kg/ day
Subsequent kg 20 ml/kg day
What is a normal urine output?
URINE OUTPUT
~ 3 ml/ kg/ hour
What are the sources of fluid loss from the body?
FLUID LOSSES
- Urine ~ 30 ml/ kg/ day or 1-2 ml/ kg/ hr
- Stool ~ 0 - 10 ml/ kg/ day
- Insensible losses (sweat, respiration) ~ 10 - 30 ml/ kg/ day - affected by:
- ambient temp/ humidity
- fever
- caloric content of feeds
- skin quality
How much fluid much be lost (ml/kg) to cause shock Vs. clinical dehydration and what is the importance of this?
SHOCK = 20 ml/kg lost from intravascular space
CLINICAL DEHYDRATION = at least 25 ml/kg lost before evident (2.5 - 5% dehydration)
i. e. 2.5 ml fluid lost per 100 g body weight
i. e. 25 ml lost for every 1000 g
i. e. 25 ml/ kg
=> SHOCK MAY OCCUR BEFORE CLINICAL SIGNS OF DEHYDRATION!!!
Dehydration may also occur in the absence of shock.
Or both may occur together.
Depends on the rate of fluid loss and rate of fluid shifts.
What % dehydration do (a) a child without shock and (b) a child with shock have?
% DEHYDRATION
NO SHOCK: 5% dehydration
SHOCK: = / > 10% dehydration
What parameters is pathology from electrolyte changes related to?
ELECTROLYTE DERANGEMENT
Extreme levels
Rapid rates of change
What are the clinical signs of dehydration vs. shock?
CLINICAL SIGNS
DEHYDRATION VS. SHOCK
- Clinical appearance:
- unwell Vs. Pale/ lethargic/ mottled
- Dehydration only
- skin turgor: reduced
- eyes: sunken
- fontanelle: depressed
- mucous membranes: dry (except mouth breathers)
- A + B
- RR: normal / tachypnoea Vs. tachypnoea
- C
- HR: normal/ tachycardia Vs. tachycardia
- Peripheral pulses: Normal Vs. weak
- CRT: normal/ mildly prolonged Vs. prolonged
- extremities: warm Vs. cold
- BP: normal Vs. low
- D
- GCS: altered responsiveness e.g. irritable, lethargic Vs. decreased
- E
- decreased UO (both)
What is the intravascular volume of an infant and of a child? Bearing this in mind, what does e.g. 5% dehydration mean relative to these values?
INTRAVASCULAR VOLUME
Infant = 80 ml/kg
Older child = 70 ml/kg
5% dehydration = loss of 5g fluid per 100g body weight
Extrapolate –> 50 ml in 1000 ml
i.e 50 ml in 1 kg or 50 ml/kg
What are the critical clinical questions in the management of fluid and electrolyte management?
FLUID AND ELECTROLYTE Mx
CRITICAL CLINICAL QUESTIONS
- Shock? –> correct rapidly
- Dehydration? –> correct over 24 - 48 hrs
- Acid base abnormality?
- Electrolyte abnormalities?
What is the specific management of shock?
SHOCK Mx
- ABCDEFG
- Fluid bolus
- 20 ml/kg
- 10 ml/kg in raised ICP, trauma, cardiac pt’s
- 0.9% saline
- care if using Hartmann’s esp. in renal impairment - contains K+
- hyper and hyponatraemia do not affect choice of fluid during initial resus
- Electrolyte abnormalities
- correct slowly UNLESS
- dysrhythmia
- neuro abnormality
- correct slowly UNLESS
- Treat shock 1st before turning attention to hydration status/ Mx of dehydration
What is the only clinical available objective measure of total body fluid changes? What measure is used in emergency situations and why?
The only clinically available objective measure of total body fluid changes = WEIGHT
In emergencies, pre-sickness weight often not available.
So have to use clinical signs of dehydration to estimate degree of dehydration.
Define 5% and 10% dehydration. What do these values actually represent?
5% DEHYDRATION
= LOSS of 5 ml of fluid per 100g of body WT
= loss of 50 ml of fluid per 1000 g of body WT
= 50 ml/ kg
10% DEHYDRATION
= LOSS of 100 ml/ kg
Describe the specific management of dehydration.
DEHYDRATION Mx
- ABDCEFG
- Daily maintenance + Replacement
- over a 24 hour period
- monitor every 3-6 hrs
- use WT as an objective measure - appropriate rate of gain
- crystalloids
- Route
- Oral
- oral rehydration solution is preferable if the gut is functioning
- use cup and spoon
- Continue normal feeds in addition to solution esp. if breast fed
- IV
- if excessive vomiting or damaged gut
- attempt gradual re-introduction of oral rehydration during IV therapy unless there is bowel damage
- if tolerated then stop IV completely
- Oral
Describe the composition of the commonly available crystalloid fluids:
- Sodium Chloride 0.9%
- Sodium Chloride 0.45% + dextrose 5%
- Hartmann’s solution
- Dextrose 5%
- Dextrose 10%
See image.
Describe the fluid management of a 6 kg child who is clinically shocked and 10% dehydrated as a result of gastroenteritis.
6 kg child
- SHOCK
- 20 ml/kg 0.9% saline
- 20 x 6 = 120 ml
- INFUSION = DEHYDRATION + MAINTENANCE
- DEHYDRATION
- 10% i.e. loss of 100 ml/kg of body weight
- 100 x 6 = 600 ml
- MAINTENANCE = 100 ml for the first 10 kg, 50 ml for the 2nd 10 kg, 20 ml/ kg thereafter
- 100 x 6 = 600 ml
- TOTAL DEHYDRATION REPLACEMENT + MAINTENANCE = 1200 ML
- over 24 hours
- 1200 / 24 = 50 ml / hr
- DEHYDRATION
- Monitoring
- weigh after 4-6 hrs
- losing weight –> increase fluid rate
- excessive weight gain –> decrease rate
- satisfactory –> continue
- tolerating oral fluids then start giving more of maintenance fluid as oral feeds
- weigh after 4-6 hrs
What can excessive fluid administration cause?
EXCESSIVE FLUID ADMINISTRATION
- Intravascular fluid overload
- Overhydration
- Both
Describe the relative risk of dehydration and fluid overload in paediatric patients with the following conditions:
- Nephrotic syndrome
- Myocardial dysfunction
- Renal impairment
- Nephrotic syndrome
- low serum albumin
- fluid leaks out of the intravascular space into the tissues
- diffuse severe oedema
- BUT intravascular space MAY be fluid DEPLETED
- => may need to replace fluid before diuresing to avoid shock
- Myocardial dysfunction
- intravascular compartment overfilled
- signs of fluid overload
- BUT on diuretics
- MAY also be dehydrated due to total body fluid depletion
- Renal impairment
- intravascular AND total body FLUID OVERLOAD
- giving more fluid –> pulmonary oedema
Treatment of fluid overload can be complex.
Always d/w an expert.
What are the normal daily requirements in well, normal children for the following:
- Water (ml/ kg/ day)
- Sodium (mmol/ kg/ day)
- Potassium (mmol/ kg/ day)
- Energy (kcal/ day)
- Protein (g/ day)
See image.