Fluid and Electrolyte Therapy in Sick Children Flashcards
Water is the most important solvent of living organisms
• Total body water (TBW) makes up a major percentage of body weight.
• At one year TBW approximates _____% of body weight
60
TBW (L)=______ x __________
0.6 x body weight (kg)
_________ becomes the dominant fluid compartment after the first few weeks of life
Intracellular Fluid
ICF
Contributes about ___-____% of the body weight; 60% of total body water
• __________ is the major cation while __________ and __________ are the major anions
30-40%
Potassium ; phosphorus
organic acids
____________ is the dominant fluid compartment in the fetus and for the first few weeks of life
Extracellular Fluid
ECF
________ is the major cation while ________ is the major anion
• ________ and ________ make up the exchangeable part of the ECF, and both make up ________% of body weight
• The other aspects of ECF are transcellular fluid (GIT & urine, CSF, pleural, peritoneal fluid) and slowly exchangeable fluid such as in bones and cartilage
Sodium ;chloride
Plasma ; interstitial fluid
20- 25%
Water Balance
Water Gain:
• Drinking: driven by ________
– Major stimuli are plasma osmolality (_____% change) & plasma volume (_____% change)
• Oxidative processes
• Example of disease condition affecting water gain: _______,______
thirst; 1-2; 10
coma, vomiting,
Water balance
Water Loss: via the
• Kidneys: as ________ (e.g. renal impairment, ________)
• GIT: in ________ (e.g. ________)
• Lungs & Skin: as ________ losses (e.g. ________ neonates, ________). This is called ________ fluid loss and amounts to ________ ml/m2/day
urine; diabetes insipidus
faeces ; gastroenteritis
evaporative ; premature
burns
insensible ; 400-500ml/m2/day
Daily Water Requirement
The daily fluid requirement can be calculated using any of the following formulae:
A. =???
B. = 1500ml/m2 body surface area
C. =????
• The first formula tends to ________ fluid requirement for bigger children
• The last formula is the (most or least?) precise especially in_____ persons
100ml/kg for a child weighing less than 10kg
+50ml/kg for each additional Kg up to 20kg
+20ml/kg for each Kg in excess of 20kg
Urine output + insensible water loss
overestimate; most; ill
Antidiuretic Hormone (ADH) (also called ______________ )
• A 9-aminoacid peptide produced in the __________ and stored in the __________
• Major stimuli for release are rise in _____________ and a decrease in __________
• Other stimuli include nausea & vomiting, pain, stress, hypoglycemia, hypoxaemia, perioperative state, narcotics,SSRTI
vasopressin
hypothalamus ; posterior pituitary
plasma osmolality ; plasma volume
ADH
•It acts on the ______________ cells in the nephrons to facilitate the (active or passive?) __________ of water from the urine
• The (low or high?) osmolailty of the renal medulla is also crucial to this re-absorption
• When plasma osmolality or plasma volume is ______eased , ADH helps to restore it to physiologic state
collecting duct ; passive
re-absorption ; high
decreased
Osmolality of ECF
• Osmolality refers to the ______________________________________________ in plasma.
• Usually between ________ and _______mOsm/Kg of water
concentration of individual solute particles
270 ; 290mOsm/Kg
Plasmaosmolality:
= _____ x (________+ ) + (serum ____/____) + (serum _______/_____)
Because sodium is the major cation of ECF, plasma osmolality could also be calculated as:
= ______ x _________+
2 x (serum Na+ ) + (serum urea/2.8) + (serum glucose/18)
= 2 x Serum Na+
For instance,if the serum sodium is 140mmol/L, then plasma osmolality is estimated to be ______mOsm/Kg of water
• Effective osmolality (tonicity) AND not _________________ determines direction of fluid movement
• _______ is not an effective osmol
280mOsm/Kg
calculated osmality
Urea
Urea is an effective osmol
T/F
F
Urea is not an effective osmol
Sodium Balance
(Reference range in plasma: ______-_____mmol/L)
• Balance between ECF (~140mmol/L) & ICF Na+ (~10mmol/L) is maintained closely by the activity of the ___________
• Source of body Na+ is __________________________
• Sodium loss from the body is via: – _______, as ______
– GIT, in ______
– Skin, in ________
135-145mmol/L)
Na-K ATPase
intake from food and drink
Kidneys ; urine
stool; sweat
__________ is also the major contributor to plasma osmolality
Sodium
Daily sodium requirement is estimated at _____mmol/Kg body weight
2-3
Sodium Regulation in the Kidneys
•The Kidney is central to the regulation of Na+
•Re-absorption and excretion takes place in the __________
•The collecting tubule becomes permeable to ________ only in the presence of _____________. The finer regulation of sodium balance occurs here
tubules
sodium
aldosterone
Sodium regulation in the kidneys
•Aldosterone secretion depends on the activitation of the _______________________. _________________ is the major stimulus
•______ is released into the blood by the _________________ when renal __________ is low or the concentration of _________ reaching the ______ tubule is low
renin-angiotensin system (RAS).
Angiotensin II (Ang II)
Renin ; juxtaglomerular apparatus
perfusion ; sodium chloride ; distal tubule
Disorders of serum sodium:
• The disorders of sodium are commonly associated with fluid disturbances such as __________ or __________
• These disorders may be hyponatraemia or hypernatraemia
dehydration or fluid overload
Hyponatraemia: serum Na+ <135 mmol/L
• Commonest electrolyte disturbance worldwide, especially among sick persons: 15-20% of emergency admissions
• Arises from more sodium loss relative to water or intake of hypotonic fluid
• Severity (biochemical):
_________ (mild)
_________(moderate)
_________ (severe)
• Severity (clinical):
________ without ________, headaches, ________ (moderately severe)
________, abnormal/deep sleep, ________, ________, cardiorespiratory distress (severe)
134-130 (mild)
129-125 (moderate)
<125 (severe)
nausea ; vomiting ; confusion
vomiting ; seizures
coma
Some Causes of Hyponatraemia
• Use of __________ IV fluids
• ——— failure, __________ syndrome
• __________ fluid losses as in __________, pancreatitis, ______________, ____ failure, sepsis
• _____________
• _______
• Severe __________ /vomiting
• Via the skin as in severe _______ , cystic fibrosis
• Chronic diuretic therapy, especially thiazides
• Adrenal insufficiency
• Some renal tubulopathies
• Primary polydipsia
hypotonic ; Heart failure
nephrotic syndrome; Third space fluid
nephrotic syndrome ; bowel obstruction
liver failure; Acute kidney injury
SIADH; diarrhoea
burns
SIADH
• Whenever ADH is released from the ___________ in the absence of increased _________________ or decreased _______________
• Drivers of SIADH in sick persons include ———-, nauseas, _________, severe ________, emotional stress, general anaesthesia etc.
• It complicates several conditions: both surgical & medical but commonly disease of the _______ & ________
• It is unusual in the presence of ___________
posterior pituitary ; serum osmolality
circulatory volume; pain
vomiting; drugs
lungs ; CNS ; dehydration
SIADH is a diagnosis of exclusion
T/F
T
List 3 hypotonic fluids
List 5 isotonic fluids
5% DW
5%D +0.5% S
4.3%D +0.18 S
5%D +0.9%S
Ringer’s lactate
5%D+ Ringer’s
0.9% S
Clinical Features of Hyponatraemia
• Acute (<48 hours): Clinical features of hyponatraemia may be subtle or overt, and are mostly ___________ due to ___________ (RICP): ___________, nausea, ___________, weakness, muscle ___________, confusion, ___________, coma
• Chronic (>48 hours): _______ abnormalities, falls, impairment in _________ and ___________, osteoporosis, bone fractures, death
neurologic ; cerebral oedema
headaches ; vomiting
cramps ; seizures
gait ; concentration ; cognition
Treatment of hyponatraemia
• Treat symptomatic or severe hyponatraemia
• Correct sodium level not faster than _____ meq/hr (12 meq/24 hr)
• For milder ones treat the underlying cause
• Provide sodium for deficit, maintenance and ongoing losses
• Do frequent serum sodium monitoring
0.5
Dehydration
• Refers to net loss of fluid from the body. Usually from the _________
• Commonest complication of _________
ECF
diarrhoea
___________ is Commonest fluid disturbance in children
Dehydration
____________ is Responsible for most of the diarrhoeal deaths
Dehydration
In terms of severity dehydration could be _______,_______, or _________
in terms of type dehydration could be __________,_________,_________
mild, moderate or severe
hyponatraemic, isonatraemic or hypernatraemic
_____natraemic dehydration is the commonest type
Iso
