Please enable JavaScript.
Coggle requires JavaScript to display documents.
Fluid Balance (Electrolyte balance (Sodium Hypernatremia - >145 mEq/L …
Fluid Balance
Electrolyte balance
Sodium
Hypernatremia - >145
mEq/L
Signs
Thirst
Dryness and wrinkling of skin
Reduced blood volume and pressure
Circulatory collapse
Causes
Dehydration
Loss of hypotonic fluid
Treatment
Ingestion of water or intravenous infusion of hypotonic solution
Hyponatremia - <135
Signs
Disturbed CNS function
Confusion
Hallucinations
Convulsions
Coma - death
Causes
Infusion or ingestion of large volume of hypotonic solution
Treatment
Diuretic use and infusion of hypertonic salt solution
Potassium
Hyperkalemia > 5.0
Signs
Severe cardiac arrhythmias (irregular heartbeat)
Muscle spasm
Causes
Renal failure
Use of diuretics - chronic acidosis
Treatment
Infusion of hypotonic solution
Selection of different diuretics
Infusion of buffers
Dietary restrictions
Hypokalemia < 3.5
Signs
Muscular weakness
Paralysis
Causes
Low potassium diet
Diuretics
Hyper-secretion of aldosterone
Chronic alkalosis
Treatment
Increase dietary K+
Ingestion of K+ tablets or solutions
Calcium
Hypercalcemia > 5.3
Signs
Confusion
Muscle pain
Cardiac arrhythmias
Kidney stones
Calcification of soft tissue
Causes
Hyperparathyroidism
Vitamin D toxicity
Calcium supplement overdose
Treatment
Infusion of hypotonic fluid to lower Ca+ levels
Surgery to remove parathyroid gland
Administration of calcitonin
Hypocalcemia <4.3
Signs
Muscle spasms
Convulsion
Intestinal cramps
Weak heartbeat
Osteoporosis
Cardiac arrhythmias
Causes
Lack of vitamin D
Renal failure
Hypoparathyroidism
Hypomagnesemia
Treatment
Calcium supplements
Vitamin D administration
Magnesium
Hypermagnesemia > 2.0
Signs
Confusion
Lethargy
Respiratory depression
Hypotension
Causes
Overdose of magnesium supplements or antacids (rare)
Treatment
Infusion of hypotonic solution to lower plasma concentration
Hypomagnesemia <1.4
Signs
Hypocalcemia
Muscle weakness
Cramps
Cardiac arrhythmias
Hypertension
Causes
Poor diet
Alcoholism
Severe diarrhoea
Kidney disease
Malabsorption syndrome
Ketoacidosis
Treatment
Intravenous infusion of solution high in Mg2+
Phosphate
Hyperphosphatemia > 3.0
Signs
No immediate symptoms
Chronic elevation leads to calcification of soft tissues
Causes
High dietary phosphate intake
Hypothyroidism
Treatment
Dietary reduction
PTH supplementation
Hypophosphatemia < 1.8
Signs
Anorexia
Dizziness
Muscle weakness
Cardio myopathy
Osteoporosis
Causes
Poor diet
Kidney disease
Malabsorption syndrome
Hyperparathyroidism
Vit D deficiency
Treatment
Dietary improvement
Vit D and/or calcitrol supplementation
Chloride
Hyperchloremia > 108
Signs
Acidosis
Hyperkalemia
Causes
Dietary excess
Increased chloride retention
Treatment
Infusion of hypotonic solution to lower plasma concentration
Hypochloremia < 100
Signs
Alkalosis
Anorexia
Muscle cramps
Apathy
Causes
Vomiting
Hypokalemia
Treatment
Diuretic use and infusion of hypertonic salt solution
Electrolyte concentration regulation
Regulation of fluid balance
Fluid accumulation or depletion
Alter ECF volume and may change its osmolarity
These effects are detected by receptors
Leads to compensatory changes in intake and loss
Isotonic
ECF & ICF are in balance
Hypotonic
Concentration is less outside the cell and higher inside the cell
Solutions have more water in
Hypertonic
Concentration is lower inside the cell and higher outside the cell
Solutions have less water in
Electrolytes in body fluid
Ions form when electrolytes dissolve and dissociate
4 functions
Control osmosis of water between body fluid compartments
Help maintain the acid base balance
Carry electrical current
Serve as cofactors
Electrolyte balance
Requires rates of gain and loss of each electrolyte in the body to be equal
Concentration directly affects water balance
Concentrations of individual electrolytes affect cell functions
Key electrolytes
Sodium
Potassium
Magnesium
Chloride
Phosphate
Fluid & electrolyte imbalances
Common in patients with illness
Directly caused by illness or disease - burns, heart failure, renal disease, liver disease, diabetes insipidus
Also laxative abuse and marathon runners
Inappropriate therapeutic measures - IV fluid replacement, diuretics
Dehydration
When water loss is greater than water gain
Decrease in volume, increase is osmolarity of body fluids
Stimulates thirst centre in hypothalamus
Decrease flow of saliva
Hypovolemia & hypervolemia
Hypovolemia
ECF volume deficit / State of decreased blood volume
GI sodium loss (vomiting, diarrhoea)
Skin sodium loss (sweating, burns)
Renal sodium loss (diuretics, renal disease)
Haemorrhage
Leads to reduction in
Blood volume and venous return
Therefore reduction in cardiac output which results in reduction in renal perfusion
Which results in increase in renin release from the kidneys
Consequently plasma levels of angiotensin II rise and stimulate thirst
Dehydration refers to loss of total body water, producing hypertonicity
Hypovolemia (volume depletion) refers to a deficit in ECF volume
Clinical features
Thirst
Dizziness on standing
Confusion
Postural hypotension
Dry mouth
Reduced skin turgor
Reduced urine output
Weight loss
Hypervolemia
Fluid volume excess
Intravenous (IV) therapy
Renal sodium retention in heart and renal failure
Water intoxication
Drinking too much fluid can be dangerous, leading to hyponatremia
Severe cases can result in lung congestion, brain swelling, headache, fatigue, lethargy, confusion, vomiting, seizures and eventually coma
Stages
Too much water intake
Decreased Na+ concentration of interstitial fluid and plasma (hyponatremia)
Decreased osmolarity of interstitial fluid and plasma
Osmosis of water from interstitial fluid to intracellular fluid
Water intoxication (cells swell)
Convulsions, coma, and possible death
Clinical features
Ankle swelling
Breathlessness
Oedema
Pulmonary precipitations (crackling sound)
Hypertension (sometimes)
Weight gain
Gerontologic considerations
Structural changes in liver decrease ability to conserve water
Hormonal changes lead to decrease in ADH and ANP
Loss of subcutaneous tissue leads to increased loss of moisture
Reduced thirst mechanism results in decreased fluid intake
Hormones involved in water & electrolyte balance
Fluid output
Regulated through modulation of renal sodium and water reabsorption by:
Stimulation of anti-diuretic hormone release
Stimulation of aldosterone secretion (stimulated by hormone angiotensin II)
Stimulation of atrial natriuretic peptide (ANP) hormone release
Regulation of aldosterone
Dehydration, Na+ deficiency or haemorrhage
Leads to decreased blood volume & pressure
Juxtaglomular cells (granular cells) in kidneys secrete enzyme renin
Liver - angiotensinogen - increased angiotensin I
Lungs - angiotensin converting enzyme - increase angiotensin II
Adrenal cortex - Increased aldosterone
In kidneys the increased aldosterone causes increased Na+ and water reabsorption and increased secretion of K+ and H+ in urine
This leads to increased blood volume
Blood pressure increases until returns to normal
Angiotensin II also causes vasoconstriction of arterioles that increase blood pressure until returns to normal
Increased K+ in extracellular fluid
Na+ Cl- hormonal regulation
Increase NaCl intake
Increased plasma concentration of Na+ & Cl-
Increased osmosis of water from ICF to interstitial fluid and plasma
Increased blood volume
Increased blood volume/blood pressure causes:
Increased stretching of atria of heart
Increased release of atrial natriuretic peptide
Decreased released of renin by kidneys
Decreased formation of angiotensin II
Decreases
lead to - Increased glomerular filtration rate, decreased release of aldosterone
Changes caused by increased blood volume leads to reduced reabsorption of NaCl by kidneys
This increases the loss of Na+ & Cl- in urine (natriuresis)
Increases water loss in urine by osmosis
All causes decreased blood flow
Learning outcomes
Name the main hormones involved in water and electrolyte balance and describe their action to maintain homeostasis.
Explain the causes and consequences of hypovolemia and hypervolemia.
Describe how electrolyte concentrations are regulated.
Infusates
Infusion - Patient attached to a drip that delivers fluid into the bloodstream (the liquid is the infusate)
Replace or correct abnormalities of fluid or electrolytes in the body