Fluid and Electrolyte balance Flashcards Preview

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Flashcards in Fluid and Electrolyte balance Deck (34):

Describe the different body fluid compartments and the approximate proportion of fluid inside each one.

Two fluid compartments:

The intracellular space (fluid inside the cell) approx (40%) 2/3rd of body fluids

The extracellular space (fluid outside the cell) (20%) 1/3rd of body fluids. The ECF compartment is further divided into the intravascular fluid called plasma (5%), interstitial (15%) and transcellular fluid space.


Discuss the pressures involved in the movement of water between the plasma, interstitial fluid, lymphatic vessels and intracellular fluid.



Explain how an increase in capillary hydrostatic pressure causes oedema, and how a decrease in capillary oncotic pressure causes oedema.

Capillary Hydrostatic pushes water across the interstitial space build up fluid in the air sacs

Capillary Oncotic, because plasma proteins pull fluid back into the capillary


Describe what is meant by fluid being in the third space.

It is the loss of extracellular fluid into a space that does not contribute to equilibrium between the ICF and ECF. It is basically a shift of fluid from the vascular space into an area where it is not available to support normal physiological process.


Briefly describe how sodium, chloride and potassium are normally kept in balance.

Sodium Levels
+ Sodium plays a critical role in maintaining charge balances in cell membranes, usually operating outside cell walls. As a positively charged ion, sodium contrasts with potassium, which is found inside cell walls, creating a gradient known as membrane potential. The balance of sodium influences the activity of membrane potential, allowing the body to control charge-driven functions like nerve impulse transmission and normal muscular activity. The amount of sodium in the body also determines the volume of extracellular fluid in circulation, making it critical for maintaining blood pressure.

Chloride's Role
Like sodium, chloride influences neural activity and muscle function, but chloride carries a negative charge rather than a positive one. Chloride is primarily found along with sodium in ordinary table salt, otherwise known as sodium chloride, and because it is in most foods, insufficient intake is rare. Chloride, in the form of hydrochloric acid, is also a major component of gastric juice, which in turn digests and absorbs essential nutrients from food.

Potassium Needs
Together with sodium, potassium maintains and influences membrane potential, except it acts from within cell walls rather than from extracellular fluid. Because sodium intake is usually high in Western society, potassium requirements correspondingly increase to maintain the balance. In addition to its effects on neural and muscular activity, potassium is important for maintaining bone health.


Briefly list some common causes of water deficit.

Blood loss  
Fluid loss – 
Severe vomiting/diarrhoea
Third spacing


List some causes of water excess. Why is the healthy body unable to remain in a state of water excess?

It results when both water and sodium are retained in the body. It may be caused by fluid overload (excess water and sodium intake) or by impairment of the mechanisms that maintain homeostasis. The conditions that cause retention of both sodium and water include HF, cirrhosis of the liver, renal failure, adrenal gland disorders. The body is unable to remain in a state of water excess because of the increase in sodium and water is isotonic, the serum sodium and osmolality remain normal and the excess fluid remains in the extracellular space.


Discuss why metabolic dysfunctions occur in potassium deficiency and in potassium excess.



What is the most prominent ECG change associated with hyperkalaemia?

Moderate elevation with wide, flat P wave, wide QRS complex and peaked T wave.


What is the most prominent ECG change associated with hypokalaemia?

Flattening of the T wave and the appearance of a U wave


Identify four clinical manifestations associated with respiratory alkalosis.

Dry mouth
Decrease BP or normal


Explain how hyperglycaemia contributes to dehydration and metabolic acidosis.



Identify five risk factors associated with the development of fluid, electrolyte and acid-base imbalances.

Chronic disease
Acute conditions
Inability to access food and water
Extremes of age


Explain the clinical implications of hypovolaemia and hypervolaemia.


Acute weight loss
Decrease skin turgor
Concentrated urine
Postural hypotension
Weak, rapid HR
Increased temp
Decreased CVP
Cool clammy skin due to peripheral vasoconstriction


Crackles, abnormal lung sounds
Increased BP
Increase pulse rate
Increased CVP
Increased weight
Increase urine output
SOB and wheezing


Discuss the role of Antidiuretic hormone in maintaining homeostasis of body fluids.

The antidiuretic hormone helps to control blood pressure by acting on the kidneys and the blood vessels. Its most important role is to conserve the fluid volume of your body by reducing the amount of water passed out in the urine.


What is PAO2?

It is partial pressure of carbon dioxide. (normal 35-45 mm Hg) reflects the respiratory status of patients as it measures the carbon dioxide content in the blood.


What is Base Excess?

is defined as the amount of H+ ions that would be required to return the pH of the blood to 7.35 if the pCO2 were adjusted to normal. It is used as an indicator of the degree of metabolic disturbance.


What is Haematocrit?

is a measurement of the proportion of blood that is made up of cells, it is the ratio of the volume of red blood cells to the total volume of blood.


What is Diffusion?

Movement of fluids and solutes and equalisation of solute concentration


What is Osmosis?

Movement of fluids to an area of high solute concentration and eventual equalisation of solute concentration


What is Active Transport?

The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.


Discuss the difference between osmolarity and osmolality.

Osmolality and osmolarity are units of measurement.

Osmolarity is the concentration of an osmotic solution. This is usually measured in osmoles. Osmolarity is also used to determine certain medical conditions, like the dissolved particles in urine.

Osmolality deals with the concentration of the particles that are dissolved in a fluid. In medical science, osmolality is used to determine several conditions like diabetes, dehydration and shock.


Discuss the difference between osmotic pressure and tonicity.

Osmotic pressure:
Is the amount of hydrostatic pressure needed to stop the flow of water by osmosis, primarily determined by the concentration of solutes.

The ability of all the solutes to cause an osmotic driving force that promotes water movement from one compartment to another.


Compare the mechanism of action of Potassium-sparing, Thiazide and Loop diuretics and provide one example of each.

Thiazide promotes excretion of sodium, potassium, chloride and water by decreasing the absorption in the distal tubules, examples include:

Pottasium-sparring promotes excretion of sodium and water by inhibiting Sodium-Potassium exchange in the distal tubule, examples include:

Loop diuretics inhibit sodium and chloride reabsorption in the ascending loop of Henle, it also excretes sodium, chloride, water and potassium


Metabolic Acidosis cause and effect, on ABG'S.

Excess of nonvolatile acids and bicarbonate deficiency.

PH decreases
Decrease of HCO3
Decrease of PaCO2


Metabolic Alkalosis cause and effect, on ABG'S.

Bicarbonate excess

Increase PH
Increase HCO3
Increase PaCO2


Respiratory Acidosis cause and effect, on ABG'S.

Retained CO2 and excess carbonic acid

Decrease PH
Increase PaCO2
Increase HCO3


Respiratory Alkalosis cause and effect, on ABG'S.

Loss of CO2 and deficient and carbonic acid

Increase PH
Decrease PaCO2
Decrease HCO3


Identify the regulatory mechanisms triggered by hypovolaemia.



What is Diuretics?

Increase urinary excretion of water and sodium
Three major groups
Loop diuretics
Treat vascular fluid overload and oedema


Hypovolaemic shock – signs and symptoms

HR increase
RR increase
BP decrease
Urine output decrease


Diagnostic tests for Hypovolemic shock

- Oxygen
- Serum lactate


Hypovolaemic shock - treatment

IV fluids
Blood transfusion
Coagulation factors
Treat cause
Modified trendelenburg


Hypovolaemic shock – Nursing Care

A to E assessment
Increased frequency of observations (BP, TPR)
2 x large bore IV Cannulas
Cardiac monitoring
Administer medications/fluids as charted
Reassure patient
Escalate care to ICU
Position patient