FLUIDS AND ELECTROLYTE IMBALANCES

A condition where losses of bodily fluids from whatever cause has led to significant disturbance in the normal fluid and electrolyte levels needed to maintain physiological functions.

Causes

Disorders may occur in the fluid volume, concentration (sodium composition), and distribution of fluid and other electrolytes and ph.

The main cause is problems in intake, loss and/or distribution and balance between water and electrolytes, as shown in the table below.

MECHANISM EXAMPLES
Gastrointestinal
loss
  • Excessive vomiting and diarrhoea
  • Nasogastric drainage
  • Fistula drainage
Haemorrhage
  • Internal or external
Fluid
sequestration
  • Paralytic ileus, intestinal
    obstruction
  • Peritonitis
Loss through
skin/wounds
  • Sweating
  • Extensive burns
Urinary loss
  • Decompensated diabetes
Fluid retention
and electrolytes
or water
imbalances
  • Renal, hepatic and heart
    failure (see specific section for
    management)
Reduced intake
  • Post operative patients
Excessive intake
  • Water intoxication, IV fluids
    overload

Clinical features

  • Dehydration in mild/moderate fluid (water and electrolytes) deficiency
  • Hypovolaemic shock in severe fluid deficiency
  • Oedema (including pulmonary oedema) in fluid excess
  • Specific effects due to electrolytes imbalances

Management

IV fluids and electrolytes therapy has three main objectives:

  • Replace lost body fluids and continuing losses
  • Correct eventual imbalances
  • Maintain daily fluid requirements

Always use an IV drip in patients who are seriously ill (except patients in congestive heart failure; for these, use only an indwelling needle) and may need IV drugs or surgery.
If the fluid is not needed urgently, run it slowly to keep the IV line open.

Maintenance fluid therapy

  • Administer daily fluid and electrolyte requirements to any patient not able to feed
  • The basic 24-hour maintenance requirement for an adult is 2.5-3 litres
    • One third of these daily fluids should be (isotonic) sodium chloride 0.9% infusion (or Ringer’s Lactate), the other two thirds Glucose 5%
      infusion
  • As well as the daily requirements, replace fluid lost due to the particular condition according to the assessed degree of dehydration

Notes

  • Closely monitor all IV drips to ensure that the rate is adjusted as required
  • Check the drip site daily for any signs of infection; change drip site every 2-3 days or when the drip goes into tissues (extravasation)

Replacement therapy in specific conditions

See dehydration

Diarrhoea and vomiting with severe dehydration, paralytic ileus, intestinal obstruction

  • Replace fluid losses with isotonic (sodium) solutions containing potassium e.g. compound sodium lactate infusion (Ringer’s Lactate solution)
  • Or half-strength Darrow’s solution in 2.5% glucose infusion

Haemorrhage

If there is blood loss and the patient is not in shock

  • Use sodium chloride 0.9% infusion for blood volume replacement giving 0.5-1 L in the 1st hour and not more than 2-3 L in 4 hours

If there is blood loss >1 litre

  • Give 1-2 units of blood to replace volume and concentration

Shock

  • Give Ringer’s Lactate or sodium chloride 0.9% infusion 20 ml/kg IV over 60  minutes for initial volume resuscitation
    • Start rapidly, closely monitor BP
    • Reduce the rate according to BP response
  • In patients with severe shock and significant haemorrhage, give a blood transfusion

Notes

  • Closely monitor all IV drips to ensure that the rate is adjusted as required
  • Check the drip site daily for any signs of infection; change drip site every 2-3 days or when the drip goes into tissues (extravasation)