Basic Concepts of Fluid and Electrolyte Therapy

Central
Modern single or multi lumen polyurethane or silastic cannulae
inserted via the internal jugular or subclavian vein have even greater
potential than peripheral cannulae to cause morbidity and mortality
unless inserted and maintained by skilled staff observing strict protocols.
Sub-cutaneous route (Hypodermoclysis)
This method has been used in paediatrics and geriatrics for many
years, but it is so effective for replacing small or medium fluid and
electrolyte losses in patients unable to maintain balance by the oral
route, that it deserves wider use. One of its virtues is that patients or
their carers can be taught to manage it at home. We have found it
particularly useful for domiciliary use in adult and elderly patients
with salt and water losses from gastrointestinal diseases.
0.9% saline (500-2000 ml daily) or 5% dextrose (500 ml) containing
up to 20 mmol K + and/or 4 mmol Mg 2+ per litre may be infused over
3-4 hours via a fine butterfly cannula inserted into the subcutaneous
fat, usually over the torso.
Infusion pumps
When fluid is delivered by either the enteral or parenteral route, what
is prescribed is not necessarily what is delivered and patients may
receive either too much or too little as a result of inaccuracies in
delivery rates. It is now recommended that fluids should be delivered
with infusion pumps at predetermined rates, which can be up to
999 ml/h. This increases the accuracy of fluid delivery. Nevertheless,
delays in changing fluid bags once they are empty may still lead to
inaccuracies.
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