Quick Links :
 
 

 

 

Module 3 : Prescribing

 

 

Water Content

 

We require a certain volume of water every day (Typically 2-3L – see physiology). Most people can obtain this from oral intake of food and drinks – this includes hospital in-patients! The human body is much better at judging its own fluid requirements than doctors are, and therefore all patients who can eat and drink should be encouraged to do so. However, there are a number of situations in which we must provide some or all of a patient’s daily fluid requirements (for example, patients who are nil by mouth).

 

 

  Test Yourself !  
   
  You may see a number of different fluid 'regimens' being used on the wards. Which of these is the best?

That's correct, well done!
 

None of these - This is a trick question! There is no 'best regimen'. In fact, although blanket regimens such as these may work for some patients, they can be very dangerous for others. To work out a patients fluid requirements you should be using the patient's fluid charts, biochemical and clinical assessment, and above all: Your brain!

 

Two sugar one salt (2 L 5% glucose + 1L 0.9% NaCl) – wrong! See above

 

Two salt one sugar (2 L 0.9% NaCl + 1L 5% glucose) – very wrong! This is a commonly prescribed mistake. 2 L of NaCl would be overdose most patients with sodium, as we will discuss later.

 

Half half half (3 L 0.45% NaCl) - wrong! See above

 

Hartmanns, Hartmanns, Hartmanns (3 L Hartmanns ) –wrong

 

Sorry, that's incorrect!
 

None of these - This is a trick question! There is no 'best regimen'. In fact, although blanket regimens such as these may work for some patients, they can be very dangerous for others. To work out a patients fluid requirements you should be using the patient's fluid charts, biochemical and clinical assessment, and above all: Your brain!

 

Two sugar one salt (2 L 5% glucose + 1L 0.9% NaCl) – wrong! See above

 

Two salt one sugar (2 L 0.9% NaCl + 1L 5% glucose) – very wrong! This is a commonly prescribed mistake. 2 L of NaCl would be overdose most patients with sodium, as we will discuss later.

 

Half half half (3 L 0.45% NaCl) - wrong! See above

 

Hartmanns, Hartmanns, Hartmanns (3 L Hartmanns ) –wrong!

 

 

 

 

In order to determine a patient's daily fluid requirements you should consider:

 

1.The losses and gains from the previous day (or days)

-- Requires careful assessment of their weight and fluid charts.

 

2.Anticipated losses today

-- Based on the previous days and any changes today. For example, have they developed diarrhoea, are they becoming more pyrexial (see Physiology : Fluid balance in disease)

 

3.Their current hydration status

-- There is little point painstakingly matching todays fluid outputs and inputs if they are already fluid over- or under-loaded. The previous weight and balance charts will help, but clinical and biochemical (blood results) assessment is key.

 

 

The method above should provide a solid tool for assessing a patient's daily fluid volume requirements. It is important to understand that this may be radically different from the often quoted ‘2-3 L’, especially in unwell patients with altered physiology.

 

It is also helpful to appreciate that in post-operative patients, as a natural consequence of surgical stress, physiological antidiuresis ensues mediated by ADH. This will resolve by itself and so giving too much fluid to these patients should be avoided (particularly to women, and particularly as 5% dextrose) as it can cause severe, life threatening hyponatraemia.

 

Previous Next

 

 

This tab has icon in it.

Suspendisse blandit velit eget erat suscipit in malesuada odio venenatis.