Monday 15 May, 2006

Subcutaneous fluids

Posted in Medicine, Michael Tam, Procedures, Wards at 11:52 by Michael Tam

Original article by: Michael Tam :: Printer friendly

Butterfly needle

Subcutaneous fluids (i.e., parental fluid hydration through a subcutaneous line) is a fantastic option in some patients, especially those with mild dehydration, with difficult venous access or the elderly with agitation, be it from delirium or dementia.

Remember that a subcutaneous line can also be used for many medications (e.g., morphine, midazolam).

Unlike intravenous cannulation, there isn’t usually a problem with “access” with a subcutaneous line and most nursing staff are qualified in their insertion.

Fluids through a subcutaneous line in the intrascapular area is most useful in the delirious/combative elderly patient with poor oral intake. Running 500-1000 mL of 0.9% NaCl solution overnight will help prevent dehydration.

There are specific subcutaneous needles that can be used, but in their absence, you can substitute with the more readily available 19- or 21-gauge butterfly needle.

The needle should be inserted into an area where it is stable and unlikely to be dislodged. The upper chest, interscapular area, abdomen and lateral aspect of thighs are all suitable locations. The needle should be sited such that it lies within the subcutaneous space but superficial to the underlying fascia. A sterile adhesive dressing (e.g., an Opsite) should be placed over the needle to keep the site sterile and fixed.

The interscapular area is a particularly good location for the agitated patient as they are unlikely to pull out the line.


  • Specific subcutaneous line, or
  • 19 or 21 gauge butterfly needle


  • upper chest
  • interscapular area (preferred)
  • abdomen
  • lateral aspect of thighs

Fluid choice:

  • 0.9% NaCl (normal saline)
  • avoid dextrose and additives


  • absolute maximum: 80 mL/h
  • aim for 60 mL/h or lower if possible


  • local skin problems (cellulitis, skin tears, rash)
  • existing tissue oedema
  • significant dehydration

The absolute maximum fluid rate is 80 mL/h, though this is often not tolerated over a 24 hour period. For a continuous infusion, try to keep the rate of fluid at or below 60 mL/h. You will need to use a lower rate if the patient develops tissue oedema. Areas such as the abdomen and interscapular area can generally tolerate more than the upper thigh.

Given the limitations of the rate of fluid and the fact that the fluid does not directly enter the intravascular space, subcutaneous fluids are a inappropriate choice for anything worse than mild dehydration.

The safest fluid for subcutaneously usage is isotonic saline, i.e., 0.9% NaCl (normal saline). You should probably avoid giving any solution with dextrose through a subcutaneous line as it can cause pain and fibrosis. Additives should also be avoided. Be aware that there is no consensus.

Obviously, you cannot give subcutaneous fluids if there is local inflammation or cellulitis.

Subcutaneous fluids is pointless if the patient has a condition that results in generalised tissue oedema (e.g., hypoalbuminaemia) as the fluid will simply stay in the interstium.

Change the subcutaneous line every 48-72 hours.

Please read the disclaimer


  1. ravindran said,

    it is great plaesure to a very precised material about the lines .thank you

  2. donna givans said,

    i need to administer subq normal saline to a 9 week old puppy. I have been taught to administer the med, but through research I have read that normal saline without additives is best. The saline I purchased is labelled bacteriostatic and contains benzyl alcohol. It is indicated for intravenous infusions. Can I use this for subq infusion as well? Thanks

  3. Michael Tam said,

    I really can’t give you an informed opinion donna. I can only assume that if you have in fact obtained “normal” saline for intravenous infusion in humans, that it would be adequate for subcutaneous infusion (in humans) as well.

    However, I am not a veterinarian and nor am I in the business of manufacturing medical fluids.

  4. dr.kesavan.menon,m.d said,

    exellent article.

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