Isotonic saline solution

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One 500 ml NaCl infusion bottle

The isotonic saline solution , also isotonic saline solution , is an iso- osmotic solution of saline ( sodium chloride ) in injection-suitable water to the blood plasma . It contains 9 g of table salt per liter ( 9 g / l ) and has an osmolarity of 308 mOsm / l. The isotonic saline solution is inexpensive and the most widely used infusion solution in the world .


The term “physiological saline solution” should not be used because the osmolarity is physiological, but not the concentration of sodium and chloride ions . With 154 mmol / l each, both ions are significantly more concentrated than in human serum (serum sodium: 135–145 mmol / l; serum chloride: 98–109 mmol / l). This imbalance is necessary because the osmotic effect of the other components contained in human blood (such as other electrolytes , other components such as proteins ) must be taken into account.

The sterile and pyrogen-free isotonic saline solution in containers (plastic or glass ampoules or bottles and plastic bags ) from 2 ml to 30 l (veterinary medicine) is available as a solution for medical use .

The Balanced Salt Solutions are further developments of the isotonic saline solution with various salts .


Isotonic saline solution is used as a carrier solution for drugs , to keep venous access in patients open and to rinse catheters , wounds, nose or eyes. In addition, the saline solution is also used in medicine for treating dehydration .

When this electrolyte solution is infused , there is no significant fluid shift between the intra- and extracellular space due to the osmolarity . Overloading the body with sodium and chloride ions leads to an inhibition of the renin-angiotensin-aldosterone system and stimulation of the ANP . The lack of other electrolytes in the blood plasma, particularly hydrogen carbonate , can lead to diluent acidosis . For these reasons, there are only a few indications for using isotonic saline solutions for fluid therapy, since better alternatives are available with fully electrolyte solutions .

Individual evidence

  1. ^ MD Stoneham, EL Hill: Variability in post-operative fluid and electrolyte prescription . In: Br J Clin Pract. , 1997 Mar, 51 (2), pp. 82-84, PMID 9158250 .
  2. R. Zander: Fluid Therapy. Bibliomed, Melsungen 2009, ISBN 978-3-89556-040-8 (not in bookshops) ( Memento of the original from July 5, 2011 in the Internet Archive ; PDF; 1.75 MB) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /