No evidence so far to support use of isotonic saline as a maintenance fluid instead of hypotonic saline

It is common practice to give intravenous (i.v.) fluids to patients with serious acute infections but there is no agreement as to what the sodium concentration of these fluids should be. Doctors have traditionally used intravenous fluid that contains a lower sodium concentration than is found normally in human serum; this is known as hypotonic saline. However, as patients with severe infections often have low sodium levels and adverse effects sometimes occur with the use of large amounts of hypotonic saline, it has been proposed to use intravenous fluids that have a sodium concentration similar to that of a healthy person − isotonic saline. This review has been unable to find any data from randomised trials that establish which is best.

Authors' conclusions: 

Although there is ample evidence elsewhere that administration of large volumes of hypotonic fluids has led to severe hyponatraemia and adverse neurological outcomes in many patients with a variety of medical and surgical conditions, we found no randomised controlled trials investigating whether use of isotonic saline as maintenance fluid in those who require intravenous fluid would a be safer alternative. Careful research with adequate design and sample sizes is needed to evaluate the benefits and safety of using isotonic saline as maintenance fluid in a variety of acute clinical conditions.

Read the full abstract...

Hypotonic saline (such as 0.18−0.3% NaCl with dextrose) is commonly used as maintenance fluid in the management of acute infections. In recent years there have been numerous reports of hypotonic saline solutions being associated with adverse outcomes. To reduce the rates of adverse outcomes, use of isotonic saline as maintenance fluid has been proposed.


To assess adverse events and benefits associated with infusion of hypotonic saline compared with isotonic saline solutions in the management of acute infections.

Search strategy: 

We searched MEDLINE, EMBASE, the Cochrane Controlled Trials Register, Current Controlled Trials and the Specialised Register of the Injuries Group.

Selection criteria: 

Randomised trials comparing hypotonic saline to isotonic saline in the management of acute infections.

Data collection and analysis: 

Three reviewers independently evaluated all potentially relevant articles, examined each study for possible inclusion and assessed the methodology quality using the Cochrane guidelines.

Main results: 

No trials met our inclusion criteria.