Ficha Cientifica

Isotonic versus hypotonic solutions for maintenance intravenous fluid administration in children


Abstract
Background
Maintenance intravenous fluids are frequently used in hospitalised children who cannot maintain adequate hydration through enteral intake. Traditionally used hypotonic fluids have been associated with hyponatraemia and subsequent morbidity and mortality. Use of isotonic fluidhas been proposed to reduce complications.
Objectives
To establish and compare the risk of hyponatraemia by systematically reviewing studies where isotonic is compared with hypotonic intravenous fluid for maintenance purposes in children.
Secondly, to compare the risk of hypernatraemia, the effect on mean serum sodium concentration and the rate of attributable adverse effects of both fluid types inchildren.
Search methods
We ran the search on 17 June 2013. We searched the Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase (OvidSP), and ISI Web of Science. We also searched clinical trials registers and screened reference lists. We updated this search in October 2014 but these results have notyet been incorporated.
Selection criteria
We included randomised controlled trials that compared isotonic versus hypotonic intravenous fluids for maintenance hydration in children.
Data collection and analysis
At least two authors assessed and extracted data for each trial. We presented dichotomous outcomes as risk ratios (RR) with 95% confidence intervals (CIs) and continuous outcomes as meandifferences with 95% CIs.
Main results
Ten studies met the inclusion criteria, with a total of 1106 patients. The majority of the studies were performed in surgical or intensive care populations (or both). There was considerable variation in the composition of intravenous fluid, particularly hypotonic fluid, used in the studies. There was a low risk of bias for most of the included studies. Tenstudies provided data for our primary outcome, a total of 449 patients in the analysis received isotonic fluid, while 521 received hypotonic fluid. Those who received isotonic fluid had a substantially lower risk of hyponatraemia (17% versus 34%; RR 0.48; 95% CI 0.38 to 0.60, high quality evidence). It is unclear whether there is an increased risk of hypernatraemia when isotonic fluids are used (4%versus 3%; RR 1.24; 95% CI 0.65 to 2.38, nine studies, 937 participants, low quality evidence), although the absolute number of patients developing hypernatraemia was low. Most studies had safety restrictions included in their methodology, preventing detailed investigation of serious adverse events.
Authors' conclusions
Isotonic intravenous maintenance fluids with sodium concentrations similar tothat of plasma reduce the risk of hyponatraemia when compared with hypotonic intravenous fluids. These results apply for the first 24 hours of administration in a wide group of primarily surgical paediatric patients with varying severities of illness.
 

Plain language summary
Fluids for hydration in children
Background
Many children in hospital need fluid through an intravenous line (or 'drip')because they cannot eat or drink enough and they need to remain hydrated. This fluid can cause rare but serious side effects due to the salt level in the body decreasing. When the salt level in the body decreases quickly brain swelling can occur, which can result in death.
There has been uncertainty regarding how much salt the intravenous fluid should contain.
Review question
Traditionally, fluidscontaining lower salt levels than blood (hypotonic) have been administered. This analysis compared these fluids with fluid containing a similar salt level to blood (isotonic). We aimed to determine how many patients had low salt levels in the blood when an isotonic fluid was used compared with a hypotonic fluid.
Key results
Studies conducted prior to 17 June 2013 were reviewed. We included 10...