Is 10 litres of 4% dextrose in 0.18% saline NICE?

We read with great interest Stroud et al.'s defence of the National Institute for Health and Care Excellence (NICE) guidelines on intravenous fluids 1, written in response to the concerns raised by Woodcock about the same 2. Whilst we agree with the majority of the NICE guidance 3, we believe that Stroud et al. have inadequately responded to Woodcock's concern regarding the use of 4% dextrose in 0.18% saline as the preferred maintenance solution for use on the general wards, as advocated by the NICE guideline development group (GDG). There are no published trials to indicate the ideal intravenous maintenance fluid. Therefore, we assume that the NICE GDG recommendation of 4% dextrose in 0.18% saline, rather than 5% dextrose in 0.45% saline, for routine maintenance was formulated primarily on economic grounds. The economic model used by the GDG is flawed, with the cost comparisons between the different types of solution having been made on the basis of administering 2 l fluid daily for five days; that is, 10 l of 4% dextrose in 0.18% saline. Four percent dextrose in 0.18% saline is known to cause hyponatraemia, as the GDG and Stroud et al. recognise. The GDG recommends a daily sodium intake of 1 mmol.kg−1.day−1, when the daily reference nutrient intake is 1.6–2.4 g, equivalent to 70–100 mmol 4. In order to achieve sodium balance for a 70-kg person using the GDG's guidelines, 2.3 l of 4% dextrose in 0.18% saline is required, exceeding the GDG's recommended daily fluid requirement (25–30 ml.kg−1.day−1) by 9.5–31.4%, such that the use of 4% dextrose in 0.18% saline will always be associated with hyponatraemia. This explains why the Medicines and Healthcare products Regulatory Agency (MHRA) stated in 2012 that the use of 4% dextrose in 0.18% saline was contraindicated in children 5. Currently, in the UK, 5% dextrose in 0.45% saline is classified as a ‘special’ rather than a routine fluid, enabling the fluid manufacturers to charge up to ten times as much for 5% dextrose in 0.45% saline compared with 4% dextrose in 0.18% saline. Until the cost differential is reduced, the ubiquitous use of 5% dextrose in 0.45% saline will be discouraged in the UK. In the USA, where the prices of all crystalloids are similar 6, 0.45% saline has become the preferred maintenance fluid; the physiological benefits supporting its use are not countered by economic considerations. Without daily assessment, routine use of 5% dextrose in 0.45% saline can lead to sodium overload. However, subject to daily assessment, alternating administration of 1 l of 4% dextrose in 0.18% saline and 1 l of 5% dextrose in 0.45% saline over 24 hours will approximate the daily sodium and fluid requirements of many patients. It is unfortunate that the GDG did not recommend this regimen based on physiological calculations. By not recommending the use of 5% dextrose in 0.45% saline, its cost will remain excessively high, and it will continue to be a ‘special’ fluid, being routinely unobtainable on the wards. Consequently, in the UK, we will continue to subject our ward patients unnecessarily to the dangers of fluid and electrolyte mismanagement. Perhaps NICE has missed a golden opportunity really to improve the fluid and electrolyte management on the wards?