For patients who are obese, adjust the IV fluid prescription to their ideal body weight. Use lower range volumes per kg (patients rarely need more than a total of 3 liters of fluid per day) and seek expert help if their BMI is more than 40 kg/m2. Consider prescribing less fluid (for example, 20–25 ml/kg/day fluid) for patients who: Are older or frail Have renal impairment or cardiac failure Are malnourished and at risk of refeeding syndrome (see the NICE guideline Nutrition support in adults External Web Site Policy [NICE clinical guideline 32]). When prescribing for routine maintenance alone, consider using 25–30 ml/kg/ day sodium chloride 0.18% in 4% glucose with 27 mmol/l potassium on day 1 (there are other regimens to achieve this). Prescribing more than 2.5 liters per day increases the risk of hyponatremia. These are initial prescriptions and further prescriptions should be guided by monitoring. Consider delivering IV fluids for routine maintenance during daytime hours to promote sleep and wellbeing.
