Fluid Therapy

Key points

• NICE routine IV maintenance in adults: initially prescribe 25–30 mL/kg/day water , approximately 1 mmol/kg/day each of sodium, potassium and chloride , and 50–100 g/day glucose to limit starvation ketosis, with individual adjustment.
• Worked example for 80 kg: approximately 2.0–2.4 L water/day and about 80 mmol/day each of sodium, potassium and chloride, subject to clinical reassessment.
• Reassess fluid status, electrolytes and renal function regularly ; NICE recommends ongoing monitoring and adjustment rather than treating the initial prescription as fixed.
• Large volumes of 0.9% sodium chloride can cause or worsen hyperchloraemic metabolic acidosis because of its relatively high chloride content.
• Hartmann's solution contains potassium , but the presence of potassium is not by itself an absolute contraindication in hyperkalaemia; fluid choice should be individualised according to potassium level, renal function, acid-base status and the clinical indication.
• MRCP trap: maintenance fluid is not resuscitation. Do not give 25–30 mL/kg/day automatically to a shocked patient; resuscitation requires a separate assessment and regimen.
• Fluid prescribing must be individualised in older/frail patients, renal impairment and heart failure; NICE suggests lower volumes such as 20–25 mL/kg/day in these groups.