IV MAINTENANCE FLUIDS

Complex fluid or electrolyte replacement or abnormal distribution issues

Electrolyte and glucose abnormalities

• If Na⁺ <135 mmol/L, follow Hyponatraemia guideline
• If Na⁺ >150 mmol/L, follow Hypernatraemia guideline
• If K⁺ >6.0 mmol/L, follow Hyperkalaemia guideline
• If plasma K⁺ <2.5 mmol/L with persistent losses/poor absorption or plasma K⁺ either persistently <3.0 mmol/L or <3.0 mmol/L and combined with new tachyarrhythmia or muscle weakness follow Hypokalaemia guideline

• see Triage of patients with hyperglycaemia guideline

Continuing Excess losses

Does the patient continue to have excess fluid loss?

• Vomiting
• Nasogastric tube losses,
• Diarrhoea,
• Fistulae
• Stoma
• Drains
• Continuing blood loss,
• Polyuria
• Sweating
• Lactation

Action if excess fluid loss

• Seek senior help
• Measure volume of losses and type of fluid lost
• consider biochemical analysis of fluid e.g. haematocrit, biochemistry and serum protein
• Replace volume using an appropriate fluid in addition to maintenance regimen
• if GI losses >1500 mL, check chloride level. If patient hypochloraemic, use sodium chloride 0.9% +/- potassium chloride
• replace diarrhoea/small bowel/bowel preparation losses with compound sodium lactate (Hartmann’s) solution

Co-morbidities

Does the patient have co-morbidities?

• Frail elderly/malnourished
• Severe sepsis
• Chronic cardiac failure
• Chronic renal failure
• Chronic liver failure – seek advice of liver specialist
• Neurosurgical/neurological pathology
• Obese with BMI > 40

Action if co-morbidities

• Seek senior help

“Normal” adult fluid, electrolyte and glucose maintenance requirements

Water

• 25–30 mL/kg/day
• if no fever present, estimate is 25ml/kg/24hr
• if fever present, estimate is 30ml/kg/24hr

Sodium

• 50–170 mmol/day (1–2 mmol/kg/day)

Potassium

• 25–85 mmol/day (1 mmol/kg/day)

Chloride

• 80–120 mmol/day (1–1.5 mmol/kg/day)

Glucose

• 50–100 g/day to limit starvation ketosis
• but this does not address nutritional needs
• see Practice and ethics of nutritional support in medical patients

Amount of fluid and electrolyte

• Estimate maintenance volume and electrolyte required for a “normal” patient
• If patient has other sources of maintenance fluid and electrolyte intake from drugs e.g. IV nutrition, blood and blood products reduce the maintenance prescription accordingly
• excluding resuscitation/replacement of excess losses

Choice of fluid

• Within fluid, give glucose 50-100g/day
• e.g. Glucose 5% contains 5g/100ml
• Round weight-based potassium prescriptions to the nearest common fluids available
• e.g. a 67 kg person could have fluids containing 20 mmol and 40 mmol of potassium in a 24-hour period
• Always use commercially produced pre-mixed bags of any fluid with potassium chloride

• For the ‘general’ patient, prescribe Maintelyte (1L contains: Na⁺ 40mmol, K⁺ 20mmol, Mg2⁺ 1.5mmol, Cl- 40mmol and glucose 50g) at 1ml/kg/hr
• if unavailable, prescribe sodium chloride 0.18% with glucose 4% with potassium chloride 20 mmol/L; but remember prescribing > 2.5 litre increases risk of hyponatraemia
• Adjust quantity and content of maintenance fluid used as indicated by most recent biochemical results

How to deliver

• Beneficial to deliver daily maintenance requirement over daytime hours
• more physiological and will promote sleep and wellbeing
• increase rate and limit time that infusion should run accordingly
• Give as much fluid volume as possible orally or enterally
• give remainder IV or, in selected medical patients, SC
• Suggestion-place a handwritten label on any bag containing potassium warning staff not to increase infusion rate

Cautions

• Stressed patients (e.g. post-operative, septic) are at risk of complication from excess of:
• chloride (hyperchloraemic acidosis caused by sodium chloride 0.9%)
• free water (e.g. acute hyponatraemia, seizures, brain damage and death if glucose solutions with inadequate sodium content are used)
• 1000 mL over 8 hr is not indicated for maintenance alone
• even for the largest pyrexial patients

Administer resuscitation fluid separately

• Many unstable patients need maintenance fluids with repeated fluid boluses for resuscitation
• Do not increase rate of maintenance fluids to resuscitate
• content of maintenance fluid (especially hypotonic or high potassium-content) is inappropriate/dangerous when given in large volumes required for resuscitation
• see Fluid resuscitation guideline

Chart

Hourly

• If continuing excess losses or patient haemodynamically unstable, urine output

6-hrly

• BP
• if patient haemodynamically unstable, increase frequency

Daily

• Fluid balance chart
• Serum U&E
• Body weight

Examine daily

• Check for peripheral oedema
• Auscultate lung fields

• Senior review daily
• Adjust quantity and content of maintenance fluid as indicated by most recent biochemical results
• As soon as possible, re-establish oral fluids and remove indwelling intravenous lines

Administer resuscitation fluid separately

• If deficit occurs despite maintenance fluid, administer adequate maintenance fluid concurrently with appropriate resuscitation fluid
• see Fluid resuscitation guideline

Fluid overload

• If signs of fluid overload appear and parenteral fluid remains necessary, restrict fluid input to maximum 1 L/24 hr or reduce input by 50%