Mannitol

Mannitol - an alcohol capable of causing an osmotic diuresis.Available as 10% and 20% solutions. Crystallisation may occur at low temperatures. It has a rapid onset of action and duration of action is up to 4 h. Rapid infusion
of mannitol increases the cardiac output and the BP.

Uses
Cerebral oedema
Preserve renal function peri-operatively in jaundiced patients
To initiate diuresis in transplanted kidneys
Rhabdomyolysis

Contraindications
Congestive cardiac failure
Pulmonary oedema (acute expansion of blood volume)
↑ Intravascular volume (further ↑ intravascular volume)

Administration
• Cerebral oedema
IV infusion: 0.5–1.0 g/kg as a 20% solution, given over 30 min

Weight (kg)	Volume of 20% mannitol at 0.5 g/kg (ml)
60	150
70	175
80	200
90	225
100	250

• Jaundice
Pre-operative:
  Insert urinary catheter
  1000 ml sodium choride 0.9% over 1 h, 2 h before surgery
  250 ml 20% mannitol over 30 min, 1 h before surgery
Per-operative:
  200–500 ml 20% mannitol if urine output <60 ml/h
  sodium chloride 0.9% to match urine output
• Kidney transplant
  IV infusion: 0.5–1.0 g/kg over 30 min, given with furosemide 40mg
  IV on reperfusion of transplanted kidney
• Rhabdomyolysis
  IV infusion: 0.5–1.0 g/kg as a 20% solution over 30–60 min

How not to use mannitol
Do not give in the same line as blood
Only give mannitol to reduce ICP when the cause is likely to be relieved surgically (rebound increase in ICP)

Adverse effects
Fluid overload
Hyponatraemia and hypokalaemia
Rebound ↑ ICP

Cautions
Extravasation (thrombophlebitis)

Organ failure
Cardiac:worsens
Renal: fluid overload

Renal replacement therapy
No further dose modification is required during renal replacement therapy