Non-reabsorbable sugar -> osmotic diuretic
inhibits water reabsportion in proximal convuluted tubule (mainly), as well as thing descending loop and collecting ducts
Water loss>>electrolyte loss
- early oliguria
- early brain edema
- postischemic acute renal failure
- Neurosurgical anesthesia for good operating conditions
Retention of mannitol –> further volume expansion –> pulmonary edema in CHF patients.
Half life 100 minutes, with 15 minute onset to ICP reduction.
I/O use for rapid reduction of brain volume.
Dose = 0.25g/kg (some evidence this works but doesn’t last as long) to infusion of 100g for all. 1g/kg also used.
Infusion always, if given too fast –> hyperosmolarity –> vasodilatory effect –> brain engorgement –> increase ICP
Concerns regarding entering the parenchyma, or whether it is effective only if BBB is preserved, make some reluctant to use – best to give a test dose. If it decreases ICP / improves surgical field, then repeat.
Theoretical ‘acceptable’ upper limit of osmolarity 320 mOsm/L, but evidence is “soft” and incrimental doses of 12.5g used until no longer see a clinical response.
From Miller’s Anesthesia 2015 ch70, Anesthesia for Neurosurgery; and Pharmacology and Physiology for Anesthesia: Foundations and Clinical Application 2013.