OzEMedicine - Wiki for Australian Emergency Medicine Doctors

see also diuretics, head_injury, glaucoma

• Must be:
  • freely filtered by glomerulus;
  • limited reabsorption in tubule;
  • relatively inert;
  • given in sufficiently large doses to incr. osmol. of plasma & glom.filtrate;
• Result in:
  • decr. prox. tubule water reabsorption → decr. luminal [Na];
  • decr. tubule Na reabs. due to: abn. low tub. [Na]
  • incr. Na flux from peritub. → lumen;
  • decr. med. osm. → decr. thin asc. Na reabs.
    • via incr. medullary blood flow;
    • PG effect of mannitol;
  • thus → potentially very high diuresis rates & all often → headache/N/V;

• acute renal failure prophylaxis & early Rx may decr. [toxin] in tubules;
• decr. CSF volume & pressure; decr. intraocular pressure;

• mannitol, urea, glucose in diabetes, urographic/angiographic agents, isosorbide, glycerin;

• Not absorbed from GIT → 5-25% IV solutions;
• Distributed in ECF → short term Rx may incr. ECF osm. → incr. ECFV;
• Dose:
  • diuretic: 200mg/kg over 3-5min test dose should → > 30ml/hr urine 2-3hrs;
  • 50-200g/d adults adjusted to maintain urine flow 50ml/hr;
  • CSF/glaucoma: 1.5-2g/kg 15-25% over 30-60min.
• C/I:
  • anuria; marked pulmonary oedema; marked dehydration;
  • i/cranial haemorrhage unless prior to craniotomy;
• Toxicity: terminate if pulm. oedema/CCF/ incr. renal dysfunction;

• less effective as 50% reabs.; more irritating tissues; 30% IV 1-1.5g/kg;
• thrombosis/pain if extravasation;

• metab. → hyperglycaemia & glycosuria & little diuresis, but oral esp. for glaucoma;