Mannitol
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Mannitol is an osmotic diuretic that is freely filtered by the glomerulus but not reabsorbed by renal tubules. It works by increasing the osmolarity of renal tubular fluid and drawing fluid from intracellular to extracellular spaces. Main uses include prophylaxis of acute renal failure, treatment of acute oliguria and increased intracranial pressure. While it reduces ICP, mannitol provides limited benefit for oxygenation compared to hypertonic saline and risks cardiac failure and electrolyte imbalance with higher doses.
Mannitol
- 1. MANNITOL DR GEETANJALI S VERMA DEPT OF ANESTHESIA GEETANJALI S VERMA
- 2. • Osmotic diuretic – Freely filterable at glomerulus – Ltd reabsorption fm renal tubules – Resist metabolism – Pharmacologically inert • 6 carbon sugar GEETANJALI S VERMA
- 3. • Doesn’t undergo metabolism • Not absorbed from GIT • Doesn’t enter cells • Clearance from plasma by glomerular filtration GEETANJALI S VERMA
- 4. MOA Completely filtered at glomeruli ↓ Increases osmolarity of renal tubular fluid Prevents re absorption of water ↓ Na+ dilution in retained water Less re absorption of Na+ ↓ Urinary excretion of Na+, Cl-, HCO3- (urinary pH not altered) GEETANJALI S VERMA
- 6. Increases plasma osmolarity ↓ Draws fluid fm intra to extra cellular spaces ↓ Acute expansion of intravascular fluid volume ↓ Decreases brain bulk, increases renal blood flow to medulla GEETANJALI S VERMA
- 7. Oxygen radical scavenger ↓ Prevents cellular swelling Reduces renal tubular obstruction GEETANJALI S VERMA
- 8. USES 1. Prophylaxis against acute renal failure 2. D/d of acute oliguria 3. T/t of increased ICP 4. To decreased IOP GEETANJALI S VERMA
- 9. West J Med. 1979 October; 131(4): 277–284 • Allen R. Nissenson, MD, Raymond E. Weston, MD, and Charles R. Kleeman, MD • Author information ► Copyright and License information ► Abstract • Mannitol may be useful clinically both as a diuretic and as an obligate extracellular solute. As a diuretic it can be used to treat patients with intractable edema states, to increase urine flow and flush out debris from the renal tubules in patients with acute tubular necrosis, and to increase toxin excretion in patients with barbiturate, salicylate or bromide intoxication. As an obligate extracellular solute it may be useful to ameliorate symptoms of the dialysis disequilibrium syndrome, to decrease cerebral edema following trauma or cerebrovascular accident, and to prevent cell swelling related to renal ischemia following cross-clamping of the aorta. Largely unexplored uses for mannitol include its use as an osmotic agent in place of dextrose in peritoneal dialysis solutions, its use to maintain urine output in patients newly begun on hemodialysis, and its use to limit infarct size following acute myocardial infarction. GEETANJALI S VERMA
- 10. • Acute renal failure prophy – After cardiovasc surg, transplantn, extensive trauma, surg in jaundiced pt, nephrotoxic condn – Van Valenberg et al , 1984 : ARF less in pts receiving mannitol prior to revascularisation of transplanted kidney GEETANJALI S VERMA
- 11. • Diagnosis of acute oliguria – 0.25g/kg IV – Urine output increased = intravasc fluid vol depletion – No increase = glomerular/ renal tubular fn compromised GEETANJALI S VERMA
- 12. • t/t of increased ICP – 0.25-1 g/kg – Increases plasma osm – withdraws fluid fm brain tissues – Vasodil of vasc smooth muscle – Decreases rate of formn of CSF – Effective within 10-15mins of adm, lasts for 2hrs – No rebound increase GEETANJALI S VERMA
- 13. Bratton – J Neurotrauma - 2007 GEETANJALI S VERMA
- 14. Francony – Crit Care Med - 2008 GEETANJALI S VERMA
- 15. Mannitol … but No oxygenation improvement compared to HS Oddo – JNNP - 2009Sakowitz – J Trauma - 2007 Mannitol PtiO2 PitO2: - normal = 35 mm Hg - Ischemic threshold < 10-15 mm Hg GEETANJALI S VERMA
- 16. NATO study To prove non-inferiority of HS vs mannitol on brain metabolism Sample size : 30 patients 15 mannitol (1 g/kg), 15 HS 7.5% (2 mL/kg) Same osmotic load Main objective : effects on lactate/pyruvate ratio (redox potential) Secondary objectives : effects on ICP, PtiO2, cerebral glucose GEETANJALI S VERMA
- 17. Conclusion ICP reduction Improved oxygenation Effects on neuroinflammatory response Haemodynamic benefit Limited volume Mannitol Yes No Limited No No HS Yes Yes Yes Yes Yes GEETANJALI S VERMA
- 18. • Reduction of IOP – Increases plasma osm, withdraws fluid fm intraocular space GEETANJALI S VERMA
- 19. C/I • Well established anuria due to severe renal disease. • Severe pulmonary congestion or frank pulmonary edema. • Active intracranial bleeding except during craniotomy. • Severe dehydration. • Progressive renal damage or dysfunction after institution of mannitol therapy, including increasing oliguria and azotemia. • Progressive heart failure or pulmonary congestion after institution of mannitol therapy. • Do not administer to patients with a known hypersensitivity to mannitol. GEETANJALI S VERMA
- 20. A/E • Cardiac failure pts – pulm edema • Hypovolemia • Electrolyte imbalance • Plasma hyperosmolarity GEETANJALI S VERMA
- 21. AVAILABILITY Conc % g/100ml mOsm/L pH 5 5 274 6.3 10 10 549 6.3 15 15 823 6.3 20 20 1098 6.3 25 25 1372 5.9 GEETANJALI S VERMA