<prompt> In a head injury patient, Mannitol should not be used for control of increased intracranial pressure whenSerum osmolality is more than 320 mOsmolkgAerial PaCO2 is less than 34 mm HgAerial PaO2 is more than 100 mg HgAerial pH is less than 7.35  <response>: Mannitol Mannitol is widely used to reduce ICP Commonly used preparation : 20 solution, 0.25-1 gmkg is given IV as bolus. Serum osmolality should not be allowed to go 320 mOsmL, to avoid systemic acidosis and renal failure Uses of Mannitol To reduce increased ICT or intra ocular tension To maintain GFR and urine flow in impending renal failure Forced diuresis in hypnotic or other poisoning To counteract low osmolality of plasmaECF due to rapid haemodialysis or peritoneal dialysis Contraindications of Mannitol Acute tubular necrosis Anuria Pulmonary edema Acute left ventricular failure. CHF Cerebral hemorrhage Ref: Harrisons 19th edition Pgno : 1779-1780 