Introduction: Osmotherapy forms an integral part in the management of patients with severe traumatic brain injury (TBI). An ideal choice between mannitol and HTS remains to be conclusively proven. More importantly, attention has not been paid to the long term osmolarity changes during the therapy. The current prospective randomised study aims at evaluating the effect of serum and urine osmolarity and sodium achieved with mannitol and HTS on ICP and outcome.

Methods: Thirty-eight patients of severe TBI, aged between 15 and 70 years and managed as per BTF guidelines were allocated to receive equiosmolar doses of either 20% mannitol or 3% HTS for refractory intracranial hypertension. Demographic data, physiological variables, ICP, serum and urine osmolarity/sodium were collected over five days. Data was analyzed for relationship between serum and urine sodium over five days in patients receiving mannitol and HTS for severe TBI.

Results: A total of 301 and 186 boluses of mannitol and HTS respectively were administered over five days. There was no difference between mannitol and HTS with respect to demography,type of brain injury and GOS. Serum sodium and osmolarity changes were similar between the groups(p=0.16 and 0.35 respectively). Urinary sodium excretion was significantly higher with HTS(p=0.02).The mean fall in ICP following a dose of hyperosmolar agent was 8.9 ± 8.4 mm Hg in the mannitol group and 10.1 ± 8.7 mm Hg in the hypertonic saline group (p - 0.135).

Conclusions: During long-term administration of hyperosmolar agents in TBI, HTS is no more effective than mannitol in controlling ICP. A major reason for this lack of benefit is an increased urinary loss of sodium with HTS and consequent inability to achieve higher serum sodium and osmolarity levels.Therapy aimed at retaining sodium holds the key for superior osmolar effect and good outcome.

Patient Care: This study aims at finding a better osmolar agent in the managenment of severe TBI. The reasons for inefficiency of HTS was investigated. The results gives a plethora of oppurtunities in improving its osmolar effect and hence improving the outcomes

Learning Objectives: By the conclusion of this session,participants should be able to 1) compare the effects of mannitol and hypertonic saline in severe TBI 2) should be able to discuss the reasons for the similarities between the two osmolar agent 3) participants should be able to discuss the methods to improve the osmolar effect of HTS by other means.

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