An equiosmolar study on early intracranial physiology and long term outcome in severe traumatic brain injury comparing mannitol and hypertonic saline

• Mannitol and hypertonic saline (HTS) in equiosmolar concentrations had a similar effect on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) over 6 days.
• The duration for which the ICP remained below 20 mmHg on day 6 was higher in the HTS group.
• The duration of inotrope requirement in the HTS group tended to be less compared to mannitol group.
• The slope of fall in ICP in response to a bolus dose at a given baseline value of ICP was higher with HTS.
• In-hospital mortality tended to be lower in the HTS group.

The impact of hypertonic saline (HTS) on long term control of intracranial hypertension (ICH) is yet to be established. The current prospective randomized controlled study was carried out in 38 patients with severe traumatic brain injury (TBI). Over 450 episodes of refractory ICH were treated with equiosmolar boluses of 20% mannitol in 20 patients and 3.0% HTS in 18 subjects. Intracranial pressure (ICP) was monitored for 6 days. ICP and cerebral perfusion pressure (CPP) were comparable between the groups. The mannitol group had a progressive increase in the ICP over the study period (p = 0.01). A similar increase was not seen in the HTS group (p = 0.1). The percentage time for which the ICP remained below a threshold of 20 mmHg on day 6 was higher in the HTS group (63% versus 49%; p = 0.3). The duration of inotrope requirement in the HTS group was less compared to the mannitol group (p = 0.06). The slope of fall in ICP in response to a bolus dose at a given baseline value of ICP was higher with HTS compared to mannitol (p = 0.0001). In-hospital mortality tended to be lower in the HTS group (3 versus 10; p = 0.07) while mortality at 6 months was not different between the groups (6 versus 10; p = 0.41). Dichotomized Glasgow Outcome Scale scores at 6 months were comparable between the groups (p = 0.21). To conclude, immediate physiological advantages seen with HTS over mannitol did not translate into long term benefit on ICP/CPP control or mortality of patients with TBI.