Critically evaluate the use of hypertonic saline and mannitol in the management of severe closed head injury.
Hypertonic Saline has theoretical advantages in the initial resuscitation of head injured patients because smaller volumes of fluid are required and blood pressure restoration is more effective. Brain oedema may be decreased to lower ICP and CPP may be increased. Post resuscitation use is less clear. In this setting, reduction in intracranial hypertension is due to improved systemic and cerebral haemodynamics and modulation of vasospasm. Adverse effects include renal impairment, rebound ICP rise and osmotic myelinolysis. Trials are continuing and a well defined role is not apparent as yet.
Mannitol has a long history of use in the management of head injuries. It lowers ICP initially by increasing CBF and producing a compensatory vasoconstriction. An osmotic effect and diuresis produce delayed fall in ICP. Efficacy would be dependent initially on the presence of adequate brain with intact autoregulation. Prolonged use may lead to leak into damaged brain with concomitant increase in ICP and swelling. The accepted role is in the urgent lowering of ICP before definitive therapy (eg. evacuate haematoma or perform decompression craniectomy). Chronic use is not supported by evidence.
Another question is very similar- Question 4 from the first paper of 2007. It asks one to discuss hypertonic saline, which of course is impossible without discussing mannitol.
aised intracranial pressure falls within the realm of osmotherapy, which enjoys a thorough discussion elsewhere:
- Intracranial pressure as a therapeutic target
- Management of raised intracranial pressure
- Osmotherapy for management of raised intracranial pressure
From those summary, a table of comparison can be compiled, which is presented below.
Chapter 43 (pp. 563) Cerebral protection by Victoria Heaviside and Michelle Hayes, and
Chapter 67 (pp. 765) Severe head injury by John A Myburgh.
Francony, Gilles, et al. "Equimolar doses of mannitol and hypertonic saline in the treatment of increased intracranial pressure*." Critical care medicine 36.3 (2008): 795-800.
Kamel, Hooman, et al. "Hypertonic saline versus mannitol for the treatment of elevated intracranial pressure: A meta-analysis of randomized clinical trials*."Critical care medicine 39.3 (2011): 554-559.
Nau, Roland. "Osmotherapy for elevated intracranial pressure." Clinical pharmacokinetics 38.1 (2000): 23-40.
Rickard, A. C., et al. "Salt or sugar for your injured brain? A meta-analysis of randomised controlled trials of mannitol versus hypertonic sodium solutions to manage raised intracranial pressure in traumatic brain injury." Emergency Medicine Journal (2013).
Lazaridis, Christos, et al. "High-Osmolarity Saline in Neurocritical Care: Systematic Review and Meta-Analysis*." Critical care medicine 41.5 (2013): 1353-1360.
Bhardwaj, Anish, and John A. Ulatowski. "Hypertonic saline solutions in brain injury." Current opinion in critical care 10.2 (2004): 126-131.
Arbabi, Saman, et al. "Hypertonic saline induces prostacyclin production via extracellular signal-regulated kinase (ERK) activation." Journal of Surgical Research 83.2 (1999): 141-146.
R LAWRENCE REED, I. I., et al. "Hypertonic saline alters plasma clotting times and platelet aggregation." Journal of Trauma-Injury, Infection, and Critical Care 31.1 (1991): 8-14.