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Should I Use Hypertonic Saline to Treat High Intracranial Pressure?

Donald S. Prough

BRIEF ANSWER

Background

The use of hypertonic saline solutions to reduce brain bulk and intracranial pressure (ICP) has been studied for almost a century, especially in experimental models. In the mid-1980s, experimental studies of hypertonic solutions for resuscitation of hemorrhagic shock accompanying traumatic brain injury (TBI) generated considerable interest in the clinical use of hypertonic solutions for prehospital resuscitation of hypotensive head-injured patients.^1,2 nthusiasm for hypertonic resuscitation waned, however, at least in part because of emphasis in the United States on limiting any type of prehospital fluid resuscitation. Nevertheless, clinical investigators reported several series in which hypertonic saline solutions were used as primary fluid therapy in trauma patients (including those with TBI) or in which hypertonic solutions were used as rescue therapy for refractory intracranial hypertension. In general, these studies demonstrated that hypertonic saline solutions are effective in reducing ICP and usually improve cerebral perfusion pressure (CPP). Although authors of each of the studies noted that hypertonic saline has some theoretical advantages in comparison to mannitol, no convincing evidence demonstrated that hypertonic saline solutions are superior to mannitol. Moreover, because the designs of the studies varied so greatly and because the doses and compositions of the infused fluids were substantially different, no firm conclusions could be drawn.

Literature Review

Physiologic Effects

Hypertonic saline clearly reduces brain bulk and ICP. In a study in which patients undergoing elective craniotomy were randomly assigned to receive either 7.5% saline (1283 mEq/L) or 20% mannitol for reduction of brain bulk and lumbar cerebrospinal fluid pressure, Gemma et al³ found that the two regimens had equal efficacy (class II data). Munar et al⁴ (class II data) infused 1.5 mL/kg of 7.2% saline (1232 mEq/L) over 15 minutes in 14 patients aged 18 years with moderate or severe TBI. They demonstrated a significant reduction of ICP to 30% of baseline values without significant changes in mean arterial blood pressure or cerebral arteriovenous oxygen content difference. De Vivo et al⁵ (class II data) also reported equivalent reductions of ICP in neurosurgical patients receiving mannitol, 3% hypertonic saline, or a combination of the two.

Fisher et al6 randomized 18 head-injured children to receive 10 mL/kg of either 3% or 0.9% saline in a randomized crossover trial in which reduction of ICP was the primary end point (class II data). The hypertonic saline significantly reduced ICP in the majority of children, whereas 0.9% saline had no apparent effect. Suarez et al⁷ (class III data) used 30 mL of 23.4% saline as rescue therapy in eight patients with 20 episodes of intracranial hypertension refractory to hyperventilation, mannitol, and furosemide; several patients had also received cerebrospinal fluid drainage or barbiturate infusion. ICP decreased from a median of 41.5 mmHg to a median of 17 mmHg at 1 hour and 14 mmHg at 3 hours after administration of hypertonic saline; significant decreases persisted for more than 6 hours. Hartl et al⁸ (class II data) used a combination of 7.5% saline and 6% hydroxyethyl starch to treat six patients with refractory intracranial hypertension and reported that the average ICP decreased from 45±15 mmHg to 25±14 mmHg, although one of the six patients died of uncontrollable intracranial hypertension. Schatzmann et al⁹ (class III data) used 10% saline to treat increased ICP in 42 episodes of intracranial hypertension in six patients and achieved a median ICP reduction of 43%; the reduction persisted for a median duration of 93 minutes. Horn et al¹⁰ (class II data) demonstrated that 2.0 mL/kg of 7.5% saline effectively reduced ICP in 48 episodes of intracranial hypertension in 10 patients in whom ICP was increased secondary to TBI or subarachnoid hemorrhage. In eight stroke patients with 22 episodes of intracranial hypertension that did not respond to infusion of mannitol, Schwarz et al¹¹ (class II data) infused 75 mL of 10% saline and demonstrated prompt reduction of ICP that persisted throughout the 4-hour observation period. In a randomized, crossover study of nine stroke patients with 30 episodes of increased ICP, Schwarz et al¹² (class II data) infused either 100 mL of a combination of 7.5% saline and 6% hydroxyethyl starch or 200 mL of 20% mannitol and reported that the hypertonic saline/hydroxyethyl starch therapy seemed to reduce ICP at least as effectively as mannitol but was less effective at increasing CPP.