University of Colombo NHSL / Clinical Applications and Management of Hypertonic Fluids in Hyponatremia and Increased Intracranial Pressure, June 2008. 1 Clinical Applications and Management of Hypertonic Fluids in Hyponatremia and Increased Intracranial Pressure Indunil Karunarathna 1 , T Hapuarachchi 1 , Asoka Jayawardana 1 , Sau Bandara 1 1. University Of Colombo / NHSL Colombo, Sri Lanka. Abstract: Hypertonic fluids, including hypertonic saline and mannitol, are essential in the management of hyponatremia and increased intracranial pressure (ICP). This review discusses the indications, mechanisms of action, administration protocols, monitoring requirements, adverse effects, and contraindications associated with these treatments. Hypertonic saline is FDA-approved for hyponatremia and ICP and works by increasing blood osmolarity, thereby reducing brain edema and improving cerebral blood flow. Mannitol, primarily used for ICP and intraocular pressure reduction, acts by inducing diuresis through increased glomerular filtrate osmolarity. Proper administration requires careful monitoring of fluid and electrolyte balance, particularly serum sodium and potassium levels. An interprofessional team approach ensures optimal patient outcomes through comprehensive monitoring and timely intervention. Despite their proven efficacy, further research is necessary to expand the understanding of hypertonic fluids, particularly in pre-hospital settings. Keywords: Hypertonic fluids, Hypertonic saline, Mannitol, Hyponatremia, Increased intracranial pressure (ICP), Fluid management, Electrolyte monitoring, Interprofessional team, Osmotic gradient, Diuresis, Critical care, Neurocritical care Key Points Indications: Hypertonic saline is FDA-approved for treating hyponatremia and increased intracranial pressure (ICP). Mannitol is FDA-approved for reducing ICP and intraocular pressure. Mechanism of Action: Hypertonic fluids create an osmotic gradient, drawing fluid from the interstitial space into the intravascular space, enhancing mean arterial pressure, stroke volume, and cardiac output. Hypertonic saline stimulates vasopressin release, reducing renal water loss. Mannitol increases the osmolarity of the glomerular filtrate, inducing diuresis. Administration: Hypertonic saline: 100 mL boluses of 3% HS for severe hyponatremia, pediatric treatment with 6.5 to 10 mL/kg bolus. Mannitol: 0.25 to 2 g/kg body weight over 30 minutes to 1 hour for ICP and intraocular pressure reduction. Monitoring: Continuous monitoring of fluid and electrolytes, especially serum sodium and potassium. Evaluate renal and circulatory function before and during mannitol treatment. Measure cerebrospinal fluid (CSF) pressure within fifteen minutes of mannitol administration for ICP. Adverse Effects: Hypertonic saline: Hyperchloremic metabolic acidosis, hypernatremia, osmotic demyelination syndrome, and administration-related complications such as infection, thrombophlebitis, and hypervolemia. Mannitol: Pulmonary congestion, electrolyte abnormalities, dehydration, headache, and injection site reactions. Contraindications: Hypertonic saline: Caution in patients with congestive heart failure or renal insufficiency. Mannitol: Established anuria, pulmonary congestion, active internal bleeding, severe dehydration, hypersensitivity to mannitol. Interprofessional Team Approach: Involves clinicians, nurses, and pharmacists. Essential for comprehensive monitoring, timely intervention, and optimal patient outcomes. Research Needs: Further studies are needed to better understand the applications of hypertonic fluids, particularly in pre-hospital settings for hypovolemia and shock. Introduction Hypertonic fluids, such as hypertonic saline and mannitol, play a crucial role in various clinical scenarios, including