Sodium Imbalance Issues in the PICU Tarek Hazwani, MD Assistant Consultant Pediatric Intensivist King Abdulaziz Medical City

‫بسم هللا السحمه السحيم‬ Estimated time : 30 min 40 slides We aim by this presentation to provide the foundation for an understanding of the pathophysiologic , diagnosis, management of sodium disturbances

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Brief physiology Hyponatremia CSW SIADH Hypernatremia DI

Brief physiology • When fluid is delivered to the tubules, solute absorption varies depending upon the segment: • The proximal tubule accounts for 65% of filtrate reabsorption, including that of Na+, K+, and water. • The descending thin limb of the loop of Henle is permeable to water, urea, and other solutes • the ascending thin limb is relatively impermeable to water. • The thick ascending limb and the initial segment of the distal tubule avidly absorb Na+ and other solutes but are impermeable to water

Brief physiology • Strict regulation of body water is critical for preserving ECF osmolality within a narrow range(280-290 mOsm/kg H2O). • Cell membranes are freely water permeable. As a result, when a concentration gradient develops between ECF and ICF, water passively moves from the compartment with the lower to the higher gradient, thus restoring equilibrium.

‫األطفال األشقياء هم فقط أطفال الغيس‬

Sodium • Sodium and its attendant anions are the primary contributors to extracellular fluid (ECF) tonicity. An excessive increase or decline in the plasma sodium concentration leads to osmotically driven water gradient across the cell membrane

Hyponatremia

• Hyponatremia is defined as a serum Na+ of