Sodium plays a critical role in surgical physiology, influencing fluid balance, blood pressure stability, electrolyte regulation, and immune modulation. During surgery, shifts in fluid status and hormonal responses can place patients at risk for hyponatremia, hypotension, and inflammatory dysregulation. Sodium helps maintain extracellular volume and activates the renin-angiotensin-aldosterone system (RAAS), which is essential in supporting vascular tone, fluid retention, and potassium excretion under surgical stress. It also modulates immune cell activity in the interstitial space, balancing pro- and anti-inflammatory signaling.

Mechanisms of Action and Benefits

Fluid and Electrolyte Balance
Sodium is the primary extracellular cation and is essential for maintaining plasma osmolality, intravascular volume, and blood pressure stability. It prevents hyponatremia and supports tissue perfusion, particularly important during fluid shifts caused by anesthesia or blood loss [2,3].

RAAS Activation and Surgical Stress Response
The renin-angiotensin-aldosterone system (RAAS) is activated under surgical stress. Sodium intake influences aldosterone-mediated sodium reabsorption and potassium excretion, helping preserve vascular volume and stabilize blood pressure during and after surgery [1].

Immune Modulation in the Interstitial Environment
Sodium affects immune signaling by modulating T-cell polarization and macrophage activation. These effects can enhance immune defense but must be balanced, as excessive sodium may exacerbate pro-inflammatory cytokine expression [2].

Inflammatory Control and Perfusion Support
By supporting circulatory volume and tissue hydration, sodium indirectly reduces inflammatory signaling and supports oxygen and nutrient delivery to healing tissues. Adequate sodium availability may help reduce the risk of postoperative complications tied to poor perfusion or immune dysregulation [1,3].

References:

1. Engquist A, Blichert-Toft M, Olgaard K, Brandt MR, Kehlet H. Inhibition of aldosterone response to surgery by saline administration. Br J Surg. 1978;65(4):224-227.
2. Strazzullo P, Leclercq C. Sodium. Adv Nutr. 2014;5(2):188-190. Published 2014 March 1.
3. https://www.msdmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/overview-of-sodium-s-role-in-the-body accessed November 2024