Hypervolemic States

Etiology:

• Increased total body Na+

  • Primary d/o

  • Decreased effective circulating volume:

    • CHF

    • Cirrhosis

    • Profound hypoalbuminemia

Dx:

• Expansion of interstitial compartment = edema, effusions

• Expansion of intravascular compartment = lung crackles, JVD, HJR, S3 gallop, elevated BP.

  • Overt si of hypervolemia may not manifest until 2 - 4 L of fluid retention.

    • Gradual rise in wt. is the earliest indication of Na+ retention.

• Sx: dyspnea, orthopnea, abdominal distension, swelling of extremities.

• Labs: Hypervolemia is a clinical diagnosis

  • Urine Na <15 mEq/L with decreased effective circulating volume, reflecting renal Na+ retention.

• Imaging: CXR may show pulmonary edema or pleural effusions, but clear lung fluids do not exclude volume overload.

Tx:

• • Tx underlying causes.

  • Correct ECF volume excess

    • diuretics enhance renal excretion of Na+ by blocking the various sites of Na+ reabsorption along the nephron.

      • THZ block NaCl transporters in the DCT.

        • Impair urine dilution capacity and often stimulate a responsive increase in the proximal tubule reabsorption.

      • Loop diuretics block Na-K-2Cl cotransporter in the ascending loop of Henle.

        • Brisk and immediate diuresis in acute vol overload.

        • Also enhance Ca++, and Mg++ excretion.

        • Impair urinary concentration, by increasing renal free water excretion.

      • K+ sparing diuretics act by decreasing Na reabsorption in the collecting duct.

        • Aldosterone antagonist do not require tubular secretion, and useful in low renal perfusion or impaired tubular function.

    • Limit Na+ intake.

  • Water restriction

    • if (Urine Na + Urine K)/Sr. Na, <0.5, restrict to 1 L/day

    • if (Urine Na + Urine K)/Sr. Na is 0.5 - 1, restrict to 500 mL/day

    • if (Urine Na + Urine K)/Sr. Na is >1, the Pt has negative renal free water clearance and is actively reabsorbing water.