Interstitial

Definition

Interstitial refers to the extracellular space between cells and tissues. Interstitial fluid comprises most of the extracellular fluid volume and exchanges nutrients and waste with blood.

Clinical Relevance

• Edema results from excess interstitial fluid
• Third-spacing: fluid shifts into interstitial spaces or body cavities, causing intravascular depletion (burns, sepsis, surgery)
• Interstitial lung disease: fibrosis of the interstitial space impairs gas exchange
• Interstitial cystitis: painful bladder condition

Nursing Considerations

Monitor for edema and hypovolemia (third-spacing). Assess lung sounds, daily weights, I&O. Replace lost intravascular volume while treating underlying cause, for interstitial lung disease, provide oxygen support, pulmonary rehab.

NCLEX Relevance

Third-spacing: patient may be hypovolemic despite fluid overload elsewhere.