extravascular fluid (3rd space)

Introduction

Extracellular fluid outside of the vascular compartment.

Sequestration of fluid in this compartment may occur. The fluid is effectively lost from the vascular compartment & hypovolemia can result despite the fluid in this 3rd space.

Examples of extravascular fluid include:

• peritoneal cavity (hepatic cirrhosis, peritonitis)
• retroperitoneal space (acute pancreatitis)
• subcutaneous tissues (burns)
• bowel lumen (intestinal obstruction)
• pleural space (pleural effusion)