Change in circulating blood volume following craniotomy

Area of Science:

• Neurosurgery
• Critical Care Medicine
• Physiology

Background:

• Perioperative management of critically ill patients requires monitoring of circulating blood volume (CBV).
• Craniotomy is a significant surgical stressor impacting fluid regulation.

Purpose of the Study:

• To investigate changes in CBV after craniotomy using indocyanine-green pulse spectrophotometry.
• To correlate CBV changes with stress hormones and fluid balance.

Main Methods:

• CBV and plasma hormones were measured in 17 patients undergoing craniotomy (preoperatively, and 1, 2, 7 days postoperatively).
• Indocyanine-green pulse spectrophotometry was used for CBV assessment.
• Mean intraoperative water and sodium balances were recorded.

Main Results:

• CBV decreased from 82 ml/kg preoperatively to 64 ml/kg (78%) immediately postoperatively, gradually recovering by Day 7.
• Stress hormones (adrenaline, noradrenaline, etc.) peaked immediately postoperatively.
• CBV showed significant negative correlation with noradrenaline and positive correlation with serum sodium.

Conclusions:

• Craniotomy causes a significant decrease in CBV due to fluid shift into interstitial spaces from surgical stress.
• Postoperative hypovolemia should be suspected with a decrease in serum sodium.
• Close monitoring of CBV is essential in patients undergoing craniotomy.