Related Experiment Videos
The blood volume and the renin-angiotensin-aldosterone system following open-heart surgery
Insights
Open-heart surgery impacts blood volume, with fluid shifting from vessels to tissues. Cardiopulmonary bypass significantly alters aldosterone and plasma renin activity post-surgery.
Area of Science:
- Cardiovascular Surgery
- Endocrinology
- Physiology
Background:
- Postoperative fluid shifts are common after cardiac surgery.
- Understanding hormonal responses is crucial for patient management.
Purpose of the Study:
- To compare circulating blood volume, electrolytes, aldosterone, and plasma renin activity (PRA) in patients undergoing open-heart surgery with and without cardiopulmonary bypass (CPB).
Main Methods:
- Studied 14 patients with CPB and 14 without.
- Monitored circulating blood volume, plasma electrolytes, aldosterone, and PRA.
- Analyzed changes in the postoperative period.
Main Results:
- Both groups showed a decrease in circulating blood volume despite positive fluid balance, indicating fluid extravasation.
- The CPB group exhibited increased plasma aldosterone post-operation, peaking on day one.
- The non-CPB group showed a decrease in aldosterone, reaching lowest levels on day three.
- Postoperative PRA changes mirrored aldosterone levels in both groups.
Conclusions:
- Fluid shifts from vascular to extravascular spaces occur post-cardiac surgery.
- The renin-angiotensin-aldosterone system activation likely drives observed aldosterone level changes after surgery.
Abstract:
The circulating blood volume changes, plasma electrolytes, aldosterone as well as plasma-renin-activity (PRA) were studied in 14 patients following open-heart surgery with cardiopulmonary bypass (CPB) and in 14 patients following cardiac surgery without CPB. In both the groups a postoperative decrease of circulating blood volume was observed. This decrease occurred in spite of the positive fluid balance, and so a shift of fluid from vascular to extravascular compartment was likely. In the bypass group the plasma aldoserone level rose immediately after the operation and reached the peak on the first postoperative day. In the non-bypass group the aldosterone level started to fall after the operation, and reached the lowest level on the third postoperative day. The pattern of the postoperative PRA changes was almost identical with the aldosterone level changes in both the groups studied, which suggests that the activation of renin-angiotensin-aldosterone axis might be responsible for the observed plasma aldosterone changes.