Effects of flunixin meglumine on blood pressure and fluid compartment volume changes in ponies given endotoxin.

This research explores how endotoxin-induced shock affects fluid shifts in ponies, and if flunixin meglumine, a nonsteroidal anti-inflammatory drug (NSAID), influences these changes. It was found that flunixin meglumine treatment seemed to attenuate some of the endotoxin-induced alterations in body fluid compartments and helped maintain normal blood volume.

Experiment Overview

• The study included 12 ponies, half of which were administered flunixin meglumine (1.1 mg/kg of body weight) one minute before intravenously injecting Escherichia coli endotoxin (100 micrograms/kg of body weight, LD100), which is lethal in 100% of cases if untreated.
• Total blood, red blood cell (RBC), and plasma volumes were measured with the use of 51Cr-labeled RBC and packed cell volume (PCV) methods, corrected for any trapped plasma.
• Arterial blood pressure was recorded directly with a blood pressure transducer.
• Total body water was estimated by the distribution of tritiated water (3HOH).

Findings and Observations

• In both treated and control ponies, PCV and RBC volume increased after endotoxin administration. This increase was believed to be due to splenic contraction leading to an increase in circulating RBC. However, the elevation was less in ponies treated with flunixin meglumine.
• In ponies not treated with flunixin meglumine, total blood volume and plasma volume significantly decreased in the first hour after endotoxin injection. The loss of plasma into the interstitial space further increased hemoconcentration.
• In treated ponies, total blood volume remained fairly stable, and plasma volume saw only a slight decrease.
• The administration of flunixin meglumine appeared to reduce plasma loss, thus limiting hemoconcentration and ensuring blood volume remained normal.
• Overall, total body water remained constant in both treated and non-treated ponies after endotoxin administration.

Interpretation and Implications

• The study shows that endotoxin-induced shock can lead to significant shifts in the body fluid compartments of ponies. This effect appears to be reduced with the administration of flunixin meglumine.
• The minimization of these fluid shifts could have a significant impact on the treatment of endotoxin-induced shock, potentially reducing the severity of this condition and increasing survival chances.
• This research could inform the treatment strategies for conditions involving body fluid shifts not only in ponies but potentially in other species too.