Plasma colloid osmotic pressure and total protein trends in horses during anesthesia.

The research investigates the effects of routine general anesthesia on the colloid osmotic pressure (COP) and total protein (TP) concentrations in horses. The study shows that both COP and TP decrease progressively during anesthesia.

Methodology

• The study involved two groups of adult healthy horses – a group of twelve horses that were going through elective surgery and the other group of 14 horses under routine check.
• All horses received premedication with xylazine, and anesthesia was induced using a cocktail of ketamine, diazepam, and guaifenesin.
• The anesthesia was maintained by isoflurane for 2.5 hours, during which Lactate Ringer’s solution was administered at 11 mL kg(-1) hour(-1).
• A variety of parameters were measured with commercial analyzers – such as osmolality, COP, electrolytes, glucose, and lactate.
• TP was determined using a refractometer, and packed cell volume was determined using centrifuged capillary tubes.
• In the second group of 14 horses, samples were taken from both venous and arterial sites and the measurement of the above parameters were performed.

Results and Conclusion

• The results indicated that both COP and TP reduced significantly within the first 15 minutes of anesthetic induction (from initial values of around 22.2 +/- 2 mmHg for COP and 6.9 +/- 0.4 g dL(-1) for TP).
• The decrease in both COP and TP continued in a linear pattern throughout the procedure.
• By the end of the anesthesia, the average COP was valued at 15 +/- 1.3 mmHg and TP at 5.1 +/- 0.2 g dL(-1).
• An attempt to calculate COP from TP values did not provide accurate results, emphasizing the necessary independent measurement of each parameter.
• Moreover, the study found that neither the COP nor TP varied with the site of blood sampling (arterial or venous) in anesthetized horses.
• This study concluded that like TP, COP also decreases over the course of routine anesthetic management of horses, regardless of the site of sampling.