Pressure profile in the caudal extradural space of standing horses before and after extradural drug administration.

The research investigates the pressure levels in a horse’s caudal extradural space before and after the administration of an extradural drug, with the aim of establishing if change in pressure can be a reliable tool for confirming correct needle placement. Findings indicate that pressure in most horses was below atmospheric levels and that injection of the drug majorly increased this pressure for approximately 10 minutes. However, pressure wave occurrence was inconsistent, hence deemed of limited usefulness in affirming correct needle placement.

Introduction and Objectives

• The study had a two-fold objective – primarily, it aimed to measure the pressure in the caudal extradural space of standing horses; secondly, it aimed to assess the reliability of pressure waves in identifying the correct needle placement during extradural drug administration.

Methods

• The study involved twelve healthy horses. In each horse, caudal extradural pressure was measured at different stages – after puncture, after testing for lack of resistance (LOR), immediately after injection of lidocaine, and ten minutes post-injection.
• Pressure readings and any extradural pressure waves were logged and recorded for future evaluation.

Findings

• All extradural drug administrations were confirmed successful.
• The collected data revealed a varying pressure profile at different stages of drug administration. Immediately after injection, the median extradural pressure increased significantly, but reduced to nearly initial levels 10 minutes post-injection.
• Most horses had sub-atmospheric extradural space pressure before the injection. The process of injection raised this pressure significantly, with the increased pressure persisting for up to ten minutes after injection.
• Extradural pressure waves, conversely, showed fluctuating occurrence and did not always show up as expected.

Conclusion

• The findings from the study conclude that extradural pressure waves are of limited usefulness in confirming the correct placement of the needle for extradural drug administration.