Correct occlusive bladder width for indirect blood pressure measurement in horses.

This research article investigates how the width of an occlusive bladder can affect the accuracy of indirectly measuring a horse’s blood pressure, using a doppler ultrasound technique at the middle coccygeal (tailbone) artery. The study determines the best ratio between the bladder width and tail girth for accurate systolic and diastolic pressure readings in horses.

Study Participants and Method

• The study involved six horses that were anesthetized for uniformly conducted measurements.
• The blood pressure of the horses was measured indirectly via the middle coccygeal artery using a doppler ultrasound technique with varying occlusive bladder widths.
• The research uncovered the influence of occlusive bladder width on these blood pressure measurements and the ideal bladder width to tail girth ratio.

Bladder Width to Tail Girth Ratio

• The relationship between bladder width (BW) and tail girth (TG) was investigated both on hairy and hairless tails. The data was grouped into three categories:
  • Unclipped tails (TT-1)
  • Clipped tails (TT-2)
  • A collective group of unclipped and clipped tails (TTB)
• The optimal BW/TG ratios were identified to be:
  • 0.296 (systolic pressure) and 0.866 (diastolic pressure) for TT-1
  • 0.376 (systolic pressure) and 1.156 (diastolic pressure) for TT-2
  • 0.339 (systolic pressure) and 0.983 (diastolic pressure) for TTB
• Despite the variations in ratio between TT-1 and TT-2, the correlation did not have significant differences, justifying the classification of the data under TTB.

Effects of BW/TG ratio on Blood Pressure Measurement

• The data revealed that a ratio of 0.482 between bladder width and tail girth would cause an underestimation of systolic pressure (SP) and overestimation of diastolic pressure (DP) by approximately 8.8%.
• In Thoroughbred horses with an average tail girth of 21.5 cm, this ratio would correspond to a bladder width of 10.4 cm.

Comparison of Direct and Indirect Blood Pressure Measurements

• Direct blood pressure measurements from the greater metatarsal artery were significantly different from those measured indirectly in the middle coccygeal artery in individual horses.
• However, when averaged, there was no statistically significant differences between the two measurement methods, demonstrating that the indirect measurement method is generally reliable across populations.