Effect of a Standardized Sedation Protocol on Portal Vein Velocity Measurements in Hospitalized Dogs Using Triplex-Doppler Ultrasonography.

Abstract

Portal vein velocity (PVV) is a useful indirect indicator of portal pressure. Reference values for PVV have been previously established in healthy, non-sedated dogs with reported ranges of 14.7&#xa0;&#xb1;&#xa0;2.5 and 18.1&#xa0;&#xb1;&#xa0;7.6&#xa0;cm/s. PVV may be influenced by physiological and pathological factors; for example, a correlation between body weight and PVV has been documented; however, the effect of other factors is unknown. The primary aims of this prospective comparative study were to investigate the effect of standardized intravenous sedation protocol of medetomidine (2-3&#xa0;&#xb5;g/kg) and butorphanol (0.3&#xa0;mg/kg) on PVV and to determine whether post-sedation PVV results would fall below the portal hypertension threshold of 10&#xa0;cm/s. Six triplex-Doppler PVV measurements were obtained pre- and post-sedation on 15 client-owned dogs undergoing abdominal ultrasonography for conditions unrelated to primary liver disease. The mean PVV pre-sedation was 14.9&#xa0;&#xb1;&#xa0;3.98&#xa0;cm/s and 3-min post-sedation was 10.4&#xa0;&#xb1;&#xa0;3.73&#xa0;cm/s, representing a statistically significant reduction in PVV (p&#xa0;<&#xa0;0.001). The mean PVV was below 10&#xa0;cm/s in 3/15 (20%) dogs pre-sedation and below 10&#xa0;cm/s in 9/15 (60%) dogs post-sedation. There was no effect of age, sex, or weight on PVV before and/or after sedation. Sedation with medetomidine and butorphanol caused a significant reduction in PVV at 3-min post-administration. This finding should be considered when evaluating hepatic and portal hemodynamics in dogs, as 60% (9/15) of the sedated cases with presumed normal hepatic function exhibited post-sedation PVV at levels seen with portal hypertension.