Effects of Sedation With Midazolam and Butorphanol on Resistive and Pulsatility Indices in Healthy Dogs

Abstract

Resistive index (RI) and pulsatility index (PI) are indirect measurements of blood flow resistance that may be measured by pulsed wave Doppler ultrasonography. Chemical restrain may potentially alter the indices although it is required to perform ultrasonography in some patients. The purpose of this study was to describe values for both intrarenal and ocular RI and PI within the same subject in clinically normal dogs sedated with a midazolam and butorphanol combination and evaluate if there are any significant changes between sedated and nonsedated dogs. Fifteen healthy Beagle dogs were studied by Duplex Doppler interrogation in interlobar or arcuate arteries of the kidney and long posterior ciliary artery. Pulse rate and systolic blood pressure were also determined. All measurements were recorded before and after the administration of a sedative combination of midazolam (0.2 mg/kg) and butorphanol (0.2 mg/kg). Mean comparison tests (paired t-tests or Wilcoxon's rank-sum test) were used to determine if any significant differences existed between right and left renal values or right and left ocular values. A correlation study (Pearson or Spearman) was applied between RI, PI, and systolic pressure, and pulse rate. RI and PI were significantly higher in sedated Beagles than in unsedated Beagles. There was neither correlation between index and systolic blood pressure nor pulse rate. In conclusion, provided that normal RI and PI increase in sedated animals, then reference ranges should be higher when sedated--healthy or ill--animals are evaluated.

The use of colour Doppler imaging to determine the effects of administration of butorphanol, medetomidine and ketamine on indices of feline ocular impedance

“…Lee et al (2002), Sindak et al (2003) and Novellas et al (2007b) reported that there were no significant differences in the RI values between the left and right eyes, or between male and female dogs of different breeds. The results of this present study support the findings of these authors, because we similarly did not find any significant differences in RI between left and right eyes or between male and female cats.…”

“…The effects of certain sedative protocols on Doppler variables of different canine ocular arteries has already been character- Novellas et al 2007b). Intramuscular administration of midazolam and butorphanol increases ocular blood flow resistance (Novellas et al 2007a).…”

Non-invasive blood pressure measurement in ferrets ( Mustela putorius furo ) using high definition oscillometry

“…In dogs, a similar decrease in BP has been observed during the first 20 min post-injection of a butorphanol-midazolam combination (Kojima et al, 1999), with intramuscular doses of 0.2 mg/kg each decreasing SAP by 15 mmHg (Novellas et al, 2007). Since we could not measure NIBP in unsedated ferrets, it was not possible to determine whether midazolam and butorphanol affected BP at the dosages used in our study.…”

Midazolam in rabbits terminates dysrhythmias caused by intracerebroventricular ropivacaine

“…Several studies (Greenblatt et al, 1992;Kanaya et al, 1998) have suggested that isoflurane modifies responses to endotheliumdependent vasodilators and peripheral vascular resistance, which leads to the decrease of artery blood pressure. Experiments (Wiktorowska et al, 1999;Novellas et al, 2007) have shown that iv midazolam caused a gradual fall of artery blood pressure. In Ahmad et al (2000)'s study, two groups of piglets (1-3 d old, 1.0-1.5 kg) received either (1) a loading dose of 300 μg/kg of midazolam over 15 min, followed by a continuous intravenous infusion of 100 μg/(kg·h) (n=6), or (2) equivalent volume bolus and intravenous infusions of 0.05 g/ml dextrose (control, n=8).…”