Hemodynamic effects of medetomidine in the dog: A dose titration study

Bruno H Pypendop, John P. Verstegen

Research output: Contribution to journalArticle

210 Citations (Scopus)

Abstract

Objective - To characterize the hemodynamic effects of medetomidine administered intravenously at doses ranging from 1 to 20 μg/kg, and to determine whether these effects are dose dependent. Study Design - Prospective randomized multidose trial. Animals - Twenty-five clinically normal male beagles (5 groups of 5), aged 1 to 4 years and weighing 13.5 ± 1.7 kg. Methods - Medetomidine, at a dose of 1, 2, 5, 10, or 20 μg/kg, was administered intravenously at time 0. Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and packed cell volume were measured immediately before and at selected times after medetomidine administration (3, 7, 10, 20, 30, 40, 50, and 60 minutes in all groups, at 90 minutes for the 10 and 20 μg/kg groups, and at 120 minutes for the highest dose). Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, and left and right ventricular stroke work indices were calculated. The degree of sedation was subjectively scored by an observer who was blinded to the treatment used. Results - Heart rate, rate-pressure product, cardiac index, and left and right ventricular stroke work indices decreased below baseline values. Central venous pressure and systemic vascular resistance index increased above baseline measurements. Except in the 2 μg/kg group, after an initial and short lasting increase, a prolonged decrease in arterial pressure was observed. Conclusions - Hemodynamic changes were observed with the intravenous (IV) administration of medetomidine, at any dose. However, the two lowest doses (1 and 2 μg/kg) produced less cardiovascular depression. Clinical Relevance - Medetomidine is an alpha-2 adrenoceptor agonist widely used in dogs, producing sedation, analgesia and cardiovascular depression. When using IV medetomidine, a reduction of the recommended dosage (ie, ±30 to 40 μg/kg) by up to 6 times did not significantly influence the cardiovascular effects.

Original languageEnglish (US)
Pages (from-to)612-622
Number of pages11
JournalVeterinary Surgery
Volume27
Issue number6
StatePublished - Nov 1998
Externally publishedYes

Fingerprint

Medetomidine
medetomidine
hemodynamics
titration
Hemodynamics
Dogs
dogs
dosage
Vascular Resistance
Arterial Pressure
Central Venous Pressure
Stroke
stroke
blood vessels
lungs
sedation
Heart Rate
Pressure
heart rate
Pulmonary Wedge Pressure

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Hemodynamic effects of medetomidine in the dog : A dose titration study. / Pypendop, Bruno H; Verstegen, John P.

In: Veterinary Surgery, Vol. 27, No. 6, 11.1998, p. 612-622.

Research output: Contribution to journalArticle

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abstract = "Objective - To characterize the hemodynamic effects of medetomidine administered intravenously at doses ranging from 1 to 20 μg/kg, and to determine whether these effects are dose dependent. Study Design - Prospective randomized multidose trial. Animals - Twenty-five clinically normal male beagles (5 groups of 5), aged 1 to 4 years and weighing 13.5 ± 1.7 kg. Methods - Medetomidine, at a dose of 1, 2, 5, 10, or 20 μg/kg, was administered intravenously at time 0. Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and packed cell volume were measured immediately before and at selected times after medetomidine administration (3, 7, 10, 20, 30, 40, 50, and 60 minutes in all groups, at 90 minutes for the 10 and 20 μg/kg groups, and at 120 minutes for the highest dose). Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, and left and right ventricular stroke work indices were calculated. The degree of sedation was subjectively scored by an observer who was blinded to the treatment used. Results - Heart rate, rate-pressure product, cardiac index, and left and right ventricular stroke work indices decreased below baseline values. Central venous pressure and systemic vascular resistance index increased above baseline measurements. Except in the 2 μg/kg group, after an initial and short lasting increase, a prolonged decrease in arterial pressure was observed. Conclusions - Hemodynamic changes were observed with the intravenous (IV) administration of medetomidine, at any dose. However, the two lowest doses (1 and 2 μg/kg) produced less cardiovascular depression. Clinical Relevance - Medetomidine is an alpha-2 adrenoceptor agonist widely used in dogs, producing sedation, analgesia and cardiovascular depression. When using IV medetomidine, a reduction of the recommended dosage (ie, ±30 to 40 μg/kg) by up to 6 times did not significantly influence the cardiovascular effects.",
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