Advertisement

Effect of a 30-minute infusion of dobutamine hydrochloride on hind limb blood flow and hemodynamics in halothane-anesthetized horses

Anthea L. RaisisCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.

Search for other papers by Anthea L. Raisis in
Current site
Google Scholar
PubMed
Close
 PhD
,
Lesley E. YoungCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.

Search for other papers by Lesley E. Young in
Current site
Google Scholar
PubMed
Close
 PhD
,
Karen J. BlissittCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.
Present address is the Department of Veterinary Clinical Studies, Royal School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, UK.

Search for other papers by Karen J. Blissitt in
Current site
Google Scholar
PubMed
Close
 PhD
,
Karen WalshCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.

Search for other papers by Karen Walsh in
Current site
Google Scholar
PubMed
Close
 BVSc
,
Hylton B. MeireCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.
Present address is the Department of Radiology, Kings College Hospital, Denmark Hill, London, SE5 9RS, UK.

Search for other papers by Hylton B. Meire in
Current site
Google Scholar
PubMed
Close
 PhD
,
Polly M. TaylorCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.
Present address is the Department of Clinical Veterinary Medicine, School of Veterinary Medicine, University of Cambridge, Madingley Rd, Cambridge, CB3 0ES, UK.

Search for other papers by Polly M. Taylor in
Current site
Google Scholar
PubMed
Close
 PhD
, and
Pierre LekeuxCentre for Equine Studies, Animal Health Trust, PO Box 5, Newmarket, Suffolk, CB8 8JH, UK.

Search for other papers by Pierre Lekeux in
Current site
Google Scholar
PubMed
Close
 PhD

Abstract

Objective—To evaluate the hemodynamic effects of dobutamine hydrochloride (0.5 µg/kg of body weight/min) in halothane-anesthetized horses.

Animals—6 adult Thoroughbred horses.

Procedure—Anesthesia was induced by use of romifidine (100 µg/kg) and ketamine (2.2 mg/kg), IV. Anesthesia was maintained by halothane (end-tidal concentration 0.9 to 1.0%). Aortic, left ventricular, and right atrial pressures were measured, using cathetermounted strain gauge transducers. Cardiac output (CO), velocity time integral, maximal aortic blood flow velocity and acceleration, and left ventricular preejection period and ejection time were measured from aortic velocity waveforms obtained by transesophageal Doppler echocardiography. Velocity waveforms were recorded from the femoral vessels, using Doppler ultrasonography. The time-averaged mean velocity and early diastolic deceleration slope (EDDS) were measured. Pulsatility index (PI) and volumetric flow were calculated. Microvascular perfusion was measured in the semimembranosus muscles by laser Doppler flowmetry. Data were recorded 60 minutes after induction of anesthesia (control) and at 15 and 30 minutes after start of an infusion of dobutamine (0.5 µg/kg/min).

Results—Aortic pressures were significantly increased during the infusion of dobutamine. No change was observed in the indices of left ventricular systolic function including CO. Femoral arterial flow significantly increased, and the PI and EDDS decreased. No change was observed in the femoral venous flow or in microvascular perfusion.

Conclusions and Clinical Relevance—At this dosage, dobutamine did not alter left ventricular systolic function. Femoral blood flow was preferentially increased as the result of local vasodilatation. The lack of effect of dobutamine on microvascular perfusion suggests that increased femoral flow is not necessarily associated with improved perfusion of skeletal muscles. (Am J Vet Res 2000;61:1282–1288)

Abstract

Objective—To evaluate the hemodynamic effects of dobutamine hydrochloride (0.5 µg/kg of body weight/min) in halothane-anesthetized horses.

Animals—6 adult Thoroughbred horses.

Procedure—Anesthesia was induced by use of romifidine (100 µg/kg) and ketamine (2.2 mg/kg), IV. Anesthesia was maintained by halothane (end-tidal concentration 0.9 to 1.0%). Aortic, left ventricular, and right atrial pressures were measured, using cathetermounted strain gauge transducers. Cardiac output (CO), velocity time integral, maximal aortic blood flow velocity and acceleration, and left ventricular preejection period and ejection time were measured from aortic velocity waveforms obtained by transesophageal Doppler echocardiography. Velocity waveforms were recorded from the femoral vessels, using Doppler ultrasonography. The time-averaged mean velocity and early diastolic deceleration slope (EDDS) were measured. Pulsatility index (PI) and volumetric flow were calculated. Microvascular perfusion was measured in the semimembranosus muscles by laser Doppler flowmetry. Data were recorded 60 minutes after induction of anesthesia (control) and at 15 and 30 minutes after start of an infusion of dobutamine (0.5 µg/kg/min).

Results—Aortic pressures were significantly increased during the infusion of dobutamine. No change was observed in the indices of left ventricular systolic function including CO. Femoral arterial flow significantly increased, and the PI and EDDS decreased. No change was observed in the femoral venous flow or in microvascular perfusion.

Conclusions and Clinical Relevance—At this dosage, dobutamine did not alter left ventricular systolic function. Femoral blood flow was preferentially increased as the result of local vasodilatation. The lack of effect of dobutamine on microvascular perfusion suggests that increased femoral flow is not necessarily associated with improved perfusion of skeletal muscles. (Am J Vet Res 2000;61:1282–1288)