Dobutamine improves haemodynamics and oxygen delivery in standing and isoflurane-anaesthetised horses.
Authors: Gorenberg, Slack, Stefanovski, Theiss, Hopster
Journal: Equine veterinary journal
Summary
# Editorial Summary Dobutamine remains standard practice for managing hypotension during equine anaesthesia, yet robust data comparing its effects across conscious and anaesthetised states have been lacking. Gorenberg and colleagues conducted a randomised cross-over study in six healthy horses, measuring haemodynamic variables (heart rate, mean arterial pressure, cardiac output) and oxygen delivery parameters at baseline and during dobutamine infusions of 0.5, 1, and 2 mcg/kg/min in both standing and isoflurane-anaesthetised conditions. Mean arterial pressure increased significantly in both groups—from 92 ± 8 mmHg to 119 ± 8 mmHg in standing horses and from 58 ± 12 mmHg to 91 ± 16 mmHg under anaesthesia—whilst cardiac output rose substantially (standing: 39 to 68 L/min; anaesthetised: 21 to 38 L/min), demonstrating dose-dependent improvements in oxygen delivery that accompanied a decrease in oxygen extraction ratio and right-to-left shunting in anaesthetised animals. The finding that 2 mcg/kg/min dobutamine restores standing baseline haemodynamics in anaesthetised horses provides clinicians with quantifiable dosing guidance for maintaining tissue perfusion during surgery, though the lateral recumbency model and small sample size warrant cautious extrapolation to other positions and larger populations.
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Practical Takeaways
- •Dobutamine effectively restores blood pressure and cardiac output in both standing and anaesthetised horses, supporting its use as first-line therapy for intraoperative hypotension
- •A dosage of 2 mcg/kg/min appears optimal for anaesthetised horses to restore haemodynamic parameters approaching awake baseline values
- •Improved oxygen delivery with dobutamine infusion suggests enhanced tissue perfusion, which is critical during general anaesthesia when horses are at risk of hypotensive complications
Key Findings
- •Dobutamine increased MAP dose-dependently in both standing (92±8 to 119±8 mmHg) and anaesthetised horses (58±12 to 91±16 mmHg, p<0.001)
- •Cardiac output increased significantly with dobutamine infusion in standing horses (39±5 to 68±5 L/min) and anaesthetised horses (21±2 to 38±3 L/min, p<0.001)
- •Oxygen delivery improved significantly in both groups with dobutamine infusion (p<0.001), while oxygen extraction ratio decreased (p<0.001)
- •Dobutamine 2 mcg/kg/min achieved standing baseline MAP and CO values in anaesthetised horses