The Effect of Differing Rates and Injection Sites on the Amount of Protamine Delivered Before Detection of Hemodynamic Alterations in Dogs

• Published in: Veterinary surgery 2000-09, Vol.29 (5), p.442-448
• Main Authors: Morgan, M.R., Monnet, E., Gaynor, J.S.
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Blood Loss, Surgical - prevention & control; Blood Loss, Surgical - veterinary; Cardiotonic Agents - administration & dosage; Cardiotonic Agents - blood; Cardiotonic Agents - toxicity; Coronary Artery Bypass - veterinary; Dobutamine - administration & dosage; Dobutamine - blood; Dobutamine - toxicity; Dogs - physiology; Dogs - surgery; Drug Administration Schedule - veterinary; Female; Hemodynamics - drug effects; Heparin Antagonists - administration & dosage; Heparin Antagonists - blood; Heparin Antagonists - toxicity; Male; Prospective Studies; Random Allocation
• ISSN: 0161-3499; 1532-950X
• DOI: 10.1053/jvet.2000.9136

Objectives— To determine the effect of the route and rate of protamine administration on the amount of protamine that could be delivered before a hemodynamic reaction occurred in dogs. Study design— Prospective randomized experimental study. Animals— Twenty adult mixed‐breed dogs weighing 25.1 ± 2.5 kg. Methods— Before vascular surgery, the dogs were heparinized to reach an activated clotting time (ACT) of 300 seconds. After completion of the vascular surgery, protamine was administered intravenously until a hemodynamic reaction was recorded. The 4 groups of dogs were given protamine at 5 mg/min (slow) or 10 mg/min (fast) via the cephalic or the jugular veins. Systemic and pulmonary arterial pressures, central venous pressure (CVP), and pulmonary arterial occlusion pressure (PAOP) were recorded before and after protamine administration. The dose of protamine was recorded when a reaction occurred, which was defined as mean arterial pressure (MAP) 20 mm Hg or more than double the baseline value. Results— Significant decreases in systolic arterial pressure (SAP), MAP, and diastolic arterial pressure (DAP) and significant increases in systolic (SPAP), mean (MPAP), and diastolic (DPAP) pulmonary arterial pressures were recorded after protamine administration. The cephalic slow group had significantly fewer protamine reactions than other groups (chi‐square = 8.57, P = .03, df = 3). Significantly more protamine could be delivered from the cephalic vein (52.5 ± 14.5 mg) compared with the jugular vein (37.6 ± 16 mg) before a reaction occurred (P = .048). Conclusion— The rate of administration did not have an effect on the amount of protamine delivered. Adverse reactions were minimized when protamine was administered via the cephalic vein at a slow rate. Clinical Relevance— We would recommend delivering protamine after cardiopulmonary bypass or vascular surgery through a peripheral venous route.