The effect of differing rates and injection sites on the amount of protamine delivered before detection of hemodynamic alterations in dogs.
OBJECTIVE
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.


METHODS
Prospective randomized experimental study.


METHODS
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) <60 mm Hg or mean pulmonary arterial pressure (MPAP) >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).


CONCLUSIONS
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.


CONCLUSIONS
We would recommend delivering protamine after cardiopulmonary bypass or vascular surgery through a peripheral venous route.
Morgan
M R
MR
Department of Clinical Sciences, Colorado State University, College of Veterinary Medicine and Biomedical Sciences, Fort Collins 80523-1620, USA.
Monnet
E
E
Gaynor
J S
JS
D000704:Analysis of Variance; D000818:Animals; D016063:Blood Loss, Surgical / Q000517:prevention & control / Q000662:veterinary; D002316:Cardiotonic Agents / Q000008:administration & dosage* / Q000097:blood / Q000633:toxicity; D001026:Coronary Artery Bypass / Q000662:veterinary; D004280:Dobutamine / Q000008:administration & dosage* / Q000097:blood / Q000633:toxicity; D004285:Dogs / Q000502:physiology* / Q000601:surgery; D004334:Drug Administration Schedule / Q000662:veterinary; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006494:Heparin Antagonists / Q000008:administration & dosage* / Q000097:blood / Q000633:toxicity; D008297:Male; D011446:Prospective Studies; D011897:Random Allocation
D002316:Cardiotonic Agents; D006494:Heparin Antagonists; D004280:Dobutamine