[Comparison of vascular effects of magnesium sulfate and nicardipine during extracorporeal circulation].
OBJECTIVE
To evaluate the hypothesis that magnesium sulphate (SO4Mg), usually administered for protecting the myocardium and decreasing the rate of arrhythmias in cardiac surgery, was able to control the hypertensive peaks occurring during cardiopulmonary bypass (CPB), as efficiently as nicardipine (N).


METHODS
Randomized controlled trial.


METHODS
Forty patients were allocated into two groups when hypertensive peaks occurred during CPB. The patients of the N group were then given nicardipine 0.016 mg.kg-1 and those of the SO4Mg group received magnesium sulphate 50 mg.kg-1.


METHODS
Anaesthesia technique was identical and during normothermic CPB the flow remained constant at 2.4 L.min-1, during the 10 min following N or SO4Mg administration. The usual haemodynamic variables were monitored.


RESULTS
Both N and SO4Mg decreased significantly the MAP and the SVR over the 9 min following their administration. The decrease was more marked after SO4Mg. As the flow of the pump was unchanged after their injection the decrease can be attributed to the relaxing effect of these agents on the smooth vascular muscles.


CONCLUSIONS
SO4Mg permits to treat hypertensive peaks occurring during CPB as efficiently as N. Three grammes of SO4Mg have an hypotensive effect equivalent to that of 1 mg of nicardipine. However repetitive injections of SO4Mg cannot be recommended because of the risk for hypermagnesemia.
D000368:Aged; D000768:Anesthesia, General / Q000379:methods; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D006348:Cardiac Surgical Procedures; D005112:Extracorporeal Circulation; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D007431:Intraoperative Complications / Q000188:drug therapy; D008278:Magnesium Sulfate / Q000494:pharmacology*; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009529:Nicardipine / Q000494:pharmacology*
D000959:Antihypertensive Agents; D008278:Magnesium Sulfate; D009529:Nicardipine
Comparaison des effets vasculaires du sulfate de magnésium et de la nicardipine pendant la circulation extracorporelle.