Cardiovascular effects of a nifedipine infusion during fentanyl-nitrous oxide anesthesia in dogs.
The hemodynamic effects of a nifedipine infusion were investigated in eight dogs given fentanyl/pancuronium/nitrous oxide/oxygen anesthesia. Nifedipine (20 micrograms/kg) was given intravenously over two minutes immediately prior to each 30-minute infusion at 2 micrograms/kg/min, 4 micrograms/kg/min, and 6 micrograms/kg/min. The range of plasma nifedipine levels obtained was 52.1 to 113.7 ng/mL. The predominant hemodynamic effects were significant reductions in systemic vascular resistance (SVR) and mean aortic pressure (MAP), accompanied by a rise in cardiac index and heart rate (HR). Administration of calcium chloride (20 mg/kg) after the nifedipine infusion had no effect on SVR or MAP, but HR was significantly reduced. Serum epinephrine and norepinephrine levels increased after the infusion of nifedipine and suggested that fentanyl did not completely overcome the sympathetic response to the profound vasodilatation. The resulting tachycardia in combination with diastolic hypotension from nifedipine could have a detrimental effect on the myocardial oxygen balance.
Griffin
R M
RM
Department of Anesthesiology, School of Medicine, (CUNY), New York 10029.
Dimich
I
I
Jurado
R
R
Pratilas
V
V
Shiang
H
H
Fagerstrom
R
R
Kaplan
J A
JA
D000769:Anesthesia, Inhalation; D000771:Anesthesia, Intravenous; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D004562:Electrocardiography / Q000187:drug effects; D004837:Epinephrine / Q000097:blood; D005283:Fentanyl / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007275:Injections, Intravenous; D009543:Nifedipine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D009609:Nitrous Oxide; D009638:Norepinephrine / Q000097:blood; D011651:Pulmonary Artery; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects; D016276:Ventricular Function / Q000187:drug effects
D009543:Nifedipine; D009609:Nitrous Oxide; D005283:Fentanyl; D009638:Norepinephrine; D004837:Epinephrine