The influence of nicardipine-, nitroglycerin-, and prostaglandin E(1)-induced hypotension on cerebral pressure autoregulation in adult patients during propofol-fentanyl anesthesia.
We investigated the influence of drug-induced hypotension at a mean arterial pressure (MAP) of 60-70 mm Hg on cerebral pressure autoregulation in 45 adult patients during propofol-fentanyl anesthesia. Time-averaged mean blood flow velocity in the right middle cerebral artery (Vmca) was continuously measured at a PaCO(2) of 39-40 mm Hg by using transcranial Doppler ultrasonography. Hypotension was induced and maintained with a continuous infusion of nicardipine, nitroglycerin, or prostaglandin E(1). Cerebral autoregulation was tested by a slow continuous infusion of phenylephrine to induce an increase in MAP of 20-30 mm Hg. From the simultaneously recorded data of Vmca and MAP, cerebral vascular resistance (CVR) was calculated as MAP/Vmca. Furthermore, the index of autoregulation (IOR) was calculated as DeltaCVR/DeltaMAP, where DeltaCVR = change in CVR and DeltaMAP = change in MAP. The test was performed twice for each condition on each patient: baseline and hypotension. The IOR during baseline was similar among the groups. During nitroglycerin- and prostaglandin E(1)-induced hypotension, IOR was not different from baseline. In contrast, during nicardipine-induced hypotension, IOR significantly decreased compared with baseline (0.37 +/- 0.08 versus 0.83 +/- 0.07, P < 0.01). In conclusion, nicardipine, but not nitroglycerin or prostaglandin E(1), significantly attenuates cerebral pressure autoregulation during propofol-fentanyl anesthesia.


CONCLUSIONS
Vasodilators may influence cerebral autoregulation by changing cerebral vascular tone. Nicardipine, but not nitroglycerin or prostaglandin E(1), attenuated cerebral pressure autoregulation in normal adult patients during propofol-fentanyl anesthesia.
Endoh
Hiroshi
H
Department of Emergency and Critical Medicine, Niigata University Faculty of Medicine, Niigata, Japan. endoh@med.niigata-u.ac.jp
Honda
Tadayuki
T
Ohashi
Satomi
S
Hida
Seiji
S
Shibue
Chieko
C
Komura
Noboru
N
D000527:Alprostadil / Q000494:pharmacology*; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects*; D019296:Capnography; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D005260:Female; D005283:Fentanyl; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D007023:Hypotension, Controlled; D008297:Male; D008875:Middle Aged; D009529:Nicardipine / Q000494:pharmacology*; D005996:Nitroglycerin / Q000494:pharmacology*; D010100:Oxygen / Q000097:blood; D010656:Phenylephrine / Q000494:pharmacology; D015742:Propofol; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D018686:Anesthetics, Intravenous; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D009529:Nicardipine; D000527:Alprostadil; D005996:Nitroglycerin; D010100:Oxygen; D005283:Fentanyl; D015742:Propofol