[Propofol depresses the activity of hypoglossal nerve more than that of phrenic nerve in rabbits].
BACKGROUND
Respiratory depression, such as obstruction of upper airway and inadequate ventilation, often appears during sedation and anesthesia. We studied the effect of propofol on the upper airway patency and the inspiratory drives.


METHODS
Experiments were performed on the adult rabbits vagotomized, paralyzed and ventilated with nitrous oxide-oxygen-sevoflurane. We evaluated and compared depressant effect of propofol on the peak amplitude of both hypoglossal nerve (AMP-HG) and phrenic nerve (AMP-PH) activities, inspiratory time (Ti), expiratory time (Te) and respiratory cycle (Tc).


RESULTS
Bolus injections of propofol transiently reduced AMP-HG more than AMP-PH (18 and 70% of control, respectively). But AMPs returned to the control levels about 10-15 min after the injection. For 0.5 mg.kg-1.min-1 continuous infusion, propofol soon began to reduce both AMPs. AMP-HG was reduced to about 20% and AMP-PH to 60% of control. Administration of propofol with 1.0 mg.kg-1.min-1 caused more reduction in AMPs with respiratory slowing and AMP-HG disappeared in some animals.


CONCLUSIONS
During the sedation with low dose of propofol, we need to pay attention to potential upper airway obstruction. In addition to the above, high doses of propofol could reduce spontaneous inspiratory drive, and we need to keep both upper airway patency and sufficient ventilation.
Nakamura
Shinichi
S
Department of Anesthesiology, Saitama Medical School, Saitama 350-0451.
Hayashi
Kazuhito
K
Sakamaki
Hideo
H
Murakami
Yasuo
Y
Tsuchiya
Masahiko
M
Mishima
Masaru
M
Nishida
Masaaki
M
Takahara
Tomohiro
T
Hitosugi
Naoko
N
Hatsukari
Ikusuke
I
Mizukami
Satoshi
S
Nagasaka
Hiroshi
H
Miyata
Yoshihiko
Y
D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D003864:Depression, Chemical; D007002:Hypoglossal Nerve / Q000187:drug effects*; D010791:Phrenic Nerve / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology*; D011817:Rabbits; D012119:Respiration / Q000187:drug effects
D018686:Anesthetics, Intravenous; D015742:Propofol