The effect of halothane on mucociliary activity in the rabbit maxillar
y sinus in vivo was recorded photoelectrically. Administration of halo
thane (1%, 2% or 4%) into the maxillary sinus induced a temporary acce
leration of mucociliary activity. The peak increase (39.1% +/- 9.1%, p
< 0.05, n = 5) was seen after the 4% concentration. Long-term exposur
e (60 minutes) of the maxillary sinus to halothane (2%) first induced
an increase of 28.4% +/- 4.6% (p < 0.05, n = 6), lasting approximately
four minutes, and followed after about 15 minutes by a decrease of mu
cociliary activity. The maximum decrease during the 60-minute period w
as 19.6% +/- 2.8% (p < 0.05, n = 6). Mucociliary activity returned to
its baseline level approximately 25 minutes after withdrawal of haloth
ane. Halothane delivered to the rabbit through a tracheal cannula at 1
.1% for 60 minutes did not impair mucociliary activity in the maxillar
y sinus. On the contrary it initially stimulated mucociliary activity,
19.9% +/- 2.7% (p < 0.05, n = 5). There was also an initial increase
in respiratory rate from 62 +/- 7.3 to 89 +/- 12.9 breaths per minute
(p < 0.05), which was noticeable offer approximately 10 seconds and la
sted 4 to 5 minutes. The dose-dependent increase in mucociliary activi
ty seen after short-term exposure to halothane is probalby due to stim
ulation of afferent C fibers, because halothane may be considered an a
irway irritant. The reversible depressant effect seen after 15 minutes
of exposure is in accordance with findings in previous studies in vit
ro. The mechanism by which halothane Impairs mucociliary activity is a
t present not known. However, halothane administered to the lower airw
ays does not impair mucociliary activity in the maxillary sinus, indic
ating that halothane affects the ciliated epithelium directly and that
the state of anesthesia itself has no effect on mucociliary activity.