Effect of exogenous surfactant on ventilatory and clearance function of the rat's eustachian tube.
OBJECTIVE
The Eustachian tube has three important functions with respect to the middle ear: ventilation, clearance, and protection. Surfactants are assumed to be important to maintain these functions. The administration of exogenous surfactant may therefore be effective to improve the function of the Eustachian tube. This randomized, double-blind, placebo-controlled study was designed to investigate the effect of exogenous surfactant on the function of the Eustachian tube in rats.


METHODS
Exogenous surfactant was administered into the middle ear of 10 otologically healthy rats, and 10 other rats received placebo. The effect on the opening and closing pressure (passive ventilatory function) and the dye clearance time (clearance function) of the rat's Eustachian tube was measured.


RESULTS
A significant decrease in the opening pressure was seen after the administration of surfactant. Both surfactant and placebo caused an increase in the closing pressure. A serious disturbance of the dye clearance time was induced in 13 rats, and the test failed in 1 rat. In the remaining 6 rats, no significant differences in the dye clearance time were observed between the two groups.


CONCLUSIONS
Exogenous surfactant decreased the closing forces of the Eustachian tube even in otologically healthy rats. No significant effect on the mucociliary clearance was observed, but this may have resulted from the small number of rats. Additional randomized, double-blind, placebo-controlled trials should be conducted to determine the clinical relevance of these changes and to further assess the effect of surfactant on the function of the Eustachian tube.
van Heerbeek
Niels
N
Departmentof Otorhinolaryngology, University Medical Center Nijmegen, The Netherlands. N.vanHeerbeck@kno.azn.nl
Tonnaer
Edith L G M
EL
Ingels
Koen J A O
KJ
Curfs
Jo H A J
JH
Cremers
Cor W R J
CW
D000158:Acoustic Impedance Tests; D000818:Animals; D001688:Biological Products; D004432:Ear, Middle / Q000187:drug effects*; D005064:Eustachian Tube / Q000187:drug effects*; D007537:Isometric Contraction / Q000187:drug effects*; D009079:Mucociliary Clearance / Q000187:drug effects*; D011663:Pulmonary Surfactants / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D001688:Biological Products; D011663:Pulmonary Surfactants; C072197:beractant