Rate of nitrous oxide exchange across the middle ear mucosa in monkeys before and after blockage of the mastoid antrum.
OBJECTIVE
We tested the hypothesis that mastoid volume buffers the rate of change in middle ear pressure caused by transmucosal, inert gas exchange.


METHODS
Twelve monkeys were randomly assigned to group 1 or group 2. Right ears of group 1 had sham surgery and of group 2 had obstruction of the mastoid antrum. Before and after surgery, the time constant for transmucosal N(2)O exchange was estimated from N(2)O breathing experiments. The hypothesis predicts that the postoperative time constant measured for right ears of group 2 but not group 1 is greater than that measured before surgery.


RESULTS
Mastoid antrum block significantly decreased right middle ear volume but did not affect the time constant for transmucosal N(2)O exchange.


CONCLUSIONS
A mastoid gas-reserve function is not supported by the experimental data.


CONCLUSIONS
These results for monkeys and the theory developed to explain the effect of mastoid volume on transmucosal inert gas exchange suggest that the results for previous experiments in humans interpreted as evidencing a mastoid gas-reserve function are consistent with alternative explanations.
Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, 3705 Fifth Ave, Pittsburgh, PA 15213 USA. Docdoyle2@aol.com
William J
WJ
Doyle
Cuneyt M
CM
Alper
Juliane M
JM
Banks
J Douglas
JD
Swarts
D000818:Animals; D001837:Body Weights and Measures; D004432:Ear, Middle / Q000378:metabolism*; D008252:Macaca fascicularis; D008416:Mastoid / Q000378:metabolism* / Q000503:physiopathology / Q000601:surgery*; D023421:Models, Animal; D008962:Models, Theoretical; D009092:Mucous Membrane / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism*; D013506:Otologic Surgical Procedures; D011312:Pressure
D009609:Nitrous Oxide