Related Experiment Videos
Middle ear gas exchange in the air phase
Ulrik N Felding1, Juliane M Banks, William J Doyle
1Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, Pennsylvania 15213, USA.
Acta Oto-Laryngologica
|October 25, 2003
Summary
Gas exchange between the tympanum and mastoid in cynomolgus monkey ears is rapid. This suggests pressure gradients are not crucial for middle ear pressure regulation in this model.
Area of Science:
- Otolaryngology
- Physiology
- Comparative Anatomy
Background:
- Middle ear pressure regulation is vital.
- Gas exchange between the tympanum and mastoid plays a role.
- Cynomolgus monkeys are a key model for middle ear studies.
Purpose of the Study:
- To quantify gas exchange rates between the tympanum and mastoid.
- To determine equilibration times for inert gases (argon, helium).
- To assess the role of gas exchange in middle ear pressure regulation.
Main Methods:
- Experiments conducted on 5 cadaveric cynomolgus monkey temporal bones.
- Helium or argon introduced into the tympanum to increase pressure.
- Partial pressures measured via mass spectrometry at set time intervals (0-15 min).
Main Results:
- Initial tympanum:mastoid partial pressure ratios were high (4.7 for helium, 3.9 for argon).
- Ratios rapidly decreased, approaching equilibrium by 5 minutes (1.2 for helium, 1.1 for argon).
- Indicates swift gas diffusion across middle ear structures.
Conclusions:
- Air-phase gas exchange between the tympanum and mastoid is fast.
- Partial pressure gradients dissipate quickly.
- These gradients are unlikely to be significant factors in middle ear pressure regulation in this model.