Repeated inflation does not prevent otitis media with effusion in a monkey model

Intranasal phenylephrine-surfactant treatment is not beneficial in otitis media with effusion

BACKGROUND

Otitis media is the most common reason for non-well-child visits to the primary care physician. Various treatments are in use to try to ameliorate the pain arising from Eustachian tube (ET) dysfunction. One such treatment is topical phenylephrine spray, despite clinical evidence disputing its use. Previous research by this laboratory has demonstrated the beneficial effect of topical surfactant treatment in reducing ET opening pressure, allowing the tube to open. This study is designed to test the effectiveness of topical phenylephrine, delivered with surfactant, in reducing days of effusion in OME, in an animal model.

METHODS

OME was generated by injecting Klebsiella pneumoniae lipopolysaccharide into the right bullae of 28 gerbils. After frank OME resulted, the animals were divided into four groups. Group 1 received no treatment or propellant spray alone (placebo). Group 2 received intranasal surfactant spray once daily. Group 3 received intranasal surfactant-phenylephrine spray once daily. Group 4 received intranasal surfactant-phenylephrine spray twice daily. All animals were evaluated on a daily basis by both otomicroscopy and tympanometry, and treatment was ceased when the ear returned to normal appearance. Evaluations were continued for a total of 30 days. Chi-squared analysis with significance set at .05 was performed.

RESULTS

In the untreated and placebo groups, middle ear effusion resolved at 16.25 days by otomicroscopy and 28.26 days by tympanometry. In Group 2 (surfactant alone), effusion resolved at 10.57 days and 15.71 days, respectively. In Group 3 (surfactant-phenylephrine once daily), effusion resolved at 15.67 days and 28.33 days. In Group 4 (surfactant-phenylephrine twice daily), effusion resolved at 18.67 days and 28.33 days. These results were statistically significant.

CONCLUSIONS

Intranasal phenylephrine-surfactant treatment is shown to be at least ineffective, and possibly detrimental, in the resolution of OME, in this animal model. The hypothesis is that surfactant potentiates the drying effect of phenylephrine at the ET by allowing it to get to the ET more easily; in addition, the drying effect of phenylephrine prevents full surfactant action. We believe that these results can be extrapolated to humans and that phenylephrine should be avoided in these cases.

Studies in otitis media: Children's Hospital of Pittsburgh-University of Pittsburgh progress report--2004

OBJECTIVES/HYPOTHESIS

The present Progress Report has summarized the key otitis media clinical trials and laboratory studies conducted since 1969 by investigators at the Children's Hospital of Pittsburgh-University of Pittsburgh (Pittsburgh, PA).

STUDY DESIGN

Review.

METHODS

Included in the discussion are the following: 1) studies of the epidemiology and risk factors; 2) anatomy and pathology of the eustachian tube-middle ear from human temporal bone histopathological specimens; 3) physiology and pathophysiology of the eustachian tube-middle ear in humans and animal models; 4) pathogenesis; 5) otitis media in special populations (e.g., patients with cleft palate, Native Americans, patients with Down syndrome); 6) microbiology; 7) diagnosis; 8) outcomes of randomized clinical trials that evaluated efficacy of nonsurgical and surgical methods of treatment and prevention; 9) studies of certain complications and sequelae (e.g., effect of middle-ear effusion on hearing, early child development, and the vestibular system; chronic suppurative otitis media). Also included are relevant summary tables and 256 references.

The effects of changing middle ear pressure and gas partial pressure on mucosal blood flow and vascular permeability in the chinchilla

OBJECTIVE

To determine if middle ear (ME) gas composition and/or total pressure regulates local mucosal blood flow (MBF) and vascular permeability. The hypotheses tested are: (1) relatively high local CO2 tensions and/or low O2 tensions increase the ME MBF and vascular permeability; and (2) sub-atmospheric total ME pressure provokes similar effects.

METHODS

The responses of ME MBF and vascular permeability parameters were measured during 60 min exposures of chinchilla MEs to one of two test gas mixtures (16.3% O2, 5.1% CO2, balance N2, or 5.3% O2, 15.6% CO2, balance N2) applied at different levels of underpressure (ref. ambient). In the first set of experiments (n = 19), mucosal perfusion parameters were recorded using a Laser Doppler Flowmeter for 60 min before and 60 min after exposure to the experimental conditions. In the second set of experiments (n = 19 chinchillas, 38 ears), the MEs were exposed to the gas mixtures and then maintained for 60 min at ambient pressure or at negative pressures of -200, -400, -600 mmH2O. Fifty minutes into the experiment, the animals were injected intravenously with 60 mg/kg of horseradish peroxidase (HRP). The animals were killed and existing effusion was aspirated, its volume recorded and then analyzed for total protein. From surface preparations of the ME mucosa, vascular leakage sites were measured as percent total surface area using an image analysis program with the threshold window set to discriminate HRP stain.

RESULTS

Throughout the 120 min in the first set of experiments, the measured MBF parameters decreased in all exposure groups. Comparisons among groups for the absolute magnitude of the change from baseline showed that high local CO2 partial pressures decreased MBF and ME underpressures increased MBF, but the effects did not achieve statistical significance. The results of the second set of experiments demonstrated no effect of gas composition on any of the measured parameters of vascular permeability. All measures of permeability were linearly related to the magnitude of the underpressure.

CONCLUSION

These data support a role for total ME pressure, but not CO2 partial pressure in regulating ME MBF and vascular permeability.