The effects of anesthesia on middle-ear effusions

Effect of positional change and inhalant anesthesia on parameters of acoustic reflectometry

OBJECTIVE

Purpose of this study was to find out the effect of positional change and inhalant anesthesia on acoustic reflectometry (AR) parameters (reflectivity and curve angle).

METHOD

AR parameters were measured on 58 ears with otitis media in sitting position before anesthesia and in supine position under inhalant anesthesia, subsequently.

RESULTS

Under anesthesia, ears with effusion disclosed more changes in reflectivity (Chi-squared analysis, chi2-test; P<0.05) and curve angle (P>0.1) than those without effusion. Further, inhalant anesthesia caused more changes in the false negative ears (63.63%) than in those with effusion having positive test before anesthesia (12.90%) (P<0.001).

CONCLUSIONS

From the data of this study, it could be said that reflectivity shows changes according to the amount of effusion which is in contact with the tympanic membrane under anesthesia, and that curve angle becomes more sensitive to detect effusion when anesthetic gas diffuses into the middle ear with effusion, probably due to the pushing of effusion towards the tympanic membrane.

Validation of a portable tympanometer for use in primary care

OBJECTIVE

to determine the accuracy of a handheld, portable tympanometer, the microtymp, in comparison with a reference instrument, the AR 85 tympanometer, and with the gold standard: presence or absence of middle-ear fluid.

DESIGN

comparison of results from the microtymp with results from the reference tympanometer, the AR 85 and the gold standard.

SETTING

University Children's Hospital, Utrecht and the General Hospital, Overvecht, Utrecht.

SUBJECTS

142 children (284 ears) aged between 6 months and 12 years, who were referred by their General Practitioner or Ear, Nose and Throat surgeon for myringotomy and/or tympanostomy tube insertion.

MAIN OUTCOME MEASURES

tympanometry with the AR 85 and presence or absence of middle-ear fluid.

RESULTS

In 243 ears, of the included 284 ears, the test results of the microtymp were compared with those of the reference instrument, the AR 85 tympanometer. Sensitivity 0.96 (95% C.I.: 0.93, 0.99), Specificity 0.81 (95% C.I.: 0.71, 0.91). In 233 ears, of the included 284 ears, the test results of the microtymp were compared with the gold standard. Sensitivity 0.94 (95% C.I.: 0.90, 0.98), specificity 0.48 (95% C.I.: 0.37, 0.59).

CONCLUSION

The microtymp is a valid instrument for diagnosing middle-ear effusions. The results of the microtymp are highly comparable with traditional tympanometers: high sensitivity and much lower specificity. Use in primary care can increase diagnostic accuracy of otitis media with effusion (OME) and makes follow-up possible. This will help to discriminate between those OME cases who need further treatment and those who will resolve spontaneously.

Validity of tympanometry in the diagnosis of middle ear effusion

A group of 266 children (515 ears), ranging in age from 5 months to 11 years, was studied. These children were candidates for the insertion of ventilation tubes, or adenoidectomy and/or tonsillectomy with myringotomy. Before surgery, tympanometry was performed. The surgical and tympanometric findings were compared afterwards. Two different tympanometers were used (GSI-27A and TYMP-85TT). This study showed a comparable validity of these two tympanometers. The sensitivity and specificity of tympanometry in the age group of 5 months to 2 years did not show a significant difference from that in the age group of 2-12 years. Otoscopy has limited value for the diagnosis of middle ear effusion in this age group.