Effect of audiological testing on programmable ventriculoperitoneal shunts.

OBJECTIVE: This study aimed at measuring the magnetic field strength of commonly used types of audiological testing equipment and determine their effects on the three most commonly used programmable ventriculoperitoneal (VP) shunts to try and quantify the risk of a VP shunt being reprogrammed during audiological testing. DESIGN: In this in vitro study, magnetic field strength was measured for TDH 39 supra-aural earphones, B71 bone vibrator, ALGO 3i probe, Bio-logic Nav Pro probe, Otodynamics otoport insert earphone and Madsen Zodiac tympanometry probe. STUDY SAMPLE: Magnetic field strength associated with transducers placed on a model of a skulls having implanted Miethke ProGAV 2.0, Medtronic Strata II and Codman Hakim programmable VP shunts was measured. RESULTS: The supra-aural earphones had a magnetic field strength of 14 mT at 0 mm, which dropped to 0 mT at 10 mm away from the transducer. All other equipment had a magnetic field strength of 3.5 mT or less at 0 mm. There was no instance of reprogramming of the shunts by the transducers. CONCLUSIONS: The findings suggest that the risk of inadvertent valve-reprogramming by the transducers is extremely small. However, care should be taken to avoid placing any of the transducers directly over the shunt.

Use of an autoinflation device does not lead to a clinically meaningful change in hearing thresholds in children with otitis media with effusion.

DESIGN: The objective of this study was to establish whether autoinflation was an effective intervention in a paediatric audiology service. This was a pragmatic retrospective study with historical controls using a paired availability design. SETTING: The study took place at a single paediatric audiology service in England. PARTICIPANTS: All children seen in the clinic over a two-year period who were aged between 3 and 11 years and who had a type B tympanogram in at least one ear were included. The Otovent autoinflation device was available as a treatment option over the second year (Cohort B) but not the first (Cohort A). There were 976 children included in the study: Cohort A comprised 513 children, Cohort B comprised 463 children. MAIN OUTCOME MEASURES: The aims were to evaluate whether there was improvement in hearing thresholds following introduction of an autoinflation device, and whether there was a reduction in further audiology follow-ups, and in referrals to an ear, nose and throat specialist for consideration of ventilation tube insertion. RESULTS AND CONCLUSIONS: There was a statistically significant improvement in hearing thresholds in Cohort B compared to Cohort A, however the improvements were clinically minimal with small effect sizes. There was no significant difference in improvement of tympanometry results between the two cohorts. Significantly more children in Cohort B (autoinflation group) were referred to an ear, nose and throat specialist after their second appointment compared to Cohort A. It was feasible to introduce autoinflation into the care pathway, however there was no evidence of clinically meaningful improved outcomes for patients.