Use of the nine-step inflation/deflation test as a predictor of middle ear barotrauma in sports scuba divers.

ABSTRACT

Middle ear (ME) barotrauma, the most common disorder encountered in diving, results from inadequate pressure equilibration between the ME and the ambient environment. Eustachian tube function plays a key role in the pathogenesis of barotrauma. This study was designed to investigate the predictive value and efficiency of tympanometric tests of Eustachian tube function (Valsalva test, Toynbee test and nine-step inflation/deflation test) in predicting ME barotrauma in 44 ears of 22 sports scuba divers who had normal audiometry, tympanometry and otorhinolaryngological examination without previous history of ear disease. The divers were counselled to refer to the investigators if any symptoms occurred during and/or after diving. All symptomatic ears were examined within 24 hours of diving by one investigator who was unaware of the pre-symptomatic test results. Decision matrix analysis was applied to the results of Eustachian tube function tests for predicting ears with barotrauma. Values were also evaluated for a battery of tests by 'Lax' (positive on A, B or C) and 'Strict' (positive on A, B and C) criteria. The nine-step test was found to be the most efficient (93%) test with highest predictive values (PPV 83%; NPV 95%), whereas the Valsalva and Toynbee tests were unreliable in predicting barotrauma, whereas the Valsalva and Toynbee tests were unreliable in predicting barotrauma (PPV of the Valsalva and Toynbee tests were 0% and 25% respectively). Combining the nine-step and Toynbee tests into a two-test battery in a strict approach increased the PPV (100%). It appears that the nine-step inflation/deflation test is a reliable method of predicting ME barotrauma sufferers, especially when applied with the Toynbee test. The nine-step test may have value in the evaluation of Eustachian tube function of sports scuba diving candidates after routine otorhinolaryngological, audiological and tympanometric evaluation.