The Development of a Tympanic Membrane Model and Probabilistic Dose-Response Risk Assessment of Rupture Because of Blast.

INTRODUCTION: There is no dose-response model available for the assessment of the risk of tympanic membrane rupture (TMR), commonly known as eardrum rupture, from exposures to blast from nonlethal flashbangs, which can occur concurrently with temporary threshold shift. Therefore, the objective of this work was to develop a fast-running, lumped parameter model of the tympanic membrane (TM) with probabilistic dose-dependent prediction of injury risk. MATERIALS AND METHODS: The lumped parameter model was first benchmarked with a finite element model of the middle ear. To develop the dose-response curves, TMR data from a historic cadaver study were utilized. From these data, the binary probability response was constructed and logistic regression was applied to generate the respective dose-response curves at moderate and severe eardrum rupture severity. RESULTS: Hosmer-Lemeshow statistical and receiver operation characteristic analyses showed that maximum stored TM energy was the overall best dose metric or injury correlate when compared with total work and peak TM pressure. CONCLUSIONS: Dose-response curves are needed for probabilistic risk assessments of unintended effects like TMR. For increased functionality, the lumped parameter model was packaged as a software library that predicts eardrum rupture for a given blast loading condition.

Assessment of hearing loss induced by tympanic membrane perforations under blast environment.

PURPOSES: This study provides an approach to estimating tympanic membrane perforation-induced hearing loss (HL) using a human middle ear model. METHODS: Sixty-one cases of tympanic membrane perforation originating from fireworks were reported from the Ear-Nose-Throat Department. The otoscope, audiometry data and diagnosis records were organized, and gender, age, etiology, perforation size and diseased ear side were classified as independent variables. A multinomial regression model was used to analyze the potential effects of the variables on HL. Meanwhile, a human middle ear model was implemented to calculate the ensued HL resulting from different perforation areas and sites. In addition, linear regression models were used to establish functions between perforation size and HL. RESULTS: The audiometry data indicate that HL at high frequencies (f > 2 kHz) is much more profound than that at the speech frequency band (f < 1 kHz). Compared with mild HL (<15 dB), mediate HL (15-30 dB) was correlated with the perforation area (p < 0.05, 95% CI), while severe HL (>30 dB) was affected by both perforation size and age (p < 0.05, 95% CI). However, other factors, including gender and diseased ear side, do not show a statistically significant effect on HL. Furthermore, the Kruskal-Wallis test result reveals that HL at frequencies of 0.25 kHz ≤ f ≤ 8 kHz is strongly associated with the perforation size (p < 0.05, 95% CI). CONCLUSIONS: It is conclusive that HL is positively proportional to the perforation size. However, HL is not correlated with the perforation site for small perforation areas of < 10% (p > 0.05, 95% CI).

Clinical and economic evaluation of minimally invasive cartilaginous palisade myringoplasty.

OBJECTIVES: To test the clinical and audiometric efficacy of a minimally invasive myringoplasty technique, combining cartilaginous palisades while avoiding flap elevation, for small and wide perforations. METHODS: Over 4 years, this retrospective study included all patients over 6 years of age presenting an indication for myringoplasty. Several clinical and economic criteria were noted at 7 d, 2 months, 6 months and 2 years postoperative. The main outcome was the absence of perforation 2 years postoperative. The secondary outcomes were an audiometric gain at 6 months and the evaluation of the treatment cost. RESULTS: Thirty patients underwent the minimally invasive technique and 28 patients the technique with an elevation of the tympanomeatal flap. The minimally invasive surgical procedure was shorter (p = .001). At 2 years, the tympanic closure rate was equivalent (95% versus 89.5%, p = .77). The audiometric gain was similar between the two techniques (p = .09). From a medico-economic point of view, the minimally invasive procedure was the most effective because it was three times less expensive than the conventional technique with no reduction in efficacy (p = .02). CONCLUSION: This quick and easy technique could be developed in an ambulatory setting or even in conditions adapted to consultation.

Ear syringing: minimising the risks.

The patient, 61 years of age, saw the general practitioner for a repeat prescription for her blood pressure medication. During the consultation, the patient mentioned that she had some discomfort in her left ear. The GP examined the patient's ears and noted that both external auditory canals were blocked by wax. He recommended that the patient have her ears syringed and arranged for the practice nurse to perform the procedure. The GP did not see the patient again.

[Tubal mucociliary transport: evaluation with saccharin solution]. / Transporte mucociliar tubárico: valoración mediante solución de sacarina.

We have studied the tubaric mucociliar transport time using a saccharin solution in: 1. A control group with normal eustachian tubes being the transport time smaller than 20 minutes. 2. A group of 30 ears with chronic middle ear disease with a central perforation; 23% of them had a transport time within normal range, in 46% the transport time was prolonged and in 30% transport was absent.

An evaluation of tympanometry, otoscopy and palpation for assessment of the canine tympanic membrane.

Three techniques for the assessment of the integrity of the canine tympanic membrane were evaluated experimentally. Tympanometry, an objective technique, was shown to be very accurate for the evaluation of the integrity of the ear drum. Otoscopic examination by experienced personnel was shown to be moderately accurate under controlled conditions when the external ear canal was not inflammed. However, under field conditions when otitis externa was present, visual inspection of the tympanic membrane was seldom possible even after lavage of the ear. Palpation of the tympanic membrane with a blunt probe was shown to be very inaccurate and led to rupture of the tympanic membrane in a high proportion of cases. These results imply that two widely used techniques for the examination of the canine tympanic membrane are unsatisfactory. Furthermore, they suggest that previous reports of the prevalence of ear drum perforations in dogs may need reappraisal. Tympanometry is a non-invasive, objective and practical technique for the assessment of ear drum integrity which is worthy of further evaluation.

An assessment of the current state-of-the-art of incapacitation by air-blast.

Target vulnerability methodology requires a criticality measure for all international components which contribute to a system or to a system's weapon effectiveness, including that of the human target. Such measures have been developed for personnel targets and for kinetic energy penetrators; however, there is presently no generally accepted quantitative measure of incapacitation to infantry or crew personnel from the prime blast threat. Vulnerability analysts presently use lethality data derived from Lovelace Foundation research to infer an incapacitation level for blast, but these criteria are not very realistic in that they tend to underestimate casualty production from blast threats. Thus, a generalized criteria for estimating incapacitation to military personnel from air blast overpressures is urgently needed to provide vulnerability analysts a realistic measure of blast effectiveness as well as to establish a common base for comparing incapacitation to personnel from blast and from kinetic energy threat mechanisms.