Middle ear pressure changes during different inhalation anesthesia comparative study by tympanometry between modern and old inhalational anesthetic agents

This investigation examined the effect of modern inhalant anesthesia [isoflurane and sevoflurane] in comparison with older inhalational agent [halothane] with or without nitrous oxide on middle ear pressure [MEP]. Tympanometry was used to measure MEP variations. Seventy-six subjects were examined with tympanometry prior to inhalant anesthesia and baseline tympanometry was performed. This study found that the changes of MEP are significantly greater when nitrous oxide added to any of modern or older inhalational agents. The results have shown that administration of nitrous oxide with these agents should be used with great care during tympanic membrane grafting, ossiculoplasty or ossicular replacement prosthesis

Effects of noise on peripheral hearing of bus drivers [a conventional and extended high frequency audiometry study]

Hearing threshold evaluation was assessed by pure tone audiometry for 100 subjects working as bus drivers, they were constantly exposed to buses noise for at least five years. Other causes for hearing impairment, either conductive or sensorineural, were excluded. The study group was compared with a control group of 30 normal hearing subjects. Elevation in hearing threshold was noticed in the study group, especially at high frequencies and the differences were statistically significant. Normal hearing was found in 43%, high frequency SNHL above 4 KHz in 14%, mild SNHL in 33%, moderate SNHL in 4% and moderately severe to severe SNHL in 6%. The degree of hearing loss was directly proportional to duration of noise exposure. The subjects with normal hearing sensitivity in the ordinary frequency range [0.25-8 KHz] showed statistically significant elevation in the extended high frequency range [9-IS KHz]. This signified the value of extended high frequency audiometry in the early detection of susceptibility of hearing to noise insult