Tissue response evaluation of the mucosa of the tympanic cavity of guinea pigs, when receiving biodegradable implant

PURPOSE: To evaluate the tissue response of the mucosa of the tympanic cavity of guinea pigs, when receiving biodegradable implant. METHODS: A total of 20 male guinea pigs were divided into 2 groups. After paracentesis in both ears, a biodegradable polymer of poly lactic-co-glycolic acid was implanted in only one middle ear. Histological analysis using neutrophil exudate and vascular neoformation (acute inflammation) and fibroblast proliferation and mononuclear inflammatory cells (chronic inflammation) as parameters was performed after 10 and 30 days of survival (groups 1 and 2, respectively). RESULTS: Four ears in group 1 and 7 in group 2 had an increase of neutrophil exudate. Vascular neoformation occurred in ears with or without the implant, in both groups. Fibroblast proliferation and mononuclear inflammatory cells (lymphocytes and macrophages) increased in ears with implant in group 2. CONCLUSION: The tissue response by histological analysis of the mucosa of the tympanic cavity of guinea pigs, when receiving biodegradable implant, showed no statistically significant difference between ears with or without the implant. .

Avaliação de alterações timpanométricas em pacientes submetidos à anestesia geral com óxido nitroso

O óxido nitroso é um gás inalatório que pode aumentar a pressão intratimpânica durante o ato anestésico, bem como causar pressão negativa após sua suspensão, principalmente em pacientes com disfunção da tuba auditiva. Estas variações pressóricas podem trazer implicações clínicas, como ruptura de membrana timpânica, desarticulação da cadeia ossicular, hemotímpano, barotrauma, deslocamento de prótese de estapedotomia e lateralização do enxerto nas timpanoplastias, além da entrada de fluido seroso na orelha média durante a fase de pressão negativa. OBJETIVO: Avaliar a influência do óxido nitroso na pressão da orelha média em uma população sem disfunção tubária, realizando timpanometria no pré e pós-operatório. FORMA DE ESTUDO: Coorte transversal. MATERIAL E MÉTODO: Foi realizado um estudo prospectivo com pacientes internados no Hospital Universitário Clementino Fraga Filho - UFRJ, submetidos à anestesia geral com o uso do óxido nitroso a 50 por cento, durante o período de abril a julho de 2003. Avaliou-se ainda se a duração da cirurgia, anestésicos associados, presença de rinite alérgica e desvio de septo nasal poderiam influenciar no aparecimento das alterações da pressão intratimpânica. RESULTADOS: A amostra constituiu-se de 50 pacientes, encontrando-se em quase metade (48 por cento) alterações timpanométricas no pós-operatório (curva tipo C), quando comparado às de controle do pré-operatório (curva tipo A). Sexo e idade não interferiram no aparecimento das alterações timpanométricas no pós-operatório, bem como a duração da cirurgia. O tipo de anestésico volátil associado, desvio de septo nasal e rinite alérgica não exerceram influência na pressão da orelha média no pós-operatório. CONCLUSÃO: O óxido nitroso altera a pressão na orelha média tanto na fase de indução quanto na fase de resolução anestésica.

protective effects of vitamin E versus vitamin C against cisplatin ototoxicity in guinea pigs [histological and audiological study]

The protective effects of both vitamin E and C against cisplatin induced ototoxicity were assessed histologically and audiogically. This was done by quantifying the extent of cochlear damage with the light microscope, scanning electron microscope and with measurement of the Distortion Product Otoacoustic Emissions [DPOAEs]. Twenty-five adult male guinea pigs were used in this study. They were divided into control group, cisplatin group that was injected 8 mg/kg cisplatin intra-peritoneally [i.p.], vitamin E group that was injected 500 mg/kg of vitamin E i.p.30 mm prior to cisplatin injection, and vitamin C group which was given 200 mg/kg of vitamin C i.p. 30 min before cisplatin administration. When administered alone, cisplatin induced loss and vacuolation of outer hair cells [OHCs] as seen by LM examination. Scanning EM revealed fusion, disarrangement and loss of some stereocilia in the remaining OHCs especially in the basal turn. In contrast, inner hair cells resisted cisplatin ototoxicity. Audiological assessment demonstrated reduction in DPOAEs amplitudes and S/N values in all frequencies. Both vitamin E and C reduced cisplatin ototoxicity, with better protection achieved by vitamin C administration. Scanning EM examination showed that OHCs were similar to the control configuration after vitamin C administration while after protection with vitamin E, OHCs of the third row showed fusion and absorption of the stereocilia in some parts. In addition, both DPOAEs amplitudes and S/N ratio were near the control values up to 4 KHz. However, above 4 KHz both vitamins failed to achieve the full protection, with vitamin C showing better performance in these high frequencies. We conclude that both vitamins had protective effects against cisplatin induced ototoxicity, with vitamin C inducing more protection in the used regimen

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

Characteristics of middle ear pressure in children under enflurane and isoflurane anaesthesia

Fourty seven children were selected to study the effect of enflurane and isoflurane on the middle ear pressure and the time required to achieve the pressure changes. The data was recorded by using an Interacoustics impedance audiometer model AZ7. From the results of this study, it appeared that Isoflurane is the least unsatisfactory agent to use in middle ear and tympanic cavity surgery