Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942001000600007
Brazilian Journal of Anesthesiology
Scientific Article

Efeitos de baixas pressões no balonete da máscara laríngea na mucosa faringolaríngea do cão

Effects of low laryngeal mask cuff pressure on the laryngopharyngeal mucosa of dogs

Regina Helena Garcia Martins; José Reinaldo Cerqueira Braz; José Marcos Pechula Moura; Graziela de Araújo Costa; Lídia Raquel de Carvalho

http://dx.doi.org/10.1590/S0034-70942001000600007 Braz J Anesthesiol, vol.51, n6, p.518-527, 2001
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Resumo

JUSTIFICATIVA E OBJETIVOS: Lesões da mucosa faringolaríngea e compressões de vasos e de nervos têm sido relatadas e atribuídas às altas pressões no balonete da máscara laríngea (ML). O objetivo deste trabalho foi estudar em cães a mucosa faringolaríngea em contato com o balonete da ML sob baixas pressões e avaliar as condições ventilatórias durante a anestesia. MÉTODO: Em 8 cães sob anestesia com pentobarbital foi inserida ML de número 4, mantendo-se a pressão no balonete em 60 cmH2O. Os atributos: freqüência de pulso (FP), pressão arterial média (PAM), pressão inspiratória (PI), pressão expiratória final de CO2 (P ET CO2) e saturação de pulso de O2 (SpO2) foram estudados em 0 (controle), 30, 60, 90 e 120 minutos após a inserção da ML. Após eutanásia, realizou-se biópsias nas áreas da contato da mucosa faringolaríngea com a ML para exame à microscopia óptica (MO) e eletrônica de varredura (MEV). RESULTADOS: Os atributos estudados mantiveram-se sem alterações significativas durante o experimento, ocorrendo apenas pequeno aumento dos valores da PAM e da P ET CO2 nos tempos finais do experimento. À MO, o epitélio da mucosa faringolaríngea apresentou-se sem alterações na grande maioria das áreas examinadas, mas em algumas áreas houve pequena infiltração inflamatória de polimorfonucleares neutrófilos e leve congestão na camada subepitelial, sem diferença significativa entre as áreas (p < 0,05). O estudo à MEV também mostrou epitélio da mucosa laringofaríngea sem alterações significativas. CONCLUSÕES: Em cães, a utilização de pressão de 60 cmH2O no balonete da ML assegura perfeita manutenção da permeabilidade das vias aéreas e não provoca alterações na mucosa faringolaríngea.

Abstract

BACKGROUND AND OBJECTIVES: Injuries to laryngopharyngeal tissues and artery and nerve compression have been reported and attributed to high laryngeal mask (LM) cuff pressure. This study aimed at evaluating the laryngopharyngeal mucosa of dogs when in contact with LM cuff under low pressures and studying ventilatory conditions during anesthesia. METHODS: This study involved 8 mixed-breed dogs anesthetized with pentobarbital and maintained on mechanical ventilation after insertion of a number 4 LM. Pulse rate (PR), mean blood pressure (MBP), inspiratory pressure (IP), end tidal CO2 (P ET CO2) and oxygen saturation (SpO2) were evaluated at 0 (control), 30, 60, 90 and 120 minutes after LM insertion. After euthanasia, laryngopharyngeal mucosa regions in contact with LM were biopsed and examined under light microscopy and scanning electron microscopy (SEM). RESULTS: The attributes studied have shown no significant changes during the experiment but a minor MBP and P ET CO2 increase towards the end of the experiment. At light microscopy, laryngopharyngeal epithelium was normal in most examined areas, but in some areas a minor inflammatory reaction with infiltration of polinuclear neutrophils and mild congestion of the subepithelial layer was seen, without significant differences among areas (p < 0.05). At SEM no significant differences in the laryngopharyngeal mucosa was observed. CONCLUSION: In dogs, low LM cuff pressure (60 cmH2O) is safe for airway patency maintenance and does not affect laryngopharyngeal mucosa.

Keywords

ANIMAL, EQUIPAMENTOS

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