Diaphragmatic plate electrode stimulation of the hamster diaphragm

Abstract

We developed a new technique of diaphragmatic stimulation by apposing plate electrodes directly against the diaphragm (DPS) in adult Golden Syrian hamsters. The electrophysiological and the mechanical responses to DPS were compared with those with phrenic nerve stimulation. In four animals, evaluation of the electromyogram before and after curare demonstrated that plate electrode stimulation occurred via the phrenic nerve filaments. In four animals, similar transdiaphragmatic pressure was produced at maximal current with DPS and phrenic nerve stimulation. Using DPS increasing current beyond a certain level resulted in recruitment of muscles besides the diaphragm. In six animals, an external abdominal pressure of 15 cmH2O produced maximal transdiaphragmatic pressure, suggesting that the diaphragm was contracting near optimal position with this external abdominal pressure. In another four animals the twitch and pressure-frequency characteristics with the use of DPS were found to be reproducible over a 2-h period. We conclude that DPS is an effective method of diaphragmatic stimulation and should prove to be a valuable technique to study the diaphragm in long-term studies of small rodents.

Effectiveness of diaphragmatic stimulation with single-channel electrodes in rabbits

“…( 3 - 5 ) An animal study comparing phrenic nerve stimulation and intramuscular stimulation showed similar results in terms of transdiaphragmatic pressure generation and latency of nerve conduction velocity. ( 6 ) …”

“…The findings are consistent with those of experimental and clinical studies. ( 5 , 6 , 9 - 11 ) Full activation of the diaphragm depends on proper electrode implantation into the diaphragm motor points, the entrance area, and the ramification of the phrenic nerves in the muscle; therefore, it is essential to explore the muscle and identify the points at which contraction is more consistent. One of the challenges was to design a specific electrode for diaphragmatic stimulation, given that, in rabbits, the diaphragm is thinner and more delicate than the peripheral muscles.…”

“…( 3 - 5 ) Um estudo em animais comparando os métodos de estimulação através do nervo frênico e estimulação intramuscular mostrou resultados semelhantes na geração da pressão transdiafragmática e na latência na velocidade nervosa. ( 6 ) …”

“…Os achados são consistentes quando comparados aos de estudos experimentais e clínicos. ( 5 , 6 , 9 - 11 ) A ativação completa do diafragma depende da adequada implantação dos eletrodos sobre os pontos motores do diafragma, a área de entrada e a ramificação do nervo frênico no músculo; para isso, é fundamental a exploração do músculo e a identificação dos pontos onde a contração é mais consistente. Um dos desafios enfrentados foi a concepção de um eletrodo específico para a estimulação do diafragma, uma vez que o diafragma do coelho é mais fino e delicado que os músculos periféricos.…”