DIAPHRAGM AND ACCESSORY RESPIRATORY MUSCLE STIMULATION USING INTRAMUSCULAR ELECTRODES

We tested the hypothesis that electrical stimulation of respiratory mu scles can be obtained from intramuscular electrodes, In acute anesthet ized dogs, suture-type intramuscular electrodes were placed in each he midiaphragm and needle electrodes were placed in various intercostal r egions of the thorax, During a hyperventilation induced period of apne a a 2-second stimulation was applied to the diaphragm or to the thorac ic electrodes, followed by a combined thoracic-diaphragm stimulation p eriod. Thoracic expansion and tidal volumes were measured as indices o f inspiratory effort, We found that diaphragm stimulation produced tid al volumes between 104% and 180% of spontaneous breathing, Electrodes in the upper thorax produced chest expansion and when combined with di aphragm stimulation increased tidal volumes (p <.05). We conclude that intramuscular electrodes represent a feasible method for long-term el ectrogenic ventilation. Also, thoracic support for diaphragm pacing in quadriplegics could produce a more effective long-term system that is less prone to fatigue and failure.