Diaphragmatic plate electrode stimulation of the hamster diaphragm

Effectiveness of diaphragmatic stimulation with single-channel electrodes in rabbits

Every year, a large number of individuals become dependent on mechanical ventilation because of a loss of diaphragm function. The most common causes are cervical spinal trauma and neuromuscular diseases. We have developed an experimental model to evaluate the performance of electrical stimulation of the diaphragm in rabbits using single-channel electrodes implanted directly into the muscle. Various current intensities (10, 16, 20, and 26 mA) produced tidal volumes above the baseline value, showing that this model is effective for the study of diaphragm performance at different levels of electrical stimulation

Respiratory muscle injury in animal models and humans

Respiratory muscle injury may result from excessive loading due to a decrease in respiratory muscle strength, an increase in the work of breathing, or an increase in the rate of ventilation. Other conditions such as hypoxemia, hypercapnia, aging, decreased nutrition, and immobilization may potentiate respiratory muscle injury. Respiratory muscle injury has been shown in animal models using direct muscle or phrenic nerve stimulation, acute inspiratory resistive loading, tracheal banding, corticosteroids, phrenic nerve section, and the mdx mouse. Although numerous examples of diaphragm injury have been shown in animal models, evidence in humans is sparse. Potential mechanisms which may contribute to respiratory muscle injury include high levels of intracellular calcium-activated degradative enzymes, non-uniformity of stresses and strains, plasma membrane disruptions, and activation of the inflammatory process.

A digital technique for stimulus artifact reduction

A method of recovering compound muscle action potentials which are overwhelm by a stimulus artifact is presented. In the specific example reported, such action potentials were recorded from the hamster diaphragm using an apposing platinum electrode for both stimulation and recording. To recover the artifact-free action potential, a combination of digital data acquisition and simple signal processing was employed. The recording of a stimulus artifact from a sub-threshold stimulus was used to subtract the artifact component from subsequent recordings and thus faithfully reveal the action potentials. The technique should find application in other preparations.