Comparison of Wire and Disc Leads to Activate the Inspiratory Muscles in Dogs

Abstract

ObjectiveHF‐SCS is a unique method of inspiratory muscle activation which results in coincident activation of the diaphragm and inspiratory intercostal muscles via spinal cord pathways and has the potential to provide respiratory support in ventilator dependent persons with spinal cord injury (SCI). The purpose of the present study was to examine the effectiveness of wire leads, which can be placed using minimally invasive techniques, to activate the inspiratory muscles.MethodsIn 5 anesthetized dogs, in separate trials, disc and wire leads were inserted onto the ventral epidural space at the T1–T4 spinal cord levels. The effects of electrical stimulation with disc, single wire, and two wire leads placed in parallel were compared.Outcome measuresAirway pressure generation following stimulation with disc and various configurations of wire leads were compared.ResultsSeveral different configurations of wire leads resulted in airway pressures that were similar to those generated with monopolar stimulation with disc leads (D). For example, monopolar stimulation (3mA, 300Hz, 0.2ms) with parallel wire leads in which each of the electrode contacts at the T2 were connected together and functioned as a common cathode (Y‐connection) and monopolar stimulation (separate cathode) at T2 both with a remote ground resulted in airway pressures that were 91±6 and 92±4%, respectively, of those achieved with D (NS for both). Bipolar stimulation (3mA, 300Hz, 0.2ms) with parallel wire leads using Y‐connection and with a separate cathode at the T2 and T3 level resulted in airway pressures that were 96 ± 4 and 94 ± 4%, respectively, of the pressures achieved with D (NS for both).ConclusionThese results suggest that specific configurations of wire leads, which can be placed via minimally invasive techniques, result in comparable activation of the inspiratory muscles compared to disc leads and may be a useful technique to restore ventilatory support in persons with SCI.Support or Funding InformationSupportNIH‐NINDS (R01NS064157)DisclosureDr. DiMarco is a founder of and has a significant financial interest in Synapse BioMedical, a manufacturer of diaphragm pacing systems and holds patents for spinal cord stimulation to restore cough and respiration (5,678,535; 5,911,218; 5,999,855; 8,751,004). Drs. DiMarco and Kowalski hold the U.S. patents for technology related to the content of this manuscript: Respiratory Muscle Activation by Spinal Cord Stimulation (8,352,036).