Spiral nerve cuff electrode for recordings of respiratory output

The feasibility of using the spiral nerve cuff electrode design for recordings of respiratory output from the hypoglossal (HG) and phrenic nerves is demonstrated in anesthetized, paralyzed, and artificially ventilated cats. Raw neural discharges of the HG nerve were analyzed in terms of signal-to-noise ratios and frequency spectra. The rectified and integrated moving average activity of the HG nerve had a peak value of 1.74 +/- 0.21 microV and a baseline value of 0.72 +/- 0.11 microV at elevated respiratory drive induced by increases in CO2 or oxygen deprivation when recorded with 10-mm-long cuffs. The frequency content of the HG electroneurogram extended from several hundred hertz to 6 kHz. Spiral nerve cuff recordings without desheathing of the nerve provided large enough signal-to-noise ratios that allowed them to be used as a measure of respiratory output and had much wider frequency bandwidths than the hook electrode preparations. A major advantage of the cuff electrode over the hook electrode was its mechanical stability, which significantly improved the reproducibility of the recordings both in terms of signal amplitudes and frequency contents.