SPIRAL NERVE CUFF ELECTRODE FOR RECORDINGS OF RESPIRATORY OUTPUT

The feasibility of using the spiral nerve cuff electrode design for re cordings of respiratory output from the hypoglossal (HG) and phrenic n erves is demonstrated in anesthetized, paralyzed, and artificially ven tilated cats. Raw neural discharges of the HG nerve were analyzed in t erms of signal-to-noise ratios and frequency spectra. The rectified an d integrated moving average activity of the HG nerve had a peak value of 1.14 +/- 0.21 mu V and a baseline value of 0.72 +/- 0.11 mu V at el evated respiratory drive induced by increases in CO2 or oxygen depriva tion when recorded with 10-mm-long cuffs. The frequency content of the HG electroneurogram extended from several hundred hertz to 6 kHz. Spi ral nerve cuff recordings without desheathing of the nerve provided la rge enough signal-to-noise ratios that allowed them to be used as a me asure of respiratory output and had much wider frequency bandwidths th an the hook electrode preparations. A major advantage of the cuff elec trode over the hook electrode was its mechanical stability, which sign ificantly improved the reproducibility of the recordings both in terms of signal amplitudes and frequency contents.