Spectral Analysis of Respiratory Responses to Tracheobronchial and Laryngeal Stimulation in Cats

Abstract

Baráni H., M. Javorka, J. Jaku‰, I. Poliaãek, A. Stránsky: Spectral Analysis of Respiratory Responses to Tracheobronchial and Laryngeal Stimulation in Cats. Acta Vet Brno 2005, 74: 191-198.The power spectral analysis of the phrenic nerve activity during eupnoeic inspiration and during inspiratory phase of mechanically induced tracheobronchial and laryngeal cough was performed on cats anaesthetized by chloralose or pentobarbital. Distribution of the spectral power was analysed in the four frequency bands: p0-20, p20-40, p40-60, p60-80, which represent frequency range of the corresponding percentage intervals of total spectral power. The computed spectra were compared. The total power of cough inspiratory activity was several times higher, comparing to inspiration during quiet breathing. Cough spectra revealed the higher power at lower frequency range, being demonstrated as a narrower p0-20, comparing to the quiet breathing. No significant differences were determined in spectral power distribution between tracheobronchial and laryngeal coughs. The effect of anesthesia was manifested by narrower power interval p0-20 for eupnoeic inspiration and p40-60 for both types of cough (inspiratory phase) in cats under chloralose anesthesia, compared to those under pentobarbital anesthesia. Our findings indicate the significant differences in power spectra of phrenic nerve activity during eupnoea and cough. Phrenic nerve activity, quiet breathing, tracheobronchial and laryngeal cough, pentobarbital and chloralose anesthesiaAn important feature of the respiratory neural control system is a tight coordination among different respiratory motoneuron populations working together in order to assure an adequate ventilation. During inspiration, the phrenic and external intercostal motoneurons fire to produce inspiratory (I) airflow, whereas motoneurons innervating laryngeal abductors are activated in I phase of breathing in order to widen the laryngeal calibre. The synchrony of these firing activities implies the possible existence of common inputs from the neuronal circuits from breathing central pattern generator to the different respiratory motoneuron pools.The method of power spectral analysis (Ackerson et al. 1983;Cohen et al. 1987;Baráni et al. 1987;Richardson 1988;Marchenko et al. 2002;St. John and Leiter 2003) was successfully used to study the electrophysiological signals during breathing. Two prominent fast rhythms are generally involved in the phrenic neurogram, being manifested as periodic bursts of the phrenic nerve activity and the peaks in the power spectrum of this activity. These rhythms were named the medium-frequency oscillations (MFOs, with usual frequency range 20 -50 Hz) and the high-frequency oscillations (HFOs, in frequency range 50 -100 Hz) (Cohen et al. 1987). The similar rhythms during eupnoea are also detectable in the diaphragmatic muscle activity, as well as in I bursting activities of other nerves (e.g. the recurrent laryngeal or hypoglossal nerves) in cats under a variety of conditions (anaest...

Wavelet Analysis of Electrical Activities from Respiratory Muscles during Coughing and Sneezing in Anaesthetized Rabbits

“…On the contrary, our present data on rabbits showed lower relative contribution of lower frequencies (PP 6I ) to the total power in the cough, when compared to quiet respiration. We have to emphasize that present analysis and that of Baráni et al (2005) were done qualitatively on different types of electrical signal (DIA vs. phrenic nerve) using different filtering and methods of calculating spectral characteristics. Moreover, experiments were performed on a different species (rabbits vs. cats).…”

“…Power spectral analysis has been applied on inspiratory activity of the phrenic nerve during cough and quiet breathing before (Baráni et al 2005) with the results indicating a significant increase of power in the cough spectra not proportional to the power distribution in the spectra for quiet inspiration in anaesthetized cats. The spectral power was concentrated within the range of low frequencies in cough compared to quiet inspiration.…”

“…Previous studies preferred the Fourier transformation to analyze frequency characteristics of inspiratory motor output during quiet breathing (Ackerson et al 1983;O'Neal et al 2005), the cough reflex (Baráni et al 2005), and the aspiration reflex (Tomori et al 1995), but the Fourier transform decomposes a signal into infinitely long harmonic components, thus losing temporal resolution. Short Time Fourier Transform (STFT) uses an equal length of the weighting function during analysis resulting in a constant time-frequency resolution making the method appropriate for stationary signals with properties that are stable over time.…”

“…Power spectral analysis derived from the Fourier transformation is a commonly used method of frequency analysis (Ackerson et al 1983;Baráni et al 2005). Typical characteristics of the power spectrum in respiratory motor output are the centroid frequency (Watchko et al 1987) and high frequency oscillations (HFOs).…”