State and chemical drive modulate respiratory variability

Abstract

The quantification of respiratory variability may provide insight into the integrative control of breathing. To test the hypothesis that sleep and/or increased chemical drive modifies respiratory variability, six male adult Sprague-Dawley rats were instrumented with diaphragm electromyographic (EMG) electrodes and exposed to 0, 2.5, and 5.0% CO2 with a balance of room air during wakefulness and behaviorally determined sleep. Respiratory interval (Ttot), peak diaphragm EMG, and ventilation index (peak diaphragm EMG/Ttot) were calculated for 1,024 sequential breaths. The variability of breathing was quantified with a measurement of signal complexity, the approximate entropy, and two autocorrelation measurements, the autoregressive power spectrum slope and the detrended fluctuation analysis slope. Elevated chemical drive and/or sleep significantly modulated the variability of ventilation index and Ttot. There were also significant interactions between state and CO2 drive in all respiratory parameters. We conclude that state (sleep or wakefulness) and increased chemical drive affect respiratory variability differentially.

Sleep Breathing Flow Characteristics as a Sign for the Detection of Wakefulness in Patients with Sleep Apnea

“…Further studies have observed that respiratory variability is diminished during sleep, when compared with wakefulness [14]. However, there is an absence of studies in which the breathing patterns of wakefulness have been applied during sleep to improve the outcomes of a sleep study.…”

Effects of hypercapnia and hypocapnia on ventilatory variability and the chaotic dynamics of ventilatory flow in humans

“…Normocapnic resting ventilation was recorded during both sessions, but only the first recording was retained for (61) CD Surrogate data Burioka et al (7) CD Surrogate data Sako et al (53) CD Surrogate data El Khatib et al (17) CD Kolmogorov-Sinai Entropy Burioka et al (9) ApEn CD Surrogate data BuSha and Stella (10) ApEn Surrogate data Yeragani et al (74) ApEn LLE Suyama et al (65) CD Surrogate data Burioka et al (8) ApEn Surrogate data Thibault et al (68) LLE Miyata et al (36) CD Surrogate data Wysocki et al (72) Noise titration LLE CD Numbers in parentheses is the reference number. CD, correlation dimension; LLE, largest Lyapunov exponent; ApEn, approximate entropy.…”

“…However, CO 2 also influences the variability of ventilation and its complexity. In rats, progressive hypercapnia reduces the respiratory variability and increases the complexity of breathing as evaluated by the ApEn of breathing (10). In humans submitted to an hypercapnic challenge, the picture is less straightforward.…”

The effect of metabolic alkalosis on the ventilatory response in healthy subjects

“…However, effects of increased inspiratory CO 2 levels on variability of electrical activity of the diaphragm and ventilation are variable. Busha et al found that increased inspired CO 2 in rats resulted in a decrease of the CV of peak EAdi but also an increased breath-to-breath variability, indicating a difference in short-and long-term correlations in the variability of breathing (BuSha and Stella, 2002), whereas Fiamma et al found that hypercapnia decreased the breath-to-breath variability of ventilation (Fiamma et al, 2007). It is proposed by Nattie (BuSha and Stella, 2002;Nattie, 1999Nattie, , 2000 that there are multiple sites of chemoreception throughout the brain stem where different chemosensors may be more or less active during different levels of CO 2 .…”