Effect of nasal airflow on respiratory pattern variability in rats

Introduction: The nasal airway a common route for normal breathing. Difficulty in nasal breathing due to nasal blockage is associated with abnormal respiratory pattern during sleep. The aim of this study was to investigate whether alteration in nasal airflow can change respiration pattern variability. Methods: Healthy male Wister rats were randomly divided into 4 groups including: control, saline, nasal obstruction and nasal cavity lidocaine anesthesia. The animals underwent bilateral nasal obstruction using cauterization and locally nasal cavity anesthesia using 10% lidocaine. Respiration of conscious animals recorded using whole-body plethysmography. Results: Respiratory signal analysis revealed a dramatic increase in variability of respiratory rhythm that quantified with increase in the standard deviation of inter-breath interval, inspiration time and mean of IBI, expiration and expiration to inspiration time ratio in both nasal obstruction and nasal anesthetized animals. Additionally, Power spectral density analysis showed higher variability in respiratory frequency, which characterized with broader dominant frequency and periodic respiratory pattern in nasal obstruction animals. Conclusion: These results proposed that, nasal airflow influences respiratory pattern variability. Nasal cavity flow receptors may contribute for these observations.