Multiple abdominal burst patterns observed during tracheobronchial coughing in anesthetized cats
Authors: Fullerton Amy L. , Shen Tabitha Y. , Musselwhite M Nicholas , Rose Melanie J. , Davenport Paul W. , Morris Kendall F. , Bolser Donald C. 
Published: June 2021

The cough motor pattern is classically defined as a neuromechanical sequence of inspiration, compression, and expulsion. This definition is most applicable to single coughs. However, humans routinely produce multiple expulsions per each inspiratory effort during single or repetitive coughing. The functional significance of this coughing pattern is not fully understood, but it could represent a mechanism to facilitate the stairstep movement of particulates and mucus up the airway tree against gravity in humans. This repetitive expulsion pattern following single inspiratory cough efforts has not been reported in animal models of coughing. In the anesthetized cat, repetitive coughing can be produced by either mechanical or chemical stimulation of airway afferents. We hypothesized that expulsive cough motor patterns consistent with those seen in humans could be observed in the anesthetized cat. Further, we have previously observed that thoracotomy depresses cough excitability, presumably though a decrease in pulmonary volume‐related feedback. We also hypothesized that thoracotomy would reduce the occurrence of coughs in which multiple expiratory bursts were observed. We investigated the cough patterns of 9 cats pre‐ (n=5) and post‐thoracotomy (n=4) for multiple abdominal bursting patterns during cough. Thoracotomized animals were artificially ventilated at a positive end expiratory pressure of 5 cmH2O. Electromyograms (EMGs) were recorded from the diaphragm, thyroarytenoid, and internal oblique muscles. Repetitive coughing was produced by mechanical stimulation of the intrathoracic airway. The percentage of cough epochs that contained at least one cough with a multiple bursting pattern was similar for closed (CC, 44±18%) and open chested (OC, 42±11%) animals. These patterns consisted of double abdominal bursts (71%), three abdominal bursts (23%) and four bursts (5%). Corresponding abdominal bursts had similar amplitudes in both CC and OC animals. In OC animals, the amplitude of the second abdominal burst (CC − 45±11 to 31±7%, p=n.s.; OC − 43±4 to 28±5, p<0.05) was significantly lower than the first. Thoracotomy prolonged E2 duration for coughs with only 1 expiratory burst (CC 1±0.2s; OC 2±0.4 s, p < 0.05), but not for multiple expiratory bursts (CC 0.6±0.1 s; OC 0.9±0.4 s). The time between multiple abdominal bursts (CC 232±16 msec; OC 233±32 msec) was not different after thoracotomy. In some animals, small amplitude bursts in thyroarytenoid EMGs occurred out of phase with multiple abdominal bursting, consistent with adductor/abdominal oscillations. We conclude that the anesthetized cat is capable of expressing multiple abdominal bursting following a single inspiratory effort during tracheobronchial coughing. Our results support the existence of multiple oscillatory patterns during repetitive tracheobronchial coughing in the cat. This pattern may be analogous to that exhibited by awake humans.Support or Funding InformationSupported by NIH HL 103415 and 1OT20D001983.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.