Influence of intrathoracic vagotomy on the cough reflex in the anesthetized cat

Abstract

Recurrent laryngeal afferent fibers are primarily responsible for cough in response to mechanical or chemical stimulation of the upper trachea and larynx in the guinea pig. Lower airway slowly adapting receptors have been proposed to have a permissive effect on the cough reflex. We hypothesized that vagotomy below the recurrent laryngeal nerve branch would depress mechanically or chemically induced cough. In anesthetized, bilaterally thoracotomized, artificially ventilated cats, thoracic vagotomy nearly eliminated cough induced by mechanical stimulation of the intrathoracic airway, significantly depressed mechanically stimulated laryngeal cough, and eliminated capsaicin-induced cough. These results support an important role of lower airway sensory feedback in the production of tracheobronchial and laryngeal cough in the cat. Further, at least some of this feedback is due to excitation from pulmonary volume-sensitive sensory receptors.

A prospective examination of swallow and cough dysfunction after lung transplantation

“…[49][50][51][52] The observation that UTC appears diminished in both these populations may support findings in animal studies where, irrespective of if cough is stimulated at the larynx or intrathoracic airway, lung-volume related and pulmonary vagal afferent feedback was associated with modulation of cough. 22 Our RR findings are consistent with previous reports in patients with pulmonary disease, 53,54 and further align with a scoping systematic review which suggested that elevated RR is a physiologic risk factor for aspiration. 55 In a previous investigation, Scherer et al 56 measured ventilatory regulation in LT recipients during carbon dioxide rebreathing, finding that LT recipients had significantly lower maximum tidal volume and RR compared to healthy controls.…”

“…This cohort of LT recipients who undergo denervation of the lower airway distal to anastomosis provides a unique contrast to published data in individuals undergoing total laryngectomy who lack laryngeal afferents 49–52 . The observation that UTC appears diminished in both these populations may support findings in animal studies where, irrespective of if cough is stimulated at the larynx or intrathoracic airway, lung‐volume related and pulmonary vagal afferent feedback was associated with modulation of cough 22 …”

“…Indeed, pulmonary vagal denervation involved in LT procedures 20 places patients at risk for disruption to important governing neural circuitry that can adversely impact airway protection and defense 15,21,22 . Combined with the shared neuroanatomic pathways regulating breathing, swallowing, and cough, 23–27 it is plausible that impaired respiration and cough (dystussia) contribute to unsafe swallowing in LT recipients.…”

“…18,19 Indeed, pulmonary vagal denervation involved in LT procedures 20 places patients at risk for disruption to important governing neural circuitry that can adversely impact airway protection and defense. 15,21,22 Combined with the shared neuroanatomic pathways regulating breathing, swallowing, and cough, [23][24][25][26][27] it is plausible that impaired respiration and cough (dystussia) contribute to unsafe swallowing in LT recipients. Specifically, LT recipients with impaired breathing will likely exhibit difficulties with the rapid and precise reconfiguration required of respiratory and swallow subsystems to ensure safe swallowing.…”

Chronic cough—the limitation and advances in assessment techniques

“…Cough can be elicited by the activation of mechanically sensitive vagal afferent nerves projecting to the large airways (some specialised Aδ fibres, commonly named cough receptors) and lungs [mechanoreceptors, including rapidly adapting receptors (RARs) and slowly adapting receptors (SARs)] (15). In preclinical animal studies, the invasive intratracheal mechanical stimulation was found to induce the cough reflex in anaesthetised rabbits/cats/dogs (16)(17)(18)(19)(20). For humans in clinical practice, the common area where the mechanical stimulation has been applied are the large airways level and the chest (8,9).…”