Strategies for the Integration of Cough and Swallow to Maintain Airway Protection in Humans

Abstract

These results give insight into the differences between the cat and human models in airway protective strategies related to the coordination of cough and swallow behaviors, allowing for better understanding of dystussia and dysphagia.

Coordination of airway protective behaviors and swallow: effects of afferent feedback and sex.

“…This study showed reliable integration of cough and swallow, an increase in cough epochs and an increase in inspiratory and compression phase duration during the combined stimuli protocol. The most interesting finding of this study was the participants' ability to swallow in any phase of cough, unlike the cat, to maintain a certain range of lung volume during eupnea and repetitive cough (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b). This indicated that volume targeting may play a larger role than phase preference.…”

“…Despite the progress that has been made in the last century to understand the complex behavior of swallow, our mechanistic understanding of this important behavior is limited. Classically, swallow has been regarded as a strictly brainstem-mediated behavior, but more recent studies have determined that afferent feedback is important in the coordination of swallow with breathing cycle (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b;McFarland, Martin-Harris, Fortin, Humphries, Hill, & Armeson, 2016;Wheeler Hegland, Huber, Pitts, Davenport, & Sapienza, 2011b;. In the cat, swallow normally occurs in the late expiratory (E2) phase of the cough breathing cycle , but upper abdominal laparotomy produces a significant shift of swallow to the inspiratory phase of the breathing cycle.…”

“…In the cat, swallow normally occurs in the late expiratory (E2) phase of the cough breathing cycle , but upper abdominal laparotomy produces a significant shift of swallow to the inspiratory phase of the breathing cycle. Several studies in the human demonstrate that-regardless if swallow occurs as a single (Wheeler or sequential events (Wheeler Hegland, Huber, Pitts, Davenport, & Sapienza, 2011b), with a thin or thick consistency bolus (McFarland, Martin-Harris, Fortin, Humphries, Hill, & Armeson, 2016;, or if the system is challenged to coordinate with cough epochs (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b)-swallow occurs during a targeted lung volume of 45-65% of vital capacity (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b;McFarland, Martin-Harris, Fortin, Humphries, Hill, & Armeson, 2016;Wheeler Hegland, Huber, Pitts, Davenport, & Sapienza, 2011b;. In a previous publication, we reported this and developed the concept of lung volume targeting which can explain swallow occurrence across any phase of cough in the human (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b Anesthetic level was evaluated by withdrawal reflex of the forelimb and hindlimb and licking in response to oral water administration.…”

“…The way in which breathing is analyzed or observed shapes the way we define the phases of this behvaior. Analysis of breathing from airflow traces corresponds with two phases: inspiration and expiration (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b;Wheeler Hegland, Huber, Pitts, Davenport, & Sapienza, 2011b). Analysis of breathing from inspiratory muscles such as the diaphragm results in three phases: inspiration, the transition from inspiration to expiration and expiration.…”

“…In humans, swallow timing is dependent on lung volume (Huff, Reed, Smith, Brown, Ovechkin, & Pitts, 2018b;McFarland, Martin-Harris, Fortin, Humphries, Hill, & Armeson, 2016;, which has been attributed to volume-related feedback via activation of PSRs. This is consistent with our results in the male rodents.…”