Respiratory kinematic and airflow differences between reflex and voluntary cough in healthy young adults

Abstract

Background: Cough is a defensive behavior that can be initiated in response to a stimulus in the airway (reflexively), or on command (voluntarily). There is evidence to suggest that physiological differences exist between reflex and voluntary cough; however, the output (mechanistic and airflow) differences between the cough types are not fully understood. Therefore, the aims of this study were to determine the lung volume, respiratory kinematic, and airflow differences between reflex and voluntary cough in healthy young adults.Methods: Twenty-five participants (14 female; 18–29 years) were recruited for this study. Participants were evaluated using respiratory inductance plethysmography calibrated with spirometry. Experimental procedures included: (1) respiratory calibration, (2) three voluntary sequential cough trials, and (3) three reflex cough trials induced with 200 μM capsaicin.Results: Lung volume initiation (LVI; p = 0.003) and lung volume excursion (LVE; p < 0.001) were significantly greater for voluntary cough compared to reflex cough. The rib cage and abdomen significantly influenced LVI for voluntary cough (p < 0.001); however, only the rib cage significantly impacted LVI for reflex cough (p < 0.001). LVI significantly influenced peak expiratory flow rate (PEFR) for voluntary cough (p = 0.029), but not reflex cough (p = 0.610).Discussion: Production of a reflex cough results in significant mechanistic and airflow differences compared to voluntary cough. These findings suggest that detection of a tussigenic stimulus modifies motor aspects of the reflex cough behavior. Further understanding of the differences between reflex and voluntary cough in older adults and in persons with dystussia (cough dysfunction) will be essential to facilitate the development of successful cough treatment paradigms.

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

“…Martin Harris used, “after I remove the syringe from your lip you may swallow whenever you feel comfortable,”[39] and in later studies the instructions read, “drink the liquid in your usual manner” [32]. Hegland and Troche more recently have used, “cough like something went down the wrong pipe” [45]. As have been reported by others, an instruction of, “cough like there is something in your throat” produces a robust and reliable response [45].…”

“…Hegland and Troche more recently have used, “cough like something went down the wrong pipe” [45]. As have been reported by others, an instruction of, “cough like there is something in your throat” produces a robust and reliable response [45]. Common for cued swallow is, have the participant hold the bolus in their mouth and swallow when prompted/ready [46], however McFarland, [18] demonstrated that cueing can have a significant effect on LV during swallow.…”

Cough Expired Volume and Cough Peak Flow Rate Estimation Based on GA-BP Method

“…Brandimore et al established a linear relation among CEV values, airflow rates, and number of coughs through analyzing the measured data of 25 participants (14 females and 11 males with an average of 23 years old). e results demonstrated significant linear relationships between expired volume, the total number of coughs, and cough airflow rates [6]. Particle velocimetry (PIV) method has been also used to estimate ranges of cough velocities.…”

“…When the respiratory tract is stimulated by inflammation, dust, or some particulate matters, cough behavior is performed to clear respiratory secretions to keep the respiratory tract clean and unobstructed [1][2][3][4][5]. Because of the high pressure difference between the inside and outside of the thoracic cavity, a high airflow rate is generated to impose a great shear force on the surface of secretions and propel them to the mouth [6].…”

Brainstem mechanisms underlying the cough reflex and its regulation

“…Reflex and voluntary coughing present similarities, but differ in very important respects. The cough reflex is subject to a high degree of voluntary control, so that all possible cough motor patterns can be mimicked and the frequency and intensity of spontaneous cough can be modulated up to complete suppression (see Magni et al, 2011;Mazzone et al, 2011;Ando et al, 2014;Brandimore et al, 2015 also for further Refs.). Interestingly, the habitual voluntary suppression of cough may lead to pathological processes in poorly draining lung regions and has been implicated in the Lady Windermere syndrome (see e.g.…”