title: Coupling of dyspnea perception and tachypneic breathing during hypercapnia.
abstract: Respiratory rhythm is susceptible to behavioral influences including emotions. Since laboratory dyspnea induces negative emotions, we examined whether tachypneic breathing occurs in relation to perception of dyspnea during CO(2) rebreathing (n=21). Dyspnea intensity scored by a visual analog scale and respiratory frequency started to increase rapidly once the intensity of the stimuli exceeded a threshold for the end-tidal CO(2) fraction. The thresholds for dyspnea and respiratory frequency were similar (7.5±0.1% and 7.6±0.2% of the end-tidal CO(2) fraction, respectively), while the threshold for tidal volume (8.0±0.2%), when the tidal volume had stabilized, was significantly higher than the thresholds for dyspnea (p<0.01) and respiratory frequency (p<0.05). A positive correlation was found between the thresholds for dyspnea and respiratory frequency (r=0.81, p<0.001), and these thresholds showed good agreement on a Bland-Altman plot. These findings suggest that the start of tachypneic breathing is coupled with the threshold for dyspnea.
authors.affiliation: Department of Physiology, Showa University School of Medicine, Tokyo, Japan. masahiko@med.showa-u.ac.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Izumizaki
authors.forename: Yuri
authors.initials: Y
authors.lastname: Masaoka
authors.forename: Ikuo
authors.initials: I
authors.lastname: Homma
mesh_terms: D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D006935:Hypercapnia / Q000150:complications / Q000503:physiopathology*; D008297:Male; D010465:Perception / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology; D059246:Tachypnea / Q000209:etiology / Q000503:physiopathology*; D013990:Tidal Volume; D055815:Young Adult