Sensitization in medically unexplained dyspnea: Differential effects on intensity and unpleasantness.
Chest. 2011 Oct 20;
Authors: Wan L, Stans L, Bogaerts K, Decramer M, Van den Bergh O
Abstract BACKGROUND:The present study investigated alterations in both the sensory (intensity) and affective component (unpleasantness) of dyspnea in patients with medically unexplained dyspnea (MUD) during repeated hypercapnic challenges. METHODS:The sensory and affective components were assessed every 20 sec during the baseline, rebreathing and recovery phases of three subsequent trials in patients (N=17) and matched healthy controls (N=15). Fractional end-tidal carbon dioxide (FetCO(2)) was monitored simultaneously and continuously. Peak intensity and unpleasantness were compared and intra-individual linear regression slopes between the dyspnea components and FetCO(2) were calculated. RESULTS:Both intensity and unpleasantness of dyspnea perception were higher in patients than in healthy controls. Also the regression slopes were steeper, but this was more prominent for the affective than for the sensory component in patients. Moreover, also across-trial increases in unpleasantness of peak dyspnea and of slopes of both components were observed in patients. CONCLUSIONS:MUD patients are particularly hypersensitive to the unpleasantness of dyspnea. The elevated breathlessness further increases across repeated challenges, documenting sensitization and suggesting that basic learning mechanisms contribute to exaggerated responding to respiratory challenges.
PMID: 22016486 [PubMed - as supplied by publisher]