Relief of dyspnea involves a characteristic brain activation and a specific quality of sensation

Central processing of dyspnea relief remains largely unknown.

To identify physiologic determinants, quality of sensation, and brain activation associated with dyspnea relief.

Dyspnea relief was induced in 10 healthy volunteers by decreasing an adjustable external resistive load ( approximately 15-50 cm H(2)O/L/s). Brain imaging (positron emission tomography) was performed during either dyspnea or relief.

Perceived intensity of moderate and high relief was similar to that of its preceding dyspnea (Borg scores = 5.10 +/- 1.49 vs. 5.3 +/- 1.4, and 2.78 +/- 0.94 vs. 2.99 +/- 0.94, respectively; P >/= 0.05) and was predominantly related to reversal of dyspnea-induced increased mouth pressure/ventilation ratio (r(2) = 0.88, P < 0.001). Dyspnea relief involved specific, mostly positively valenced descriptors (i.e., breathing-related pleasure and/or reward). Most significant relief-associated brain activation was detected in the left anterior cingulate cortex (Z score = 4.7, corrected P < 0.05) and additional activation (uncorrected P < 0.0001) in the posterior cerebellum and in the temporal and prefrontal cortices. For dyspnea, significant activation was located in the right caudate nucleus, the anterior cerebellum (Z = 5 and 4.65, respectively; corrected P < 0.05), and the premotor cortex, whereas deactivation occurred in the left prefrontal cortex (Z = 4.11).

Relief of acute load-induced dyspnea is not simply the neutral perception of dyspnea decrease but rather a strong, positively valenced sensation that is associated with characteristic brain activation distinct from that subserving dyspnea perception and possibly reflecting activation of a dyspnea modulation network.