Mechanisms of Dyspnea Respiratory sensations are the consequence of interactions between the efferent, or outgoing, motor output from the brain to the ventilatory muscles (feed-forward) and the afferent, or incoming, sensory input from receptors throughout the body (feedback), as well as the integrative processing of this information that we infer must be occurring in the brain (Fig. 33-1). A given disease state may lead to dyspnea by one or more mechanisms, some of which may be operative under some circumstances but not others. .