Breathlessness and inflammation: potential relationships and implications.

PURPOSE OF REVIEW: Breathlessness and chronic inflammation both span a wide range of disease contexts and hold prognostic significance. The possibility of a causal relationship between the two has been hypothesized. The aims of this article are to review the intersections between breathlessness and inflammation in the literature, describe potential mechanisms connecting the two phenomena, and discuss the potential clinical implications of a causal relationship.

RECENT FINDINGS: There is a very limited literature exploring the relationship between systemic inflammation and breathlessness in chronic obstructive pulmonary disease, heart failure, and cancer. One large study in cancer patients is suggestive of a weak association between self-reported breathlessness and inflammation. Studies exploring the relationship between inflammation and Medical Research Council Dyspnoea grade in chronic obstructive pulmonary disease patients have produced inconsistent findings. Although a causal relationship has not yet been proven, there is evidence to support the existence of potential mechanisms mediating a relationship. This evidence points to a role for the skeletal muscle and stress hormone systems.

SUMMARY: There is much progress to be made in this area. Interventional studies, evaluating the impact of anti-inflammatory interventions on breathlessness, are needed to help determine whether a causal relationship exists. If proven, this relationship might have important implications for both the treatment and impact of breathlessness.