Multidimensional measurement of breathlessness: recent advances.

PURPOSE OF REVIEW: Breathlessness is a multidimensional sensation for which a range of instruments exists for children, youth and adults, capable or unable to self-report distress with breathing. This review presents developments and applications of multidimensional assessments of breathlessness. RECENT FINDINGS: Excluding unidimensional measures and instruments assessing the impact of breathlessness, at least eight psychometrically robust instruments exist, which comprehensively assess one or more specific domains of the sensation of breathlessness (intensity, sensory quality, affective distress). These instruments have evolved from modest beginnings (describing breathlessness in various patient cohorts) to a growing use as primary or secondary outcomes in observational, clinical, and experimental trials exploring breathlessness mechanisms and intervention effects. For adults and children unable to autonomously communicate breathing discomfort, instruments include combinations of physiological and behavioural markers of distress. Nonverbal (graphic scales) have potential use beyond paediatric applications. SUMMARY: Traditionally, breathlessness has been considered as a 'black box' with unidimensional measures reflecting box size (intensity, unpleasantness). Multidimensional instruments reveal the composition of the black box of breathlessness allowing detailed descriptions of an individual's breathlessness experience, quantification of sensory qualities, affective distress, and emotional responses with the potential to capture change over time and treatment effects in each dimension.