The impact of affective states on the perception of dyspnea in patients with chronic obstructive pulmonary disease
Introduction
Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease with significant extrapulmonary (systemic) effects, which is characterized by not fully reversible and usually progressive airflow limitation based on abnormal inflammatory response of the lung to noxious particles or gases (GOLD, 2008). COPD is a leading cause of morbidity and mortality worldwide and associated with significant social and economic burden as well as considerable reductions in patients’ quality of life (GOLD, 2008, Ries, 2006). The prevalence and burden of COPD are projected to dramatically increase in the coming decades. For example, the Global Burden of Disease study concludes that COPD worldwide will increase from 1990 to 2020 its rank number of death rising from rank 6 to rank 3, and its rank number of disability-adjusted life years lost from rank 12 to rank 5 (Lopez and Murray, 1998, Murray and Lopez, 1996). The cardinal symptom of COPD is dyspnea (breathlessness), the subjective experience of uncomfortable breathing (American Thoracic Society, 1999, GOLD, 2008). At early stages of COPD, dyspnea usually develops during physical activities and exercise, whereas at later stages of the disease, it is already present at rest. The experience of this frightening sensation often leads to activity avoidance, deconditioning and subsequently greater dyspnea at lower activity levels (GOLD, 2008).
A growing body of literature suggests that psychological factors such as emotions, previous experiences, attributions, contextual, attentional and learning processes can profoundly impact the perception of dyspnea, often independent of changes in the respiratory system (Chetta et al., 2005, De Peuter et al., 2004, Lehrer et al., 2002, Rietveld and Creer, 2003, von Leupoldt and Dahme, 2007). Particularly affective states and negative emotions have been demonstrated to be associated with inadequate reporting of dyspnea. Previous studies in healthy volunteers and patients with asthma have shown that individuals characterized by high negative emotionality report more dyspnea or respiratory sensations than those with low negative emotionality, regardless of their respiratory status (Bogaerts et al., 2005, De Peuter et al., 2008, Han et al., 2004, Li et al., 2006, Put et al., 2004, Vögele and von Leupoldt, 2008). Similarly, the experimental induction of negative affective states in healthy individuals and patients led to increased reports of respiratory sensations such as dyspnea (Bogaerts et al., 2005, Rietveld and Prins, 1998, von Leupoldt et al., 2006a, von Leupoldt et al., 2006b, von Leupoldt et al., 2008). In particular the affective unpleasantness of perceived dyspnea, rather than the sensory intensity of perceived dyspnea, has been suggested as being vulnerable for affective influences (De Peuter et al., 2007, von Leupoldt et al., 2006a, von Leupoldt et al., 2008) and as being important in patients’ everyday life (Banzett et al., 2000, Lansing et al., 2009). However, little is known about the influence of affective states on the perception of dyspnea in patients with COPD (Nici et al., 2006, O’Donnell et al., 2007). Specifically in this patient group, a strong affect–dyspnea-relationship can be assumed, given the high prevalence of comorbid anxiety and depression in patients with COPD (Hill et al., 2008, Maurer et al., 2008, Mikkelsen et al., 2004, Vögele and von Leupoldt, 2008), which is further associated with less favourable treatment outcome and negative course of disease (Dahlen and Janson, 2002, Ng et al., 2007, Xu et al., 2008).
Therefore, the present study examined the impact of affective states on the perception of dyspnea in patients with mild to severe COPD. Affective states were induced by viewing affective picture series of positive and negative valence while dyspnea was simultaneously elicited by two constant cycle ergometer exercise tests (CEET). Based on the above reported previous findings in healthy individuals and patients with asthma, we hypothesized greater dyspnea ratings during a negative compared to a positive affective state. In addition, we studied the differential relationships of the affective unpleasantness versus the sensory intensity of exercise induced dyspnea with symptoms during everyday life and with health-related quality of life (HRQL).
Section snippets
Participants
Thirty patients (12 female) with mild to moderate COPD were studied after providing informed written consent. A diagnostic classification was performed by pulmonary physicians according to GOLD guidelines (GOLD, 2008). While participants were seated, spirometry was performed using a Master Screen Body Jaeger (Viasys Healthcare Inc., Conshohocken, PA) according to the joint guidelines of the American Thoracic Society and the European Respiratory Society (Miller et al., 2005). Reference normal
Affective ratings
Affective ratings differed significantly between the two CEETs in valence, t(29) = 13.84, p < 0.001 and arousal, t(29) = −7.79, p < 0.001. Valence ratings showed the expected greater pleasantness during the CEET with parallel viewing of the positive series (7.7 ± 1.5) when compared to the CEET with parallel viewing of the negative series (1.9 ± 1.1). Arousal ratings were higher during the CEET with parallel viewing of the negative series (6.7 ± 1.6) compared to the CEET with parallel viewing of the positive
Discussion
In the present study, dyspnea was induced in patients with mild to moderate COPD by two constant cycle ergometer exercise tests. Cardiopulmonary measures (FEV1, HR and SpO2) and the fixed work rate of 75% Wmax confirmed that both CEETs were performed at comparable exercise intensity. During these CEETs, the affective state of the patients was successfully modulated by parallel viewing of affective picture series, which led to significantly greater experience of pleasantness during the CEET with
Acknowledgements
The authors wish to thank F. Petermann and N. Karpinski for assistance with the German version of the SGRQ. This study was partially supported by a stipend (Heisenberg-Stipendium, DFG LE 1843/9-1) from the German Research Society (Deutsche Forschungsgemeinschaft, DFG) to A.v.L.
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