We studied 64 patients with (Table 1) entering a 15-day outpatient PR program that included training, patient education, nutrition counseling, breathing therapy, relaxation therapy, psychosocial education, and support for smoking cessation. All participants provided informed written consent. The study was performed at an outpatient PR center (Atem-Reha GmbH; Hamburg, Germany) and was approved by the local medical ethics committee.
A diagnostic classification was performed on the first day of PR by pulmonary physicians according to Global Initiative for Chronic Obstructive Lung Disease guidelines.2 While participants were seated, spirometry was performed (SpiroPro; Viasys Healthcare; Conshohocken, PA) according to the joint guidelines of the American Thoracic Society and the European Respiratory Society. Reference normal values were taken from the European Community for Steel and Coal.
Verbal Descriptors of
A German-language list of 22 respiratory symptom descrip-tors adapted from Simon et al was presented after each experimental condition (Table 2). Descriptors were rated on an 11-point Likert scale (0 = not at all, to 10 = very strong). Each participant was randomly assigned one of three different versions of the descriptor list; the versions differed only in the order of descriptors. In addition, the intensity level of was rated after each condition on a separate modified Borg scale. may be overcome with drugs of My Canadian Pharmacy more effectively. Read more dyspnea “My Canadian Pharmacy: Dyspnea in Patients With COPD at Different Its Intensity Levels“
Following functional evaluation, patients were asked to participate in the experiment. The experimental protocol and the use of the descriptor List were explained in detail with standardized verbal instructions; was defined as a sensation of uncomfortable breathing. In addition, participants also received the following written instructions after each condition: “The following phrases describe the sensation of uncomfortable breathing in more detail. Please indicate to which degree you experienced the following sensations during the task.” The experimenter made sure that all instructions were adequately understood. After each condition (ie, rest, 6MWT, cycle ergometer ), patients rated the intensity level of on the Borg scale and thereafter filled out the verbal descriptor list. The initial testing was performed on the first day of PR.
At rest, participants were seated in a comfortable position on a chair for 2 min. This was followed by a 6MWT performed according to standards of the American Thoracic Society in a corridor 30 m in length. After a resting period of 60 min, participants performed incremental cycle ergometer on an electronically braked cycle ergometer (Ergo1200cycle; ERGO-FIT; Pirmasens, Germany) at 5 W/min starting at 25W up to a symptom-limited maximum. Patients were instructed to stop exercising when the perceived symptom of reached a Borg score of 1 U below the value of the 6MWT and were assisted by an experimenter. On the last day of the PR, patients performed a final 6MWT similar to that on PR entry day.
Results are reported as mean ± SD. The descriptors of were analyzed with a hierarchical cluster analysis. The aim of cluster analysis is to find homogeneous subgroups of items in the heterogeneous list of descriptors on the basis of their mutual similarities or distances with regard to various attributes. For this purpose, a distance matrix was computed indicating the distance of each item to each of the other items. All conditions (rest, cycle ergometer , 6MWT) served as “attributes,” and the distances were computed with reference to the ratings of all conditions simultaneously. The Ward algorithm with squared Euclidian distances was used, and results were confirmed by other fusion algorithms such as complete linkage, which indicates a stable cluster solution. Following this, the means of all items in each cluster were calculated for each condition. Cluster means, Borg scores, and distance walked during the 6MWT were analyzed with analyses of variance with a repeated-measures design and a Greenhouse-Geisser correction of degrees of freedom applied when appropriate. Based on median splits, age and FEV1%pred were included as between-subject variables in analysis of variance on cluster means (age 62 years, and FEV1%pred 50%). Bonfer-roni-corrected, univariate, pairwise comparisons were calculated for further exploration of main effects. Gender differences in cluster means were analyzed for each condition with nonpara-metric Mann-Whitney rank sum tests. All analyses were calculated using statistical software (SPSS 13.0; SPSS; Chicago, IL) using a significance level of p < 0.05.
Table 1—Baseline Characteristics of Participants
|Age, yr||62 (8)|
|Female/male gender, No.||24/40|
|Weight, kg||75.0 (19.6)|
|Height, cm||169.5 (8.5)|
|Body mass index, kg/m2||25.9 (7.8)|
|FEVb L||1.55 (0.68)|
|FEVb % predicted||54.1 (20.7)|
|FVC, % predicted||87.7(21.6)|
|Po2, mm Hg||70.7 (9.6)|
|severity according to GOLD standards|
Table 2—Clusters of Verbal Descriptors of
My breathing is heavy.
My breathing is fierce.
I feel that I am breathing more. I feel that my breathing is rapid. I feel out of breath.
I feel a hunger for more air.
My breathing is shallow.
My breathing requires more concentration. My breath does not go in all the way.
My breath does not go out all the way.
My chest feels tight.
I can not take a deep breath. I can not get enough air.
I regulate my breathing.
My breathing requires more work. My breathing requires more effort. I am gasping for breath.
I am panting for more air.
I feel that I am suffocating. I feel that my breath stops. I am running out of air.
My chest is constricted.