Physiological and systemic effects of activities of daily living in COPD patients.

Chronic obstructive pulmonary disease (COPD) is a major and growing cause of
morbidity and mortality throughout the world9. Major complaints of patients
with COPD are dyspnea, fatigue and activity limitation. Patients commonly adapt
their level of activity when they become progressively dyspnoeic, leading to
further decrease of their condition. Activities of daily living (ADL), however,
are necessary for daily life and losing the capability to perform them will
have important repercussions on quality of life.

Respiratory physiology
Since dyspnea is the main complaint in COPD, the first part of this protocol
focuses on this impairment. In healthy, during relaxed tidal breathing the
lungs return to a basal level of inflation, the functional residual capacity or
end-expiratory lung volume (EELV). Inspiratory capacity (IC) represents the
volume available for inspiration after EELV is subtracted from total lung
capacity. In COPD, however, lung hyperinflation comes up. Hyperinflation is
commonly defined as an elevation of the EELV. Dynamic hyperinflation occurs
when inspiration starts before expiration has been fulfilled, which occurs in
COPD patients during exercise. Inspiratory reserve volume is calculated as the
difference between IC and tidal volume. When this reserve is less then 500ml a
so-called dyspnea limit is reached. Several real life ADL at home were
investigated in COPD patients by our group. It was shown that even ADL are
leading to dynamic hyperinflation, dyspnea limit and decreased ventilatory
reserve. It is not known, however, whether increase in disease severity is
related with increase in ventilatory impairments during ADL.

Systemic inflammation
The second part of this protocol pays attention to systemic inflammation. Since
some years COPD is not longer seen as a pulmonary disease only, but classified
as a systemic disease. Stable COPD is associated with low-grade systemic
inflammation. Apart from systemic inflammation, other systemic or
extrapulmonary effects, like weight loss, skeletal muscle dysfunction,
cardiovascular disease, depression and osteoporosis, of COPD are identified.
Systemic inflammation has been suggested to play a role in the pathogenesis of
extrapulmonary effects of COPD. Earlier research by our group revealed enhanced
systemic inflammatory responses to both maximal and submaximal exercise and
even a 6 minute walking test, a measure for functional capability, in COPD
patients. It is unknown whether real ADL also produces such systemic responses.
Therefore, we want to investigate the effect of these activities on systemic
inflammation in COPD.

1. Respiratory physiology
Does severity of ventilatory impairment during ADL increase in patients with
respectively COPD GOLD stages II, III and IV?

2. Systemic inflammation
Do ADL in COPD patients lead to an increase in systemic inflammatory markers?

This research protocol consists of two parts. In the first part, respiratory
physiology during ADL will be measured at home and in the laboratory. These
measurements also serve as validation for performing ADL in a laboratory
setting instead of at home, which is needed for the second part of the
protocol. This second part will measure systemic inflammation during ADL in the
lab. Thirty stable COPD patients will be included, 15 for validation and
respiratory physiology and 15 for repiratory physiology and systemic
inflammation. Patients are interviewed to identify a daily activity that cause
them the most dyspnea. They are asked to perform this activity at their usual
pace until symptoms limit further performance. Physiologic responses during ADL
will be measured using a portable breath-by-breath system. In our lab, a
cannula will be inserted into an antecubital vein under local anesthesia to
obtain blood in rest, at the end of the activity and 30 and 60 minutes
afterwards to investigate markers of systemic inflammation.

The procedures used are part of the usual diagnostic procedure of COPD patients
and relatively innocent.