Chronic obstructive pulmonary disease (COPD) is a progressive debilitating lung condition.

Maximising the Functional Capacity of Subjects with COPD

Pulmonary rehabilitation, which involves exercise training and patient education, is an important intervention to maximise the functional capacity of subjects with COPD. Lung volume reduction surgery (LVRS), which involves the removal of predominantly emphysematous lung tissue, is another approach which has received increasing attention in the last few years. There are a number of trials being run by the Department of Respiratory Medicine evaluating both pulmonary rehabilitation (PR) and lung volume reduction surgery (LVRS) for subjects with COPD. The following are some of the trials being performed in appropriate COPD subjects -

1. A randomised controlled trial of the effect of lung volume reduction surgery (LVRS) plus pulmonary rehabilitation (PR) compared to pulmonary rehabilitation alone on upper and lower limb exercise capacity, lung function, dynamic lung volume and quality of life.
   
   
2. Assessment of peripheral muscle dysfunction via magnetic resonance spectroscopy (31P-MRS) before and after LVRS + PR compared to PR alone
   
   
3. Assessment of VA/Q distribution using multiple inert gas technique (MIGET) before and after LVRS +PR
   
   
4. Evaluation of resting energy expenditure (REE) before and after LVRS + PR
   

Figure 1:- Set-up for the measurement of resting energy expenditure

Many patients with COPD experience inordinate breathlessness during upper limb exercise due to the competing needs of the accessory muscles of respiration to be involved in both the task performance and in maintaining ventilation. The Department of Respiratory Medicine has recently conducted a study evaluating unsupported arm exercise capacity in subjects with COPD and compared this to supported arm exercise capacity and leg exercise capacity. It was shown that unsupported arm exercise, in terms of oxygen consumption, was the most limited task performed. The COPD subjects performed less work during all forms of exercise compared to healthy subjects with ventilatory constraints limiting arm and leg exercise capacity. However, unsupported arm exercise was also limited by arm fatigue and chest wall restraint when the arms were elevated above shoulder height.

If you are interested in further information regarding these trials, please contact Zoe Barker-Whittle on (02) 9515-5234.

Night Time Ventilatory Support

The Department of Respiratory Medicine has been studying patients with advanced COPD before and after a long period of night-time ventilatory support. We have found interesting changes in the way blood and air mix in the lungs, so that uptake of oxygen and elimination of carbon dioxide are more efficient after this treatment. An important paper detailing the mechanisms of the hypercapnia (an excessive amount of carbon dioxide in the blood) accompanying oxygen administration in these patients is in press in the American Journal of Respiratory and Critical Care Medicine.

ICU Follow Up Study

Patients admitted to RPA's Intensive Care Unit with acute respiratory failure and COPD often have severe limitation in lung function. Traditionally, those patients who require intubation and mechanical ventilation are perceived as having a poor prognosis. In 1995, researchers in the Intensive Care Unit identified all patients who had been admitted to hospital with COPD and required admission to intensive care during the five years from 1989 to 1994. There were 74 patients who met this criteria. In 1998, we undertook a follow-up study of this group of patients to determine their long term outcome.

The rates of mortality in the group were as follows: 20.3 per cent had died while in hospital, 38.9 per cent at six month follow-up, 48.9 per cent at one year, 56.9 per cent at two years and 62.5 per cent at three years. The mortality rate while in hospital is similar to that described in other series.

At the time of follow-up, we also administered a quality of life survey to all 12 of the surviving patients from this group. Results showed that physical and social functioning were significantly reduced in this group, compared with Australian norms for bronchitis.

We found that the long-term outcome of this patient group was similar to that documented in patients with COPD who had a comparable impairment of lung function but were not admitted to intensive care. This outcome was unaffected by the need for intubation. In fact, our study found that the data used by medical staff to predict outcome (such as arterial blood gas measurements, spirometry, baseline level of function and acute physiological score) were not predictive of long-term survival.

Clinical Trials

The Woolcock Institute of Medical Research has been continuing its clinical trials with COPD patients. We are testing a new inhaled bronchodilator, which so far we have found to have fewer side effects than those currently available.

Many of our studies are quite different to traditional asthma studies. Because of the irreversible nature of disease of the airways, the focus of our treatment research is on achieving improved exercise tolerance or quality of life, while reducing health care resource utilisation, rather than attempting to find a cure for the disease.