Rehabilitation of Idiopathic Pulmonary Fibrosis (IPF) Patients

Rehabilitation of IPF Patients: Effects of Exercise and Oxidant Stress

The incidence and prevalence of IPF increase exponentially with age, and IPF occurs more often in older males. Cigarette smoking and environmental dust exposures are known risk factors for developing IPF. For example, the recently deployed military population, as it ages, is at especially increased risk of IPF. No effective therapies exist, although lung transplantation is used to extend survival of selected patients.

Defining specific therapy to improve exercise tolerance and dyspnea in IPF patients is thus an urgent priority of veteran-oriented research programs.

Chronic lung disease is common in the veteran population. While chronic obstructive pulmonary disease (COPD) is most prominent, fibrotic lung diseases, typified by idiopathic pulmonary fibrosis (IPF), are clearly increasing. We have developed extensive experience with a VA idiopathic pulmonary fibrosis (IPF) population in the context of a randomized, controlled clinical trial of vasodilator therapy.

Based on the current literature and our preliminary experience with exercise testing in IPF patients, we hypothesize that:

1. Formal pulmonary rehabilitation (i.e., an aerobic exercise program) will result in improved outcomes for IPF patients, demonstrable as an:

   1. Increase in exercise tolerance as quantified by 6-minute walk test (MWT) distance;
   2. Decrease in post-exercise dyspnea as quantified by the Borg dyspnea scale; and an
   3. Overall subjective improvement in quality of life as quantified by Saint George's Respiratory Questionnaire.

2. Metabolic and physiologic mechanisms of improved exercise tolerance and decreased dyspnea will include:

   1. More efficient oxygen metabolism demonstrated by maximum O2 uptake (VO2max);
   2. Decreased post-exercise oxidant stress demonstrated by post-exercise isoprostanes and plasma total antioxidant capacity (TAC); and,
   3. Maintenance of maximum inspiratory and expiratory pressures (PInmax and PExmax).

Our Specific Objectives are:

1. To investigate formal pulmonary rehabilitation and exercise tolerance in IPF patients

   The following important endpoints will be assessed to test the working hypothesis that pulmonary rehabilitation improves exercise capacity and lessens dyspnea:

   1. 6-MWT distance;
   2. Dyspnea index; and,
   3. Quality of life (Saint George's Respiratory Questionnaire [SGRQ] and International Physical Activity Questionnaire [IPAQ]).

2. To assess changes in oxygen uptake, markers of oxidant stress and pulmonary function resulting from pulmonary rehabilitation

To test the working hypothesis that improved outcomes are associated with more efficient O2 utilization, decreased markers of oxidant stress and maintained effort dependent pulmonary function, the following variables will be measured:

1. Peak oxygen uptake (VO2peak) during constant load exercise;
2. Markers of oxidant stress, including plasma and urine isoprostanes; and,
3. Maximum inspiratory and expiratory pressures (PInmax and PExmax). Completion of these Specific Objectives will position our research group to conduct future studies of 1) mechanisms of exercise limitation and 2) antioxidant therapies, both in this defined population and those who are at risk of developing pulmonary fibrosis. The long term impact of this application is thus to develop effective pulmonary rehabilitation strategies for IPF patients, based on knowledge of underlying changes in oxygen metabolism and oxidant stress.

Inclusion Criteria:

• Clinical presentation consistent with IPF with onset between three months and 48 months prior to screening.
• Diagnosis made by high-resolution computed tomographic scan showing highly probable IPF.
• Absence of severe pulmonary hypertension (i.e., PAsys must be less than 55 mm Hg, based on echocardiography) and absence of decompensated right heart failure (NYHA class I or II acceptable).
• Age 40 through 80, inclusive.
• Abnormal pulmonary function tests (FVC 40-90% predicted or DLCO 30-90% predicted or impaired gas exchange with rest or exercise).
• Six-minute walk distance 150 m and 500 m.
• Worsening as demonstrated by any one of the following within the past year: > 10% decrease in percent predicted forced vital capacity or worsening dyspnea at rest or upon exertion, based on history.
• Ability to understand and sign a written informed consent form and comply with the requirements of the study.
• Absence of clinical features suggesting infection, neoplasm, sarcoidosis or collagen-vascular disease.

Exclusion Criteria:

• Echocardiographic evidence of severe pulmonary hypertension (PAsys>55 mm Hg, based on echocardiography or TR velocity 3.2 m/sec).
• Severe heart failure (NYHA class III or IV or LVEF < 45%).
• Six-minute walk distance < 150 m or > 500 m.
• FEV1/FVC ratio < 0.7 at screening (post-bronchodilator).
• Residual volume > 100% predicted.
• Any condition other than IPF likely to result in the death of the participant within the next two years.
• History of unstable or deteriorating cardiac or neurologic disease.
• Pregnancy or lactation. Patients who are: (a) pregnant or (b) breast feeding are excluded from the study.
• Current treatment with corticosteroids (either oral or inhaled), Cytoxan, azathioprine, colchicine, pirfenidone, anti-tumor necrosis factor therapy or endothelin receptor blockers. Prior treatment is permitted, but at least four weeks of treatment washout prior to inclusion in this study are required.
• Investigational therapy for any indication within 28 days prior to enrollment.
• Degenerative arthritis, cerebrovascular accident or other limitation to mobility preventing completion of the 6-minute walk test.
• Oxygen saturation on room air <80% at rest.