Consequences of Nocturnal and Daytime Hypoxemia in COPD

Hypothesis: Isolated nocturnal hypoxemia contributes to chronic systemic inflammation in
COPD by activating circulating neutrophils.

Inclusion Criteria:

- Adult males or females with a diagnosis of COPD screened for nocturnal desaturation
as indicated above.

- Clinical stability defined by absence of treatment change or need for acute care
within the last two months.

- Weight stable, within 5%, in the previous three months as measured during office
visits.

- Willingness to participate in a clinical study.

Exclusion Criteria:

- Acute illness within the preceding 2 months.

- Patients who received systemic glucocorticoid therapy within the past month.

- Clinical and/or overnight pulse oximetry evidence of obstructive sleep apnea (OSA).
The Multivariate Apnea Prediction Questionnaire (MAP) will be given to all patients
to assess the likelihood of OSA based on common symptoms of this disorder. While we
recognize that this screening instrument was not evaluated specifically in COPD
patients, it assesses common signs and symptoms of OSA. This tool has been shown to
identify OSA with 95% sensitivity (63). In addition, the ODI 4% will be determined
from the overnight pulse oximetry recording. Patients will be excluded if the MAP
score is > 0.4 or if the ODI 4% is >15/hour, which is suggestive of the concomitant
presence of obstructive sleep apnea.

- Hypercapnia defined as PaCO2 > 50 mmHg on resting arterial blood gas

- Previous diagnosis of erythrocytosis, pulmonary vascular disease, pleural effusions,
ischemic heart disease or congestive heart failure.

- No chronic illnesses known to affect the inflammatory response such as infection,
collagen vascular disease, liver disease, thyroid disease or diabetes.

- Primary care or pulmonary physician refusal.

- Patient refusal for any reason.

- Lack of capacity to participate in the informed consent process.