Abstract
Background: Assessment of severity of chronic obstructive pulmonary disease (COPD) is the cornerstone of therapy. Spirometric measurements have traditionally remained as the popular diagnostic tool of choice. Oxygenation and carbon dioxide removal cannot be assessed by Spirometry alone, especially during exercise. Therefore, we studied whether desaturation and hypercapnea occur in response to exercise in COPD patients.

Aims and Objectives: To know whether bicycle pedaling as an exercise can unravel the gas exchange abnormalities and airflow limitation that might be precipitated by physical activity. This is done by estimating the changes in Oxygen saturation by pulse oximetry, and by estimating the changes in Blood CO2 levels by capnography.

Materials and Methods: Thirty stable COPD patients and controls were included for the study. Here we measured the change in oxygen saturation from rest to submaximal exercise (done using bicycle ergometry). Concomitantly, we measured the change in carbon dioxide levels of expired air from rest to submaximal exercise.

Results: We found that COPD patients experience oxygen desaturation. ΔSaO2 (difference between resting and exercise SaO2) was only 1% in controls whereas 8.86% in COPD. Hypercapnia occurred in response to a submaximal exercise in COPD patients (End tidal carbon dioxide of 48.87 mmHg). We also found that they become tachypneic and show greater degree of exhaustion.

Conclusion: Our study points out that exercise-induced desaturation and hypercapnia are a definite occurrence in COPD patients. It is a marker of progressive disease. It can be used as a form of stress test for the pulmonary system.

Key words: Chronic Obstructive Pulmonary Disease; Exercise Induced Desaturation; Exercise Induced Hypercapnia; Tachypnea