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Less Remains More in The Battle Against COPD

Chronic Obstructive Pulmonary Disease (COPD) is a group of progressive inflammatory diseases that cause airflow blockage and breathing-related problems (CDC, 2009). COPD damages the airways and lung tissue, and over a period of time, these changes result in more severe conditions such as pulmonary hypertension and right heart failure.

The precise pathophysiology of COPD is not entirely understood, however it is believed that a hypoxic drive exists in COPD sufferers, which acts as a stimulus to breathing. The ability of patients to tolerate CO2 retention (permissive hypercapnia) is thought to be an adaptive mechanism that lessens the work of breathing. Accordingly, there is a significant population of COPD patients who are chronic CO2 retainers while maintaining their pH in a normal range. In all cases, correction of hypoxaemia (low blood oxygen levels) takes precedence over concerns about CO2 retention.

Traditionally, there was concern in prescribing high levels of oxygen which may reduce the hypoxic drive, and in so doing remove the stimulus to breathe. Recent research however concludes that oxygen-induced hypercapnia (high carbon dioxide levels) rarely occurs, and it is even rarer that this leads to respiratory acidosis.

Low titer oxygen therapy has always been prescribed a safe and effective means of reversing hypoxaemia (low blood oxygen levels), and flow rates are usually prescribed to maintain the PaO2 between 60 and 65 mm Hg or the oxygen saturations between 90% to 92%.

Oxygen therapy must be closely monitored to prevent adverse effects such as oxygen toxicity, and CO2 retention. Individualized patient assessments and analysis of arterial blood gas measurements are important tools for clinicians to use in determining the optimal oxygen flow rate.

For further information, visit the American Thoracic Society at www.thoracic.org/ and view the latest Standards for the Diagnosis and Management of Patients with COPD at: http://www.thoracic.org/sections/copd/resources/copddoc.pdf