Exercise-induced desaturation and electrocardiogram changes in people with severe lung disease: an exploratory investigation of 25 serial cases.

Background: Arterial desaturation is a commonly accepted clinical basis for discontinuing physical activity in people with chronic obstructive pulmonary disease.

Objective: The purpose of this exploratory study was to examine the electrocardiograms of people with severe chronic obstructive pulmonary disease recovering from exercise-induced arterial desaturation.

Subjects: Subjects (n = 25) walked for 6 minutes while oxygen saturation was monitored.

Methods: When the Spo2 decreased below 90%, subjects were asked to sit and rest while the electrocardiograms were recorded. For all patients, Spo2 decreased 11.6% on average below baseline during walking. Four patients developed dysrhythmias during desaturation, with a mean lowest Spo2 of 85%. The Spo2 in six other patients continued to decrease below 80% despite rest, yet these patients did not develop new dysrhythmias.

Conclusions: Our findings suggest that a decrease in Spo2 during exercise does not necessarily correlate with cardiac rhythm.