This within-subject study compared the effects of hyperinflations with 20% above maintenance oxygen (O2) level and 100% O2 hyperinflations before and after endotracheal suction in 11 acutely ill patients with chronic obstructive pulmonary disease. Four hyperinflations were delivered at 1.5 times the calculated tidal volume (10 ml/kg) with 100% O2 or 20% above maintenance O2 level via resuscitator bag, followed by 10 seconds of continuous endotracheal suctioning. This sequence was repeated three times. No statistically significant differences (p less than 0.05) were found between the two protocols for arterial oxygen saturation, blood pressure, or heart rate (analysis of variance for repeated measures). There was no change in heart rhythm for any of the subjects. The results of this study suggest that hyperinflation with 20% above maintenance O2 level can be used for oxygenation in patients with chronic obstructive pulmonary disease before and after endotracheal suctioning. Replication is needed before clinical implementation.