Abstract: In this research,effects on arterial oxygenation for 25 post-cardiac operative patients by common suctioning,hyperoxygenation,hyperventilation and hyperoxygenation with hyperventilation were investiga-ted By statistical analysis,no obvious differences（P＞0.05）between comrnon suctioning and hyperventi-lation and between hyperoxygenation and hyperoxygenation with hyperventilation were found,but there were great differences between comrnon suctioning and hyperoxygenation and between common suctioning and hy-peroxygenation with hyperventilation（P＜0.01）.Conclusion:Hypoxemia caused by suctioning may be pre-vented by 1 minute 100%oxygen ventilation before suctioning.