Normal cardiac and respiratory functions should be maintained during pediatric cardiac catheterization. Propofol has become a popular choice for sedation in children, however, it depresses cardiac and respiratory functions. Some investigators reported that ketamine attenuates its depressant effect, but it remains unclear whether ketamine reduces cardiac and respiratory depression caused by propofol in pediatric cardiac catheterization.

Inclusion Criteria:

• 7kg-25kg (6mo-10yrs) children who undergo cardiac catheterization

Exclusion Criteria:

• patients who have neurological disease,
• endocrinological disease,
• airway anomaly, who require positive pressure ventilation