As part of the study protocol, a blood sample (5 mL) will be taken from the IV and sent for genetic analysis. (However, in order to limit the amount of blood drawn from small babies, 3 ml will be drawn, not 5 ml, if the patient is less than 6 months or less than 10kg.) The genetic testing is specifically to analyze the following genotypes only: CYP2D6 and CYP3A4, which represent the differences in cytochrome P450 metabolism of oxycodone.