We wish to examine the safety and speed of onset of giving a dose of 1mg hydromorphone followed by an additional 1mg. Eligible patients will be given 1 mg IV hydromorphone. At 15 minutes, these patients will be asked the question, "Do you need more pain medication?" Those that answer "yes" will receive an additional 1mg IV hydromorphone. Those that answer "no" will not receive additional pain medications at that time period (15 minutes). Thus, we wish to give up to 2 mg IV hydromorphone titrated to patients' pain, which we believe will result in less incidence of oxygen desaturation.