Vital signs (respiratory rate, blood pressure, heart rate, pulse oximetry) will be monitored for the two hours of the study. Continuous pulse oximetry will be used during the first study hour, and q5-minute spot-check pulse oximetry will be used during the second study hour; pulse oximetry monitoring will be changed to continuous mode during the second study hour if any spot-check reading falls below 98%. Other (non-pulse oximetry) vital signs will be monitored q5-minutes during the first study hour, and q15-minutes during the second study hour. These vital signs monitoring parameters represent the minimum for study subjects; treating clinicians or study staff physicians can increase the frequency of vital signs monitoring at their discretion. Any study subject not admitted to the hospital, will be discharged under the care of a responsible adult.