All patients included in the initial sample were taken into account when estimating the effectiveness (intention to treat basis). The primary health outcomes used in the analysis were:
the time to the observer's assessment of alertness/sedation (OAA/S), ranging from 1 (wide-awake and alert) to 5 (asleep and/or unarousable), score of 3, or return to OAA/S score of 1;
pain during injection;
preoperative side effects;
the requirement for antiemetic medication;
the time to ambulation;
the time to home-readiness;
the time to actual discharge;
episodes of nausea and vomiting;
heart rate and systolic and diastolic blood pressure;
the respiratory rate and end-expiratory CO2;
the level of sedation (OAA/S);
the change in the anxiety status, measured using a 100-mm visual analogue scale; and
changes in psychomotor function, expressed as a percentage of the preoperative (baseline) score on the digital-symbol substitution test.
The study groups were comparable at baseline with respect to their age, ASA physical status and surgery details.