Efficacy of Low Dose Promethazine for Postoperative Nausea and Vomiting

There has been an increase in ambulatory surgical procedures performed across Canada; ambulatory procedures account for almost 70% of all surgeries. Postoperative nausea and vomiting (PONV) and pain are the most frequently reported adverse events by patients prior to discharge after ambulatory surgery. The incidence can be as high as 70 to 80% in high-risk patients.

PONV is a cause of morbidity particularly in gynecological procedures and the incidence of patients experiencing PONV is as high as 58-75%. Apart from delayed recovery, the occurrence of PONV has been linked to gastric aspiration, psychological distress and wound dehiscence. The occurrence of PONV delays patient discharge and further more is a leading cause of unexpected admission after ambulatory anesthesia

Promethazine, is an antiemetic medication that has been widely used over the last 50 years, and although effective at reducing PONV, it tends to cause sedation. In this study, we are trying to determine if a smaller dose of promethazine, in addition to the standard treatment for post-surgical nausea and vomiting, will be more beneficial than the standard treatment on its own.

It is hypothesized that the use of low dose promethazine (3 mg) as part of a multimodal antiemetic regimen will be efficacious in preventing PONV without the sedative effects of promethazine.