A single-centre randomized-controlled trial to study effect of dilution on propofol-induced injection pain at injection site

BACKGROUND: Propofol is a commonly used short-acting intravenous anaesthetic agent. A major disadvantage of propofol is pain at injection site with high incidence up to 90%. Various modalities have been tried to obtund propofol-induced pain; however, search for an ideal agent continues. We assessed the effect of double and triple dilution of 1% propofol emulsion with normal saline on pain at injection site. METHODS: This randomized, double-blinded study was done on 60 adult patients of both sexes, belonging to ASA grade I and II scheduled for elective surgery under general anesthesia, divided into three groups named I, II, III of 20 patients each. The patients of group I, II, and III received 1% propofol 2 ml, 0.5% propofol 4 ml, and 0.33% propofol 6 ml, respectively, over a period of 4 s and pain felt was assessed. RESULTS: There was no statistically significant difference in the pain score in group II as compared to patients in group I. However, there was a statistically significant decrease in the pain score in group III as compared to patients in group I (P value 0.02) and group II (P value 0.03). CONCLUSIONS: We found a significant decrease in both incidence and severity of pain during injection with a 0.33% propofol solution without significant adverse hemodynamic effects. The small size of data was a limitation in our study and a large-scale study will be needed to prove its therapeutic beneficence.