Tramadol 2.5mg·kg~(-1) Appears to Be the Optimal Intraoperative Loading Dose before Patient-controlled Analgesia

Objective To identify the most appropriate inital dose to improve the quality of tramadol PCA.Methods During general anesthesia,80 patients undergoing radical operation of mastocarcinoma were randomly allocated to receive 1.25 mg/kg (Group Ⅰ), 2.5 mg/kg(Group Ⅱ), 3.75 mg/kg (Group Ⅲ),5mg/kg(Group Ⅳ) tramadol.The titration of additional tramadol by PCA every five minutes was performed in the postanesthesia care unit (PACU) until the visual analogue scale (VAS) score was≤3.An investigator blinded to study group recorded the VAS and side effects every ten minutes.Results In the PACU,significantly more tramadol ( 8.8 ± 2.9 vs 4.6 ± 2.3 , 2.0 ± 1.5 , 0.5 ± 0.4 , P 0.05 ),and a higher incidence (19/20 vs 6/20,4/20,3/20, P 0.05 ) of PCA use was observed in Group I compared to Groups Ⅱ-Ⅳ.VAS was significantly higher in Group I than in Groups Ⅱ-Ⅳ at zero and ten minutes ( P 0.05 ).Unexpected delayed emergence anesthesia (min) was observed in Group Ⅲ ( n =1) and in Group Ⅳ( n =2).Sedation was more important in Groups Ⅲ and Ⅳ than in Groups Ⅰ and Ⅱ( P 0.05 ).Conclusion When considering efficacy and side-efect profile, 2.5 mg·kg -1 of tramadol is the optimal intraoperative dose of this drug to provid effective postoperative analgesia with minimal sedation.