Levobupivacaine – dextran mixture for transversus abdominis plane block and rectus sheath block in patients undergoing laparoscopic colectomy: a randomised controlled trial

We performed a randomised controlled double‐blinded study of patients having laparoscopic colectomy with bilateral transversus abdominis plane block plus rectus sheath block, comparing a control group receiving 80 ml levobupivacaine 0.2% in saline with a dextran group receiving 80 ml levobupivacaine 0.2% in 8% low‐molecular weight dextran. Twenty‐seven patients were studied in each group. The mean (SD) maximum plasma concentration of levobupivacaine in the control group (1410 (322) ng.ml^?1) was higher than the dextran group (1141 (287) ng.ml^?1; p = 0.004), and was reached more quickly (50.6 (30.2) min vs 73.2 (24.6) min; p = 0.006). The area under the plasma concentration–time curve from 0 min to 240 min in the control group (229,124 (87,254) ng.min.ml^?1) was larger than in the dextran group (172,484 (50,502) ng.min.ml^?1; p = 0.007). The median (IQR [range]) of the summated numerical pain rating score at rest during the first postoperative 24 h in the control group (16 (9–20 [3–31]) was higher than in the dextran group (8 (2–11 [0–18]); p = 0.0001). In this study, adding dextran to levobupivacaine decreased the risk of levobupivacaine toxicity while providing better analgesia.