Levobupivicaine + Dextran for TAP & Rectus Sheath Blocks - Prolongs block? - Anaesthesia

Dextran is a complex branched glucan (polysaccharide made of many glucose molecules) composed of chains of varying lengths (from 3 to 2000 kilodaltons). It is used medicinally as an antithrombotic (antiplatelet), to reduce blood viscosity, and as a volume expander in hypovolaemia.

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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. "
© 2016 The Association of Anaesthetists of Great Britain and Ireland.

QUESTIONS ARISING
1. Very neat data.
2. Low weight average of patients ~60kg, ?equivalent population - they were lap colectomy patients
3. Two very experienced anaesthetists doing the block, not trainees.
4. None lost to follow up
5. Small study, ?power/ability to actually demonstrate harm, rather than simple block prolongation
6. Availability of dextran in your organisation
7. Applicability to other LA blocks/agents other than levobupivicaine