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The Transplant Evidence Alert provides a monthly overview of the 10 most important new clinical trials in organ transplantation, selected and reviewed by the Peter Morris Centre for Evidence in Transplantation (Oxford University).
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Efficacy of Clonidine as an Adjuvant to Ropivacaine in Transversus Abdominis Plane Block in Adult Renal Transplant Recipients: A Double-blinded Randomized Controlled Trial

Anesth Essays Res. 2022 Apr-Jun;16(2):231-237 doi: 10.4103/aer.aer_92_22.

Transversus abdominis plane (TAP) block has been used to provide analgesia in renal transplant surgery with varying results. This study was designed to assess if the addition of clonidine in TAP block would decrease 24-h postoperative morphine consumption in adult renal transplant recipients.


Forty adult patients undergoing renal transplantation under general anesthesia in a tertiary care hospital were randomized into either group RC (TAP block with 20 mL of 0.5% ropivacaine plus 2 μ clonidine) or group R (TAP block with 20 mL 0.5% ropivacaine) after induction of anesthesia. Postoperative analgesia was provided using patient-controlled morphine. The primary outcome was 24-h patient-controlled morphine consumption. The secondary outcomes were a) intraoperative hemodynamics, b) fentanyl and ephedrine requirement, c) postoperative pain using the Visual Analog Scale at 0, 2, 6, 12 and 24 hours, d) time to first postoperative analgesia, e) postoperative hemodynamics, and f) side effects.


There was no significant difference in postoperative morphine consumption between the groups (25 mg in group RC vs. 28.5 mg in group R) (median interquartile range) (P = 0.439). Postoperative pain scores were comparable between the groups. Intraoperatively, fewer patients required rescue fentanyl in group RC (7 patients) as compared to group R (17 patients) (P = 0.003). Significantly more patients in group RC required ephedrine boluses as compared to group R (9 patients in group RC vs. 2 in group R, P = 0.014).


The addition of 2 μ clonidine to ropivacaine in TAP block did not reduce 24-h postoperative morphine consumption after renal transplantation. It reduced the need for intraoperative analgesics but increased the need for intraoperative ephedrine administration.

CET Conclusion
Reviewer: Mr Keno Mentor, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion: This randomised controlled trial examines the potential benefit and harm of adding clonidine to the current standard transversus abdominis plan (TAP) block regimen in patients undergoing renal transplantation. The primary endpoint was reduction in patient-controlled morphine consumption in the 24-hour post-operative period, which was shown to be similar between the test and control arms. One of the secondary endpoints, the rate of intra-operative hypotension, was significantly higher in the clonidine group. The mechanism of action and pharmacokinetics of clonidine in TAP blocks is poorly understood, making the effective dose and interaction with other agents difficult to predict. The authors cite several other studies using different doses of clonidine in various surgical scenarios, with conflicting results. The data from this study suggest that there is little benefit from the addition of clonidine to TAP blocks. Furthermore, the harm of intra-operative hypotension, which is a consistent finding in other studies, may have more serious implications in patients undergoing renal transplantation in terms of long-term graft survival.
Methodological quality
Jadad score 4
Allocation concealment YES
Data analysis PER PROTOCOL
Study Details
Aims: The aim of this study was to examine if adding clonidine in transversus abdominis plane (TAP) block would reduce the consumption of 24‑h postoperative morphine in adult kidney transplant recipients.
Interventions: Participants were randomised to receive either TAP block with ropivacaine plus clonidine (group RC) or TAP block with ropivacaine (group R) following the induction of anesthesia.
Participants: 40 adult (age 18–65 years) kidney transplant recipients.
Outcomes: The primary endpoint was 24‑h postoperative morphine consumption. The secondary endpoints were requirement for intraoperative fentanyl, postoperative pain, need for rescue analgesia (number of morphine bolus) and side effects.
Follow Up: 24 hours
Funding: No funding was received for this study
Publication type: Randomised Controlled Trial
Trial registration: CTRI/2017/07/009102
Organ: Kidney
Language: English
Author email:
MeSH terms: Kidney Transplantation