Comparing lidocaine versus mepivacaine in obturator nerve block for transurethral resection of the bladder
During transurethral resection of the bladder (TURB) adductor muscle contraction can occur due to obturator nerve stimulation. Obturator nerve blockade (ONB) is a accepted method to decrease the risk of obturator nerve reflex (ONR) during TURB. Insufficient ONB and subsequent leg jerking lead to bladder perforation, increased bleeding and early tumor relapse. The use of a sufficient local anesthetic (LA) and an ultrasound (US)-based ONB technique lower the risk of an ONB failure. In this study we report the effect of two types of LA (lidocaine vs. mepivacaine) on the success rate of ONB as well as of other parameters.
In a non randomized, non blinded prospective trial the occurance of ONR was investigated in dependence of the LA. Patients in period 1 were treated with lidocaine, patients in period 2 with mepivacaine during TURB in a single institution. Further paramaters such as ONB techniques with or without US-guidance, TURB techniques (monopolar vs. bipolar), training level of surgeons and anesthesiologists and others were measured. Training level was grouped in medical doctors in training (residents) and specialists. Any kind of ONR was recorded as ONB failure. Pearson chi square test or t-test or Mann Whitney U test were used for statistical analyses with a p-value
In 277 ONB with following TURB in our institution, performed between 06/2014 and 07/2017, an overall success rate of 254/277 (91.7%) could have been showed. In the lidocaine-group an ONB-failure occurred in 18/138 (13.0%) while in the mepivacaine group a failure occurred in 5/139 (3.6%) (p=0.005). Grouped by the training level of the performing anesthesiologist, 15/105 (14.3%) failures occurred in the residents-group while 8/171 (4.7%) occurred in the senior-group (p=0.005). In the classic pubic approach ONB-group a failure occurred in 17/139 (12.2%) while in the US-guided technique 6/138 (4.4%) failures occurred (p=0.028). Other parameters did not show any significant difference. The parameters were tested in a logistic regression analysis. The odds ratio (OR) for the LA was 0.288 (CI = 95%-confidence interval 0.101-0.823). The OR for the ONB technique was 0.334 (95%-CI 0.123 - 0.911). The OR for the training level was 0.264 (95%-CI 0.105 - 0.664).
The use of mepivacaine instead of lidocaine for ONB in TURB reduces the risk of an ONB-failure with 71.2%. While the effects and side effects of the two LA are comparable, based on the results of our study we suggest the use of mepivacaine. The US-based technique showed less failures than the landmark-based techniques. So far in this series, a risk reduction of 66.6% was found when the US-based technique was used. An advanced training level finally showed a significant reduction in the failure rate of 73.6%.