European Journal of Cardiovascular Medicine

Bladder cancer, the most common urological malignancy, is diagnosed and managed primarily through cystoscopy and transurethral resection of bladder tumor (TURBT). The goal of TURBT is to remove all visible bladder lesions, including underlying muscle tissue. TURBT is performed via a scope inserted through the urethra into the bladder and can be done under general or regional anaesthesia. Regional anaesthesia, with its ease of administration, reduced bleeding risk, and early detection of bladder perforation, is particularly beneficial for the elderly patients with multiple comorbidities, reducing their morbidity.1

A major drawback of spinal anesthesia in TURBT is that it does not block the obturator nerve (ON), which runs near the lateral bladder wall. Electrical stimulation during the procedure can activate the ON, causing sudden adductor muscle contraction, potentially leading to bladder perforation or vascular injury.2 This risk is higher in lateral wall tumors due to their proximity to the ON, increasing the likelihood of deep bladder cuts, perforation, and excessive bleeding.3

The ON originates from the L2-L4 lumbar plexus and supplies the thigh's adductor muscles, running close to the inferolateral bladder wall, bladder neck, and prostatic urethra. During transurethral surgeries, inadvertent ON stimulation can cause forceful leg jerking, disrupting the procedure and increasing the risk of complications.4 Research indicates that ON block (ONB) during TURBT can extend the time to tumor recurrence, suggesting that ONB stabilizes the surgical field and allows for complete tumor resection. Multiple studies confirm that ONB immobilizes the surgical field, enhancing the effectiveness of lateral wall tumor resection.5

Several ONB techniques exist. The "3-in-1" block, proposed by Winnie, attempts to block the femoral, femoral cutaneous, and obturator nerves with a single injection but remains controversial regarding its effectiveness for ONB.6 ONB can be performed using anatomical landmarks, a peripheral nerve stimulator, or ultrasound guidance. The nerve stimulator confirms adductor muscle contraction, while ultrasound improves precision by visualizing the injection site. Combining both methods may enhance the success rate. Various local anesthetics have been used for ONB, including lignocaine, bupivacaine, levobupivacaine, and ropivacaine, but limited data exist on ropivacaine's effectiveness. This prospective randomized controlled study investigates the effect of nerve stimulator-guided ONB with 0.5% ropivacaine on adductor spasm in TURBT patients with lateral wall bladder tumors under spinal anesthesia.

This prospective, randomized double blind study was undertaken after obtaining due approval from the Institutional Ethical Committee, RNT Medical college Udaipur Rajasthan, IRB approval number: ACAD/IEC/2023/658 Dated:18/04/2023,and registration at CTRI (CTRI/2024/04/065913) on 18/04/2023. A total of 82 patients of ASA grade I and II, including male and female, age 20 and 70 years, underwent TURBT surgery who have been diagnosed with inferolateral and bladder neck tumours. Patient with ASA Grade III and above, with known history of local anesthetics sensitivity, pregnancy, scars in the ONB region, coagulopathy, or neuromuscular disease were excluded. All patients were randomly assigned to either Group A or Group B using a computer‑generated table of random numbers. Group A received spinal anaesthesia alone, while group O received spinal anaesthesia plus an obturator nerve block using 10 ml of 0.5% ropivacaine with a nerve stimulator. All patients are cannulated with an 18-G IV cannula, preloaded with 10 to 15 ml/kg, and attached to a multipara monitor for heart rate, noninvasive blood pressure, and oxygen saturation. After aseptic preparation, all patients received a subarachnoid block in the L3–4 or L4–5 interspace in the sitting position. A total volume of 2.5 ml of 0.5% bupivacaine heavy was administered into the subarachnoid space, and patients were placed in the supine position and subsequently waited for 5 min for drug fixation. They were then thoroughly assessed for sensory motor block using a pin-prick test and the Modified Bromage Scale. Surgeons were allowed to perform surgery after the T10 sensory block was achieved in group A, while in group O, ONB was conducted in the supine position using a nerve stimulator (PAJUNK®). Insert a 10-mm Teflon-insulated needle perpendicularly 2 cm inferiorly using a nerve stimulator and 2 cm laterally to the pubic tubercle. As per the traditional approach, we adjusted the nerve stimulator to 1.5-2 mA and the pulse width to 0.1 ms. Consequently, insert the needle through the skin to the inferior ramus of the pubic bone. It was then slightly pulled back and redirected anterolaterally, contacting the nerve at a depth of 2 to 4 cm. Administered 10 ml of 0.5% ropivacaine when contraction was observed in the adductor muscle groups at 0.3 to 0.5 mA current, and after aspiration was negative. Surgery was initiated after 10 minutes following the injection. The anaesthesia doctor who performed the ONB was not involved further in the study; the same urologist, blinded to the ONB, operated on patients in both groups and evaluated the obturator signs. During the operative procedure, the primary endpoints of the study were tumour resectability (hampered vs unhampered), adductor reflex (defined as jerky adduction), external rotation of the thigh at the hip joint, and the number of interruptions. Sample size was calculated based on previous study Dr. Rajesh Negmoth et al7, 83.3% proportion of patient had obturator nerve reflex in spinal anaesthesia group, 90% power, 3.3% adductor reflex in obturator nerve , assumed 0% superiority limit of the difference in proportions, 20%minimum expected difference in proportion of obturator nerve reflex to be detected and calculate 37sample in each group . Assuming a dropout of 10% a final size was estimated to be 41 patients in each group So, total 82 participants were included in study. Statistical analysis was performed using SPSS version 20 (Neon laboratories). The data were tabulated as a mean ± standard deviation and significance was analyzed by using independent sample t-test for continuous variables and categorical variables were compared with Chi square test.

The demographic profiles of patients in both study groups are outlined in [Table 1]. Both studies demonstrated that the mean time to achieve a T10 sensory block and the peak sensory level after spinal anaesthesia were statistically insignificant, with P values greater than 0.05  Regarding the duration of surgery, Group A exhibited a mean time of 61.36 ± 5.328 minutes, while Group O had a mean of 59.29 ± 4.910 minutes. Importantly, there was no statistically significant difference between the groups (p = 0.706) [Table 3]. Moreover, hemodynamic parameters showed no statistically significant changes in either group (P > 0.05. The mean duration of analgesia and the mean duration of sensory block also showed no statistically significant differences between the study groups (P > 0.05). However, the incidence of adductor muscle contraction was notably higher in Group A (41.5%, n=17) compared to Group O (14.6%, n=6), which indicates a statistically significant difference (p = 0.006) [Table 2]. Additionally, the severity of adductor muscle contraction was significantly greater in Group A (26.83%, n=11) than in Group O (4.9%, n=2), again demonstrating a statistically significant difference (p = 0.013) [Table 3]. The surgeon satisfaction score was remarkably high at 87.81% in Group O, in stark contrast to the 26.83% in Group A, further underscoring a statistically significant difference (p = 0.008) [Table 4]. Lastly, it is noteworthy that no statistically significant adverse effects were observed in either group (P > 0.05).

Table 1: Demographic distribution among study group

Chi-square test applied, P>0.05 (Not Significant)

Table 2: Comparison of incidence of Adductor muscle contraction among    two study groups

Chi square test applied; P (<0.05%) (Significant), Data are expressed as in (%)

Table 3: Comparison of severity of Adductor muscle contraction among two   study groups

 *Chi square Test Applied; P<0.05 (Significant). Data are expressed as (%)

During transurethral resection surgery (TUR), accidental stimulation of the obturator nerve can cause violent adductor contraction, leading to serious intraoperative complications. The study aims to validate nerve stimulator guided obturator nerve block  which could improve anesthesia precision and patient safety during TUR procedures, encouraging progress in clinical techniques.8

The present study was carried out in patients undergoing transurethral resection of bladder tumour under Spinal anaesthesia with or without nerve stimulator guided obturator nerve block.

Several methods have been used to abolish the reflex, such as reducing diathermy power and using bipolar rather than monopolar cautery, but none have been entirely successful.Venkatramani et al9 compared monopolar with bipolar cauterisation for TURBT and concluded that bipolar TURBT was not superior to unipolar TURBT with respect to obturator jerk, bladder perforation, and hemostasis. The variation in nerve stimulation settings, such as current of 50 W and 40 W for cutting and coagulation, highlights the complexity of optimizing procedures, which can reassure the audience about the importance of technical expertise.Gupta et al.10 successfully eliminated nerve stimulation by utilizing power settings as low as 50 W for cutting and 40 W for coagulation. However, it has been noted that these power levels may be insufficient for achieving satisfactory resection outcomes.

Various  other modality Implementing various techniques, such as partially filling the bladder during resection and resecting the tumor in thinner slices, significantly reduces the risk of complications during surgery. By mastering these approaches, you can greatly enhance patient outcomes, particularly in environments where laser systems are not available or are severely limited. It's important to note that while laser systems offer advantages, they are often considered a luxury not accessible at many centers. Furthermore, general anesthesia is generally unsuitable for this age group due to its association with increased pulmonary complications. Embracing these methods will allow you to provide safer and more effective care, such     as partial filling the bladder during resection  and modifications               like resecting the tumour on thinner slices, are important options that can help you avoid complications during surgery. Recognizing these approaches can empower you to improve patient outcomes, especially when laser systems are unavailable or limited in your center.11,12  Laser systems are luxurious and not readily  available at many centres. General anaesthesia is not a suitable option as it is associated with pulmonary complications, which are prevalent in this age group

Combined subarachnoid anesthesia for obturator nerve blockage (ONB) is a highly effective technique for transurethral resection of bladder tumors (TURBT) and can be easily implemented. Numerous methods for achieving obturator nerve blocks have been thoroughly documented in the literature. Notably, Prentiss et al.13 and later Parks and Kennedy14 introduced a nerve stimulation technique that has achieved impressive success rates between 83.8% and 85.7%. In our study, we experienced similar  success rate of 85.36% with this

nerve stimulation approach. Another study done by Cesur et al2 found that obturator reflex was prevented in 33 out of 39 (84.6%) patients in ONB group.

In the present study, we used a nerve stimulator with a current power of 1.5 to 2 mA to administer 10 ml of 0.5% Ropivacaine, achieving a 85.36% success rate. The rationale for selecting Ropivacaine is its superior cardiostability compared to other local anesthetics, such as Lignocaine and Bupivacaine. Gasparich et al.15 effectively utilized a nerve stimulation technique at 0.5 mA, administering 3–4 ml of 1% lignocaine and achieving an impressive success rate of 100%. In comparison, Kobayashi et al.16 also employed nerve stimulation with 0.5 mA but injected between 7 and 40 ml of 0.25% bupivacaine, which yielded a strong success rate of 89.4%. Our results align with studies by Bolat D et al.5 and Nagmothe RV et al.7, which showed 88.6% and 96% success rates, highlighting the significance of efficacy data in guiding clinical practice.

In present study, we observed notable differences in surgeon satisfaction scores across groups, emphasizing the importance of these findings for surgical outcomes. Similar findings in Alavi CE et al17 further support the significance of surgeon satisfaction improvements in related procedures.

Our study presents some limitations that should be acknowledged. We utilized distal approach for the obturator nerve block (ONB), and this technique is effective, although it has the potential for block failure if the obturator nerve branch diverges proximal to the inguinal crease and is not adequately blocked. While our sample size was relatively small, consisting of patients with lateral and posterolateral wall tumors undergoing transurethral resection of bladder tumours (TURBT), the findings still offer valuable insights. To enhance the precision of our results, future studies with larger sample sizes and longer durations will be essential.

As such, further investigation is warranted to evaluate the reliability of PNS-guided ONB specifically in this high-risk population.

We concluded that using spinal anaesthesia combined with an obturator nerve block of 0.5% ropivacaine for TURBT surgeries effectively reduces the incidence of obturator nerve reflexes, improves surgical conditions, and enhances surgeon satisfaction without increasing complications.

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