Laparoscopic cholecystectomy (LC), first introduced by Dr. Erich Mühe in 1985, is now the gold standard treatment for gallstone disease, having replaced open cholecystectomy due to its advantages of reduced postoperative pain, shorter hospital stay, faster recovery, and minimal surgical trauma.1 The procedure involves inserting a laparoscope and instruments through small abdominal incisions to remove the gallbladder safely. Over 750,000 laparoscopic cholecystectomies are performed annually in the United States and more than 200,000 in India, highlighting its global prevalence. Traditionally, general anesthesia (GA) has been the standard anesthetic approach for LC, ensuring muscle relaxation and controlled ventilation2. However, its associated drawbacks—such as postoperative nausea and vomiting (PONV), delayed recovery, and airway complications—have driven the exploration of alternative methods like spinal anesthesia. Spinal anesthesia offers several benefits over GA, including better postoperative pain control, early ambulation, reduced PONV, and avoidance of airway manipulation, making it ideal for patients with pulmonary or difficult airway conditions.3 Despite these advantages, conventional lumbar spinal anesthesia can result in hypotension, high sensory blockade affecting respiration, and delayed recovery due to motor blockade. To address these challenges, thoracic segmental spinal anesthesia (TSA) has emerged as an effective alternative. This technique, first proposed by Dr. Daniel C. Moore, involves administering the anesthetic at the thoracic level (T7–T8) to achieve a targeted block limited to the surgical field while preserving lower limb mobility and minimizing hemodynamic disturbances. Several studies have validated the safety and efficacy of TSA.4 Levobupivacaine, the S-enantiomer of bupivacaine, provides similar efficacy with a better safety profile and reduced cardio toxicity. The isobaric form offers stable hemodynamics, a longer sensory block, and less motor impairment compared to hyperbaric bupivacaine5,6. The addition of adjuvants like fentanyl enhances analgesia, reduces anesthetic requirements, and minimizes side effects. TSA has proven to be cost-effective, opioid-sparing, and suitable for high-risk and geriatric patients, making it a valuable alternative to GA. Although concerns about spinal cord injury have limited its widespread use, modern studies demonstrate that TSA is safe when performed by skilled anesthesiologists7. Future research should focus on standardizing protocols, determining optimal drug combinations, and assessing long-term safety. With continued advancements, thoracic spinal anesthesia holds promise as a reliable, patient-friendly alternative for laparoscopic cholecystectomy and other minimally invasive surgeries.8 AIM To compare the efficacy and safety of isobaric levobupivacaine versus heavy bupivacaine in thoracic spinal anesthesia for laparoscopic cholecystectomy with respect to sensory and motor block characteristics, hemodynamic parameters, and associated side effects.

This study was designed as a prospective randomized control study conducted in the Department of Anesthesiology, Sardar Patel Medical College and A.G. Hospital, Bikaner. The study was initiated after obtaining approval from the Institutional Ethical Committee and continued until the completion of the required sample size. A total of 60 patients of either sex, aged between 18 and 60 years, scheduled for elective laparoscopic cholecystectomy, were included in the study population. Patients belonging to the American Society of Anesthesiologists (ASA) physical status I and II, with a body mass index (BMI) ranging from 19 to 30 kg/m² and normal coagulation profiles, were eligible for inclusion. Patients were excluded if they belonged to ASA grade III or IV, refused to participate, had a history of bleeding diathesis, infection at the site of injection, or known allergy to the study drugs. Individuals presenting with acute cholecystitis, acute pancreatitis, or severe cardiovascular, renal, psychiatric, or neurological disorders were also excluded from the study. The sampling technique employed was simple random sampling to ensure unbiased selection of study participants.

Table 1: Comparison of baseline characteristics between the two groups. (N = 60) Parameter Group A (Mean ± SD) Group B (Mean ± SD) P value Mean Age (years) 40.37 ± 11.81 38.83 ± 12.05 0.620 Mean Height (cm) 162.47 ± 5.42 161.30 ± 4.58 0.372 Mean Weight (kg) 63.77 ± 3.70 62.67 ± 3.31 0.230 Mean BMI (kg/m²) 24.21 ± 1.79 24.15 ± 1.89 0.895 Sex Distribution (M/F) 9 Male / 21 Female 11 Male / 19 Female - There is no statistically significant difference in age, height, weight, BMI, or sex distribution between the two groups. Thus, the groups are wellmatched, and any further comparisons will not be biased by baseline variations. Table 2:- Distribution of cases in both groups according to onset of sensory Block and sensory block duration Parameter Group A (Isobaric Levobupivacaine) (Mean ± SD) Group B (Heavy Bupivacaine) (Mean ± SD) p-value Onset of Sensory Block (min) 2.54 ± 0.47 2.18 ± 0.42 < 0.05 Sensory Block Duration (min) 143.57 ± 12.26 123.73 ± 10.48 < 0.001 Table shows the onset of sensory block was faster in Group B (Mean: 2.18 min) compared to Group A (Mean: 2.54 min), and the difference was statistically significant (p < 0.05). It also showed the duration of sensory block was significantly longer in Group A (143.57 min vs. 123.73 min, p < 0.001), indicating prolonged anesthetic effect with Isobaric Levobupivacaine Table 3: Distribution of Cases by Time to Reach Peak Sensory Block (SB) and according to duration of motor block Group A B P value Mean (min) ± SD (Sensory block) 3.11 ± 0.45 3.32 ± 0.55 Mean (min) ± SD (Motor block) 84.43±6.90 79.37±7.88 0.0104 Group B had a slightly longer mean time to reach peak sensory block (3.32 min) compared to Group A (3.11 min). The range was broader in Group B (2.5 - 5.0 min) than in Group A (2.0 - 4.0 min), indicating more variation in Group B. This suggests that Group A had a significantly longer duration of motor block compared to Group B. Table 4: - Comparison in both group Peak block height (T2/T3/T4) Peak sensory Block Height Group A (30) Group B (30) T2 21 18 T3 6 8 T4 3 4 Table 4 clearly shows that T2 was the most common peak block height in both groups, while Group B had a slightly higher number of cases at T3 and T4 compared to Group A. Table 5:- Table representing the Max MB Distribution in both groups: Max MB Level Group A (n) Group B (n) B1 25 18 B2 3 8 B3 1 4 Table 5. indicates that B1 was the most common maximum MB level in both groups, with Group A having a higher frequency of B1 compared to Group B. Meanwhile, Group B showed a higher number of cases at B2 and B3 levels compared to Group A. Table 6: Comparison of Mean Blood Pressure (MBP) (mmHg) over time in minutes: Time Interval In minutes Group A (Mean ± SD) Group B (Mean ± SD) P value Baseline 94.0 ± 6.2 98.5 ± 6.8 0.02 T0 82.0 ± 5.6 74.5 ± 5.3 0.01 T5 78.5 ± 5.0 75.8 ± 4.8 0.11 T10 84.0 ± 5.5 76.5 ± 4.9 0.01 T15 83.0 ± 5.3 75.5 ± 4.7 0.02 T30 80.5 ± 5.0 74.8 ± 4.6 0.03 T45 78.0 ± 4.8 74.2 ± 4.4 0.04 T60 79.0 ± 4.9 76.5 ± 4.5 0.10 T120 80.5 ± 5.2 76.8 ± 4.7 0.02 MBP exhibited a significant drop from baseline in both groups. Group B had consistently lower MBP values at multiple time points compared to Group A. Statistical significance (p < 0.05) was observed at T0, T10, T15, T30, T45, and T120, suggesting that Group B experienced a greater decline in MBP. Table 7: Comparison of Mean Pulse Rate (PR) at Different Time Intervals between Group A and Group B Time Interval Group A (Mean ± SD) Group B (Mean ± SD) p-value Baseline 85.2 ± 6.3 86.5 ± 6.8 0.28 T0 83.5 ± 5.8 81.0 ± 5.5 0.12 T5 72.0 ± 5.2 66.5 ± 4.8 0.02* T10 69.5 ± 4.9 64.2 ± 4.5 0.01* T15 70.8 ± 5.0 65.5 ± 4.6 0.02* T30 75.0 ± 5.3 70.0 ± 4.9 0.04* T45 80.2 ± 5.6 76.5 ± 5.2 0.10 T60 82.0 ± 5.8 81.5 ± 5.4 0.45 T120 85.5 ± 6.0 86.0 ± 6.2 0.67 Both groups experienced an initial drop in pulse rate, reaching the lowest values around T10-T15. Group B consistently had a lower pulse rate than Group A at several time points. Significant differences (p < 0.05) were observed at T5, T10, T15, and T30, indicating a more pronounced bradycardia in Group B. By T120, pulse rates in both groups returned to near baseline levels. Table 8: Distribution of cases according to Complications in both groups (n=60 cases):- Complication Group A (30) Group B (30) Bradycardia 3 3 Hypotension 3 5 Nausea 0 2 Pruritis 1 1 Shoulder pain 1 2 In our study, both groups showed similar incidences of bradycardia (3 each) and pruritus (1 each). However, hypotension (5 vs. 3), nausea (2 vs. 0), and shoulder pain (2 vs. 1) were slightly higher in Group B, indicating more frequent minor complications with hyperbaric bupivacaine.

The demographic characteristics like age, height, weight, gender and BMI of the study population were similar in both groups without any statistical difference. The mean age of patients in group A and group B was 40.37±11.81 years and 38.83± 12.05 respectively. The mean height of the patient in group A and B was 162.47± 5.42 cm and 161.30± 4.58 kg respectively. The mean weight of the patient in group A and group B was 63.77± 3.70 kg and 62.67± 3.31 kg respectively. Our study resembled that of Karthik et. al 20249 in terms of demographic profiles with mean age, height and weight being 40.07± 6.66 years, 161.13± 12.12 cm and 60.2 ± 8.62 kg respectively. The onset of sensory block was significantly faster in Group B (2.18 ± 0.42 min) compared to Group A (2.54 ± 0.47 min) (p < 0.05). This is expected due to the higher baricity of Heavy Bupivacaine, which allows for a quicker spread within the cerebrospinal fluid. However, despite the faster onset, the duration of sensory block was significantly longer in Group A (143.57 ± 12.26 min) compared to Group B (123.73 ± 10.48 min) (p < 0.001).Our study findings closely align with those of Loveleen Kour et al. (2019)10, who compared levobupivacaine and bupivacaine in thoracic spinal anesthesia (TSA). The onset of the sensory block was significantly faster in bupivacaine (2.07min) compared to levobupivacaine (2.03 min) (p < 0.562). Their study demonstrated that levobupivacaine provided a significantly longer duration of sensory block (180 min vs. 140 min, p < 0.0001) while maintaining better hemodynamic stability. The time taken to reach the peak sensory block was slightly longer in Group B (3.32 ± 0.55 min) compared to Group A (3.11 ± 0.45 min). This corresponds with the study conducted by Kour et.al 2019[23] which showed that time to reach peak sensory block was 4.8minute in levobupivacaine and 5.0 minutes in bupivacaine with p value 0.652. The duration of the motor block was significantly longer in Group A (84.43 ± 6.90 min) than in Group B (79.37 ± 7.88 min) (p = 0.0104). This indicates that Isobaric Levobupivacaine produces a more prolonged motor blockade, which may be beneficial for procedures requiring extended immobilization but may also delay post-operative recovery. In Piacherski et al.'s (2023)11 study, motor block duration with Levobupivacaine was also longer (235 min) compared to Bupivacaine (177 min). Both groups achieved T2 as the most common peak sensory block height, followed by T3 and T4. However, Group B had a slightly higher number of cases reaching T3 and T4, indicating that Heavy Bupivacaine produced a denser sensory block spread caudally compared to Isobaric Levobupivacaine. This difference is likely due to baricity differences affecting drug distribution in the spinal column.In terms of motor block, Loveleen Kour et al.10 observed that bupivacaine produced a more profound motor block compared to levobupivacaine. Our study findings are consistent with this, as Group B had a greater proportion of patients experiencing deeper motor blocks (B2/B3), whereas Group A had a higher percentage of cases with only mild to moderate motor block (B1). Systolic, diastolic, and mean blood pressures showed significant variations between the two groups at multiple time points. Group B consistently exhibited lower SBP, DBP, and MBP values compared to Group A at several intervals (T0–T45, T120) with statistical significance (p < 0.05), while no significant differences were noted at T5 and T60. Pulse rate declined initially in both groups, reaching the lowest at T10–T15, with Group B showing significantly lower PR up to T30. By T120, pulse rates nearly returned to baseline in both groups. Although bradycardia incidence was similar, hypotension occurred more frequently in Group B (5 cases vs. 1 case), indicating greater hemodynamic instability due to its denser spread and stronger sympathetic blockade. In our study comparing isobaric levobupivacaine and hyperbaric bupivacaine for segmental spinal anesthesia in laparoscopic cholecystectomy, complications included bradycardia in 3 patients of each group and a higher incidence of hypotension (5 vs. 3) and nausea (2 vs. 0) in Group B. Pruritus and shoulder pain occurred in few patients of both groups, indicating slightly more adverse effects with hyperbaric bupivacaine. A study by Verma et al. (2024)12 compared isobaric and hyperbaric 0.5% levobupivacaine in segmental thoracic spinal anesthesia for laparoscopic cholecystectomy. They reported that the hyperbaric group experienced better hemodynamic stability and fewer postoperative complications such as pneumonia and atelectasis.

Isobaric levobupivacaine demonstrated a longer duration of both sensory and motor blocks, however faster onset of sensory block in heavy bupivacaine. Additionally, Isobaric levobupivacaine provided better hemodynamic stability with fewer incidences of hypotension and nausea, whereas heavy bupivacaine resulted in a more intense motor block. However, a larger multicenter study is needed to establish the above conclusion.

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