Subarachnoid block is the most commonly used anaesthetic technique in performing infraumbilical surgeries. It is safe, reliable, relatively easy to administer, offers a high level of perioperative analgesia and hence satisfaction for patients. Administration of the appropriate choice and dose of local anaesthetic into the subarachnoid space results in the surgical anaesthesia with a high degree of success.¹

Hyperbaric Bupivacaine is the most commonly used drug for spinal anaesthesia in the clinical practise till recently, providing longer durations of anaesthesia with adequate motor blockade compared to other local anaesthetics². But there have been cases reported where unintended intravascular injection of bupivacaine during attempted neuraxial anaesthesia resulted in sudden cardiac arrest refractory to resuscitation.²

Later, the S enantiomer of Bupivacaine, the Levobupivacaine having better cardiovascular profile is being employed as a commonly used alternative in spinal anesthesia.²

Compared to plain solutions, hyperbaric solutions of local anaesthetic drugs are expected to provide a more predictable and effective block, with early onset compared to the plain solutions ² and has an added advantage of adjusting the level of block in relation to the gravitational forces by changing the position of the patient following the subarachnoid block.³

Hence, we decided to evaluate the block characteristics (the onset of sensory and motor block) of intrathecal hyperbaric levobupivacaine versus intrathecal isobaric levobupivacaine for elective major lower limb orthopaedic surgeries.

Study population: Patients admitted to CHAMARAJANAGARA INSTITUTE OF MEDICAL SCIENCES HOSPITAL, CHAMARAJANAGAR, posted for elective major lower limb orthopaedic surgery.

Place of study: In the Department of Anaesthesiology, CHAMARAJANAGARA INSTITUTE OF MEDICAL SCIENCES HOSPITAL, CHAMARAJANAGAR

1. Study design: Prospective, randomized, double-blinded comparative
2. Study period: One and a half years from August 2022 to February 2024 Inclusion criteria:

• Patients with ASA grade 1 and 2 of either
• Patients in the age group between 18 to 60 years posted for elective major lower limb
• Patient willing to participate with written informed consent. Exclusion criteria:
• Patients with coagulation disorders, on
• Spinal deformity and any local infection at the site injection for spinal
• Allergic to amide local
• Body mass index>30 kg/m2

1. Sampling method:

• Randomized controlled study
• 40 Patients who were posted for elective major lower limb orthopaedic surgery in CIMS,
• They were randomly allocated into two groups of 20 each using an opaque sealed envelope method, depending on the drug regime used for spinal anaesthesia. Randomization was done by computer-generated randomized numbers.
• Group HL: a group of 20 patients will receive 3 ml of 0.5% Hyperbaric Levobupivacaine (15 mg) intrathecally.
• Group IL: a group of 20 patients will receive 3 ml of 5% Isobaric levobupivacaine (15 mg) intrathecally.
• Both the patient and the investigator were
• Randomization was done by computer-generated randomized
• The person who was not involved in the study prepared the drug mixture for the study groups

Sample size:

• Sample size for the study is estimated with a 95% confidence interval and power of 80%
• Formula:
• The total sample size N = N1+N2 • N1 = size of the control group, N2 = size of the study group, as we are taking the same sample size for each group N1=N2, so N = 2*N1
• N1 = [(σ12 + σ22) (𝑍1− 𝛼 2 + 𝑍1− 𝛽) 2 ] / [(𝜇1 − 𝜇2) 2 ].⁴
• Where Z1-α/2 is a standard error associated with the chosen level of significance with α = 5% and Confidence Interval = 95%, where Z1-α/2 = 96
• Where Z1-β is standard error associated with power with 1-β = 80%, where Z1-β = 842
• Based on the reference taken from a previous study conducted by Sanansilp V, et al (the onset of sensory block- the time taken to attain sensory blockage of T10).⁵
• Where σ1 = 1 and σ2= 4.7 are standard deviations, and
• Where µ1 = 8 and µ2 = 6.6 are means,
• The means and standard deviations are the time taken to achieve sensory blockade of the T10 level for hyperbaric and isobaric groups
• N1 = [ (1.1 2+4.7 2) x (1.96 + 842)2] / (2.8-6.6)2 = [(1.21+22.09) x7.85] / 14.44 ~ 15
• Dropout rate – A 10% dropout rate was considered
• Total sample size = N +10% of N = 2N1 + 10% of N = 2*15 + 10% of 30 = 30 + 3 =33 ~ 40 (rounded off to) Therefore, the required sample size for our study was

METHOD OF COLLECTION OF DATA

After Institutional Ethical Committee clearance, 40 patients with ASA physical status 1 and 2 of either sex with age group between 18 to 60 years posted for elective major lower limb surgeries, with informed written consent were randomized using computer generated numbers into two groups, into group HL who received 3 ml of 0.5% Hyperbaric Levobupivacaine (15 mg) and Group IL who received 3 ml of 0.5% Isobaric levobupivacaine (15 mg) intrathecally. The study design was a prospective randomized controlled double blinded study. A thorough pre anaesthetic evaluation and optimization were done and relevant investigations were ordered. On the night before the surgery, premedication with Tab Ranitidine 150 mg and Tab Alprazolam 0.5 mg were given. The patients were instructed NPO for at least 6 hrs as per institutional protocol for spinal anaesthesia. On the day of surgery patient were assessed again, vitals were monitored and an 18-gauge intravenous cannula was inserted and was preloaded with RL fluid. Pre medications Inj. Ranitidine 50 mg, Inj. ondansetron 4 mg were given intravenously. Before shifting the patient to OT, the monitors and the anaesthesia machine were checked and emergency drugs were kept ready. On shifting the patient to OT, vitals were noted, Standard ASA monitoring (pulse oximeter, electrocardiogram, and non-invasive blood pressure) applied to all patients. Under all aseptic precautions subarachnoid block was given with patients in sitting position, a lumbar puncture was performed in the L3-L4 or L4-L5 interspace, using Quincke 25G spinal needle. The study drug was administered intrathecally after confirmation of free and clear flow of cerebrospinal fluid (CSF) based on group allocation and the patients were placed supine. The parameters like time of onset of sensory and motor blockade were recorded. The hemodynamic parameters and any side effects during the study were also recorded.

STATISTICAL ANALYSIS

Data was entered into Microsoft excel data sheet. Categorical data was represented in the form of frequencies and proportions. Chi-square test was used as test of significance for qualitative data. Fischer’s exact test as well as Yates correction were used as test of significance for qualitative data which does not fulfill the criteria for Chi-square test (for 2x2 tables only). Independent t test was used as test of significance to identify the mean difference between two quantitative variables. Mann Whitney U test was used as test of significance to identify the median difference between two quantitative variables with skewed distribution. MS Excel was used to obtain various types of graphs such as bar diagram, line diagram etc. p- value of <0.05 was considered as statistically significant after assuming all the rules of statistical tests.

In the comparison of age distribution between the groups receiving hyperbaric and isobaric levobupivacaine, the mean age of the subjects was 44.80 years and 43.75 years, respectively. The p-value of 0.808 indicates that there is no statistically significant difference in the age distribution between the groups.

In the study, 15.0% of the subjects were male, while majority i.e., 85.0% were female in Group HL. Similarly, in Group IL, 25.0% were male, and majority i.e., 75.0% were female. The p-value of 0.429 indicated no statistically significant difference in the gender distribution between the two groups.

The study compared anthropometric measurements between two groups, Group HL and Group IL, which focused on height and weight, evaluated using independent t-tests. The mean height for Group HL is 163.85 ± 8.07 cm, while Group IL has a mean height of 161.00 ± 9.62 cm. The p-value for height comparison is 0.317, indicating no statistically significant difference between the two groups. For weight, Group HL had a mean of 63.85 ± 6.01 kg, and Group IL had a mean of 66.95 ± 5.95 kg. The p-value here was 0.109, which also suggests no significant difference between the groups.

In Group HL, 25.0% subjects were classified as ASA Grade I, while 75.0% subjects were classified as ASA Grade II. In Group IL, 35.0% subjects were ASA Grade I, and 65.0% subjects were ASA Grade II. The p-value for this comparison was 0.490, indicating no statistically significant difference in ASA grading distribution between the two groups.

The procedures in the study included Bipolar, Intertrochanteric, Femur Nailing, and Tibia Nailing. The p-value of 0.721 indicated no statistically significant difference in the distribution of procedures between the two groups.

The time to achieve T10 sensory level was significantly faster in the hyperbaric levobupivacaine group, with a mean onset time of 3.40 minutes compared to 7.30 minutes in the isobaric group, a difference that is statistically significant (p < 0.001).

The time to achieve M3 motor onset between the two groups showed that the hyperbaric levobupivacaine group reached M3 level faster, with a mean time of 3.80 minutes compared to 9.25 minutes in the isobaric group (p < 0.001) with statistical significance.

Table 1: Comparison of mean age between the groups

Figure 1

Table 2: Comparison of gender distribution between the groups

Figure 2

Table 3: Comparison of anthropometric measurements between the groups

Figure 3

Table 4: Comparison of ASA grading between the groups

Figure 4

Table 5: Comparison of procedures between the groups

Figure 5

 Table 6: Comparison of sensory block characteristics between the groups

Figure 6

Table 7: Comparison of motor block characteristics between the groups

Figure 7

Patients were comparable in terms of demographic variables, anthropometry and type of surgery performed. In our study as per operational definition, the onset of sensory block was considered as loss of sensation to pinprick at T10. The mean time for sensory block onset was earlier 3.40 + 1.05 mins in HL group compared to 7.30 + 2.72 mins in IL group with statistically significant p value of <0.001 and the mean time to onset of motor block in Group HL is 3.80 + 2.78 mins and Group IL is 9.25 + 3.45 mins. On comparing the mean between two groups there was statistically significant difference (p = <0.001) with early onset in group HL.

Our study correlate with the study conducted by Vimolluck Sanansilp et al where there was statistically significant difference in the time taken for onset of sensory blockade by the intrathecal 3ml of 0.42% hyperbaric levobupivacaine, compared with 3ml of 0.42% of intrathecal isobaric levobupivacaine, with faster spread to T10 level with hyperbaric levobupivacaine (2.8 ± 1.1) compared to (6.6 ± 4.7 minutes), in isobaric levobupivacaine group with P = 0.039.⁵

Our study correlate with the study conducted by H.Sen et al where the time to onset of T10 sensory block, time to maximum sensory block, time to motor block Bromage 1, time to motor block Bromage 3, were all smaller with heavy group who received13.5 mg of hyperbaric levobupivacaine, compared to the plain group who received 13.5 mg isobaric levobupivacaine, both intrathecally in a 3 mL total volume. All their P values were <0.05, which was statistically significant.⁶

The study conducted by Ramya Metta et, where in the study it showed that in comparison of Isobaric Levobupivacaine with Hyperbaric Bupivacaine in spinal anesthesia in patients undergoing Lower Abdominal Surgeries, had a early onset of sensory block with 3ml 0.5% (15mg) of intrathecal hyperbaric bupivacaine than with 3ml 0.5% (15mg) of intrathecal isobaric levobupivacaine with significance of p < 0.001.²

Opas Vanna MD et al conducted a study between equal volumes of 0.5% isobaric levobupivacaine and 0.5% hyperbaric bupivacaine intrathecally in patients undergoing transurethral endoscopic surgery under spinal anaesthesia, which indicated that both groups showed equal potencies with regard to onset time and duration of sensory block.⁷

Kaya, et al. conducted a study to compare the clinical effects and characteristics of Hyperbaric and Hypobaric Levobupivacaine for unilateral spinal anaesthesia. The level and duration of sensory block, intensity and duration of motor block were recorded. It was concluded that Hyperbaric and Hypobaric Levobupivacaine both provided satisfactory unilateral spinal anaesthesia with good hemodynamic stability for arthroscopic surgeries, but frequent unilateral spinal anaesthesia was more observed with Hyperbaric group.⁸

From the present study it can be concluded that, there was statistically significant difference in the time to achieve onset of sensory block, with early onset observed with group HL compared to IL group and there was a statistically significant difference in the time taken for the onset of motor block with rapid onset observed with group HL compared to group IL.

Hence, we conclude that, Hyperbaric Levobupivacaine by the virtue of its early onset of sensory and motor block was found to be a better choice for spinal anaesthesia in elective major lower limb orthopaedic surgeries compared to Isobaric Levobupivacaine intrathecally.

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