Background- Levobupivacaine and ropivacaine, both relatively new amide local anesthetic agents, have been developed to overcome the problems associated with bupivacaine toxicity. This study was conducted to compare clinical efficacy and characteristics of 0.5% hyperbaric levobupivacaine with 0.75% hyperbaric ropivacaine for subarachnoid block in lower limb orthopaedic surgeries. Methods- This was a prospective randomized double-blind study conducted among 60 patients scheduled for elective lower limb orthopaedic surgeries under spinal anaesthesia. The patients were randomly allocated into two groups Group L and Group R. Group L (n = 30) received 3ml of 0.5% hyperbaric levobupivacaine and Group R received 3 ml of 0.75% hyperbaric ropivacaine. Onset and duration of sensory and motor blockade, hemodynamic parameters, patient satisfaction score and adverse effects were recorded. The data was analysed using SPSS version 24.0 with appropriate tests and a P<0.05 was considered significant. Results-The distribution of patients was comparable with respect to age, sex, ASA grades and duration of surgery (P>0.05). Mean time to reach highest sensory level was significantly higher in Group L (19.2±1.4 min) than Group-R (17.9±1.2 min) (P<0.05). The mean time of two segment regression from highest sensory level blockade was less in group R (Group R 65.7±3.3 min Group L 72.4±5.1 min; P<0.05). However, the time of regression from highest sensory level to S1 was significantly less in Group L (Group L 180.8±7.3 min; Group R 188.4±3.7 min; P<0.05). Mean time of onset of motor blockade (Bromage scale 3) was 19.2±1.3 min in group L and 19±1.2 in group R and the difference was not statistically significant (p = 0.484). Patients in hyperbaric ropivacaine group had a significantly faster recovery from motor blockade recorded as mean regression to motor blockade (Bromage scale 0) (Group R 119.5±6 min vs Group L 128.8±7 min; P< 0.05). Both drugs were also found to be safe and comparable in terms of impact on hemodynamic parameter and no complication was observed. Conclusion- Hyperbaric levobupivacaine and hyperbaric ropivacaine are reliable in term of efficacy and safety for subarachnoid block in lower limb surgery. However, hyperbaric ropivacaine is a better alternative than hyperbaric levobupivacaine in patients where early mobilisation is required as it offers a faster recovery from motor blockade.
Subarachnoid block is a widely used regional anaesthesia method employed for lower limb orthopaedic surgeries because of its cost-effectiveness and reduced incidence of significant perioperative complications.[1] Bupivacaine has been the preferred drug for subarachnoid block. However, a relatively extended duration of action slows motor function recovery and extends post anaesthesia care unit stay. Furthermore, multiple studies have demonstrated that bupivacaine has greater neurological and cardiac damage than other local anaesthetics.[2] This prompted the need for development of alternative 'single enantiomeric' local anaesthetic agents with minimal cardiac and CNS toxicity. Hence, Levobupivacaine and Ropivacaine, two new amide local anaesthetic agents, have been created.[3]
Levobupivacaine is a potent, long-acting local anaesthetic with a gradual onset of action. .[4] Compared to its racemic form, it has a decreased propensity to block inactivated sodium and potassium channels and dissociates faster.[5] Anaesthetists feel comfortable working with levobupivacaine because it has a higher threshold for cardiac and neurotoxicity than racemic bupivacaine.[6]
Ropivacaine is the 'S' isomer of the propyl analogue of bupivacaine, with a prolonged duration of action, low lipid solubility, potency, and cardiovascular and CNS toxicity.[7] It inhibits nerve fibers involved in pain transmission (Aδ and C fibers) more than those controlling motor function (Aβ fibers).[8] As a result, ropivacaine has been shown to produce less strong motor blockade than bupivacaine. Therefore, its shorter duration, quicker recovery of motor function, and reduced toxicity have been recognized as a potential advantage in surgeries of intermediate duration.
Numerous studies have investigated the efficacy and block characteristics of bupivacaine, levobupivacaine and ropivacaine. However, limited research exists on the comparison between hyperbaric levobupivacaine and hyperbaric ropivacaine in lower limb orthopaedic surgeries. Therefore, we planned a study to compare the efficacy, sensory and motor block characteristics of hyperbaric levobupivacaine 0.5% and hyperbaric ropivacaine 0.75% at equipotent doses for elective lower limb orthopaedic surgeries.
This prospective double-blind randomized study, was conducted among 60 patients scheduled for elective lower limb orthopaedic surgeries at UPUMS Saifai Etawah, from November 2023 to August 2024, after approval from the Institutional Ethics Committee [Ethical Clearance Number is 43/2022-2023]. This study was registered with Clinical Trials Registry India (CTRI) [Reg no-CTRI/2023/10/059168] and it was conducted according to the principles of the Declaration of Helsinki and good clinical practice guidelines.
Inclusion Criteria
After taking written informed consent, 60 patients of either sex 18-65 years of age, of ASA grades I and II, BMI between 18-30 kg/m2 and scheduled to undergo elective lower limb orthopaedic surgeries, estimated to last between 60-180 minutes, under subarachnoid block, were enrolled for the study.
Exclusion Criteria
Patients with known allergies to study drug, contraindication to regional anaesthesia, local infection at the spinal site, raised intracranial pressure, coagulation abnormalities and for whom informed consent could not be obtained were excluded from the study.
Sample size was calculated using formula:
n = [Z(1-α/2)2 (S1+S2)]/ d2
Where,
n = Sample size in each group
Z(1-α/2) = Standard normal deviate, for two tailed at α=0.05, and 95% CI is 1.96
S1, S2 = Standard deviation of two populations/ groups to be compared (values obtained from previous study)
d = margin of error, here taken as 4%
From a previous study conducted by Singh G. et al (2019) , S1 was calculated to be 8.5 and S2 was calculated to be 6.31, for time to two segment regression of sensory level in group 1 (R) and group 2 (L) respectively.
Putting all these values in above formula,
n = (1.96)2 [(8.5)2 + (6.31)2] / (4)2
n = 26
So, on rounding of, sample size for each group is 30. Thus, the total sample size was calculated to be 60.
STUDY PROCEDURE
All the patients were assessed before surgery in pre-anaesthetic check-up which included detailed history, general and systemic examination and laboratory investigation. After detailed explanation of the anaesthetic procedure, written and informed consent was obtained from all the patients who fulfilled the inclusion criteria. Patients were instructed to keep fasting for 6 hrs and were premedicated with tab alprazolam 0.5 mg orally, the night before surgery. Randomization was done using computer generated random numbers table and the group allocation was done through sequentially numbered sealed opaque envelope technique. A total 60 patients were assigned into two groups of 30 patients each.
Group R (n =30): Received 22.5 mg (3 ml) of 0.75% hyperbaric ropivacaine.
Group L (n=30): Received 15 mg (3 ml) of 0.5% hyperbaric levobupivacaine
In preoperative room, patients were premedicated with Inj. metoclopramide 10 mg IV and Inj. Ranitidine 50 mg IV, administered one hour before shifting the patients to operation theatre. In the operation theatre, standard monitors, that included non-invasive blood pressure, five-lead ECG and finger pulse oximetry (SpO2), were attached and baseline parameters were recorded. Patients were pre-loaded with ringer lactate 10 ml/kg and under strict aseptic precautions, the subarachnoid block was performed in the sitting position at the level of L4-L5 intervertebral space after local infiltration with 1 ml of 2% inj Lidocaine. A 25G Quincke spinal needle was used to inject 3 ml of hyperbaric ropivacaine (0.75%) in group R and 3 ml of hyperbaric levobupivacaine (0.5% )in group L using a midline approach after free flow of cerebrospinal fluid (CSF) seen . The patients were made to lie supine immediately and the time of injection of the study drug was noted (0 min). Hemodynamic monitoring was done after the subarachnoid block and hemodynamic parameters (systolic blood pressure, diastolic blood pressure, mean blood pressure, heart rate, arterial oxygen saturation (SpO2), were recorded at 0 min, at every 5-min interval for the first 30 minutes post injection and, 10-min interval thereafter until 120 minutes. After 120 minutes, assessments were conducted every 15 minutes until 150 minutes
.
SENSORY BLOCK ASSESSMENT- It was checked by pin prick method using a hypodermic needle. Time interval between the injection of drug and the time taken to achieve the highest level of sensory blockade, time taken for two segment regression and time of regression to S1 level was recorded.
MOTOR BLOCK ASSESSMENT -It was checked using Bromage scale. Time of onset of Bromage scale 3 (patients is unable to move the hip, knee and ankle joint) and time of regression to Bromage scale 0 (patients is able to move the hip, knee and ankle joint) was recorded.
The satisfaction of patient was assessed using a
Likert Verbal rating scale
1-Extemely dissatisfied;
2-Dissatisfied;
3-Somewhat dissatisfied;
4-Undecided;
5-Somewhat satisfied;
6-Satisfied;
7-Extemely satisfied, immediately after surgery.
All patients of both the groups were monitored for side effects and complications. Any heart rate below 50 beats per minute was treated with atropine 0.6 mg iv. Hypotension, defined as decrease in mean arterial pressure of more than 20%, was treated with crystalloid I.V. and a bolus dose of i.v. mephentermine (6 mg).
The quantitative variables compared using unpaired t-test and expressed as mean±sd. Qualitative variable were compared between groups using Chi-square test. The data was stored in MS Excel spreadsheet and statistical analysis was performed using IBM Statistical Package for Social Sciences (SPSS) version 24.0. A p value <0.05 was considered as statistically significant
In the present study, a total of 60 patients were analyzed
Table 1 - Physical characteristics and duration of surgery in both groups.
|
Parameter
|
Group L |
Group R |
P-value |
|
Age (Years)
|
41.6±13.4 |
36.9±13.9 |
0.189 |
|
Gender M/F
|
23/7 |
21/9 |
0.55 |
|
ASA physical status I/II |
20/10 |
24/6 |
0.76 |
|
Duration of surgery(minutes) |
105.3±18.6 |
100.8±18.7 |
0.353 |
p>0.05 not significant, M-male F- female, values are presented as mean±standard deviation L-levobupivacaine R-ropivacaine
ASA-American Society of Anesthesiologists.
|
PARAMETERS |
GROUPL Mean±SD |
GROUP RMean±SD |
P VALUE |
|
Mean Time from injection to highest sensory blockade level (min) |
19.2±1.4 |
17.9±1.2 |
<0.001 |
|
Mean time of two segment regression from highest sensory blockade level (min) |
72.4±5.1 |
65.7±3.3 |
<0.001 |
|
Mean time of two segment regression to S1 from highest sensory level (min) |
180.8±7.3 |
188.4±3.7 |
<0.001 |
|
Mean time of onset of motor blockade (Bromage 3 scale ) (min) |
19.2±1.3 |
19±1.2 |
0.484 |
|
Mean time of regression to motor blockade (Bromage 0 scale) (min) |
128.8±7 |
119.5±6 |
<0.001 |
|
Mean patient satisfaction score |
6.1±0.3 |
6.2±0.4 |
0.456 |
Table 2 - Sensory and motor blockade characteristics
p>0.05 not significant, M-male F- female, values are presented as mean±standard deviation L-levobupivacaine R-ropivacaine
One of the key goals of the anaesthesiologist while performing a subarachnoid block is to obtain appropriate effects for the needed duration without producing any severe physiological changes or negative effects. Till now, bupivacaine has been the primary choice for subarachnoid block. However, the risk of potential cardiotoxicity and neurotoxicity have been reported. [2] This necessitated a need for safer local anaesthetics with low side effects while ensuring adequate sensory and motor blockade [9] and therefore the development of levobupivacaine and ropivacaine. In this study we aimed at understanding the comparative performances of hyperbaric ropivacaine (0.75%) and hyperbaric levobupivacaine (0.5%) in terms of their efficacy and sensory, motor blockade and recovery characteristics, as we believe it will provide valuable insights into their clinical advantages, limitations and help in choosing the appropriate local anaesthetic suited to the patient requirement.
In our study, the demographic profile of patients like age, sex and BMI, ASA grading and duration of surgery was comparable between both the study groups.
The mean time from intrathecal injection to highest sensory level blockade was significantly longer in levobupivacaine group (19.2±1.4 min) than ropivacaine group (17.9±1.2 min). Our finding is consistent with a study conducted by Singh G et al[10] who conducted a trial in 60 patients undergoing lower abdominal and lower limb surgery and reported a delayed highest sensory blockade in levobupivacaine group (22.07±1.93 min) than ropivacaine group (20.5.9±1.81 min). Another study conducted by P.Gautier et al[11] reported that delayed highest sensory blockade was observed in levobupivacaine group(17±9 min) than ropivacaine group (15±9 min).
In our study, the mean time of two segment regression from the highest sensory level blockade (min) was significantly earlier in ropivacaine group (65.7±3 min) than levobupivacaine group (72.4±5.1 min). This finding can be attributed to ropivacaine’s better sensory motor dissociation feature.[8]. This finding was similar to a study done by Singh G et.al[10] (Group L vs. R: 69±8.5 min vs.61.83 ±6.31 min) and P. Gautier et al[11] (Group L vs. R: 69±14 min vs.60 ±21 min). Despite the early regression of two segment in the ropivacaine group, the total duration of sensory block (regression to S1) was 180.8±7.3 min in group L and 188.4±3.7 min in group R. Suri et al.[13] reported a lesser duration of sensory blockade in group L (189.4±19.53 min) than group R (196.78±20.31 min) and concluded that patients in ropivacaine group maintained a good sensory blockade until the end of surgery.[12]
In our study there was no significant difference observed in onset of motor blockade (Bromage scale 3) between the study groups (Group L vs. R: 19.2±1.3 min vs. 19±1.2 min p=0.484). Our finding align with the findings of Singh G et.al[10] where the onset of motor blockade was 25.07±1.97 min in group L vs 24.37 ±1.70 min in Group R. In another study conducted by Suri et al.[13] the time of onset of motor blockade was recorded to be 24.09±3.07 min in group L and 25.47 ±4.13 min in Group R. The difference was found to be not significant. The time of regression of motor blockade (Bromage scale 0) was significantly less in ropivacaine group (119.5±6 min) than levobupivacaine groups (128.8±7 min) (p= 0.0001). The probable explanation is that ropivacaine has lower penetration into myelinated motor fibers, and thus lesser motor blockade, due to lower lipid solubility.[8] These findings are in concordance with a study conducted by Singh G et.al[10] who reported that the duration of motor blockade was 116.73±29.95 min in group L and 112.93±15.40 min in group R. In another study, Luck JF et.al[14]also reported early regression of motor blockade in ropivacaine group. Early return of motor function is associated with a lower incidence of venous thromboembolism due to early mobilisation and and it also leads to early recovery.
In our study, patient satisfaction score, as measured using a Likert verbal rating scale, demonstrated a high level of patient satisfaction (Group L 6.1±0.3; Group R 6.2±0.4) and comparable results between the study groups (p = 0.456).
Hemodynamic monitoring indicated that heart rate, systolic and diastolic blood pressure, mean arterial pressure, and peripheral oxygen saturation were effectively maintained during study with both drugs.Top of Form
In our study the incidence of hypotension was observed in 3 patients (10%) in the levobupivacaine group and 2 patients (6.67%) in the ropivacaine group. All cases were mild and managed effectively with intravenous fluids and iv mephentermine. The difference between the two groups was not statistically significant (p=0.45). No patients in either group experienced bradycardia, nausea or vomiting, suggesting that both the groups exhibit a comparable safety profile.
There were certain limitations to our study. Firstly, our study was conducted in ASA grade I and II patients, which may limit the applicability of the findings to patients with ASA grade III and onwards. Secondly, this was a single-centre study conducted in patients undergoing elective surgeries. Hence, the findings cannot be generalised across different clinical settings and time-sensitive emergency settings. Thirdly, the absence of dose adjustments according to age, height and weight of the patients may have affected the accuracy of dosing and related outcomes.
From this study, it can be concluded that hyperbaric ropivacaine 0.75% in subarachnoid block has earlier onset of highest sensory blockade, earlier two segment regression for sensory blockade and shorter duration of motor blockade than hyperbaric levobupivacaine 0.5%. Both the drugs provide hemodynamic stability and can be used for population that is at a higher risk of cardiovascular co-morbidities. As ropivacaine shows an early recovery from motor blockade it can facilitate early mobilisation, enhances patient satisfaction and can be considered as a better intrathecal anaesthetic agent for patients who are at a high risk for venous thromboembolism.
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