|Year : 2014 | Volume
| Issue : 3 | Page : 349-353
Effects of intrathecal hyperbaric ropivacaine versus hyperbaric bupivacaine for lower limb orthopedic surgery
Somjit Chatterjee, Bikash Bisui, Anamitra Mandal, Jagabandhu Sheet, Swapnadeep Sengupta, Shakya Majumdar, Sarbari Swaika
Department of Anaesthesiology and Critical Care, Bankura Sammilani Medical College and Hospital, Bankura, West Bengal, India
|Date of Web Publication||17-Oct-2014|
Department of Anaesthesiology and Critical Care, Bankura Sammilani Medical College and Hospital, Bankura - 722 102, West Bengal
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Regional anesthesia, increasingly used for infraumbilical surgery, has advantages of decreased stress response to surgery, nausea, vomiting, and cardio-respiratory depression with improved postoperative analgesia, in comparison to general anesthesia. Intrathecal isobaric ropivacaine (RP) had been found, in various clinical studies, to be shorter acting in comparison to bupivacaine (BP). Our present study was, hence, aimed to compare the anesthetic and analgesic efficacy of intrathecal hyperbaric RP relative to hyperbaric BP in lower limb orthopedic surgery.
Materials and Methods: A total of 100 patients aged ranges between 18 and 60 years of either sex, ASAPS 1 and 2, undergoing elective lower limb orthopedic surgeries were divided into two groups, RP group and BP group receiving intrathecal 0.75% RP 3 ml and glucose 50%, 0.5 ml and 0.5% hyperbaric BP 3 ml and 0.9% normal saline 0.5 ml, respectively. The efficacy in terms of onset and duration of anesthesia and analgesia were assessed along with the heart rate, blood pressure at regular intervals throughout the perioperative period.
Result: The two study groups were comparable in terms of demography and duration of surgery. Patients in group RP experienced significantly late onset and shorter duration of sensory and motor block in comparison to patients in group BP. There were clinically insignificant differences in perioperative hemodynamics and side-effects noted in each group. Hence, it was observed in this study that equipotent dose of hyperbaric RP had shorter duration of analgesia and anesthesia than with equipotent dose of hyperbaric BP.
Keywords: Hyperbaric bupivacaine, hyperbaric ropivacaine, lower limb orthopedic surgery
|How to cite this article:|
Chatterjee S, Bisui B, Mandal A, Sheet J, Sengupta S, Majumdar S, Swaika S. Effects of intrathecal hyperbaric ropivacaine versus hyperbaric bupivacaine for lower limb orthopedic surgery. Anesth Essays Res 2014;8:349-53
|How to cite this URL:|
Chatterjee S, Bisui B, Mandal A, Sheet J, Sengupta S, Majumdar S, Swaika S. Effects of intrathecal hyperbaric ropivacaine versus hyperbaric bupivacaine for lower limb orthopedic surgery. Anesth Essays Res [serial online] 2014 [cited 2020 Feb 23];8:349-53. Available from: http://www.aeronline.org/text.asp?2014/8/3/349/143138
| Introduction|| |
Spinal anesthesia is a widely used technique, providing a fast onset and effective sensory and motor blockade. Bupivacaine (BP), an amino amide local anesthetic, a racemic (50:50) mixture of S and R enantiomers,  has been used as the drug of choice for spinal anesthesia since its introduction in 1956, due to its longer duration of action, producing profound sensory and motor blockade.
Ropivacaine (RP) the optically pure S(−) enantiomeric form of the parent chiral molecule propivacaine, belongs to the pipecoloxylidide group of local anesthetics, with a propyl group added to the piperidine nitrogen atom compared to a butyl group in BP.  Though RP structurally resembles BP with similar anesthetic properties, it has reduced potential for cardiotoxicity and neurotoxicity with improved relative sensory and motor block profile. , RP, being a pure S-enantiomer, has low lipid solubility and blocks nerve fibers involved in pain transmission to a greater degree than those involved in motor function and has been used extensively for local infiltration, epidural, and peripheral nerve block. 
Various studies with other local anesthetics have shown that the addition of glucose improved the cephalic spread and reliability of anesthesia. Addition of glucose to RP has proved to increase the speed of onset, block reliability, duration of useful block and speed of recovery. 
Considering these relative advantages and disadvantages of both the drugs, an endeavor was made to compare the effects of intrathecal hyperbaric RP versus hyperbaric BP for lower limb orthopedic surgery, in respect to onset and duration of anesthesia, perioperative hemodynamic and any adverse effects.
| Materials and methods|| |
After getting approval from institutional ethics committee, written informed consent were obtained from 100 patients of either sex aged between 18 and 60 years of ASA physical status 1 and 2 undergoing elective lower limb orthopedic surgery for our prospective, randomized, double-blind study.
Our exclusion criteria were any contraindication for neuraxial block, allergy to study drugs, and patients who were obese and on chronic anticoagulation or antiplatelet drugs. Complete preanesthetic evaluation was performed in each patient including detailed history taking, thorough physical check-up and routine preoperative investigations. Patients were instructed on the methods of sensory and motor assessments at the preoperative visit. All patients received ranitidine 150 mg and alprazolam 0.5 mg orally on the morning of surgery as premedication.
The patients were randomly assigned to one of two study groups: RP group (n = 50) received 3 ml 0.75% RP (22.5 mg) and glucose 50%, 0.5 ml and BP group (n = 50) were given 0.5% hyperbaric BP 3 ml (15 mg) and 0.9% normal saline (NS) 0.5 ml, thereby giving a total volume of 3.5 ml in both groups. All solutions were prepared and injected by a second investigator who was otherwise not involved in the study directly. Patients, surgeons and first investigator, who was involved in patient's clinical assessment and treatment, were blinded to group assignment.
After receiving the patients in operation theater, an intravenous line was established with an 18G intravenous cannula and preloading was done with prewarmed ringer's lactate solution 15 ml/kg body weight, infused over 15 min.
Patients were attached to noninvasive monitor such as SpO 2 , non-invasive blood pressure and electrocardiography. After skin preparation in a sitting position 16G Tuohy needle was inserted at L 2 -L 3 or L 3 -L 4 interspace. Epidural space was identified by loss of resistance to air technique and an epidural catheter was passed with 3 cm of it kept within the epidural space for postoperative analgesia. Separate L 4 -L 5 interspace was used to perform intrathecal injection using 25G quincke needle. Once the intrathecal space was confirmed by free flow of cerebrospinal fluid, the study drugs, which were presented in identical syringes, were injected and the patients were turned supine immediately.
Sensory changes were recorded bilaterally along the mid clavicular line by assessing changes in pinprick sensation by use of a safety pin protruding 2 mm through a guard every 1 min till no sensation (Grade 2) was achieved (Graded according to Gromley and Hill [normal sensation - 0, blunted sensation - 1, no sensation - 2]). Assessments were continued at 30 min interval following the completion of surgery until normal sensation returned.
The degree of motor block was assessed using modified bromage scale (0 = no motor block, 1 = inability to raise extended legs, 2 = inability to extend knees, and 3 = inability to extend ankle joints). Heart rate and arterial pressure were recorded using standard noninvasive monitors before intrathecal injection (baseline) and thereafter at 5, 10, 15, 20, 25, 30, 45, and 60 min, then hourly until 6 h postinjection. Hypotension was treated with intravenous mephentermine 3-9 mg or phenylephrine 50 μg and additional lactated Ringer's solution.
Duration of analgesia was assessed from the onset of sensory block to first request for rescue analgesic by epidural route when visual analog scale >4 and the total amount of epidural RP or BP in first 24 h following surgery were noted. On each request epidural RP (10 ml of 0.2%) or BP (10 ml of 0.125%) were given to the RP and the BP group, respectively. Patients were followed up daily for any adverse events during their hospital stay.
Expected mean differences of duration of motor block between two groups were considered 45 min with a SD of 50 min in each group. A sample size of 41 in each group was calculated with a power of the study and alpha error of 90% and 5%, respectively. Assuming a dropout rate of 10%, we attempted to recruit 50 patients in each group. The sample size was calculated using software "N master version 2.0," Department of Biostatistics, CMC, Vellore, Tamil Nadu, India. Numeric parametric data were presented mean ± standard deviation. Ordinal and nominal data was expressed in cross table as number (percentage) of patients in each ordinal and nominal category. Numeric parametric data were compared by unpaired t-test (independent sample t-test). Nominal and ordinal data were compared by Fischer's exact test or Mann-Whitney U-test. P < 0.05 was considered as statistically significant and P < 0.0001 was considered statistically highly significant. All the statistical analysis was performed using SPSS (IBM) version 20.
| Result and analysis|| |
Both the groups were comparable in respect to age, sex, weight, and height and duration of surgery in our study [Table 1].
Onsets of sensory and motor block were found to be significantly faster in gr-BP than gr-RP (P < 0.001). When we compared duration of sensory and motor block, gr-BP again, showed longer in respect to gr-RP [Table 2].
|Table 2: Onset and duration of sensory and motor block with time to first rescue analgesic|
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The time to first request of rescue analgesic was significantly earlier in RP group than in BP group as P < 0.001.
There was statistically significant difference noted in heart rate and mean arterial pressure at different time points during our assessment period, as shown in [Figure 1] and [Figure 2].
|Figure 1: Comparison of heart rate in two groups at different time interval|
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|Figure 2: Comparison of mean arterial pressure in two groups at different time interval|
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There were no statistically significant side effects like shivering, nausea and vomiting noted in either group of our study population.
| Discussion|| |
Spinal anesthesia, an age-old technique, used popularly for various lower limb surgeries, has traditionally used hyperbaric BP as the drug of choice. However, RP, owing to its lower cardio and neurotoxic profile, as evident from a number of studies, has been emerging as a useful alternative.
In dogs intrathecal RP has been shown to produce effective local anesthesia with an equipotent sensory block but shorter duration of motor block than intrathecal BP.  The efficacy of intrathecal RP had, thus, been proved in various surgeries such as total hip replacement, trans-urethral resection of prostate, lower abdominal and limb surgeries from different studies. 
McNamee et al.,  again in their study comparing the efficacy and safety of two glucose-free solutions, RP 5 mg/ml and BP 5 mg/ml, found that both solutions produced similar results in terms of onset and spread of analgesia. However, variation in the degree of spread of sensory block in both the groups was also found, which, they concluded might be attributed to the use of a plain solution.
Khaw et al.  showed in their study that the addition of glucose to intrathecal RP produced spinal anesthesia with a more frequent success rate and a less frequent incidence of intraoperative pain compared with plain solution requiring epidural top-up in cesarean delivery.
This study was, hence, undertaken to compare the efficacy of hyperbaric RP in comparison to hyperbaric BP via the intrathecal route in terms of onset and duration of effective anesthesia and analgesia.
The mean onset time of sensory block found to be longer in group RP than in group BP, in our study, was similar to the findings of Chung et al.,  who observed that the onset of sensory block to T10 or to the maximal level took longer in the RP group than in the BP group (P < 0.05). Whiteside et al.  compared equal doses (15 mg) of intrathecal 0.5% RP in 10 mg/ml or 50 mg/ml glucose in two groups of patients undergoing a variety of minor surgical procedures. They showed that the onset of sensory block to T10 was significantly faster in the glucose 50 mg/ml group, but that max extent of sensory block, time to block regression and quality and duration of motor block were similar in both groups corroborating our findings, where all patients in group RP showed sensory block adequate for surgery.
The mean onset time of motor block in group RP was slower than Group BP, which was corroborative with the study of Whiteside et al.,  who found the time to maximum degree of motor block in BP group was 10 (2-15) min compared with RP group 15 (10-25) min, with a P < 0.0001, denoting highly significant result, whereas Chung et al.,  in their study found that the time to complete motor blockade was similar in both groups.
Chung et al.  in their study found that duration of sensory block was shorter in the RP group than in the BP group (P < 0.05). Al-Abdulhadi et al.  in their study of hyperbaric spinal for elective cesarean section, RP versus BP, also found that time for the sensory block to recede in PACU was significantly shorter in the RP compared with the BP (105 ± 15 vs. 150 ± 15) (P < 0.001). Whiteside et al.  in their study, again, found significant difference in duration of sensory block at T 10 level with BP up to 118 (80-238) min and RP up to 56.5 (28-145) min with a P < 0.001. Similar finding was demonstrated in a study on plain RP 5 mg/ml with BP 5 mg/ml for major orthopedic surgery by McNamee et al.  who found that sensory block at the T 10 dermatome was significantly longer in the BP group: 3.5 h compared with 3.0 h in the RP group (P < 0.0001). Thus, the findings of these studies were all corroborating with the finding of our study where the mean duration of sensory block in group RP was, similarly, lesser than in group BP.
The mean duration of motor block in group RP was significantly shorter than in group BP. Chung et al.  in their study found significant longer duration of motor block in BP group (105-225 min) (P < 0.001) than RP group (90-135 min). Whiteside et al.,  also, found significant difference, with total duration of 180 (120-210) min in BP group and 90 (60-180) minutes in RP group, however that might be due to lower concentration of RP used in their study. Other similar studies, like one by McNamee et al.  also found that motor block duration was significantly shorter in the RP group compared to BP group (2.1 h vs. 3.9 h, P < 0.001), thus, being at par with our finding.
The mean time of request for rescue analgesic was earlier in RP group than in BP group that was supported by the study of Al-Abdulhadi et al.,  in which time to complete recovery of sensory block were 173.6 ± 8.6 min in RP group and 217.6 ± 16.4 in BP group. Whiteside et al.  also found that the first rescue analgesic requirement was significantly longer in BP group (150-420 min, mean 255 min) compared to RP group (120-270 min, mean 180 min).
| Conclusion|| |
Hence, it was observed in the study that 0.75% RP 3 ml and glucose 50%, 0.5 ml (total volume of 3.5 ml), provided effective spinal anesthesia with shorter duration of sensory and motor block compared to hyperbaric BP 0.5% 3 ml and 0.9% NS 0.5 ml (total volume of 3.5 ml) for lower limb orthopedic surgery. Hence, it can be concluded that RP has a less potent effect on motor nerves, with both the degree and duration of motor block produced by RP being less, still adequate for the scheduled surgery.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]