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Anesth Essays Res. 2017 Jul-Sep; 11(3): 561–566.
PMCID: PMC5594767

A Prospective Comparative Observational Study of Clinical Efficacy of Isobaric Ropivacaine 0.75% with of Isobaric Bupivacaine 0.5% Intrathecally in Elective Inguinal Hernia Repair Surgeries

Abstract

Aims:

To evaluate the efficacy of intrathecal isobaric Ropivacaine and its comparison with intrathecal isobaric Bupivacaine in elective inguinal hernia repair surgeries.

Settings and Design:

A prospective, randomized study was conducted in a tertiary care hospital with 80 patients of ASA grade I-III undergoing elective inguinal hernia repair surgery under spinal anaesthesia. Ethical committee clearance and written consent taken. The patients were randomly divided into two equal groups to the Ropivicaine group (Group R) and to theBupivicaine group (Group B). Parameters observed were onset and duration of sensory and motor block, maximum sensory level achieved degree of motor blockade, two segment regression, and haemodynamic changes.

Results:

The development of sensory block was faster with Isobaric Ropivicaine (12.1 ± 4.9 minutes) as than isobaric Bupivicaine (13.94 ± 4.52 minutes) but the difference was not statistically significant. Onset of Grade III Motor block was longer with Isobaric Ropivicaine (8.51 ± 3.39 minutes) as compared to isobaric Bupivicaine (8.51 ± 3.39 minutes), but the difference was not statistically significant. Time of Complete Sensory Regression was significantly shorter with Isobaric Ropivicaine (212.69 ± 27.31 minutes) with statistical significance. Time to complete motor recovery was significantly shorter in Ropivacaine group (253.38 ± 27.13 minutes)as compared to Bupivacaine group (258.55 ± 35.81min), with statistical significance. Time to achieve discharge criteria was relatively shorter with Isobaric Ropivicaine. Haemodynamic Parameters did not differ significantly in both the groups during the entire study period.

Conclusion:

Intrathecal administration of isobaric Ropivacaine (0.75%) 15 mg provides similar quality of spinal anaesthesia but of significantly shorter duration, maintaining similar hemodynamic stability and discharge criteria without significant adverse effects when compared to isobaric Bupivicaine (0.5%) 10 mg.

Keywords: Hernia repair surgery, isobaric bupivacaine, isobaric ropivacaine

INTRODUCTION

The recent trend in health-care facility is to provide cost-effective care to the patient. Increasing trend toward ambulatory surgery is an important part of that. Repair of inguinal hernia is a superficial surgery without much complexity, which can be completed in 60–90 min and does not have many intra- and post-operative complications. Hence, it is an ideal procedure for outpatient setting.

The ideal anesthetic for ambulatory surgery should produce rapid and smooth onset of action, intraoperative analgesia and amnesia, good surgical condition, and short recovery period free of side effects.

Spinal anesthesia is traditionally popular regional anesthesia technique. It can provide rapid onset, good intraoperative, and immediate postoperative analgesia at minimum cost. Complications of general anesthesia are avoided, and recovery is early with minimal alteration in cognitive psychomotor function which helps in early discharge.

Low incidence of transient radicular pain with bupivacaine made it the drug of choice for ambulatory spinal anesthesia. However, longer duration of action and potential for cardiotoxicity is the limiting factors to consider bupivacaine as an ideal drug for ambulatory spinal anesthesia.

Ropivacaine is a new amino amide group of local anesthetic drug. Bupivacaine is a racemic mixture of S and R isomers, whereas ropivacaine is a pure S-enantiomer. S-enantiomer is less cardiotoxic,[1] whereas R isomer is more arrhythmogenic. Ropivacaine has consistently demonstrated an improved safety profile over bupivacaine with a reduced central nervous system and cardiotoxic potential, with a wide clinical utility at different doses.

With this background, we compared the clinical efficacy of isobaric ropivacaine 0.75% (7.5 mg/cc) with of isobaric bupivacaine 0.5% (5 mg/cc) intrathecally in elective inguinal hernia repair surgeries.

SUBJECTS AND METHODS

After obtaining approval from the Ethical Committee, eighty patients were chosen who were scheduled to undergo elective inguinal hernia surgeries under spinal anesthesia at a tertiary care hospital. The duration of this study was 2 years. Written informed consents were taken. The inclusion criteria were American Society of Anesthesiologists (ASA) Physical Status I to III, age 18–65 years. Patients were excluded if they had a history of drug allergy, patient refusal, coagulation disorder, patient on anticoagulant therapy, skin infection at the site of block, patients with neurological deficit, or abnormalities of the spine.

This prospective randomized study was designed to compare 2 ml (15 mg) of 0.75% isobaric ropivacaine with 2 ml (10 mg) of 0.5% isobaric bupivacaine for subarachnoid block with respect to level, duration, and sensory blockade along with hemodynamic stability and side effects.

A thorough preanesthetic checkup was performed 1 day before surgery. All patients kept nil per oral for 12 h before surgery. The procedure to be performed was explained and informed consent was obtained. In the preoperative room, pulse and blood pressure were recorded. All the patients were premedicated with injection glycopyrrolate 0.008 mg/kg intramuscularly 30 min before surgery. After securing an intravenous line, 500 ml of Ringer's lactate was given as preload. The patients were randomly divided into two groups of forty patients each by a computer-generated randomization chart.

  • Group R: Injection isobaric ropivacaine (0.75%) 15 mg–2cc intrathecally
  • Group B: Injection isobaric bupivacaine (0.5%) 10 mg–2cc intrathecally.

After the patient was shifted to operation theater, standard monitors such as pulse oximeter, noninvasive blood pressure, and 3-lead electrocardiogram were connected. Injection midazolam 1 mg was given intravenously. Spinal anesthesia was then given under strict aseptic precautions with spinal needle 25 G in sitting position at L3–L4 space with the hub of spinal needle facing cephalad. The patient was kept in sitting position for 2 min and then made supine. After noting the time of induction, the sensory and motor effects were checked every 3 min for the first 15 min, then every 5 min up to 30 min. The surgeon was allowed to start surgery when T10 level was attained. Patient was monitored for pulse, blood pressure every 3 min for the first 15 min, then every 5 min up to 30 min, and then at 10 min interval subsequently.

Duration from intrathecal injection to attain T10 level, highest sensory level, two-segment sensory regression, and regression to T10 dermatome were noted. Motor block onset, highest scale of motor block, and time to complete motor block resolution were noted.

Sensory block was assessed by pinprick method.

Motor block was assessed by Bromage scale as follows: Grade 0: none (no motor blockade); Grade 1: partial (just able to move the knees); Grade 2: almost complete (able to move the feet only); and Grade 3: complete (unable to move the lower extremities).

To judge the quality of anesthesia, patient was assessed for feeling of sensation during the operation and was graded as: no sensation throughout the operation: excellent; sensation on manipulation of sac but no pain: good; mild pain during operation but no need of analgesia: fair; and pain and need of analgesia: poor.

If the pain was severe enough that the patient did not allow surgery to continue, then rescue analgesia was given with injection ketamine 0.5 mg/kg intravenously. These patients were included in the study. General anesthesia was given to patients not responding to injection ketamine. Data of these patients were taken up to induction of general anesthesia.

Postoperatively, patients were monitored every 15 min for recession of motor and sensory effects. The times to reach discharge criteria were noted. Discharge criteria were following: no breathing difficulties, stability of hemodynamic parameters, ability to walk, full orientation to time and place, ability to drink without nausea or vomiting, voluntary micturition, and no more than slight pain.

All patients were watched for side effects such as hypotension (systolic blood pressure <20% of baseline value), bradycardia (pulse rate <50/min), high spinal (>T2), decreased respiratory rate (<8/min), and SpO2 <90%.

OBSERVATION AND RESULTS

In this prospective randomized study, eighty patients aged 18–65 years of ASA Grade I to III undergoing elective inguinal hernia repair were studied after being given spinal anesthesia with either 2 ml of isobaric ropivacaine 0.75% (7.5 mg/cc) and 2 ml of isobaric bupivacaine 0.5% (5 mg/cc) with respect to the efficacy of both drugs, onset and regression of sensory and motor blockade, alteration of hemodynamic parameters, side effects, and time to attain discharge.

Sample size was determined by power analysis. Patients listed for surgery were enrolled and assessed for eligibility. Those not meeting the inclusion criteria or those refusing to participate were excluded from the study. The data collection sheets were checked daily by the principal investigator for correctness and consistency. All data are presented as mean (standard deviation) except where specified. The unpaired Student's t-test of OpenEpi software (OpenEpi Software, Copyright (c) 2003, 2008 Andrew G. Dean and Kevin M. Sullivan, Atlanta, GA, USA) was used for intergroup comparisons. P < 0.05 were considered significant and <0.001 were considered highly significant.

Demographic profile

There were no statistical differences between the groups regarding age, weight, and duration of surgery. All the patients in this study were male. All the data were statistically insignificant and thus comparable [Table 1]

Table 1
Demographic profile

Onset of sensory block

Onset of sensory block was defined as time interval from intrathecal injection to the absence of pinprick sensation at T10 dermatome.

Time to onset of sensory analgesia at T10 dermatome was 7.62 ± 4.57 min in ropivacaine group while 8.6 ± 3.02 min in bupivacaine group.

Time to achieve peak level which was defined as time interval from intrathecal injection to highest sensory level achieved.

Time to achieve highest sensory level was 12.1 ± 4.9 min in ropivacaine group while 13.94 ± 4.52 min in bupivacaine group.

Highest level of sensory analgesia was T7 in terms of thoracic segments in both the groups.

No statistical significant differences were observed between the groups with regard to the sensory block [Table 2]

Table 2
Onset of sensory block

Onset of motor block

The motor block was assessed using Bromage scale.

Time to onset of Grade I motor block was 3.8 ± 2.16 min in ropivacaine group while 3.6 ± 1.88 min in bupivacaine group.

Time to onset of Grade II motor block was 6.25 ± 3.22 min in ropivacaine group while 5.63 ± 2.69 min in bupivacaine group.

Time to onset of Grade III motor block was 8.51 ± 3.39 min in ropivacaine group while 8.34 ± 3.61 min in bupivacaine group.

No statistically significant differences were observed between the groups [Table 3].

Table 3
Onset of motor block

Regression of sensory effects

Time to two segment regression was 72.05 ± 20.48 min in ropivacaine group while 72.23 ± 19.61 in bupivacaine group.

Time of regression to T10 level was 83.46 ± 22.28 min in ropivacaine group while 90.69 ± 24.8 min in bupivacaine group.

The difference between the groups was not statistically significant.

Time of complete sensory regression was 212.69 ± 27.31 min in ropivacaine group while 233.28 ± 30.71 min in bupivacaine group. The duration of complete sensory regression was significantly shorter in ropivacaine group with statistical significance (P = 0.03) [Table 4].

Table 4
Regression of sensory effects

Recovery from motor blockade

Mean time to complete motor recovery was 253.38 ± 27.13 min in ropivacaine group and 258.55 ± 35.81 min in bupivacaine group which was significantly shorter in ropivacaine group as compared to bupivacaine group and showed statistical significance (P = 0.002) [Table 5].

Table 5
Recovery from motor blockade

Discharge criteria

Patient was able to walk without support after about 419.05 ± 44.29 min in ropivacaine group and 433.02 ± 43.78 min in bupivacaine group.

Mean time to drink water was 387.67 ± 53.5 min in ropivacaine group and 406.16 ± 35.02 min in bupivacaine group.

Mean time to micturition was 451.8 ± 47 min in ropivacaine group and 466.47 ± 58 min in bupivacaine group.

None of the differences were statistically significant.

The data suggest that even though complete sensory and motor recovery was significantly faster in ropivacaine group, recovery of patient's ability to walk without support, to drink water, and to voluntarily micturate was comparable in both the groups [Table 6].

Table 6
Recovery of parameters for achieving discharge criteria

Quality of analgesia

In ropivacaine group, 57.61% had excellent analgesia, 14.28% had good analgesia, 2.38% had fair analgesia, and 14.28% had poor analgesia.

In bupivacaine group, 68.42% had excellent analgesia, 14.28% had good analgesia, and 23.68% had poor analgesia.

There was no statistical difference in quality of analgesia between both the groups [Table 7].

Table 7
Quality of analgesia

Comparison of hemodynamic parameters

Graphs Graphs11 and and2:2: hemodynamic parameters at different time intervals

Graph 1
Mean pulse rate at different time intervals
Graph 2
Mean systolic blood pressure at different time intervals

Baseline pulse rate and systolic blood pressure were comparable in both the groups. No significant statistical difference was observed in hemodynamic parameters between the groups.

DISCUSSION

Eighty patients aged 18–65 years of ASA Grade I–III undergoing elective inguinal hernia repair were studied after being given spinal anesthesia with either isobaric ropivacaine 0.75% (7.5 mg/cc) or isobaric bupivacaine 0.5% (5 mg/cc).

Both groups were given similar standardized anesthesia and were compared with similar parameters.

The two groups were comparable in terms of demographic data.

Ropivacaine is commercially available as glucose-free (isobaric) solution. Hence, we used isobaric ropivacaine (0.75%) 15 mg in Group R and compared it with isobaric bupivacaine (0.5%) 10 mg Group B.

We decided to use 10 mg of isobaric bupivacaine as dose lower than this was associated with a high failure rate. An equipotent dose of ropivacaine (0.75%) 15 mg was chosen.

van Kleef et al. conducted a study using 0.5% and 0.75% isobaric ropivacaine in patients undergoing lower limb surgery. They concluded that the duration of motor block and analgesia is dependent on concentration, where 0.75% ropivacaine provides satisfactory conditions for lower limb surgeries and 0.5% ropivacaine is suitable for transurethral or minor orthopedic surgeries.[2]

Gautier et al. evaluated intrathecal ropivacaine for ambulatory surgery using 10 mg of isobaric bupivacaine and 8, 10, 12, and 15 mg of isobaric ropivacaine. They found that isobaric ropivacaine 15 mg produced sensory and motor blockade comparable to isobaric bupivacaine 10 mg.[3]

The mean onset of sensory blockade (maximum sensory level in min) in Group R was 7.62 ± 4.57 min and Group B 8.6 ± 3.02 min. The mean onset of motor blockade (Bromage score 3) in Group R was 8.51 ± 3.39 min and in Group B 8.34 ± 3.61 min. The statistical analysis shows no significant differences in the onset of both sensory and motor blockade.

This was comparable to Malinovsky et al.[4] and McNamee et al.,[5] who compared intrathecal isobaric ropivacaine (0.5%) to isobaric bupivacaine (0.5%) for major orthopedic surgeries and found the onset times to T10 anesthesia were not different between the groups.

The onset of motor blockade in our study was rapid in both groups with a mean onset of 8.51 ± 3.39 min in Group R and 8.34 ± 3.61 min in Group B and these observations are in accordance with the similar studies conducted by McNamee et al.[5] and Malinovsky et al.[4] The time required to achieve individual Bromage score was also similar in both groups with no statistically significant difference, which is supported by a study conducted by Gudul et al.[6]

Malinovsky et al.[4] and Gautier et al.[7] similarly compared intrathecal isobaric ropivacaine (0.75%) to isobaric bupivacaine (0.5%) and observed that the time to maximum motor block was similar in both the groups.

The mean duration of sensory blockade (full sensory blockade recovery at T10) in our study in Group R was 212.69 ± 27.31 min and Group B was 233.28 ± 30.71 min. The mean duration of motor blockade (Bromage score back to zero) in Group R was 235.38 ± 27.13 min and in Group B 258.55 ± 35.81 min. The statistical analysis shows that the differences are significant in both the duration of sensory and motor blockade with P < 0.05 between the two study groups suggesting shorter duration of sensory and motor blockade in Group R.

In our study, the duration of sensory blockade which was assessed at the level of T10 had a significantly shorter duration (i.e., full sensory blockade recovery at T10) in Group R. The similar finding was stated by Mantouvalou et al.,[8] who conducted a study comparing plain ropivacaine and plain bupivacaine for lower abdominal surgeries, in which he concluded faster resolution of sensory blockade in ropivacaine group.

Delfino et al.[9] and Gautier et al.,[7] on comparing isobaric solution of 0.75% ropivacaine with 0.5% isobaric bupivacaine, found the time to onset of pain in the operated region was significantly shorter in the ropivacaine group (150.5 ± 80 min) compared to isobaric bupivacaine (230.2 ± 20 min) and that isobaric bupivacaine provided longer duration of analgesia and was associated with a significantly superior success rate than isobaric ropivacaine.

Our study findings, where the mean duration of motor blockade in Group R was 235.38 ± 27.13 min and in Group B 258.55 ± 35.81 min indicating significantly lower duration of motor blockade in ropivacaine group (P = 0.002), are well supported by an earlier study by Gudul et al.[6] Similar conclusion regarding the duration of motor blockade was derived by Eryilmaz and Gunaydin[10] in their study of spinal anesthesia in parturients. Both groups provided excellent analgesia with only one patient having mild discomfort and another patient requiring additional analgesics due to inadequate pain relief in ropivacaine group. Only one patient in ropivacaine group required general anesthesia due to inadequate duration of blockade. The abdominal muscle relaxation was excellent with no disturbing muscle strain in patients of both the groups who underwent lower abdominal surgeries.

McNamee et al.,[5] Kallio et al.,[11] Boztug et al.,[12] Mantouvalou et al.,[8] and Singh et al.,[13] all found that duration of motor block was significantly shorter in ropivacaine group than bupivacaine group, with statistical significance, which was similar to our findings.

Although the time to achieve discharge criteria was relatively shorter in Group R, none of the values were statistically significant which was similar to findings of Boztug et al.,[12] who compared isobaric ropivacaine 0.5% and isobaric bupivacaine 0.5% for intrathecal anesthesia in outpatient surgeries and found that the first ambulation, first urination, and discharge times were similar between the two groups.

We did not note any significant differences between the two groups regarding hemodynamic variables, heart rate, and oxygen saturation. Danelli et al.[14] noticed no difference in clinical hypotension requiring ephedrine administration in sixty women undergoing elective cesarean delivery under spinal anesthesia with either isobaric ropivacaine or isobaric bupivacaine, which further supports our study findings.

Limitations of our study are that we have not included the drug serum levels at various intervals since our study was based on clinical parameters monitoring.

SUMMARY AND CONCLUSION

We summarize that in patients undergoing elective hernia repair surgeries, on comparing intrathecal isobaric ropivacaine 0.75% with isobaric bupivacaine 0.5%.

  1. The development of sensory block and motor blockade showed no significant differences with both isobaric bupivacaine and isobaric ropivacaine
  2. Time of complete sensory regression was significantly shorter with isobaric ropivacaine as compared to bupivacaine group, with statistical significance
  3. Time to complete motor recovery was significantly shorter in ropivacaine group as compared to bupivacaine group, with statistical significance
  4. Time to achieve discharge criteria was relatively shorter with isobaric ropivacaine
  5. Hemodynamic parameters did not differ significantly in both the groups during the entire study period, and hence there was no statistical significance.

Thus, we conclude that intrathecal administration of isobaric ropivacaine (0.75%) 15 mg provides similar quality of spinal anesthesia but of significantly shorter duration, maintaining similar hemodynamic stability, and discharge criteria without significant adverse effects when compared to isobaric bupivacaine (0.5%) 10 mg. These properties of ropivacaine can be used for day-care surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

REFERENCES

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