The Comparative Study of Epidural Anesthesia between Isobaric Ropivacaine 0.5% and Isobaric Bupivacaine 0.5% for Lower Abdominal Surgery.

AIM: The aim of the study was to compare the effectiveness of ropivacaine (0.5%) and bupivacaine (0.5%) in epidural neuraxial blockade for elective lower abdominal surgeries.
METHODS: The present study was conducted in sixty patients undergoing elective lower abdominal surgeries under epidural anesthesia who were included after satisfying the eligibility criteria. The patients were randomly divided into two groups. An epidural catheter was inserted in cephalad direction using Tuohy epidural needle at L2-L3 or L3-L4 with the help of loss of resistance to air technique. Twenty milliliter of the study drug was given, sensory blockade was tested using the pinprick method, and quality of motor blockade was assessed by the modified Bromage scale.
RESULTS: In our study, demographic data comparing age and sex show no statistically significant difference among both the groups. In our study, the mean time for the onset of sensory block consider at T10 in Group B was 10.05 ± 2.1 min and in Group R was 9.8 ± 1.8 min. Moreover, the mean time duration of sensory block in Group B was 5.56 ± 0.059 h and in Group R was 5.34 ± 0.073 h. The onset of motor block in Group B was 4.98 ± 1.07 min and in Group R was 5.28 ± 1.2 min, but the duration of motor block for Group B was 4.63 ± 0.39 h and for Group R was 3.53 ± 0.23 h, which is clinically and statistically significant. The maximum level of sensory blockade for Group B was T4 and for Group R was T5. The range of block in Group B was T10-T4 and in Group R was T10-T35.
CONCLUSION: The onset of sensory block was comparable in both the group, but the duration of sensory block is shorter with ropivacaine compared to bupivacaine. The onset of motor blockade was comparable in both the groups, but the duration of motor blockade was also shorter and the degree of motor block was less intense with ropivacaine compared to bupivacaine. Copyright:

INTRODUCTION

Regional anesthesia has gained popularity in recent years. The most common regional anesthetic techniques used for lower abdominal and lower limb surgery are epidural anesthesia. The advantages of epidural anesthesia are

It provides effective surgical anesthesia

It reduces the incidence of hemodynamic changes as a result of sympathetic blockade as it produces segmental anesthesia unlike subarachnoid block anesthesia

It can meet the extended duration of surgical needs

It provides postoperative analgesia.

Bupivacaine, a highly lipophilic long-acting anesthetic, is associated with a high rate of cardiac and local toxicity. Accidental overdose of bupivacaine was often fatal and it poorly responded to conventional resuscitation.[1] The toxicity of the drug is due to that it involves its stereo-specificity, with the S (-) enantiomer showing significantly less cardio depressant effects than the R (+) enantiomer.[2] Ropivacaine is a long-acting local anesthetic and has got all the advantages of bupivacaine for epidural anesthesia. The advantage of ropivacaine over bupivacaine is that it has got less cardiac toxicity.

The study is to compare the effectiveness of ropivacaine (0.5%) and bupivacaine (0.5%) in epidural neuraxial blockade for elective lower abdominal surgeries regarding the following:

Time for onset and duration of sensory blockade

Time for onset and duration of motor blockade

Time for maximum sensory blockade

Time for maximum motor blockade

Hemodynamic changes

Any adverse effects.

A total of sixty patients undergoing elective lower abdominal surgeries under epidural anesthesia were included after satisfying the eligibility criteria. The patients were randomly divided into two groups (Group R and Group B). The patient was premedicated, and the epidural catheter was inserted in cephalad direction using Tuohy epidural needle at L2/L3 or L3–L4 with the help of loss of resistance to air technique. Twenty milliliter of the study drug was given using 5 mL increments at a rate of 1 mL/s through the catheter.

METHODS

The present study was conducted in the department of anesthesiology of Dr. Vasantrao Pawar Medical College, Nashik, India. A total of sixty patients undergoing elective lower abdominal surgeries under epidural anesthesia were included after satisfying the eligibility criteria. The patients were randomly divided into 2 groups. An epidural catheter was inserted in cephalad direction using Tuohy epidural needle at L2-L3 or L3-L4with help of loss of resistance to air technique. Twenty milililiter of the study drug was given, sensory blockade was tested using the pinprick method and quality of motor blockade was assessed by modified Bromage scale.

Statistical analysis

All collected data were entered in Microsoft Excel sheet. It was then transferred to SPSS Statistics for Windows, Version 17.0. Chicago software for statistical analysis. Quantitative data were presented as mean and standard deviation and analyzed using Student's t-test. Qualitative data were presented as frequency and percentage and analyzed using Chi-square test. P < 0.05 was considered as statistically significant.

RESULTS

From Table 1, the mean (SD) age in Group B was 33.03 ± 8.22 years and the mean age in Group R was 33.81 ± 8.03 years. There was no statistically significant difference between the two groups (P > 0.05).

Table 1

Age-wise distribution of the patient

Age group (years)	Group B, n (%)	Group R, n (%)	Total
<20	1 (3.3)	1 (3.3)	2
21-30	13 (43.3)	10 (33.3)	23
31-40	10 (33.3)	14 (46.7)	24
41-50	6 (20.0)	5 (16.7)	11
Total	30 (100.0)	30 (100.0)	60
Mean±SD	33.03±8.22	34.6±7.79	33.81±8.03

SD=Standard deviation

The sensory blockade onset was assessed after attaining at level T10. The mean time of onset of sensory blockade in Group B was 10.05 ± 2.1 and in Group R was 9.8 ± 1.8. The onset of sensory blockade was clinically and statistically found nonsignificant with P = 0.61.

The mean time of duration of sensory blockade in Group B was 5.56 ± 0.059 and in Group R was 5.34 ± 0.073. The duration of sensory blockade among both the groups was found to be statistically significant (P = 0.024).

The motor blockade onset was assessed after attaining Grade 1 block. The onset of motor blockade in Group B was 4.98 ± 1.07 min and in Group R was 5.28 ± 1.2 min which was clinically and statistically nonsignificant with P = 0.31.

The duration of motor onset in Group B was 4.36 ± 0.39 h and in Group R was 3.53 ± 0.23 h which was clinically and statistically significant with P < 0.01.

The change in systolic blood pressure in both the groups was not significant which was comparable at various time intervals.

There was no significant change in diastolic blood pressure (DBP) in both the groups which was comparable at various time intervals.

DISCUSSION

Bupivacaine is an excellent drug for epidural anesthesia, but its major disadvantage is cardiotoxicity when used in high volumes required for epidural block. Ropivacaine is a long acting regional anesthetic which has been developed for purpose of reducing the potential cardio toxicity associated with bupivacaine. In our study demographic data comparing age shows no statistically significant difference among both the groups [Table 1]. The mean time for onset of sensory block consider at (T10), in group B 10.05 ± 2.1 min and group R was 9.8 ± 1.8 min. There is no statistically significant difference in the onset of sensory blockade between the groups [Table 2]. The similar was study conducted by Mc Glade DP, Kalpokas MV, et al. comparing Bupivacaine and Ropivacaine in epidural anesthesia, they found the onset of sensory block at T10 dermatomes was 10 (5-15) min for 0.5% Ropivacaine and 10(6-10) min for bupivacaine which did not find any statistically significant difference in the onset of sensory block which compares with our study.[3] The mean time duration of sensory block in Group B 5.56 ± 0.059 h. and Group R 5.34 ± 0.073 h. There was statistically significant difference between the group in duration of sensory block in our study [Table 3]. This is similar to study conducted by David L Brown, Randall L et al. who found in their study that duration of sensory block for 0.5% Ropivacaine was 333 ± 54 min a 0.5% Bupivacaine was 394±53 min which is statistically significant compared with our study.[4]

Table 2

Comparison of sensory onset in patients studied

Onset of sensory block (min)	Mean±SD	P
Group B	10.05±2.1	0.61
Group R	9.8±1.8

SD=Standard deviation

Table 3

Comparison of duration of sensory block

Duration of sensory block (h)	Mean±SD	P
Group B	5.56±0.059	0.024
Group R	5.34±0.073

SD=Standard deviation

It also correlates with the study of J. Kulkarni, R. Bengali et al. whose study reported that duration of sensory block for 0.5% ropivacaine is less than 0.5% bupivacaine.[5]

In our study the onset of motor block in Group B was 4.98 ± 1.07 min and in Group R was 5.28 ± 1.2 min which was clinically and statically not significant [Table 4]. In our study motor blockade is checked by using Bromage scale and onset was taken as soon as the patient developed grade I motor blockade. It correlates with the study conducted by David L Brown, Randall L et al. which found that the onset of motor block for 0.5% Bupivacaine was13.0 ± 10.17 min and for 0.5% ropivacaine was 10.7 ± 5.6 min which was statistically nonsignificant.[4]

Table 4

Comparison of onset of motor blockade

Onset of motor block (min)	Mean±SD	P
Group B	4.98±1.07	0.31
Group R	5.28±1.2

SD=Standard deviation

In present study duration of motor block for Group B was 4.63 ± 0.39 h and Group R was 3.53 ± 0.23 h which was clinically and statistically significant [Table 5]. This is similar to the study conducted by Patel, et al. which found that the mean duration of motor block for 0.5% Bupivacaine was 288.66 ± 36.99 min and for 0.5% ropivacaine was 211 ± 32.91 min.[6] It also correlates with study conducted by David L Brown, Randall L et al. Duration of motor block for 0.5% bupivacaine was 276 ± 52 min and for 0.5% ropivacaine was 220 ± 52 min. In our study the maximum level of sensory blockade for group-B was T4 and for group R was T5. The range of block in group B was T10-T4 and group R was T10-T5. This similar study was conducted by Katz JA Knarr D et al.[7] In our study no statistically, significant difference in SBP and DBP monitored at various interval between the two groups [Tables 6 and 7]. This was similar to study conducted by Durga Shankar Patel, A.M Lakra, et al. whose study reported that no significant statistical difference was found of Systolic blood pressure and Diastolic blood pressure in both the group. However, in Group B 2 patients had bradycardia which was treated with i.v. atropine 0.4 mg bolus and 2 patient had hypotension and in Group R 2 patient had bradycardia and 1 patient had hypotension which was treated with i.v. fluids.

Table 5

Comparison of duration of motor block

Duration of motor block (h)	Mean±SD	P
Group B	4.63±0.39	<0.01
Group R	3.53±0.23

SD=Standard deviation

Table 6

Comparison of systolic blood pressure (mmHg) between two groups of patients

SBP	Mean±SD	P
Preoperator
Group B	129.13±6.329	0.826
Group R	128.73±7.629
5 min
Group B	123.4±5.069	0.268
Group R	121.47±7.999
10 min
Group B	118.77±6.506	0.24
Group R	116.73±6.757
20 min
Group B	117.13±6.54	0.13
Group R	115.97±6.261
30 min
Group B	117.9±6.12	0.43
Group R	116.3±8.218
40 min
Group B	118.1±5.64	0.67
Group R	117.4±8.633
50 min
Group B	119.1±4.87	0.44
Group R	117.67±8.289
60 min
Group B	120.27±4.43	0.26
Group R	118.43±8.093
80 min
Group B	121.17±6.12	0.07
Group R	118.8±7.788
100 min
Group B	121.31±6.45	0.52
Group R	120.57±6.735
120 min
Group B	122.53±5.27	0.11
Group R	120.93±6.297

SBP=Systolic blood pressure, SD=Standard deviation

Table 7

Comparison of diastolic blood pressure (mmHg) between two groups of patients

DBP	Mean±SD	P
Preoperator
Group B	75.13±7.138	0.262
Group R	73.2±6.025
5 min
Group B	73±7.516	0.678
Group R	72.27±6.005
10 min
Group B	69.23±6.897	0.873
Group R	68.97±5.898
20 min
Group B	67.1±6.97	0.749
Group R	66.57±5.805
30 min
Group B	65.9±7.117	0.29
Group R	64.13±5.612
40 min
Group B	66.17±7.057	0.045
Group R	62.73±5.86
50 min
Group B	66.77±7.445	0.132
Group R	64.53±6.463
60 min
Group B	67.3±7.47	0.07
Group R	64.67±6.172
80 min
Group B	67.5±7.642	0.198
Group R	65.1±6.593
100 min
Group B	67.37±6.95	0.876
Group R	67.1±6.244
120 min
Group B	67.8±7.034	0.848
Group R	67.47±6.367

DBP=Diastolic blood pressure, SD=Standard deviation

CONCLUSION

After epidural block, the duration of sensory block was slightly more with bupivacaine. The maximum level of sensory blockade in both was comparable. The onset of sensory block was comparable in both the groups, but the duration of sensory block was shorter with ropivacaine compared to bupivacaine. The onset of motor blockade was comparable in both the groups, but the duration of motor blockade was also shorter and the degree of motor block was less intense with ropivacaine compared to bupivacaine. Hemodynamic parameters were comparable in both the groups, with a magnitude of fall in blood pressure being similar. The incidence of side effects such as hypotension and bradycardia was comparable in both the groups. Our study reveals that 20 mL of ropivacaine (0.5%) when administered epidurally provides adequate anesthesia for lower abdominal and lower extremity surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.