|Year : 2014 | Volume
| Issue : 1 | Page : 12-17
Intrathecal isobaric ropivacaine-fentanyl versus intrathecal isobaric bupivacaine-fentanyl for labor analgesia: A controlled comparative double-blinded study
Meenoti Pramod Potdar, Laxmi Laxman Kamat, Tanya Jha
Department of Anaesthesia, Dr. Lakhumal Hiranand Hiranadani Hospital, Powai, Mumbai, Maharashtra, India
|Date of Web Publication||20-May-2014|
Meenoti Pramod Potdar
Department of Anaesthesia, Dr. Lakhumal Hiranand Hiranadani Hospital, Hillside Avenue, Hiranandani Gardens, Powai, Mumbai - 400 076, Maharashtra
Source of Support: None, Conflict of Interest: None
Context: Neuraxial analgesia and walking epidural is the popular method of practicing labor analgesia. The combination of local anesthetic and opioid is advantageous as it prolongs the duration of labor analgesia. Ropivacaine is the newer local anesthetic agent having lesser motor effects and toxic effects hence would be preferred for labor analgesia.
Aims: The primary objective of the study was to assess the duration of analgesia of the intrathecal drug. The secondary objective was the assessment of onset, fixation of analgesia, motor weakness, ambulation, sedation, incidence of side-effects, maternal, and neonatal outcomes.
Settings and Design: This is prospective, randomized, controlled, double-blinded, study of 120 patients consenting for labor analgesia.
Subjects and Methods: A total of 120 primiparas with a singleton pregnancy in active labor who were given combined spinal epidural (CSE) were included in the study. These patients were randomly allocated to three groups of 40 each and received CSE. Group F-received 25 μcg fentanyl intrathecally. Group BF-received 25 μcg fentanyl with 2.5 mg isobaric bupivacaine intrathecally. Group RF-received 25 μcg fentanyl with 2.5 mg isobaric ropivacaine intrathecally.
Statistical Analysis Used: Correlations among different measurements were assessed using Pearson's correlation coefficients, P <0.05 was considered to be statistically significant.
Results: The three groups show comparable demographic data and obstetric parameters. The duration of spinal analgesia was significantly greater with Group RF 106.63 ± 17.99 min and Group BF 111.75 ± 23.58 min than the control Group F which was 60 ± 10.39 min with P = 0.001, but were comparable for Group BF and RF. The secondary outcome was comparable in all the three groups.
Conclusions: The addition of bupivacaine or ropivacaine to fentanyl intrathecally increased duration and quality of analgesia, did not affect ambulation and bearing down. The incidence of side-effects, maternal and neonatal outcomes and maternal satisfaction were comparable in all groups. Hence, the effect of both the local anesthetics with fentanyl intrathecally has similar effects, and there was no added advantage of ropivacaine over bupivacaine.
Keywords: Bupivacaine, fentanyl, intrathecal, isobaric, labor analgesia, ropivacaine
|How to cite this article:|
Potdar MP, Kamat LL, Jha T. Intrathecal isobaric ropivacaine-fentanyl versus intrathecal isobaric bupivacaine-fentanyl for labor analgesia: A controlled comparative double-blinded study. J Obstet Anaesth Crit Care 2014;4:12-7
|How to cite this URL:|
Potdar MP, Kamat LL, Jha T. Intrathecal isobaric ropivacaine-fentanyl versus intrathecal isobaric bupivacaine-fentanyl for labor analgesia: A controlled comparative double-blinded study. J Obstet Anaesth Crit Care [serial online] 2014 [cited 2019 Apr 24];4:12-7. Available from: http://www.joacc.com/text.asp?2014/4/1/12/132814
| Introduction|| |
Neuraxial analgesia and walking epidural is a popular method of practicing labor analgesia.  The neuraxial analgesia is usually accomplished with a small dose of short acting opioid like fentanyl or sufentanil.  The addition of local anesthetic to opioids for neuraxial analgesia increases the duration of sensory block. 
Ropivacaine is a newer local anesthetic agent having lesser motor blockade and toxic effects.  Hence, it is a local anaesthetic which is preferred for labor analgesia. Thus, we decided to evaluate the effectiveness of intrathecal fentanyl, isobaric ropivacaine-fentanyl and isobaric bupivacaine-fentanyl for labor analgesia. 
The primary outcome of the study was the duration of analgesia of the intrathecal drug. The secondary outcome was the assessment of onset and fixation of analgesia, motor weakness, effect on ambulation, sedation, incidence of pruritus, nausea, vomiting, urinary retention and labor and neonatal outcome.
We monitored all patients for hemodynamics parameters such as pulse rate, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP), oxygen saturation, level of spinal analgesia, assessment of somatosensory functions, and motor blockade.
| Subjects AND METHODS|| |
This is prospective, randomized, controlled, double-blinded, single centered study conducted in our hospital after ethics committee approval of 120 patients consenting for labor analgesia. These patients were randomly allocated to three groups of 40 each.
- Group F is the control group which received 25 μcg fentanyl intrathecally.
- Group BF is the study group which received 25 μcg fentanyl with 2.5 mg isobaric bupivacaine intrathecally.
- Group RF is the study group which received 25 μcg fentanyl with 2.5 mg isobaric ropivacaine intrathecally.
Patients were allocated to their respective groups by block randomization with a block of 15. Chits were labeled as F1-F5, RF1-RF5, and BF1-BF5. The labor room nurse was asked to pick up the chit, and the patients were allotted to the respective group.
Initially, a pilot study of 10 cases in each group was done and the sample size was calculated considering the difference in the duration of analgesia between groups. With the assumptions of alpha as 0.05, standard deviation (SD) as 17.67 min and maximum difference between the means of three groups as 49 min, a sample size of 25 was adequate. Hence, we decided to select a study group of 40 per group.
Patients included in the study were 38-40 weeks primiparas of American Society of Anesthesiologists status I and II, consenting to be included in the study, with a singleton pregnancy, induced labor, now in active labor with a cervical dilatation between 3 and 6 cm and expected to have a normal course of labor.
Patients refusing labor analgesia, having twin pregnancy or with malpresentation other than vertex, mode of delivery converted to cesarean section within 30 min of administration of labor analgesia, having inadequate analgesia visual analog score (VAS) of more than 5, 30 min after intrathecal study solution, were excluded from the study.
After the patient consented for labor analgesia, a peripheral venous access was secured. All patients received combined spinal epidural (CSE) in the sitting position at L2-L3 or L3-L4 spinal level with 18G Tuhoys needle and 27G spinal needle, with the loss of resistance and needle through needle technique. After confirming the free and clear flow of cerebrospinal fluid (CSF) the study drug was injected. 20G epidural catheter was inserted for 5-6 cm in the epidural space and taped securely to the back. The placement of the epidural catheter was confirmed with negative aspiration for blood and CSF. All patients were preloaded with at least 500 ml Ringer Lactate. After giving CSE, the patients were monitored by the anesthesiologist and obstetrician who were not involved in the study. Both patient and monitoring anesthesiologist were blinded to the study solution.
Patients once relieved of the pain were asked to put there foot on the ground, so as to feel the ground. They were then advised to lie down in the supine or left lateral position as per the patient's choice. They were supplemented with oxygen at 2 L/min with a nasal cannula. Patients were monitored for pulse rate, SBP and DBP, MAP, oxygen saturation and continuous fetal heart rate monitoring. These parameters were noted every 5 min for the first 15 min and thereafter every half an hour. Any incidence of hypotension was SBP <90 mm of Hg, was treated with a bolus of 100 ml of Ringer's lactate and if required with injection ephedrine in titrated doses.
The time required for reduction of pain in the subsequent contraction was assessed and was noted as the time required for the onset of analgesia. Pain was measured by VAS on the scale of 1-10 where 1 was minimal pain, and 10 was the worst pain. The time required for the patient to be pain free or VAS of 0-1/10 was noted as the time required for fixation of spinal analgesia. If the patient did not have adequate pain relief within 30 min of the study solution patient was excluded out of the study. The level of spinal analgesia was assessed by pin prick technique. The patients were assessed for the occurrence of paresthesia, ability to feel the ground and motor blockade. The assessment of motor function was done with modified Bromage scale where motor block was graded by 0 = able to straight leg raise against resistance, i.e., no detectable motor block, 1 = unable to straight leg raise, but able to flex knee, 2 = unable to flex knees but able to flex ankle, 3 = unable to move hip.
Any incidence of pruritus, nausea, vomiting, drowsiness, inability to bear down, and inability to feel the ground post study solution were noted. The duration of spinal analgesia was assessed, noted by the time at which patient complains of pain VAS >5/10, with increasing intensity, from the time of injection of the study solution. Epidural boluses of 0.1% of bupivacaine or ropivacaine with fentanyl 2 μcg/ml were given respectively for Group BF or RF and either of them to Group F for subsequent pain relief. The total duration of labor was noted. The incidence of fetal bradycardia, its reversibility and fetal outcome was noted. The outcome of labor, mode of delivery, assistance to vaginal delivery was noted.
Data were managed in Microsoft Excel spreadsheet. Demographics are described with mean, median, range, and SD. Demographics, obstetric parameters and general information such as count, average, and percentage for various parameters were calculated in Microsoft Excel. Correlations among different measurements were assessed using Pearson's correlation coefficients. A P < 0.05 was considered statistically significant. One-way ANOVA is used to investigate and model the impact of various parameters such as the onset of analgesia, duration of analgesia, duration of labor, pulse, SBP, DBP, MAP, local anaesthetic (LA) requirement for episiotomy, outcomes and complications, etc., between the three groups.
Paired t-test is used to compare hemodynamics within each group. All specific graphs drawn and statistical analysis was performed using Minitab 16.
| Results|| |
Among the 120 patients included in the study, none of them were excluded out of study for any reason.
The demographic details and obstetric parameters are shown in [Table 1].
|Table 1: The demographic details and obstetric parameters of the study groups |
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Station was graded as −3 = 0, −2 = 1, −1 = 2, 0 = 3, +1 = 4 and +2 = 5. The average station of the presenting part is between −2 and −1 in all the three groups and is comparable.
The three groups show similar demographic data and obstetric parameters.
One-way ANOVA was used to compare the above parameters.
[Figure 1] shows the VAS scores in all the groups. [Figure 2] shows the haemodynamic parameters in all the groups. Paired t-test is used to compare hemodynamics within each group.
The effects of the study solution is shown in [Table 2]. One-way ANOVA is used to investigate and model the impact of various parameters such as the onset of Analgesia, Duration of analgesia, duration of labor, LA requirement maternal and neonatal outcome [Table 3] side-effects [Table 4] etc., between the three groups.
|Table 2: The onset, fixation, duration of spinal analgesia, duration of labor, level of spinal analgesia, inability to feel the ground, number of patients requiring epidural top-ups |
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| Discussion|| |
Combined spinal epidural is the most accepted technique for labor analgesia, the advantage being quick onset of analgesia, with a lower dose of anesthetic and the ability to prolong the duration of analgesia as per the duration of labor. , Opioids like fentanyl or sufentanil are usually given intrathecally for spinal analgesia. The addition of local anesthetic to opioid prolongs the duration of spinal analgesia. 
"Walking epidural" is preferred for labor analgesia as it aids the progress and outcome of labor.  The patients should be pain free to be ambulatory. Ropivacaine causes lesser degree of motor blockade as compared with bupivacaine  as its relative potency for motor blockade in comparison to bupivacaine is 0.59 and thus would be advantageous in ambulatory labor analgesia.  As ropivacaine is available in isobaric form in our country, we decided to evaluate the effect of intrathecal isobaric ropivacaine-fentanyl and isobaric bupivacaine-fentanyl with intrathecal fentanyl for its onset and duration of analgesia, its motor effects, the effects on ambulation, and labor outcome.
We gave all epidurals in the sitting position. Isobaric solutions have a potential to spread cephalopod in the sitting position, but once the patient is in the supine position the solution is redistributed to the nondependent areas and the further cephalopod spread of the local anesthetic is restricted due to the lumbar lordosis.  They spread faster and higher as compared to hyperbaric solutions thus having a quicker onset of analgesia. ,,
We included 120 cases in our study that were allocated to the respective groups. None of the patients were excluded out of study for any reason.
The demographic data and the obstetric parameters as mentioned in [Table 1]. Such as parity, cervical dilatation, effacement, and station of the presenting part in all the three groups were comparable.
As shown in [Table 2]. The onset of analgesia was 1.03 ± 0.16 min for Group F, 1.1 ± 0.3 for Group BF and 1.08 ± 0.27 min for Group RF and was comparable. The duration for fixation of analgesia for Group F is 3.43 ± 1.15 min, 2.98 ± 1.58 min for Group BF and 2.98 ± 1.72 min for Group RF, the results being comparable. The duration of spinal analgesia was significantly greater with Group RF 106.63 ± 17.99 min and Group BF 111.75 ± 23.58 min than the control Group F which was 60 ± 10.39 min with a P = 0.001. However, the duration of analgesia between Group RF and Group BF were comparable. The duration of labor was comparable in all the groups. Hughes et al. conducted a similar study where he found both ropivacaine and bupivacaine with fentanyl had rapid and safe analgesia for labor.  Aaron Levin et al. compared bupivacaine-sufentanil with two different doses of ropivacaine-sufentanil. He concluded that both local anesthetics had similar labor analgesia duration. 
Though ropivacaine is considered to be less potent analgesic than bupivacaine the potency being 0.6 the results of our study were comparable at the selected dosage. Polley et al. demonstrated ropivacine to be less potent as an analgesic as compared to bupivacaine.  Beilin and Halpern in their study demonstrated the similar results for intrathecal ropivacaine-fentanyl and bupivacaine-fentanyl for labor analgesia and concluded that there is no advantage of ropivacaine over bupivacaine. 
The average level of spinal analgesia was between T9 and T10 level in all the groups as in [Table 2]. 11 and 12 patients respectively did complaint of transient tingling numbness in the feet and inability to feel the ground immediately after giving spinal analgesia in Group BF and Group RF. Thus, the somatosensory functions of dorsal columns were affected which are essential for ambulation and balance of the patient.  This effect reverted within 30 min. We made our patients ambulate only after the return of somatosensory functions and only when they were comfortable and confident to ambulate independently.
None of our patients had motor block as per the modified Bromage scale. This finding is contradictory to that observed by Hughes et al. where incidence of motor blockade by bupivacaine was almost 40% as compared to ropivacaine which was 5%. 
The VAS scores for analgesia as shown in [Figure 1] were comparable in all the groups.
The hemodynamic parameters as in Figure 2]a, 2b, 2c, and 2d, in all the groups with respect to pulse, heart rate, SBP, DBP, and MAP were comparable.These findings were comparable with that of Hughes et al. 
The incidence of assisted vaginal delivery as in [Table 3] was comparable in all the groups, vacuum being 5 in Group F, 4 in Group BF and 5 in Group RF and forceps being 1 each Group RF and BF and was attributed to big size babies. The incidence of Caesarean section was similar in all the groups, 2 in Group F, 1 in Group BF and 2 in Group RF. The cause of cesarean section in Group F was fetal distress with thick meconium stained liquor and fetal distress with nonprogress with occipito-posterior presentation. One patient in Group BF and two patients in Group RF underwent cesarean section due to nonprogress of labor. Beilin and Halpern had similar maternal out come in his study. 
The other most common side-effect experienced by our patients [Table 4] was pruritus 11 in group F, 10 in Group BF and 13 in Group RF and the results were comparable. In our study, the incidence of pruritus did not reduce with the addition of local anesthetic to fentanyl.  None of our patients experienced nausea, vomiting and urinary retention in the peripartum period. The incidence of fetal bradycardia after injection of control and study solutions was 2 in Group F, 3 each in Group RF and BF. This fetal bradycardia was experienced transiently post spinal injection and responded to left lateral position and inhalational of oxygen through nasal cannula. The fetal outcome of all the babies was good, APGAR scores being at least 9/10 at the first minute. None of the babies required resuscitation. The neonatal outcomes were comparable as per the Apgar scores in all the groups. Canan et al. in his study concluded that combination of bupivacaine-fentanyl and ropivacaine-fentanyl had similar maternal and fetal effects. 
None of our patients had difficulty in bearing down and all were ambulatory during labor. In the peripartum period, no patient had an incidence of post dural puncture headache.
| Conclusion|| |
We concluded from our study that addition of bupivacaine or ropivacaine to fentanyl intrathecally increased duration and quality of analgesia with similar safety profile. Addition of local analgesic did not hamper ambulation and bearing down of the patient and had similar incidence of pruritus, maternal and neonatal outcomes, with a good patient satisfaction. Hence, the effect of both the local anesthetics with fentanyl intrathecally has similar effects, and there was no added advantage of ropivacaine over bupivacaine.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]