|Year : 2017 | Volume
| Issue : 1 | Page : 47-51
Effect of intrathecal labor analgesia using fentanyl 25 μg and bupivacaine 2.5 mg on progress of labor
Pooja Mathur, Neena Jain, Lokesh Prajapat, Kavita Jain, Deepak Garg, Vishal Khandelwal
Department of Anaesthesia, Jawahar Lal Nehru Medical College, Ajmer, Rajasthan, India
|Date of Web Publication||1-Jun-2017|
B-10, Arawali Vihar Colony, Vaishali Nagar, Ajmer - 305 001, Rajasthan
Source of Support: None, Conflict of Interest: None
Background: The aim of this study was to evaluate the progress of labor and hemodynamic changes in the mother and fetus with intrathecal analgesia using bupivacaine and fentanyl during normal vaginal delivery. Materials and Methods: Sixty nulliparous parturients in the active phase of labor with a cervical dilatation of >3 cm were selected for this prospective study. Group SA (n = 30) received an intrathecal injection of 0.5% hyperbaric bupivacaine 2.5 mg and fentanyl 25 μg and compared with Group C (n = 30) who refused to give consent for neuraxial analgesia. Visual analog score, progress of labor, maternal hemodynamic variations, and fetal heart rate were recorded. Statistical analysis included an unpaired and paired two-tailed t-tests. Result: Duration of the active phase of first stage of labor was shortened in group SA as compared to group C (115.50 vs. 134.0 min, P < 0.05). Duration of second stage of labor was prolonged in group SA as compared to group C (18.03 vs. 10.13 min, P < 0.05). Rate of cervical dilation was faster in group SA as compared to group C (3.021 vs. 2.486 cm/h, P < 0.05). Mean visual analog score, pulse rate, and mean arterial pressure was significantly decreased as compared to the baseline in group SA. No significant changes were noted in the fetal heart rate as compared to the baseline in both groups. Conclusions: Single-shot intrathecal analgesia using fentanyl 25 μg and bupivacaine 2.5 mg in active phase of first stage of labor associated with fast cervical dilation rate and no delay in the progress of labor.
Keywords: Analgesia, bupivacaine, fentanyl, intrathecal, labor pain
|How to cite this article:|
Mathur P, Jain N, Prajapat L, Jain K, Garg D, Khandelwal V. Effect of intrathecal labor analgesia using fentanyl 25 μg and bupivacaine 2.5 mg on progress of labor. J Obstet Anaesth Crit Care 2017;7:47-51
|How to cite this URL:|
Mathur P, Jain N, Prajapat L, Jain K, Garg D, Khandelwal V. Effect of intrathecal labor analgesia using fentanyl 25 μg and bupivacaine 2.5 mg on progress of labor. J Obstet Anaesth Crit Care [serial online] 2017 [cited 2019 Dec 6];7:47-51. Available from: http://www.joacc.com/text.asp?2017/7/1/47/194297
| Introduction|| |
The pain of childbirth is the most severe pain any women can endure in their lifetime. The pain of the early first stage of labor arises from dilation of the lower uterine segment and cervix. Pain of the late first stage and second stage of labor arises from the descent of the fetus in the birth canal, resulting in distension and tearing of tissues in the vagina and perineum.
Labor pain is excruciating and is a significant contributor to fear, stress, and anxiety. Painful uterine contractions lead to maternal hyperventilation and increased catecholamine concentration resulting in maternal and fetal hypoxemia. Labor pain when unrelieved can have adverse effects on the course of labor as well as on the fetal wellbeing. An effective labor analgesia leads to better maternal and fetal outcome. Relief of pain during labor endeavors to make the journey of labor safe and pleasant for both the mother and baby.
Epidurals have long been associated with increased oxytocin use, increased fetal malposition, increased rates of instrumental and caesarean delivery, and longer labors. Spinal block is cheaper as well as less technically challenging when compared to epidural and combined spinal epidural block. Intrathecal analgesia alone is useful when duration of labor can be reasonably estimated. Opioid combined with a small dose of local anesthetic provides rapid analgesia and dissipates when no longer needed.
Bupivacaine because of its least placental transfer, due to high protein binding and minimal motor block compared to sensory block in lower doses, has become the popular choice for labor analgesia. Addition of neuraxial lipid soluble opioids permitted reduction in the dose and concentration of bupivacaine from 0.5% to as low as 0.065% while maintaining effective analgesia and minimizing potential adverse effects on the progress of labor and lower extremity motor block.
In view of the above, the present study was undertaken to compare the progress of labor as the primary outcome and hemodynamic changes in the mother and fetus as secondary outcome in parturients who received intrathecal labor analgesia using bupivacaine 2.5 mg and fentanyl 25 μg to a matching group C who did not receive neuraxial analgesia during normal vaginal delivery using a partogram.
| Materials and Methods|| |
After approval from the college ethical committee and obtaining written and informed patient consent, 60 nulliparous parturients at term pregnancy (American society of anaesthesiologist physical status grade I) were recruited for this prospective study. Only patients with singleton pregnancies and vertex presentation who were in the active phase of labor with a cervical dilatation of >3 cm and normal fetal heart rate (FHR) tracings were enrolled.
Patients in the group SA (n = 30) received an intrathecal injection of 0.5% hyperbaric bupivacaine 2.5 mg (0.5 mL) and fentanyl 25 μg (0.5 mL), volume made to 1.5 mL with normal saline, and compared with the matching group C (n = 30) who refused to give consent for neuraxial analgesia. The two groups were evaluated with regards to the progress of labor, maternal hemodynamic variations, fetal heart rate, and neonatal outcome during labor in parturient undergoing normal vaginal delivery.
Parturients were positioned supine with left-uterine displacement. An intravenous line was secured with an 18 G cannula on the nondominant hand and the parturients were preloaded with 500 mL of ringer's lactate solution; oxygen was administered by facemask at 3 L/min. To perform the block, parturients were placed in a sitting position as anatomical landmarks are easy to identify in the sitting position and performing the block technically easier in this position. The L3-L4 interspace was identified and 25 G spinal needle was used to enter the subarachnoid space. After return of clear cerebrospinal fluid, patients were given a single intrathecal injection of solutions mentioned previously. Then, parturients were repositioned in a supine position with left-uterine displacement. No patients were allowed to walk during the study period due to the need for continuous maternal and fetal monitoring for safety reasons. The frequency and intensity of uterine contractions, dilation, and effacement of the cervix, descent of the presenting part, and requirement of oxytocin (when cervical dilation rate was <1 cm/h) were assessed using the standard partogram chart to plot the progress of cervical dilation hourly and uterine contraction per 10 min by the obstetrician. FHR was monitored using an electronic fetal monitor. The requirement for instrumental deliveries or caesarean section and the indications for the same were also noted and such parturients were excluded from the study.
Based on a study by Tsen et al., for a 20% increment in the observed mean cervical dilation rate in the neuraxial group as compared to control group, the expected sample size requirement for 90% power and alpha error of 0.05 was 23 per group. Thus, keeping in mind the loss to follow-up due to various reasons, sample size of 30 parturients was decided in each group. Statistical analysis was performed using software Statistical Package for the Social Sciences (SPSS) version 21 (Armonk, NY: IBM Corp). Unpaired and paired student t-test was used to analyze the data; P value of 0.05 was considered to be significant.
| Results|| |
Both groups were similar in terms of age, weight, and height of parturients. Both groups were comparable in terms of mean cervical dilation and VAS score at the time of study initiation [Table 1].
The mean onset of sensory block and motor block was 2.97 ± 0.615 and 4.00 min, respectively, and mean duration of motor block was 24.0 ± 1.826 min in group SA. The highest level of sensory block attained was T8 in 30%, T9 in 66.7%, and T10 in 3.3% of group SA. The duration of analgesia was 147 ± 22.11 min.
The VAS score was significantly lower in group that was provided intrathecal analgesia at all time intervals as compared to group C (P < 0.001) [Table 2].
Thus, parturients in group SA received excellent pain relief throughout labor and VAS score remained less than 4 till delivery as compared to group C, in which VAS score was more than 7 at all time. Rate of cervical dilation was significantly faster and duration of active phase of first stage of labour was observed to be significantly shorter in parturients who received intrathecal analgesia when compared to control group [Table 3].
Mean pulse rate, mean arterial pressure are shown in the [Figure 1] and [Figure 2], respectively. No intervention was required in any of the parturients with regards to hemodynamic changes in either of the groups.
There were no significant changes in FHR as compared to the baseline in both the groups, and none resulted in intervention for fetal compromise. All FHR decelerations prior to and after intrathecal analgesia administration were transient [Figure 3]. The mode of delivery in all parturients was vaginal delivery without any instrumental delivery. The parturients who required caesarean section due to other indication were excluded from the study. APGAR score at 1 minute remained between 6 or 7 and at 5 minute remained between 7 and 9 in all neonates of both the groups. No neonatal respiratory depression was noted.
Nausea was reported in 7% parturients in group SA and 10% parturients in group C; 10% parturients in group SA complained of pruritus. Hypotension, bradycardia, vomiting, and fetal distress were not found in either group.
| Discussion|| |
Because single shot intrathecal labor analgesia attempts to achieve a 4-h window of ambulatory pain control for laboring women. Hence, it was administered in the active phase of labor (>3 cm cervical dilation) in our study.
Intrathecal fentanyl 25 μg was used in our study for its rapid onset of action; at this dose, it has maximum duration of analgesia with least maternal and fetal side effect. Palmer et al. had compared 5–50 μg fentanyl in parturients for labor analgesia, and found that at 25 μg dose, duration of analgesia was 90 min with least maternal and fetal hemodynamic changes. Bupivacaine was added to relieve somatic pain. The somatic pain of the second stage of labor cannot be effectively blocked by fentanyl alone, however, local anesthetic can effectively block them. Thus, 0.5% hyperbaric bupivacaine 2.5 mg was used in our study. Wang et al. observed a synergism between fentanyl and bupivacaine in an animal study. Palmer et al. studied different doses of bupivacaine with fentanyl and found that the duration of analgesia in only fentanyl group was 92 ± 23 min, in fentanyl and bupivacaine 1.25 mg group was 94 ± 25 min, and in fentanyl and bupivacaine 2.5 mg group was 108 ± 20 min.
The parturients who received intrathecal analgesia received excellent pain relief throughout labor as compared to group C. Group SA parturients experienced pain at the time of delivery of baby, although the VAS score was less than 4. Potdar et al. reported a similar result in bupivacaine and fentanyl group.
In our study, the mean duration of the active phase of first stage of labor was reduced by 19 min in group SA as compared to group C. The mean rate of cervical dilation in active phase of first stage of labor was faster in group SA as compared to group C. Jix et al. reported a significant decrease (P < 0.05) in the duration of first stage of labor and total duration of labor in the combined spinal epidural group by 78 min as compared to controls and inhaled nitrous oxide group. Bindu et al. reported a decrease in duration of first stage of labor in the epidural group by 20.95 min as compared to the control group. In contrast, a Cochrane review  concluded there was no difference in the duration of the first stage of labor (mean difference: 18.51 min, 95% CI: 12.91–49.92; 11 trials, 2981 patients). Small sample size in our study may account for these discrepancies. Tsen et al. demonstrated a faster rate of cervical dilation in women randomized to receive combined spinal epidural analgesia compared with those who received epidural analgesia (2.3 vs 1.3 cm/h, respectively; P = 0.015). The rapid onset of analgesia decreases the maternal catecholamine levels (mainly epinephrine that has been found to have tocolytic action), leading to increase uterine activity. This leads to a decrease in the duration of first stage of labor.
The mean duration of second stage of labor was significantly prolonged in group SA (18.03 ± 8.27 min) as compared to group C (10.13 ± 5.89 min). This difference was statistically significant (P < 0.001). A Cochrane review  concluded there was a longer second stage of labor (mean difference: 13.66 min, 95% CI: 6.67–20.66; 13 trials, 4233 patients) in those receiving neuraxial analgesia compared to those receiving systemic opioids or no analgesia. Further, recent studies suggest that a longer second stage is, in itself, not harmful to the mother or neonate as long as the FHR pattern is reassuring and there is ongoing descent of the fetal head. Possible reason for a prolonged second stage could be relaxation of the abdominal wall musculature secondary to neuraxial local anesthetic resulting in decreased effectiveness of maternal expulsive efforts.
Changes in the mean heart rate and blood pressure did not require any intervention throughout the observed period. Mendall et al. had investigated effect of subarachnoid 25 μg fentanyl in parturients and observed a significant decrease in heart rate and systolic blood pressure and diastolic blood pressure after 25 min, which was not due to vasodilatation but due to onset of effective analgesia.
In our study, intrathecal labor analgesia in healthy parturients was not found to be associated with any FHR abnormalities, fetal distress or adverse neonatal outcome. Van de Velde et al. reported that 24% of the patients in the high dose intrathecal sufentanil group developed FHR abnormalities compared to 11% in the lower dose intrathecal sufentanil and 12% in the epidural group. Decreasing epinephrine due to effective labor analgesia causes an increase in the uterine tone, which will decrease placental blood flow and may subsequently lead to fetal bradycardia. As higher doses of intrathecal opioids seem to be related to more frequent non-reassuring FHR tracings, administration of high doses of intrathecal opioids (≥7.5 μg sufentanil or >25 μg fentanyl) are usually avoided in labor analgesia.
There were no significant changes observed in the APGAR scores at 1 and 5 min. No neonatal respiratory distress was found in either group. Fyneface et al. also found APGAR score >7 and >9 at 1 and 5-min intervals after intrathecal administration of bupivacaine and fentanyl.
Most common side effect was pruritus which was seen in 3 parturients of group SA, which was mild and no intervention was required. In group SA, 2 parturients complained of nausea as compared to 3 parturients of group C.
| Conclusion|| |
In conclusion we found that single shot intrathecal analgesia using fentanyl 25 μg and bupivacaine 2.5 mg when given in the active phase of first stage of labor had rapid onset with satisfactory pain relief and minimal motor block, which completely regressed at the time of second stage of labor. It was associated with faster cervical dilation rate and no delay in the progress of labor, without significant maternal and fetal hemodynamic variation.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]