A Comparative Study on the Effects of Epidural Anaesthesia Vs Entonox on Labor Analgesia, Maternal and Fetal Outcome
Shabana Babu *1, Siri Vummaneni 2, Krithika Muthusamy 3
*Correspondence to: Dr. Shabana Babu MBBS, MS, DNB, OBGYN. Department of Obstetrics and Gynaecology. Tamil Nadu.
© 2024 Dr. Shabana Babu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 20 August 2024
Published: 10 September 2024
Abbreviations
GA - Gestational Age
Primi - Primigravida
Multi - Multigravida
motor B - Motor block
dural P - Dural puncture
N - Normal vaginal delivery
CS - Caesarean section
V - Vaccum assisted vaginal delivery
F - Forceps assisted vaginal delivery
FM - Failed Maternal efforts
CPD - Cephalo pelvic disproportion
distress - Fetal distress
Prolonged - Prolonged labour
S - Spontaneous separation
COMP - Complications
DEL - Delivery time
2ND STG - Second stage of labour duration
MODE D - Mode of delivery
INDICN - Indication
CERDIL - Cervial dilatation
VAS - Visual Analogue scale
FHR - Fetal Heart Rate
AP - APGAR
BP - Blood Pressure
NICU - Neonatal intensive care unit
Introduction
The delivery of the infant into the arms of a conscious and pain free mother is one of the most exciting & rewarding moments in medicine – Moir DD
Labor is a complex mixture of biological mechanisms with emotions and pain. A number of mechanisms are employed to alleviate this pain, from complimentary therapies to invasive procedures. However, this did not receive much support because of various medical and religious reasons till late 19th century. People believed that an attempt to abolish labor pain would be potentially dangerous to both mother and fetus, would alter uterine contractions and prolong the delivery.
James Young Simpson, the Professor of midwifery in Edinburgh, Scotland, was among the first to use ether for the relief of labor pain in 1847 which was condemned by the clergy. Queen Victoria was given relief of pain during labor by Sir John Snow using chloroform in 1853. The queen later said “Dr. Snow administered the blessed chloroform and its effect was calming and relaxing beyond measure”. (1)
Childbirth has been recognized as among the most painful experiences known thus making labor analgesia in demand today. Numerous strategies either non-pharmacologic e.g., Hypnosis, Transcutaneous nerve stimulation, Acupuncture, Abdominal decompression, Yoga, parenteral drugs, Inhalational analgesics, Obstetric blocks or epidural blockade are considered to tackle this pain.(2)
Studies suggest that providing pain relief has positive impact on both mother and fetus and the outcome of labor.(3)
The optimal analgesic is the one that can provide pain relief throughout the entire labor process, with no side effects on both mother and fetus, should provide immediate onset of pain relief, effective pain relief, with minimal motor block, intact airway reflexes, mother should be awake and responsive, with very minimal maternal and neonatal depression and should have no depressant effects on the progress of the labor and the urge to bear down. It should also provide some analgesia in the post partum period, and rapid recovery.(4)
The mother should know well before term, how she will be accommodated during labor and what will be done to achieve a safe and pleasant delivery. The mother must be encouraged to express her preference regarding posture, analgesia and mobility. Fear of the unknown is more dreadful than fear of the known, and fear or anxiety in labor is equally as detrimental to both mother and fetus as is pain in labor.(5)
Of all the analgesic methods, ACOG suggests that epidural anaesthesia is the most effective.(6) If epidural analgesia is not available or feasible, other methods of labor analgesia like parenteral opiods or inhalational agents can be tried, which are also effective in pain control.
The purpose of the present study is to compare the effects of epidural anaesthesia vs entonox on labor analgesia, maternal and fetal outcomes and to find the method of effective pain relief with least side effects.
Aims of the Study
To compare the effects of epidural anaesthesia vs entonox on labor analgesia, maternal and fetal outcomes.
Objectives of the Study
Materials and Methods
The study was conducted in the Department of Obstetrics and Gynaecology at SRM Medical College Hospital and Research Center from June 2015 to June 2016.
Study Design Prospective randomized control Study, Method of randomization- purposive sampling.
Study Population 60 Term Antenatal patients admitted in early labor.
Inclusion Criteria
Exclusion Criteria
Ethical Clearance
Ethical clearance was obtained from the Ethical Review Committee of SRM Medical College on 21.8.2015. Ethical clearance number:843/IEC/2015
Methodology
Epidural Group
Entonox Group
When the patient enters active phase of labor, the patient is advised to inhale Entonox through a self regulatory mask at the beginning of an uterine contraction. The patient is instructed to do the same till the end of 2nd stage.
Parameters Monitored in both Groups
Outcome
Statistical Analysis
Data analysis was carried out using Statistical Package for Social Science (SPSS, V 10.5).
Mann-whitney test was used to calculate the p-value in ordinal date. For quantitative data, student t test was used to calculate the p-value and for qualitative data, chi-square test was used to calculate the p-value.
A p-value of less than 0.05 was accepted as indicating statistical significance.
Results
The mean age in epidural and entonox groups are 25.67 and 24.90 respectively.
Chi square test was used to evaluate the difference in age distribution between the two groups and there was no significant statistical difference between the two groups. (p= 0.922)
We used Chi-Square test for finding the difference between parity status in Epidural and Entonox group. There was no significant statistical difference between the two groups.( p= 0.438)
The mean gestational age in epidural and entonox groups is 38.620 and 38.433 respectively.
Chi square test was used to evaluate the difference between gestational age distribution between the two groups and there was no significant statistical difference between the two groups. ( p= 0.432)
The mean VAS in 1st stage in epidural group is 1.3 and in entonox group is 2.53. The mean VAS in 2nd stage in epidural and entonox group are 2.16 and 4.3 respectively. Using T test p value was calculated as 0.028 for 1st stage and 0.008 for 2nd stage which is statistically significant.
The mean duration of 1st stage of labor in a primi in epidural and entonox groups are 174.29 and 171.88 mins respectively. Using T test p value was calculated as 0.513 for 1st stage and 0.697 for 2nd stage which is not statistically significant.
The mean duration of 1st stage of labor in a Multi in epidural and entonox groups are 159.38 and 157.69 mins respectively. Using T test p value was calculated as 0.799 for 1st stage and 0.488 for 2nd stage which is not statistically significant.
The mean duration of 1st stage of labor in epidural and entonox groups are 166.33 and 165.73 mins respectively. Using T test p value was calculated as 0.883 for 1st stage and 0.326 for 2nd stage which is not statistically significant.
The incidence of normal delivery in epidural group is 80% and in entnox group ia 83.3% with a p value of 0.886 which is statistically not significant.
The incidence of instrumental deliveries in both groups is 10% and 16.7% with a p value of 0.480 and is not significant.
Though the number of caesarean section is more in epidural group, its is not statistically significant.
Discussion
Pain relief in labor has always been surrounded with myths and controversies. Hence, providing effective and safe analgesia during labor has remained an ongoing challenge.
The experience is different for each woman and the different methods chosen to relieve pain depend upon the techniques available locally and the personal choice of the individual.
Labor analgesia strives at making child birth a less traumatic and providing a more comfortable zone for a mother to welcome her baby. To make this remarkably possible we should adopt the best possible technique which yields excellent analgesia with minimal side effects on both mother and baby.
Age, Parity and Gestational Age
In a study by Hasegawa et al(50)There were no significant differences between the cases and the controls in terms of the age and gestational age (weeks) at the delivery,but there were differences in parity. The epidural analgesia group had a higher rate of nulliparae (74.1 vs. 53.1 %, p-0.001).
In contrast, there was no statistical difference between age, parity and gestational age in our study.
Pain Relief
In the study by Khadem et al (51), comparing the effects of epidural anaesthesia and entonox , pain score was lower in all stages of labor in epidural group than entonox analgesia. Mean pain score at analgesia in the beginning of first stage labor was 5.8 in entonox group and 1.2 in epidural group (P=0.960).
In the study performed by Loughman et al(52), women who received epidural analgesia were more likely to grade their pain relief as good or excellent (83% in The first stage and 85% in the second stage) compared to those who received pethidine (56% in the first stage and 64% in the second stage).
Agrawal et al (53) in their study showed that Epidural anasthesia provides significantly more analgesia, as measured by visual analog scale in both the first and second stage of labor than parenteral opioid.
Similarly in our study, Epidural anaesthesia is more effective in pain relief than Entonox during the 1st and 2nd stage of labor with a P value of 0.028 and 0.008 which is statistically significant.
Duration of Labor
In the study by Khadem et al (51), Duration of different stages of labor was not statistically different between two groups (P=0.89).
Bofill et al (54)found no difference in the duration of first stage of labor in his study on hundred women in active labor with epidural analgesia versus narcotics. Study showed no significant differences in the length of first stage of labor (p value 0.54) or second stage of labor (p value 0.55).
Mostafa et al(55) in their study showed there was no statistical difference in the duration of the active-first and the second stages of labor.
In our study, the duration of 1st and 2nd stage of labor was maintained in both the groups with no statistical difference (p= 0.187 and p=0.107).
Mode of Delivery
Mostafa et al (55) in their study showed that Epidural analgesia by lidocaine (0.5%) and fentanyl does not prolong labor compared with parturients without analgesia and there was no statistical difference in the rate of instrumental delivery, vacuum-assisted or cesarean delivery rates between both groups.
In the study by Khadem et al (51) , caesaran rate was similar in both groups and there was no statistical significane.
Liu and Sia et al(56) in their meta-analysis that there is increased chance of instrumental delivery (OR 2.11;95%CI 0.95 to 4.65) with no increase in caesarean section rates in the epidural group.
In our study, Though the number of caesarean deliveries were more in epidural than entonox, it was not statistically significant. .
The rate of instrumental deliveries and caesarean section in both groups were not statistically significant in our study. (P=0.172).
Maternal Outcome
In the study by Leighton et al( 57), Epidural analgesia is associated with hypotension, and maternal fever (particularly among women who shiver).
In our study, two women in epidural group had hypotension but there was no statistical difference between both groups with p value of 0.150.
Arfeen at al (58) found no significant difference between episodes of desaturation among women receiving nitrous oxide and epidural.
In our study there was no statistical difference between both groups in terms of maternal oxygen saturation and pulse with p value of 0.157 and 0.444 respectively.
Fetal outcome
Apgar
In the study by Khadem et al (51), First and five minute Apgar were not statistically different between two groups (P=0.87, P=0.75,respectively).
Mostafa et al (55)in their study showed There was no statistical difference in the number of newborns with 1-min and 5-min Apgar scores less than 7 between the epidural group and non epidural group.
The mean 1 min and 5 min APGAR of new born in both groups are not statistically significant in our study with p= 0.067.
Fetal Heart Rate
Leighton BL et al (57) in 2002 reported that analgesic method does not affect fetal oxygenation, neonatal pH or 5minute Apgar score.
In our study, there was no significant difference in the fetal heart rate between both group.(p= 0.943)
The need for NICU admissions was also compared. We could not find any Significant difference (P=0.554).
Summary
This study was performed at SRM Medical College in the Department of Obstetrics and Gynecology.
The aim was to study the effects of Epidural anaesthesia and Entonox on labor analgesia, maternal and fetal outcomes.
60 antenatal patients were enrolled with 30 patients in each group.
Detailed history was taken. Vital parameters like maternal pulse, BP were recorded. Fetal heart rate was checked. At the onset of active phase of labor, patients were randomly allocated into epidural or entonox group.
Pain relief was assessed with Visual Analog Scale (VAS) and Duration of labor was noted in both groups.
The results are as follows,
Conclusion
Epidural anesthesia provides better pain relief than Entonox in labor. But it requires continuous bedside supervision by an anesthetist and is costly.
On the other hand Entonox is also a good option for 1st stage of labor and does not require continuous monitoring as it is self-regulatory and cost effective.
Patient compliance is better with epidural than Entonox.
There are no significant adverse maternal or fetal outcomes in both groups.
Thus the method of selection of labor analgesia can be based on patient preference depending on the facilities available and cost factor.
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