Real-time analgesic efficacy and factors determining drug requirements of combined spinal-epidural analgesia for labor: a prospective cohort study

Abstract

Purpose
Combined spinal-epidural analgesia (CSEA) is effective but not sufficient for labor pain. This study was conducted to assess the real-time analgesic efficacy, side effects of anesthetic drug dosage, and maternal satisfaction in labor to provide reference for the optimization of labor analgesia.

Methods
This was a prospective, cohort, single-center study that included 3020 women who received CSEA for labor analgesia. The visual analogue scale (VAS) for labor pain, real-time anesthetic drug dosage, side effects, adverse labor outcomes, factors influencing average drug dosage, and maternal satisfaction with CSEA were assessed.

Results
Overall, the VAS labor pain score was lowest at the first hour after the anesthesia was given. After 4 h for primiparas and 3 h for multiparas, the VAS score was greater than 3 but the anesthetic drug dosage did not reach the maximum allowed dosage at the same time. The average anesthetic drug dosage was positively correlated with fever, urinary retention, uterine atony, prolonged active phase, prolonged second stage, assisted vaginal delivery, and postpartum hemorrhage. The average anesthetic drug dosage was the highest in women ≤ 20 years old, those with a body mass index (BMI) ≥ 24.9 kg/m ² , and those with a primary or secondary education level.

Conclusion
Appropriate age guidance and emphasis on education of labor analgesia, weight management during pregnancy, and real-time anesthetic dosage adjustment during labor based on VAS pain score may have positive effects on the satisfaction of labor analgesia.

Clinical trial number and registry
Clinicaltrials.gov (ChiCTR2100051809).

Full text

Vol.:(0123456789)
Journal of Anesthesia
https://doi.org/10.1007/s00540-024-03368-8
ORIGINAL ARTICLE
Real‑time analgesic efficacy andfactors determining drug
requirements ofcombined spinal‑epidural analgesia forlabor:
aprospective cohort study
ShuzhenWu1· YaxinLu2· ZijingZhang1· LinjiaZhong1· HongfeiDai1· ChangpingFang1· MinliHuang1·
ZifengLiu2· LinglingWu1
Received: 9 May 2023 / Accepted: 20 June 2024
© The Author(s) 2024
Abstract
Purpose Combined spinal-epidural analgesia (CSEA) is effective but not sufficient for labor pain. This study was conducted
to assess the real-time analgesic efficacy, side effects of anesthetic drug dosage, and maternal satisfaction in labor to provide
reference for the optimization of labor analgesia.
Methods This was a prospective, cohort, single-center study that included 3020 women who received CSEA for labor anal-
gesia. The visual analogue scale (VAS) for labor pain, real-time anesthetic drug dosage, side effects, adverse labor outcomes,
factors influencing average drug dosage, and maternal satisfaction with CSEA were assessed.
Results Overall, the VAS labor pain score was lowest at the first hour after the anesthesia was given. After 4h for primiparas
and 3h for multiparas, the VAS score was greater than 3 but the anesthetic drug dosage did not reach the maximum allowed
dosage at the same time. The average anesthetic drug dosage was positively correlated with fever, urinary retention, uterine
atony, prolonged active phase, prolonged second stage, assisted vaginal delivery, and postpartum hemorrhage. The average
anesthetic drug dosage was the highest in women ≤ 20years old, those with a body mass index (BMI) ≥ 24.9kg/m2, and
those with a primary or secondary education level.
Conclusion Appropriate age guidance and emphasis on education of labor analgesia, weight management during pregnancy,
and real-time anesthetic dosage adjustment during labor based on VAS pain score may have positive effects on the satisfac-
tion of labor analgesia.
Clinical trial number and registry Clinicaltrials.gov (ChiCTR2100051809).
Keywords Analgesic effectiveness· Anesthetic drug· Dosage adjustment· Labor analgesia· Labor monitoring
Introduction
Labor pain can result in negative effects such as dystocia
and fetal distress [1]. Labor analgesia can reduce pain and
thus the chances of negative effects [2]. Combined spinal-
epidural anesthesia (CSEA) can rapidly relieve pain and its
analgesic effect was more significant compared with other
non-neuraxial analgesic protocols [3, 4], and furthermore,
it can reduce the rate of non-medically indicated cesarean
deliveries [5, 6]. However, studies have reported that as
analgesic time is prolonged the visual analogue scale (VAS)
score for pain during labor gradually rises, suggesting that
the relief of labor pain becomes insufficient [7, 8]. The spe-
cific changes of labor pain and analgesic demand during
labor remain unclear because few studies have evaluated
time-course changes in effectiveness of analgesia during
labor [9].
Jib etal. dynamically assessed pain in adolescents with
cancer and provided real-time pain treatment to decrease
the intensity of pain [10]. A recent study evaluated the pain
scores of women using ibuprofen and oxycodone/acetami-
nophen for medical abortion pain relief at regular intervals,
showing more pain relief and lower use of analgesic agents
* Lingling Wu
2806381451@qq.com
1 The Department ofObstetrics andGynecology, The Third
Affiliated Hospital Sun Yat-Sen University, No. 600 Tianhe
Road, Tianhe District Guangzhou, Guangdong, China
2 Big Data andArtificial Intelligence Center, The Third
Affiliated Hospital Sun Yat-Sen University, Guangzhou,
Guangdong510630, China

Journal of Anesthesia
[11]. These two results suggested that frequent assessment
of pain can be used as the basis for pain treatment. Ban etal.
adjusted the background drug infusion every hour based on
the anesthetic requirement in the previous 1h for improving
maternal analgesia satisfaction in their study of computer-
integrated patient-controlled epidural analgesia [12], sug-
gesting that pain assessment and adjustment of analgesia
every 1h is a feasible approach when establishing precise
and effective analgesic protocols.
Sufentanil combined with ropivacaine alleviates labor
pain significantly, but is associated with dose-dependent side
effects such as fever, urinary retention, and uterine atony
[13–15]. Studies have shown that drug dose prediction based
on influencing factors can improve medication safety [16,
17]. Thus, the effectiveness and safety of analgesics should
be always considered together and a fine balance must be
searched for to achieve optimal labor analgesia. Studies of
this nature, however, have not been performed to examine
pain scores, drug dosages, and factors influencing drug dos-
age for women in labor.
In addition, it has been reported that parity is a factor
that influences labor pain and the management standards
for primipara and multipara in the new stage of labor are not
consistent [18, 19].
To provide reference for the optimization of labor anal-
gesia in the primiparas and multiparas, this study was con-
ducted to assess the time-course of VAS scores during labor
within a pre-set CSEA protocol (drug doses included), side
effects of anesthetic drug dosage, and maternal satisfaction.
Materials andmethods
Study design
This study was a prospective, single-center observational
cohort study conducted at the Third Affiliated Hospital of
Sun Yat-sen University, an institution with 7,000 deliveries
per year and a labor analgesia rate of more than 50%. A total
of 3,020 women who delivered from July 2020 to January
2022 were included in the study. They were divided into
two groups: primiparas and multiparas. Inclusion criteria
included: (1) Singleton pregnancy; (2) Accepted CSEA with
PCEA for labor analgesia; (3) No contraindications to the
analgesics used or method of administration; (4) Cervical
dilation of 2cm before analgesia was administered; (5) No
mental illness. Exclusion criteria included: (1) Twin preg-
nancies; (2) Breech presentation; (3) Contraindications for
vaginal delivery; (4) Combination use of other analgesic
methods.
This study was registered at Clinicaltrials.gov, and given
the registration number ChiCTR2100051809. The study was
approved by the Ethics Committee of the Third Affiliated
Hospital of Sun Yat-Sen University (No. [2022] 02–051-
01), and all participants provided written informed consent.
Analgesic procedure
According to the relevant literature and guidelines, the pro-
gram of labor analgesia formulated by the Department of
Anesthesiology of this research institution was as follows
[3, 13]. With the woman in a lateral decubitus position, 5μg
sufentanil was injected into the subarachnoid space at L2-3,
and an epidural catheter attached to the PCEA pump was
inserted into the epidural space. Then, a PCEA pump con-
taining a 120ml solution of 45µg sufentanil (Yichang Renfu
Pharmaceutical Co., Ltd) and 75mg ropivacaine (AstraZen-
eca) was started. The pump provided a continuous infusion
with a background infusion dose (Dbi) of 6ml/h, a bolus
dosage (Db) of 8ml, and a lock-out time interval of 15min.
The maximum dosage (Dm) of PCEA pump was 38ml/h
(containing 14.25µg sufentanil and 23.75mg ropivacaine).
The pump was used until the completion of perineal sutur-
ing. Effective analgesia was considered a VAS pain score
of ≤ 3. If pain relief was inadequate (VAS score > 3), a sup-
plementary bolus dose of 8ml was given [1]. The number
of supplementary bolus (Ns) of the PCEA pump per hour,
total anesthetic drug dosage (Dt) used, and the time of labor
analgesia duration (t) were recorded during labor. Based on
the 2019 American College of Obstetrics and Gynecology
(ACOG) recommendations and drug instructions for the safe
dosage of sufentanil and ropivacaine (45μg/h and 28mg/h
respectively) [3], the safe dosage (Ds) of the PCEA pump
was calculated. To ensure the accuracy of data, all the sub-
jects received research education.
Data collection
A VAS pain score (with a VAS-scale printed in a paper) was
used to assess labor pain, with 0 = no pain and 10 = pain as
bad as it could be [20, 21]. In this study, scores were catego-
rized as 0 = no pain; 1–3 = mild pain; 4–6 = moderate pain;
and 7–10 = severe pain [7]. VAS pain scores were recorded
before labor analgesia, after labor analgesia that was begun
at 10min, 30min, and hourly from 1 to 10h, at full cervical
dilatation, and at 1, 2, 3, and 4h after full cervical dilata-
tion. Because this was an observational study, no additional
analgesic dose would be added despite results of real-time
assessment indicated that such a dose would be needed. To
ensure the accuracy and reliability of data, all the physicians
received standardized training.
The primary study variable was the VAS pain score. Data
collected include the real-time anesthetic dosage, average
anesthetic dosage, the occurrence of side effects including
fever, urinary retention, uterine atony, and prolonged fetal
heart rate (FHR) deceleration, and adverse labor outcomes

Journal of Anesthesia
including prolonged labor phase, assisted vaginal delivery,
postpartum hemorrhage, and neonatal asphyxia.The compli-
cations related to CSEA such as epidural hematoma, motor
block, accidental dural puncture (ADP) and post-dural
puncture headache (PDPH) were also documented. Mater-
nal satisfaction was recorded based on a scale of 1 to 5:
1 = very dissatisfied; 2 = dissatisfied; 3 = fair; 4 = satisfied;
and 5 = very satisfied [22].
The real-time dosage of the PCEA pump (Dr) was consid-
ered to indicate the real-time anesthetic drug consumption
from the PCEA pump during labor per hour. The formula
for calculating Dr was: Dr = Dbi + Ns × 8. The average dos-
age (Da) of PCEA pump was calculated by the following
formula: Da = Dt /t.
Statistical analysis
Double-entry data and consistency checks were used (Epi-
data 3.0) [23]. Data were analyzed using IBM SPSS statisti-
cal software and SAS software. Quantitative variables were
reported as mean ± standard deviation (SD), and compared
by t-test or Wilcoxon rank-sum test. Categorical variables
were reported as count and percentage, and compared by the
chi-square test or Fisher’s exact test. The reference range of
labor anesthesia duration was estimated by the 95% confi-
dence interval (CI). Generalized estimating equation (GEE)
analysis was used to analyze the repeated measures (VAS
pain score and real-time anesthetic dosage). The correlation
between the average anesthetic dosage and side effects or
adverse labor outcomes was examined using logistic regres-
sion analysis. Spearman’s correlation analysis was used to
analyze factors influencing average anesthetic drug dosage.
Linear regression analysis was used for assessing factors
influencing the average drug dosage after adjustment for
multiple factors. The level of significance was set at α = 0.05.
Results
Study participants
A total of 3,020 women participated in this study, among
which there were 2,265 primiparas and 755 multiparas
(Fig.1). The clinical information of the 2 groups and P val-
ues for assessing group differences are shown in Table1.
The epidural hematoma and motor block did not occur
because of the experienced anesthesiologist and adequate
preparation. There were 3 and 1 ADP cases in primipa-
ras and multiparas respectively, but no PDPH cases were
observed in both groups.
VAS scores andanesthetic drug dosages
As shown in Table2, the VAS pain scores for primiparas and
multiparas were lowest at the first hour after the anesthesia
was given. The duration of effective analgesia for primiparas
was 4.2 ± 1.2h, and for multiparas was 3.8 ± 1.1h, which
were significantly shorter than the duration of labor analge-
sia (Table1). After 4h of analgesia for primiparas and 3h
of analgesia for multiparas, the VAS pain scores were > 3 for
both groups (Fig.2A, B).
However, after 4h of analgesia for primiparas and 3h
of analgesia for multiparas, the anesthetic drug dosage was
below the maximum dosage (Dm) of the PCEA pump, and
below the safe dosage (Ds) of anesthetic drug (Fig.2A, B).
The average anesthetic dosage was higher in primiparas
than in multiparas (P < 0.05, Table1). The GEE analysis
Fig. 1 Patient eligibility

Journal of Anesthesia
revealed that the anesthetic drug dosage increased in tandem with the VAS pain score during the first stage
Table 1 Comparison of clinical information for primiparas and multiparas
Data are presented as mean ± SD or count (%)
BMI body mass index, FHR fetal heart rate
An orifice dilatation of ≥ 6cm was used as a marker of active stage [24]
NS as non-significant. *Evidence for an association assessed at P value ≤ 0.05
Term Primiparas (n = 2265) Multiparas (n = 755) P value
Baseline data
Age (year) 28.7 ± 3.1 32.0 ± 3.8 < 0.01*
Gestational week (week) 39.3 ± 1.3 39.3 ± 1.1 NS
Prenatal BMI (kg/m2)21.2 ± 3.3 21.6 ± 3.2 NS
Newborn Weight (kg) 3.0 ± 0.3 3.2 ± 0.3 0.05*
Education level NS
Primary/Secondary 88 (3.8) 36 (4.7)
High School Education 135 (5.9) 55 (7.2)
College/University (less than 4years) 914 (40.3) 293 (38.8)
College/University (4years and above) 1128 (49.8) 371 (49.1)
Clinical data
The way for induction NS
Combined cervical dilation balloons with contraction 245 (10.8) 76 (10.0)
Cervical dilation balloons 38 (1.7) 11 (1.4)
Small doses of contractions 207 (9.1) 73 (9.7)
None 1775 (78.3) 595 (78.7)
Labor duration (hour)
Latent phase 7.1 ± 2.7 4.8 ± 2.4 < 0.01*
Active phase 3.6 ± 1.4 2.4 ± 1.1 < 0.01*
Second stage 1.2 ± 0.8 0.4 ± 0.2 < 0.01*
The duration of effective analgesia (hour) 4.2 ± 1.2 3.8 ± 1.1 < 0.05*
The duration of labor analgesia (hour) (8.1–8.6) (4.0–4.3) < 0.05*
Average anesthetic drug dosage (ml/hour) 10.0 ± 5.0 9.2 ± 5.0 < 0.01*
Side effect
Fever 622 (27.5) 103 (13.6) < 0.01*
Urinary retention 900 (39.7) 204 (27.0) < 0.01*
Uterine atony 994 (43.9) 159 (21.1) < 0.01*
Prolonged FHR deceleration 349 (15.4) 77 (10.2) < 0.01*
Adverse labor outcome
Prolonged latent phase 211 (9.3) 69 (9.1) NS
Prolonged active phase 134 (5.9) 28 (3.7) 0.02*
Prolonged second stage of labor 78 (3.4) 15 (1.9) 0.04*
Vaginal assisted birth 156 (6.9) 18 (2.4) < 0.01*
Postpartum hemorrhage 274 (12.0) 66 (8.7) 0.01*
Complications
Epidural hematoma 0(0.0) 0(0.0) NS
Motor block 0(0.0) 0(0.0) NS
Accidental dural puncture 3(0.0) 1(0.0) NS
Post-dural puncture headache 0(0.0) 0(0.0) NS

Journal of Anesthesia
of labor for primiparas and multiparas (both, P < 0.05,
Table3).
Side effects andadverse labor outcomes
Logistic regression models were developed to determine if
the average anesthetic drug dosage was positively associ-
ated with the incidence of side effects and adverse labor
outcomes. For both primiparas and multiparas, the average
drug dosage was positively correlated with fever, urinary
retention, uterine atony, prolonged active phase, prolonged
second stage, assisted vaginal delivery and postpartum
hemorrhage (all, P < 0.05, Fig.3A–D). The side effects of
analgesia and the incidence of adverse labor outcomes were
higher in primiparas than in multiparas (both, P < 0.05,
Table1).
Univariate andmultivariate analysis
Univariate analysis indicated that primipara age, prena-
tal BMI, newborn weight, and education level, as well as
multipara age, prenatal BMI, and education level were all
related to the average anesthetic drug dosage (all, P < 0.05,
Table4). Multivariate analysis with adjustment showed
that the average anesthetic drug dosage for the 2 groups was
influenced by age, prenatal BMI, and education level. In
addition, the average anesthetic drug dosage was highest in
women ≤ 20years old, with a BMI ≥ 24.9kg/m2, and with a
primary or secondary education level (Table4).
Maternal satisfaction
The proportion of multiparas (73.5%) who felt satisfied
with labor analgesia was higher than the proportion of pri-
miparas (67.3%). An analysis of the reasons for a satisfac-
tion score ≤ 3 showed a statistical difference for primipa-
ras and multiparas, and poor analgesia was the main cause
(χ2 = 17.757). Further analysis showed that compared to
multiparas, a smaller proportion of primiparas were unsat-
isfied with the poor analgesia (55.8%), but had a higher fre-
quency of side effects (13.9%) and prolonged labor (27.1%)
(Table5).
Discussion
A study by Eran Ashwal in 2020 concluded that the cervical
dilation rate during labor analgesia differed between primip-
aras and multiparas [25]. In the current study, the VAS pain
scores were lowest at the first hour after the anesthesia was
given, and indicated ineffective analgesia after 4h for pri-
miparas and 3h for multiparas. There are a few numbers of
reasons for this finding. Firstly, the best analgesic effect may
be obtained at these times as a result of the pharmacological
action or the method of administration of the anesthetic drug
[26]. Secondly, physical exhaustion during labor might lead
to a decreased tolerance of labor pain [27], and prolonged
opioid usage can result in adaptive changes in μ receptors
leading to tolerance and hyperalgesia [28]. The tolerance for
labor pain reaches a limit after 4h of analgesia for primipa-
ras and 3h of analgesia for multiparas. Thirdly, our results
showed that the anesthetic drug dosage increased in tandem
with the VAS pain score during the first stage of labor, but
the maximum dosage of PCEA pump was not reached after
4h for primiparas and 3h for multiparas, prior to which the
pump with a pre-set CSEA protocol may provide too much
anesthetic drug dosage. After that, the PCEA pump was not
fully used, reflecting the limitations of the PCEA pump set-
tings and even the CSEA protocol.
It has been shown that multiparas require a higher median
effective concentration of ropivacaine during labor analgesia
due to psychogenic pain from previous labor pain experi-
ences [29]. This is consistent with the satisfaction survey
of this study which showed that compared to primiparas,
more multiparas experienced poor labor analgesia. So, pri-
miparas and multiparas may require different management
Table 2 Real-time VAS pain score changes during labor with analge-
sia
Data are presented as mean ± SD
Term Primiparas Multiparas
nVAS NVA S
Before labor analgesia 2265 7.52 ± 1.90 755 7.27 ± 1.90
After analgesia in the first
stage of labor (hour)
0.17 2265 1.88 ± 1.92 755 2.06 ± 2.01
0.5 2265 1.15 ± 1.51 755 1.40 ± 1.72
1 2247 1.07 ± 1.44 712 1.31 ± 1.63
2 2068 1.74 ± 1.83 536 2.15 ± 2.03
3 1592 2.73 ± 2.11 339 3.02 ± 2.22
4 1260 3.63 ± 2.17 192 3.88 ± 2.35
5 930 4.40 ± 2.10 123 4.57 ± 2.37
6 692 5.08 ± 2.08 81 5.49 ± 2.06
7 507 5.55 ± 1.81 40 5.82 ± 2.03
8 362 6.24 ± 1.98 25 6.72 ± 1.95
9 258 6.77 ± 2.09 14 7.14 ± 1.99
10 189 7.21 ± 2.03 11 7.46 ± 1.81
The second stage of labor
(hour)
0 2265 5.90 ± 2.49 755 6.52 ± 2.41
1 965 6.92 ± 1.93 93 7.28 ± 2.20
2 335 7.83 ± 2.23 14 8.00 ± 2.83
3 89 8.11 ± 2.21 310.00 ± 0.00
4 27 10.00 ± 0.00 - -

Journal of Anesthesia
Fig. 2 Comparison of analgesia efficacy between primiparas and mul-
tiparas at the same moment. The real-time VAS score with the dura-
tion of analgesia (A, B) and the real-time anesthetic drug dosage with
the duration of analgesia (C, D). Both of the real-time VAS score and
the real-time anesthetic drug dosage changed gradually over time
(P < 0.05). Dm: the maximum dosage of PCEA pump. Ds: the safe
dosage of the PCEA pump
Table 3 Analysis of real-time
VAS pain score and anesthetic
drug dosage after analgesia
Term Primiparas Multiparas
Beta SE 95% CI P value Beta SE 95% CI P value
First stage 5.37 0.12 5.13–5.60 < 0.01 3.23 0.19 2.85–3.61 < 0.01
Second stage 0.03 0.02 – 0.01 to 0.08 0.19 0.02 0.07 0.06–0.08 0.21
Fig. 3 Correlation analysis of the average anesthetic dosage with the side effect (A, B) and adverse labor outcomes (C, D)

Journal of Anesthesia
and awareness of self-management should be given more
attention. In our study, we also found that insufficient dosage
was one of the factors leading to unsatisfactory labor anal-
gesia for both primiparas and multiparas. Therefore, clini-
cians need to adjust the background infusion dose, the bolus
dosage, or the lock-out time of PCEA pump timely under
the safe dosage of sufentanil and ropivacaine (45μg/h and
28mg/h respectively [3]) and educate women that the drug
dosage may be increased according to the real-time VAS
pain score in order to provide more prolonged relief of pain
after 4h of analgesia for primiparas and 3h of analgesia for
multiparas [30, 31].
The incidence of fever is associated with the dose of anes-
thetic drugs, and fever associated with ropivacaine is due to
the release of inflammatory factors caused by ropivacaine,
while the use of sufentanil may result in impairment of the
central thermoregulatory response [32, 33]. Armstrong etal.
proposed that opioid-induced urinary retention is related to
dosage, and may be the result of detrusor muscle dysfunc-
tion or because the drug impedes the afferent and efferent
mechanisms of the voiding reflex [34]. The aforementioned
studies help to explain our observation. It also showed that
the average anesthetic drug dosage was associated with uter-
ine atony, prolonged active phase, prolonged second stage,
assisted vaginal delivery and postpartum hemorrhage. These
findings could be related to a decrease in the frequency and
intensity of uterine contractions, because the nerves inner-
vating the uterus are inhibited by CSEA resulting in uterine
atony. And uterine atony and assisted vaginal delivery are
known as risk factors for postpartum hemorrhage [35–38].
Primiparas may have a higher average anesthetic drug dos-
age due to their longer duration of labor analgesia, and this
Table 4 Analysis of factors influencing the average anesthetic dosage
*Evidence for an association assessed at P value ≤ 0.05
Term Univariate analysis Multivariate analysis
B 95% CI P value B 95% CI P value
Primiparas
Age (year)*
≤ 20 – 0.722 – 1.164 to – 0.280 < 0.01 – 0.642 – 0.966 to – 0.317 < 0.01
20–30
> 30
Prenatal BMI (kg/m2)*
≤ 18.5 – 0.704 – 1.055 to – 0.352 < 0.01 0.158 0.101–0.215 0.03
18.5–24.9
≥ 24.9
Newborn Weight (kg) 1.068 0.427–1.709 < 0.01 0.505 – 0.235 to 1.245 0.18
Education level* – 6.448 – 6.679 to – 6.218 < 0.01 – 6.453 – 6.684 to – 6.222 < 0.01
Primary / Secondary
High School Education
College/University (less than 4years)
College/University (4years and above)
Multiparas
Age (year)*
≤ 20 – 5.439 – 6.080 to – 4.799 < 0.01 – 2.399 – 2.897 to – 1.900 < 0.01
20–30
> 30
Prenatal BMI (kg/m2)*
≤ 18.5 5.589 5.090–6.088 < 0.01 2.247 1.760–2.734 < 0.01
18.5–24.9
≥ 24.9
Newborn Weight (kg) −0.465 – 1.382 to 0.453 0.32 – – –
Education level*
Primary / Secondary – 3.606 – 3.997 to – 3.216 < 0.01 – 2.168 – 2.547 to – 1.790 < 0.01
High School Education
College/University (less than 4years)
College/University (4years and above)

Journal of Anesthesia
may be why a higher proportion of primiparas were dissatis-
fied due to side effects and prolonged labor.
It has been shown that an increased BMI is linked to
increased technical difficulties and failure of epidural anal-
gesia for labor, resulting in insufficient analgesia [39]. Junge
etal. reported a strong correlation between severe fear and
labor pain. Younger women, who may feel more fear of
childbirth due to a lack of education have a higher demand
for analgesic drugs [40]. On the other hand, women with
higher education levels have a higher awareness of analgesia
and get more effective pain relief [31]. As revealed in this
study, the average anesthetic drug dosage was the highest
in the groups ≤ 20years old, BMI ≥ 24.9 kg/m2, and those
with a primary or secondary education level. The findings
of our study also demonstrated that there was still potential
for ropivacaine and sufentanil dosage adjustments of CSEA
for labor analgesia. The parturients received relevant edu-
cation before labor through various means, including net-
work courses offered by our hospital, to alleviate anxiety
and provide information on the use of anesthetics and their
side effects. However, their awareness of the current CSEA
protocol remained limited. As for the reasons of unsatis-
factory labor analgesia, insufficient analgesia was the main
cause, followed by side effects and prolonged labor, among
which the primiparas and multiparas were different. So indi-
vidualized labor analgesia programs based on real-time VAS
pain score and parity could be establish (ex. multiparas want
more analgesics, primiparas are more concerned about the
side effects of labor analgesia, etc.). Furthermore, clinicians
should strengthen weight management during pregnancy
and educate patients regarding labor analgesia awareness
to reduce the use of anesthetic drugs, in order to achieve
the balance between sufficient analgesic and side effects of
administered drugs during the whole course of labor.
There may be some possible limitations in this study.
First, the selection of 1-h intervals for VAS pain scores dur-
ing labor analgesia had the time constraint, which might be
shortened to make the assessment more specific. Second,
a future study should be conducted in multicenter study
to validate the findings in our one-institution-based study.
Third, only one CSEA protocol was researched in this study.
And fourth, there were also possible confounding factors
that have not been studied, including environmental factors,
family factors and so on.
Conclusion
Clinician should establish individualized labor analgesia
programs based on real-time VAS pain score and parity.
At the same time, education of labor analgesia should be
strengthened to enhance the effectiveness of labor analgesia,
reduce side effects, and improve maternal satisfaction.
Acknowledgements The authors thank all the parturient who partici-
pated in this study.
Author contributions Shuzhen Wu: project development, data collec-
tion, data analysis, interpretation of data, manuscript writing, approval
of the final version. Yaxin Lu: data analysis, interpretation of data,
revision of the manuscript. Zijing Zhang: data collection. Linjia Zhong:
data collection. Hongfei Dai: data collection. Changping Fang: data
collection, revision of the manuscript. Minli Huang: data collection.
Zifeng Liu: data analysis, interpretation of data. Lingling Wu: project
development, interpretation of data, manuscript writing, approval of
the final version.
Funding The authors have no sources of funding to declare for this
manuscript.
Data availability The data that support the findings of this study are
available on request from the corresponding author, [LW], upon rea-
sonable request.
Declarations
Conflict of interest The authors declare no conflicts of interest.
Open Access This article is licensed under a Creative Commons Attri-
bution 4.0 International License, which permits use, sharing, adapta-
tion, distribution and reproduction in any medium or format, as long
as you give appropriate credit to the original author(s) and the source,
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article are
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the article’s Creative Commons licence and your intended use is not
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copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Table 5 Satisfaction scores and reasons for unsatisfactory labor anal-
gesia
Data are presented as count (%)
NS as non-significant. *Evidence for an association assessed at P
value ≤ 0.05
The maternal satisfaction score ≥ 4 was considered satisfactory for
labor analgesia
Term Primiparas Multiparas P value
Maternal satisfaction < 0.01*
Satisfaction score ≥ 4 1525 (67.3) 555 (73.5)
Satisfaction score ≤ 3 740 (32.6) 200 (26.4)
Reasons for unsatisfactory
labor analgesia
Poor analgesia 413 (55.8) 124 (62.0) < 0.01*
Prolonged labor 201 (27.1) 46 (23.0) 0.02*
Side effect 103 (13.9) 21 (10.5) < 0.01*
Else (such as experience) 23 (3.1) 9 (4.5) NS

Journal of Anesthesia
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