Comparison of ultrasound-guided and traditional localisation in intraspinal anesthesia: a systematic review and network meta-analysis

Abstract

Objectives
The optimal puncture technique for neuraxial anaesthesia in different populations is unclear. We sought to obtain data from randomised controlled trials comparing the impact of ultrasound-guided technology and traditional positioning technology on the success rate of neuraxial anaesthesia.

Design
Systematic review and network meta-analysis using study populations, interventions, intervention comparisons, outcome measures and study types.

Data sources
PubMed, Embase, Cochrane Library and Web of science were searched until 31 September 2022.

Eligibility criteria
We included randomised controlled trials comparing three types of neuraxial anaesthesia: ultrasound-assisted, ultrasound real-time guidance and conventional positioning to describe which neuraxial anaesthesia modality is best for patients and to recommend the appropriate one for different populations.

Data extraction and synthesis
Five independent reviewers retrieved, screened and edited included studies using standardised methods. Assess risk of bias using the Cochrane Collaboration and Evidence Project tools. Network meta-analysis was performed using STATA V.15 statistical software.

Results
Twenty-two studies containing three different interventions were included. The SUCRA values of first-pass success rates for the three neuraxial anaesthesia methods were real-time guidance (82.8%), ultrasound-assisted (67.1%) and traditional positioning (0.1%). Both ultrasound techniques improved first-pass success rates compared with traditional localization, but there was no significant difference between the two. Subgroup analysis showed that the use of real-time ultrasound guidance for neuraxial anaesthesia in pregnant and patients with obesity improved first-pass success rates. Ultrasound-assisted technology can improve first-attempt success rates in older patients with abnormal lumbar spine anatomy.

Conclusion
Compared with conventional positioning, ultrasound guidance technology can improve the first-pass success rate of neuraxial anaesthesia, but there is no significant difference between ultrasound-assisted and real-time guidance technology. The results of subgroup analysis tell us that the most suitable neuraxial anaesthesia method is different for different groups of people.

PROSPERO registration number
PROSPERO number: CRD42022376041.

Full text

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ZhangY, etal. BMJ Open 2023;13:e071253. doi:10.1136/bmjopen-2022-071253
Open access
Comparison of ultrasound- guided and
traditional localisation in intraspinal
anesthesia: a systematic review and
network meta- analysis
Yinzhou Zhang ,1 Mingling Peng,1 Junying Wei,1 Jieling Huang,1 WuHua Ma,2
Yuhui Li2
To cite: ZhangY, PengM,
WeiJ, etal. Comparison
of ultrasound- guided and
traditional localisation in
intraspinal anesthesia: a
systematic review and network
meta- analysis. BMJ Open
2023;13:e071253. doi:10.1136/
bmjopen-2022-071253
►Prepublication history and
additional supplemental material
for this paper are available
online. To view these les,
please visit the journal online
(http://dx.doi.org/10.1136/
bmjopen-2022-071253).
Received 31 December 2022
Accepted 19 October 2023
1First Clinical Medical College,
Guangzhou University of
Chinese Medicine, Guangzhou,
Guangdong, China
2Department of Anesthesiology,
The First Afliated Hospital
of Guangzhou University of
Chinese Medicine, Guangzhou,
Guangdong, China
Correspondence to
Professor Yuhui Li;
liliuyuhui@ 126. com
Original research
© Author(s) (or their
employer(s)) 2023. Re- use
permitted under CC BY- NC. No
commercial re- use. See rights
and permissions. Published by
BMJ.
ABSTRACT
Objectives The optimal puncture technique for neuraxial
anaesthesia in different populations is unclear. We sought
to obtain data from randomised controlled trials comparing
the impact of ultrasound- guided technology and traditional
positioning technology on the success rate of neuraxial
anaesthesia.
Design Systematic review and network meta- analysis
using study populations, interventions, intervention
comparisons, outcome measures and study types.
Data sources PubMed, Embase, Cochrane Library and
Web of science were searched until 31 September 2022.
Eligibility criteria We included randomised controlled
trials comparing three types of neuraxial anaesthesia:
ultrasound- assisted, ultrasound real- time guidance and
conventional positioning to describe which neuraxial
anaesthesia modality is best for patients and to
recommend the appropriate one for different populations.
Data extraction and synthesis Five independent
reviewers retrieved, screened and edited included studies
using standardised methods. Assess risk of bias using
the Cochrane Collaboration and Evidence Project tools.
Network meta- analysis was performed using STATA V.15
statistical software.
Results Twenty- two studies containing three different
interventions were included. The SUCRA values of rst-
pass success rates for the three neuraxial anaesthesia
methods were real- time guidance (82.8%), ultrasound-
assisted (67.1%) and traditional positioning (0.1%). Both
ultrasound techniques improved rst- pass success rates
compared with traditional localization, but there was no
signicant difference between the two. Subgroup analysis
showed that the use of real- time ultrasound guidance
for neuraxial anaesthesia in pregnant and patients with
obesity improved rst- pass success rates. Ultrasound-
assisted technology can improve rst- attempt success
rates in older patients with abnormal lumbar spine
anatomy.
Conclusion Compared with conventional positioning,
ultrasound guidance technology can improve the rst-
pass success rate of neuraxial anaesthesia, but there is
no signicant difference between ultrasound- assisted
and real- time guidance technology. The results of
subgroup analysis tell us that the most suitable neuraxial
anaesthesia method is different for different groups of
people.
PROSPERO registration number PROSPERO number:
CRD42022376041.
INTRODUCTION
As a commonly used method of anaesthesia,
neuraxial anaesthesia has traditionally been
performed by manually palpating body
markers to determine the puncture site.
In recent years, ultrasound technology has
been increasingly used in neuraxial anaes-
thesia.1 There are currently two types of
ultrasound technologies used for neuraxial
anaesthesia: ultrasound- assisted technology
and ultrasound real- time guidance tech-
nology. Preoperative ultrasound scanning
helps identify puncture points and estimate
puncture depth, while ultrasound real- time
guidance technology (puncture under ultra-
sound visualisation) allows for more accu-
rate observation of the needle’s location
and trajectory. Some existing studies have
compared ultrasound- assisted technology
with traditional localization methods, and
some have compared ultrasound real- time
guidance technology with traditional local-
isation methods. However, few studies have
STRENGTHS AND LIMITATIONS OF THIS STUDY
⇒To the best of our knowledge, this is the rst study
to compare the puncture success rates of three
neuraxial anaesthesia methods using a frequentist
approach.
⇒This protocol was created strictly based on the
published Preferred Reporting Items for Systematic
Reviews and Meta- Analyses guidelines, and its re-
search results have certain reference value for clin-
ical anesthesiologists.
⇒Due to the technical difculty of real- time ultra-
sound guidance and the lack of evidence from clin-
ically relevant studies, this may be one of the main
limitations of this meta- analysis.
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2ZhangY, etal. BMJ Open 2023;13:e071253. doi:10.1136/bmjopen-2022-071253
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compared these two ultrasound techniques. Chen’s study
pointed out that ultrasound- assisted neuraxial anaes-
thesia has a higher first- pass success rate and higher
patient satisfaction than real- time guidance technology in
hip surgery in elderly patients,2 while Parli pointed out
that in the proposed operation in patients with obesity
undergoing lower limb surgery, the use of real- time ultra-
sound guidance for neuraxial anaesthesia shortens the
operation time and has a higher first- pass success rate.3
There is controversy as to which of these three methods
of neuraxial anaesthesia is the most effective. Therefore,
we reviewed articles comparing traditional positioning,
ultrasound- assisted, and real- time guidance techniques
used in neuraxial anaesthesia. A systematic review of
three methods of neuraxial anaesthesia was conducted
through network meta- analysis (NMA).
MATERIALS AND METHODS
We followed the recommendations of the Preferred
Reporting Items for Systematic Reviews and Meta- Analyses
(PRISMA)4 and registered the meta- analysis and system-
atic review in the PROSPERO database and PROSPERO
network on 28 November 2022 (registration number:
CRD42022376041). The current NMA is based on the
protocol recommended by the Cochrane Collaboration5
and follows the PRISMA guidelines.6
Search strategy
We searched the PubMed, EMbase, Web of Science and
Cochrane Library databases for all relevant articles up
to 31 September 2022. Keywords: “ultrasound real- time
guidance”, “ultrasound- assisted”, “landmark palpation”,
“traditional positioning”, “epidural anesthesia”, “spinal
anesthesia” and “combined spinal and epidural anes-
thesia”. Searches were conducted using a combination
of subject headings and free words. The complete search
strategy can be found in the online supplemental file 1.
Inclusion and exclusion criteria
We included randomised controlled trials (RCTs)
comparing two or three methods of neuraxial anaesthesia.
The information is as follows: study population: neuraxial
anaesthesia, including epidural anaesthesia, spinal anaes-
thesia, and combined spinal and epidural anaesthesia;
intervention: traditional positioning, ultrasound- assisted
positioning, and ultrasound real- time guidance; inter-
vention comparison: a neuraxial anaesthesia method;
outcome measures: the primary outcome was first- pass
success rate (defined as the needle successfully achieving
epidural puncture in one attempt without reorienta-
tion); the secondary outcome was first- attempt success
rate (defined as the needle reaching the epidural space
in one insertion attempt and allows for needle reorienta-
tion), recognition time (the time from operator contact
with the patient’s skin to marking the puncture site on
the skin and the time from placing the probe on the skin
to marking the puncture site), and puncture time (from
skin contact with needle to cerebrospinal fluid time
interval between outflows); study design: RCT.
Exclusion criteria were as follows: review articles, case
reports, case series, letters to the editor, reviews, confer-
ence proceedings, laboratory science studies and any
other irrelevant studies, as well as studies that did not
report the results of interest.
Study selection
Two authors, Yinzhou Zhang and Junying Wei, respec-
tively, searched the database according to the above
search strategy. The type of RCT or clinical trial was
selected through filters in online databases. The retrieved
documents were saved and deduplicated through docu-
ment management software (NoteExpress). The titles
and abstracts of the selected literature were read one by
one, and if the title and abstract met the criteria, the full
text was evaluated to see if the results of interest were
reported. Yinzhou Zhang, Junying Wei and Jieling Huang
also discussed whether each study should be included or
excluded to reach consensus. Disagreements regarding
inclusion or exclusion were resolved in discussions with
Yuhui Li and Wuhua Ma.
Date extraction
All relevant data from the included studies were inde-
pendently extracted and entered into standardised forms
by Yinzhou Zhang and Junying Wei, and then cross-
checked. The standardised form included the following
items: title, author name, publication date, patient type,
surgery type, body mass index, age, anaesthesia method,
sample size, first pass success rate, first attempt success
rate, identification time, procedure time, intervention
method and the best way to intervene. Age and body
mass index data were extracted as mean±SD and median
(IQR). When data from included studies were presented
in the form of IQRs, we followed appropriate methods for
transformation7–9 and finally used mean±SD for statistical
analysis.
Study quality
Jieling Huang and Wuhua Ma conducted independent
assessments using the risk of bias tool in Review Manager
(V.5.3). Quality was assessed using the following possible
sources of bias: random sequence generation, allocation
concealment, blinding of participants and personnel,
blinding of outcome assessments, incomplete outcome
data and selective reporting. The methods of each study
were rated as ‘high’, ‘low’ or ‘unclear’, reflecting the risk
of bias.5
Statistical analysis
Multiple treatment comparison is a meta- analytic
summary method that includes direct and indirect
comparisons of treatments. We used STATA V.15 software
to download the network package for statistical analysis.
The effect value of dichotomous variables used RR values,
and the effect value of continuous variables used SMD.
When the p value was >0.05, the inconsistency model was
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used to test consistency, and the node splitting method
was used for local inconsistency analysis. Perform a ring
inconsistency test on the network diagram that forms a
closed loop. If the 95% CI does not include 0, the hetero-
geneity is large, and sensitivity and subgroup analysis are
required.
A network diagram was formed connecting all included
studies to indicate the type of neuraxial anaesthesia,
the number of patients in the different studies, and the
number of pairwise comparisons. Nodes show different
neuraxial anaesthesia methods, and lines show direct
comparisons between neuraxial anaesthesia methods.
Cumulative probability plots for each neuraxial anaes-
thesia method and pairwise comparisons for each inter-
vention were plotted. We used cumulative ranking area
under the curve (SUCRA) values to present the effect
of neuraxial anaesthesia methods on first- pass success
rate and first- attempt success rate. SUCRA is a relative
ranking metric with a statistical range from 0% to 100%
that indicates the likelihood that the therapy will be rated
the best.10 Higher SUCRA values are considered better
outcomes for individual interventions.
Patient and public involvement
No patients participated in the study
RESULTS
PubMed and Embase databases were searched, and
128 and 359 studies were initially assessed. In addition,
we searched the Web of science and Cochrane Library
databases and retrieved 352 and 90 studies, respectively,
yielding a total of 929 publications. Online database filters
were used to screen for RCTs or clinical trials and 692
studies were excluded. After removing duplicates using
literature management software, 218 studies remained.
Titles, abstracts and full texts of the remaining studies
were reviewed in detail; 184 studies were not available,
20 studies were excluded due to lack of controls, and 14
studies did not report the outcome of interest (figure 1).
Figure 1 Flow diagram. RCTs, randomised controlled trials.
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Open access
Research characteristics
Tables 1 and 2 summarise the characteristics of the 22
studies. All experiments were two or three arms. Among
them, 13 studies compared ultrasound- assisted local-
isation with conventional localisation,11–23 5 studies
compared ultrasound- assisted localisation with conven-
tional localisation24–28 and 3 studies compared ultrasound-
assisted localisation with real- time guidance in the spinal
anaesthesia.2 3 19 One study compared the use of three
methods in spinal anaesthesia.20 Table 1 lists the first
author and publication year of the literature, as well as
basic information such as patient type, surgical method,
patient age and body mass index. Table 2 lists the anaes-
thesia method, study sample size, intervention measures
and main outcome indicators (first time passing success
rates) and better intervention outcomes. In all included
studies, the probes used for ultrasound were portable low-
frequency convex array probes, excluding special punc-
ture probes.
Risk of bias assessment
The quality indicators of the included studies are shown
in figure 2 . All studies used random sequence genera-
tion, 12 of which had allocation concealment. Thirteen of
the studies did not specify how participants were blinded.
One study had a high risk of bias in blinding the operator,
which could be explained by the difficulty in achieving
blinding of the procedure. Most studies had incomplete
outcome data, but five of the studies had unspecified
risks. None of the studies reported results selectively.
Synthesis of results
For all results for each outcome measure, we present
network plots, forest plots for individual studies, forest
plots for pairwise comparisons, and cumulative ranking
curves. The results are shown in online supplemental
figures 1 to 7. Results of inconsistency model detection,
consistency analysis, local inconsistency analysis, ring
inconsistency detection and funnel plots can be found
in the online supplemental file. From model testing and
funnel plots, the heterogeneity of the study was minimal.
First pass success rate
Nineteen two- arm studies and one three- arm study
documented first- pass success rates and were pooled
for analysis.2 3 11–17 19–27 29 30 Across all studies, traditional
positioning was the most frequently cited (online supple-
mental figure 1A). In this study, the puncture success rate
of the ultrasound- assisted group and real- time guidance
group seemed to be higher than that of the traditional
positioning group (online supplemental figure 1B).
However, there was no significant difference between
the ultrasound- assisted group and the real- time guidance
group (online supplemental figure 1C). The probabili-
ties of conventional positioning, assisted positioning and
real- time guidance were analysed by plotting a cumula-
tive ranking graph (online supplemental figure 1D).
According to SUCRA data, the first puncture success rate
is highest for real- time guidance (82.8%), followed by
ultrasound assistance (67.1%), and finally conventional
positioning (0.1%). The funnel plot is shown in online
supplemental figure 1E.
First attempt rate
A total of 16 trials provided data on first- attempt success
rates.2 3 11 12 14 18–22 24–28 30 The network node diagram is
shown in online supplemental figure 2A. Forest plot
results showed that the use of ultrasound was associated
with first- attempt success rate (online supplemental
figure 2B). However, there was no significant difference
between ultrasound- assisted and real- time guidance
(online supplemental figure 2C). The cumulative ranking
chart shows that ultrasound- assisted first attempt success
rate is the highest (75.3%), followed by real- time guid-
ance (74.6%) and traditional positioning (0.1%) (online
supplemental figure 2D). The funnel plot is shown in
online supplemental figure 2E.
Identication time
The network diagrams and forest diagrams of each study
are shown in online supplemental figure 3A,B. The
results2 3 11 12 17–19 21–23 26 27 30 show that the traditional posi-
tioning method has the shortest positioning time (online
supplemental figure 3D), but the ultrasound- assisted and
real- time guided puncture positioning time does not
show significant differences (online supplemental figure
3C). The funnel plot is shown in figure 3SE.
Duration of spinal anaesthesia
A total of nine studies, eight two- arm studies and one
three- arm study3 11 12 14 18 19 21 28 30 were collected to compare
the entire operation process from the puncture needle
contacting the skin to the outflow of cerebrospinal fluid.
The network diagrams and forest diagrams of each study
are shown in online supplemental figure 4A,B. Compre-
hensive analysis showed that the ultrasound- assisted oper-
ation time was the shortest (online supplemental figure
4D), and there was no significant difference between the
traditional positioning group and the real- time guidance
group (online supplemental figure 4C). The funnel plot
is shown in online supplemental figure 4E.
Subgroup analysis
In the first subgroup, we included nine studies in adults
with obesity and pregnant women (obese or not), and anal-
ysed the results of first pass success rate3 12 13 15 16 20 23 27 29
and first attempt success rate.3 12 18 20 27 For first- pass success
rate, a network plot (online supplemental figure 5A), a
forest plot for a single study (online supplemental figure
5B), a forest plot for pairwise comparisons (online supple-
mental figure 5C), a cumulative ranking curve (online
supplemental figure 5D) and a funnel plot (online supple-
mental figure 5E) are shown. The network diagram of the
first puncture success rate (online supplemental figure
6A), the forest diagram of a single study (online supple-
mental figure 6B), the forest diagram of pairwise compar-
ison (online supplemental figure 6C), the cumulative
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Table 1
The author
Time of
publication Type of patient Type of surgery Age (*‡†) BMI (*‡†)
Karthikeyan 2018 Adult Knee and hip surgery 65.3±9.7†
68.2±10.3*
30.1±6.4†
30.6±4.7*
Sangeeta Dhanger 2018 Maternal Caesarean section 23.06±3.01†
24.03±3.43*
27.2±3.8†
27.2±4.2*
Cristian Arzola 2015 Maternal Childbirth 32.3±5.8†
32.7±4.7*
29±5.1†
29.3±6*
Y. C. Lim 2014 Adult Lower limb surgery 61.1±13.3†
63.7±12.6*
25.4±5.6†
25.0±5.9
Chin 2018 Maternal Caesarean section NM 30.2§(27.0–36.5)†
30.5§(26.9–34.2)*
Bingdong Tao 2021 Maternal Caesarean section 32.3±5.2†
30.6±3.8*
28.3±3.0†
28.3±2.2*
Mohd Anas Khan 2022 Orthopaedic
patient
Lower limb surgery 54.5±12.8†
57.7±13.2*
29.3±4.6†
27.7±3.8*
Mengzhu Li 2019 Patients with
obesity
Caesarean section 29.5±3.9†
30.1±4.5*
NM
Sun- Kyung Park 2019 Old age patient Lower limb surgery 71.1±7.2†
71.2±6.1*
25.8±3.1†
25.8±3.1*
Mohamed Mohamed
Tawk
2017 Maternal Caesarean section 27.7±4†
26.7±3.8*
29.2±3†
29.2±2.9*
Sun- Kyung Park 2020 Anatomic
abnormality of
lumbar spine
Lower limb surgery 70.5±8.8†
66.5±13.2*
26.1±3.2†
25.9±2.9*
Bo Qu 2020 Old age patient Hip surgery 83.3±6.7†
82.3±7.1*
21.6±3.6†
20.6±3.0*
Xiu Ni 2021 Patients with
obesity
Caesarean section 31.8±4.8†
31.4±4.2*
33.5±2.1†
33.0±2.1*
Bertam 2017 Adult Lower limb surgery NM NM
Tanya Mital 2021 Children Chest and abdominal
surgery
2.4±1.3‡
3.0±1.7*
NM
Jatuporn Pakpirom 2020 Adult Chest and abdominal
surgery
60.0§(51.0–67.0)‡
58.5§(53.75–70.25)*
23.4±4.0‡
22.8±3.5*
Jindi Jiang 2021 Overweight
mothers
Childbirth 29.2±3.1‡
28.4±3.4*
35.6±2.0‡
35.2±2.4*
Hesham 2017 Anatomic
abnormality of
lumbar spine
Knee and hip surgery 69±10‡
70±10*
34±11‡
33±8*
Luying Chen 2021 Old age patient Hip surgery 82.7±6.6‡
84.5±6.2†
21.9±3.1‡
21.3±3.4†
Yasser Mohamed 2020 Maternal Childbirth 25.4±5.1‡
26.8±5.65†
37.9±4.3‡
38.1±4.2†
Parli Raghavan Ravi 2021 Patients with
obesity
Lower limb surgery 58.5§(50.3, 65.8)‡
59.5§(52.3, 65.8)†
34.9§(33.1, 36.35)‡
34.9§(33.1, 36.40)†
Deepak Bhardwaj 2022 Adult Lower limb surgery 39.66±13.27*
42.88±12.72†
43.6±15.24‡
22.8±2.8*
22.4±3.4†
23.9±3.0‡
*Landmark group.
†Ultrasound assisted group.
‡Real time group.
§Median (IQR).
CSE, combined spinal and epidural anesthesia; E, epidural anesthesia; NM, no mention; S, spinal anesthesia.
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Table 2
The author
Time of
publication
Method of
anaesthesia（E, S,
CSE）
Sample size
(*†,‡) Intervention
First pass
success
rate (%)
Effect
estimate
(better)
Karthikeyan 2018 S 59†
60*
Landmark versus
ultrasound assisted
43†
22*
ND
Sangeeta
Dhanger
2018 S 50†
50*
Landmark versus
ultrasound assisted
18†
74*
Ultrasound
assisted
Cristian
Arzola
2015 E 60†
68*
Landmark versus
ultrasound assisted
50†
60*
ND
Y. C. Lim 2014 S 85†
85*
Landmark versus
ultrasound assisted
7†
15*
ND
Chin 2018 CSE 105†
110*
Landmark versus
ultrasound assisted
38.2†
63.8*
Ultrasound
assisted
Bingdong Tao 2021 CSE 64†
64*
Landmark versus
ultrasound assisted
68.8†
93.8*
Ultrasound
assisted
Mohd Anas
Khan
2022 CSE 50†
50*
Landmark versus
ultrasound assisted
60†
86*
Ultrasound
assisted
Mengzhu Li 2019 CSE 40†
40*
Landmark versus
ultrasound assisted
52.5†
87.5*
Ultrasound
assisted
Sun- Kyung
Park
2019 S 40†
40*
Landmark versus
ultrasound assisted
17.5†
65.0*
Ultrasound
assisted
Mohamed
Mohamed
Tawk
2017 CSE 53†
55*
Landmark versus
ultrasound assisted
60†
58.5*
ND
Sun- Kyung
Park
2020 S 22†
22*
Landmark versus
ultrasound assisted
9.1†
50*
Ultrasound
assisted
Bo Qu 2020 CSE 40†
40*
Landmark versus
ultrasound assisted
20†
70*
Ultrasound
assisted
Xiu Ni 2021 CSE 40†
40*
Landmark versus
ultrasound assisted
40†
72.5*
Ultrasound
assisted
Bertam 2017 S 30‡
30*
Landmark versus real
time
47‡
30*
Real time
Tanya Mital 2021 E 23‡
22*
Landmark versus real
time
82.6‡
40.9*
Real time
Jatuporn
Pakpirom
2020 E 48‡
48*
Landmark versus real
time
68.6‡
35.4*
Real time
Jindi Jiang 2021 E 30‡
30*
Landmark versus real
time
56.7‡
30*
Real time
Hesham 2017 S 14‡
18*
Landmark versus real
time
72.2‡
83.3*
ND
Luying Chen 2021 S 57‡
57†
ultrasound assisted
versus real time
31.6‡
63.2†
Ultrasound
assisted
Yasser
Mohamed
2020 E 50‡
50†
ultrasound assisted
versus real time
90‡
74†
Real time
Parli
Raghavan
Ravi
2021 S 40‡
40†
ultrasound assisted
versus real time
40‡
10†
Real time
Deepak
Bhardwaj
2022 S 50*
50†
50‡
Landmark versus
ultrasound assisted
versus real time
82*
78†
80‡
ND
*Landmark group.
†Ultrasound- assisted group.
‡Real- time group.
CSE, combined spinal and epidural anesthesia; E, epidural anesthesia; ND, no difference; S, spinal anesthesia.
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Figure 2 Consensus risk- of- bias assessment of the included studies. Green, low risk; yellow, unclear; red, high risk.
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8ZhangY, etal. BMJ Open 2023;13:e071253. doi:10.1136/bmjopen-2022-071253
Open access
ranking curve (online supplemental figure 6D) and the
funnel plot (online supplemental figure 6E) are as shown
in the figure.
In a second subgroup analysis, we included patients with
a mean age over 70 years and those with abnormal lumbar
anatomy (previous lumbar surgery or scoliosis).2 19 21 22 28
The network diagram and forest diagram are shown in
online supplemental figure 7A,B. The results of the meta-
analysis showed that the first- attempt success rate seemed
to be higher in the ultrasound- assisted group (online
supplemental figure 7C), and the cumulative ranking
chart also showed that ultrasound- assisted was the most
recommended (online supplemental figure 7D). The
funnel plot is shown in online supplemental figure 7E.
DISCUSSION
In recent years, there has been increasing interest in
ultrasound guidance for spinal, epidural or combined
spinal- epidural anaesthesia.31–33 Research supports the
use of this technique to increase puncture success rates
and reduce complications.34 35 The UK National Institute
for Health and Clinical Excellence has published guid-
ance36 recommending that ultrasound can be used both
as a preoperative assessment tool and as a live puncture.
Two major indicators of difficulty in neuraxial anaes-
thesia are the number of needle turns required for
successful puncture and the time required for the entire
procedure. Multiple needle sticks are an independent
predictor of complications such as dural penetration,
vascular injury and paresthesias.37 Ideal neuraxial anaes-
thesia requires a successful puncture.24 Minimising the
number of attempts can help reduce the risk of complica-
tions and improve patient satisfaction.38 Previous studies
have shown that ultrasound scanning before puncture
can improve the success rate of puncture and reduce the
number of punctures.39 The characteristic of real- time
guidance technology is to observe the needle trajectory
in real time during the puncture process, which improves
the puncture success rate.24 40–42 This is consistent with
our analysis.
But the analysis showed no significant difference in first-
pass and first- attempt success rates between ultrasound-
assisted and real- time guidance. However, subgroup
analysis showed that real- time guidance technology was
more beneficial for pregnant women and obese people.
Ultrasound- assisted technology is more recommended
for older patients and patients with abnormal spinal
anatomy.
Let us analyse the reasons for this difference. It is
difficult for pregnant and obese patients to achieve the
ideal puncture position during neuraxial anaesthesia,
and difficulty in palpation may lead to an increase in the
number of punctures, resulting in patient discomfort or
puncture failure.43 During pregnancy, lumbar protrusion
increases and the pelvis expands and rotates, resulting
in a deeper and narrower epidural space and a narrower
‘safe zone’ between the ligamentum flavum and the dura
mater.44 These individuals are generally younger, have
soft lumbar ligaments, clear muscle- fat boundaries, and
the anterior and posterior complexes are clearly visible
under ultrasound, which can significantly reduce the
number of needle adjustments and are suitable for real-
time guidance technology.34 45 However, real- time punc-
ture is difficult for elderly patients. In elderly patients,
due to vertebral body and ligament hyperplasia and inter-
vertebral space narrowing, ordinary ultrasound probes
are more likely to block the puncture needle path, thus
affecting the observation of the puncture needle trajec-
tory. The advantage of ultrasound- assisted positioning is
that it can shorten the anaesthesia operation time. Studies
have shown that real- time guidance technology is not
superior to ultrasound- assisted localisation because real-
time guidance requires longer operation time, especially
in elderly patients, which reduces satisfaction scores.2
Of course, we cannot ignore other factors that influence
our results. The puncture paths used by the researchers
were not entirely consistent. According to previous
studies,46 the paramedian puncture route is better than
the median position because it avoids the supraspinal
and interspinous ligaments, and ligament calcification
will make puncture more difficult for the operator and
increase the number of attempts. The experience of the
operator cannot be ignored either. Operators included
in the literature were almost all anesthesiologists skilled
in the use of ultrasound techniques for neuraxial anaes-
thesia. The anaesthetist’s qualifications are also a factor
that affects the success rate of puncture, and its effect
may affect the success rate of puncture, exaggerating the
advantages of ultrasound- guided technology.47 In addi-
tion, real- time ultrasound guidance technology is diffi-
cult, requiring the operator to hold the probe and ensure
image stability while observing the needle trajectory. This
is also a challenge for anesthesiologists with many years
of experience in ultrasound- assisted localization. This
technical difference also affects our results. On the other
hand, the choice of ultrasound probe will also affect
real- time guidance of puncture. Due to the common
low- frequency convex array probe, the contact surface
of the probe does not completely fit the skin, and the
curved shell of the probe blocks the angle of the needle
during puncture. Recently, TranD45 used a new puncture
probe. An epidural needle holder is provided on the side
of the probe to adjust the needle angle in the plane of
the probe. According to the prepositioned intervertebral
space and the preset needle insertion angle, the operator
only needs to pay attention to the needle insertion depth
to complete the puncture. This method keeps the needle
in the same plane as the probe so that the needle trajec-
tory is always visible.
This study also has some limitations. Due to the diffi-
culty of real- time guidance technology, there are fewer
studies in this field and the sample size is smaller than
assisted positioning, which will also affect our analysis.
Therefore, our results cannot be extrapolated to other
related studies.
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9
ZhangY, etal. BMJ Open 2023;13:e071253. doi:10.1136/bmjopen-2022-071253
Open access
CONCLUSION
This study demonstrates that ultrasound guidance tech-
nology has significant advantages in improving the first-
pass success rate of neuraxial anaesthesia. Furthermore,
subgroup analysis showed that real- time ultrasound guid-
ance had a significant advantage in first- pass success rate.
Ultrasound real- time guidance technology is more suitable
for pregnant and patients with obesity, and ultrasound-
assisted technology is more suitable for elderly patients
with abnormal lumbar spine anatomy. Current research
evidence is insufficient, mainly because study designs
vary, real- time guidance techniques are difficult and there
are currently few studies. Future research should focus
on ultrasound real- time guidance technology and expand
the application of visualisation technology in neuraxial
anaesthesia.
Acknowledgements The authors would like to thank the teachers of the
Department of Anesthesiology, the First Afliated Hospital of Guangzhou University
of Chinese Medicine for their help.
Contributors YZ and MP are corst authors of this manuscript. YZ, JH, JW, WM
and YL were involved in the design and conception of the research scheme. YZ and
JW will screen the title, abstract and full text. If disagreement arises on inclusion
or exclusion, it will be resolved through discussion with other authors (JH, WM and/
or YL). YZ and JW will extract data from the article independently, and third party
reviewers (JH and/or WM) will check the integrity and correctness of the extracted
data in the results evaluation.YL is the guarantor of the review. All authors drafted
and revised this research protocol and approved it for publication.
Funding This work was fully supported by the Department of Anesthesiology, the
First Afliated Hospital of Guangzhou University of Chinese Medicine.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in
the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not applicable.
Ethics approval Not applicable.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available.
Supplemental material This content has been supplied by the author(s). It has
not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been
peer- reviewed. Any opinions or recommendations discussed are solely those
of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and
responsibility arising from any reliance placed on the content. Where the content
includes any translated material, BMJ does not warrant the accuracy and reliability
of the translations (including but not limited to local regulations, clinical guidelines,
terminology, drug names and drug dosages), and is not responsible for any error
and/or omissions arising from translation and adaptation or otherwise.
Open access This is an open access article distributed in accordance with the
Creative Commons Attribution Non Commercial (CC BY- NC 4.0) license, which
permits others to distribute, remix, adapt, build upon this work non- commercially,
and license their derivative works on different terms, provided the original work is
properly cited, appropriate credit is given, any changes made indicated, and the use
is non- commercial. See:http://creativecommons.org/licenses/by-nc/4.0/.
ORCID iD
YinzhouZhang http://orcid.org/0000-0001-8149-5700
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