Ultrasound-assisted Versus Real-time Ultrasound-guided Combined Spinal-epidural Anesthesia Via a Paramedian Approach in Elderly Patients: a Randomized Controlled Study
Phase: NA
Conditions: Ultrasound Therapy; Complications
Sponsor: Tongji Hospital

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Study protocol
Ultrasound-assisted vs. real-time ultrasound-guided paracentral
approach combined lumbar and epidural anesthesia in elderly
patients: a randomized controlled study
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1. Research background
Traditional body surface marker guided intraspinal anesthesia can meet most of the
clinical anesthesia needs, but for the presence of obesity, spinal deformity, senile
ligament calcification, previous lumbar surgery history, etc., intraspinal puncture
often has technical difficulties. Ultrasound-guided intraspinal puncture can provide
anatomical information related to the puncture site, including intervertebral segment,
posterior median line of the spine, vertebral canal depth, and distribution
characteristics of each ligament, providing a solution for difficult puncture and
improving the accuracy and safety of intraspinal puncture 1,2.
During the implementation of lumbar anesthesia, multiple punctures through
ligaments and dura can easily lead to postoperative headache, low back pain, and may
increase the incidence of paresthesia and spinal cord hematoma. Ultrasonic-guided
spinal anesthesia can reduce the number of passages required to enter the
subarachnoid space compared with the traditional signpost guided midline approach.
Ultrasound examination before hip and knee replacement provides guidance for
intraspinal puncture, which can significantly reduce the number of entry into the
subarachnoid space and the number of attempts3. In addition, a pre-ultrasound scan of
the spine before puncture can estimate the distance from the skin to the epidural space
and determine the appropriate puncture point, which is important in obese women
(BMI: 33~86 kg/m^2) epidural labor analgesia is especially effective when the
epidural needle is placed at the intended puncture point, 76.1% of women did not
change the point of re-puncture, 67.4% of women did not redirection4. However,
despite the ability of ultrasound to provide anatomical information about the spine, 23
(10.7%) of 218 women in a study had misidentification of 2 or more intervertebral
Spaces, which increases the risk of intraseptic puncture complications. Subgroup
analysis showed that the degree of access to the maternal spinous process had an
impact on the recognition of the lumbar space in spinal ultrasound. Women with easy
access to the spinous process have a higher success rate of ultrasound-assisted first
puncture 5. Based on the posterior longitudinal ligament ultrasonic image scoring
system, Weed JT et al. 's study showed that the puncture frequency and puncture time
were significantly reduced in the group with a high rating of clear images, suggesting
that the calcification level of the posterior longitudinal ligament may be one of the
important factors affecting the success rate of ultrasound-guided intra spinal puncture
through the posterior median approach.

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It can be seen from the above description that ultrasound assisted positioning before
intraspinal anesthesia has more technical advantages than body surface marking, but
at the same time, the puncture process of the above two methods is still a "blind
exploration" operation with or without anatomical preview, and the puncture path is
easily blocked by vertebrae and its accessory structures, and the puncture Angle is not
visible. Real-time ultrasound guidance can solve the problem of path selection in
difficult puncture. Therefore, Lee, P. J., et al. developed a technique for real-time
ultrasound guidance of intraspinal anesthesia via the Taylor approach (auxiliary
approach in the L5-S1 space) by conducting a preliminary cadential study on 5
unembalmed cadasses. Subsequently, 10 patients undergoing joint replacement
underwent successful hip arthroplasty using real-time ultrasound-guided intraspinal
anesthesia in prone position. Subsequently, Chong, S. E. et al. compared real-time
ultrasound guided (UG) and body surface marking touch (PG), and the results showed
that the success rate of the first puncture in the UG group (≤6 skin piercings with or
without redirection) was significantly higher than that in the PG group (87% vs. 43%,
P<0.001). UG also had a higher success rate of single needle passage (47% vs. 20%, p
= 0.028)8. The mean (SD) time to success of dural puncture was shorter in UG group
[0.69(1.01) and 1.60 (1.19)min, P=0.002]. This is comparable to the results of the
Conroy9 study, which showed a time of 1.2 minutes (0.2-15 minutes). It can be seen
that both real-time ultrasound-guided intraspinal anesthesia and preoperative
ultrasound-assisted intraspinal anesthesia have certain technical advantages compared
with body surface labeling.
The ultrasound imaging along the longitudinal median path of the spine has less bone
and ligament occlusion, and the intravertebral canal image is often clearer, which is
better than the transverse or longitudinal scan of the posterior median line. Therefore,
the real-time ultrasound guidance technology should adopt the paramedical approach.
Chen L et al. conducted a comparison of the effects of ultrasound assisted positioning
(USAS) and real-time ultrasound guidance (USRTG) in intra spinal anesthesia. In a
study of 114 elderly hip fracture patients (≥70 years), they found that the USAS group
had a higher success rate on the first attempt (successful dural puncture without
redirection) (80.7% vs 52.6%) and a higher success rate on the first pass (63.2% vs
31.6%). Fewer attempts (skin piercings) (1 [1-1]vs 1 [1-3]) and median pass rates
were significantly lower in the USAS group than in the USRTG group. However, the
USRTG group had a shorter positioning time (175 s [129-234 s]vs 315 s [250-390 s]).

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However, the operation time was longer (488 seconds [260-972 seconds]vs 200
seconds [127-328 seconds]) and the total time was longer (694 seconds [421-1133
seconds]vs 540 seconds [432-641 seconds]). The USAS group had higher satisfaction
scores. Overall, anesthesiologists rated the USRTG group as "more difficult." Chen L
and his colleagues believe that in elderly patients with hip fractures, USRTG
technique is not superior to USAS technique for lumbar anesthesia, because USRTG
technique has a lower success rate, longer operation time, lower satisfaction score,
and greater difficulty in operation. Therefore, USAS technology may be more suitable
for elderly patients.
Both continuous epidural anesthesia (CSA) and lumbar anesthesia (SA) can be used
in elderly patients undergoing hip fracture surgery. Based on a study of 74 elderly hip
fractures. In the SA group, 68 percent of patients experienced at least one episode of
hypotension (a decrease in systolic blood pressure greater than 20 percent of baseline
values), compared to 31 percent of patients in the CSA group. In the SA group, 51
percent of patients experienced at least one episode of severe hypotension (a drop in
systolic blood pressure greater than 30 percent of baseline value), compared to only 8
percent of patients in the CSA group. Patients in the SA group required more
ephedrine doses. Therefore, the authors suggest that CSA may reduce the onset of
hypotension and severe hypotension12. Through A review by Perlas A et al., we
found data from eight studies showing that ultrasound can identify a given lumbar
space more accurately than palpation alone. Thirteen studies reported a good
correlation between depth measured by ultrasound and needle insertion depth in the
epidural or intravaginal space, with the average difference between the two
measurements within 3 mm in most studies. Spinal canal ultrasound increased the
success rate of puncture and reduced the difficulty of puncture 1.
According to the clinical experience of our center in using ultrasound to guide
intraspinal operation, we believe that skilled use of ultrasound is also an important
factor affecting the success rate of the first intraspinal puncture and shortening the
puncture time, and the conclusion may be different from Chen L et al. Therefore, we
designed this study to explore the difference in clinical effects between the
application of ultrasound-assisted positioning by experienced operators and real-time
ultrasound-guided paramedical approach combined lumbar and epidural anesthesia in
elderly patients, providing validation for the clinical use and promotion of real-time
intraspinal ultrasound technology.

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2. Research purpose
The purpose of this study was to investigate the difference of clinical effect
between ultrasound-assisted positioning and real-time ultrasound-guided paracentral
combined epidural anesthesia in elderly patients.
3. Study design
This was a prospective randomized controlled study.
3.1 Patient selection and alloctaion.
3.1.1 sample size calculating
This study is intended to include all patients who will undergo combined spinal and
epidural anesthesia from October 2023 to October 2024. Adopt PASS V21.0.3 software
(2021; NCSS LLC) calculated the study sample size. According to a preliminary study by
Chen L et al., the success rate of the first puncture using the USAS technique and the
USRTG technique was 80.7% vs 52.6%, respectively. It was calculated that 43 patients
were required in each group at a bilateral significance level of 0.05 (α = 0.05) and 80%
efficacy (β = 0.2). Taking into account 10% of possible patients dropping out, the
sample size was increased to 48 patients per group for a total of 96 patients.
3.1.2 Inclusion criteria
1) Elderly patients (≥60 years old);
2) ASA Grade I to III.
3.1.3 Exclusion criteria
1) Severe obesity (BMI>35kg/m2);
2) Spinal deformity or surgical history;
3) Allergic to local anesthetics;
4) There are coagulation disorders;
5) Communication barriers
4. Research process
1. Preoperative records

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Patients were visited according to clinical routine on the day before
surgery, and their age, gender, height, weight, ASA grade, and operation name
were recorded. Patients were identified according to inclusion and exclusion
criteria, informed consent was signed, and basic patient information was
recorded.
2. Anesthesia protocol and intraoperative records
Based on a computer-generated table of random numbers, they were
randomly assigned to receive combined lumbar and epidural anesthesia in
either the US-AS group (n=48) or the US-RTG group (n=48). Patient
assignments are hidden by sequentially numbered and sealed opaque
envelopes that can only be opened by the attending anesthesiologist when the
patient enters the operating room. Patients know nothing about grouping.
Neither the intraoperative parameter collector nor the anesthesiologist
performing the procedure can blind the groups.
All ultrasound-guided CSEA blocks were performed by an attending
anesthesiologist (>100 cases per year) who was skilled in ultrasound-assisted
and real-time ultrasound-guided intra spinal block, and another attending
physician who was familiar with the procedure was responsible for parameter
recording. When the patient enters the room, connect the monitor. Nasal
catheter oxygen (oxygen flow 3 L/min) to establish peripheral venous access.
1. Assess the difficulty of palpating the spinous process (1 degree: easy -
slight or moderate pressure on the tissue; Grade 2: moderately significant
tissue compression; 3 degrees: Difficult/unable to palpate). 2. If the patient
could not cooperate due to hip pain, iliofascial space block (20mL, 0.4%
ropivacaine) was performed in the supine position, and 15min later, the
patient lay on his side (affected side up).
In the US-AS group, the intraspinal structure was evaluated using a portable
ultrasonic system (Sonosite, low frequency convex array probe 2-5 MHz)
(ultrasonic prescan to determine the best intervertebral space, best puncture
Angle and best puncture depth). The measurement methods (in-plane
measurement of paracentral transverse section (LTP), out-of-plane
measurement of paracentral sagittal section (LSC) and in-plane measurement

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of paracentral sagittal section (IPP)) were recorded, and the optimal puncture
section considered by the operator (the widest acoustic window at the back of
the complex) was selected to record the best gap, puncture Angle and depth. In
the sterile state, traditional blind operation was performed; The positioning
time, the depth and width of the retrodural complex, the first successful
attempt (first skin piercing without redirection), the number of skin piercings,
the number of redirects, and the operation time (probe touching the skin until
the end of the operation) were recorded. After successful epidural puncture,
25G lumbar anesthesia needle was inserted (if CSF outflow was not smooth,
the epidural needle could be rotated in place and then re-inserted into the
epidural puncture). Subarachnoid block (2.5mL/12.5mg of 0.5% ropivacaine
without high glucose) was performed immediately after CSF outflow was
smooth, followed by epidural catheter. If there is no CSF after withdrawal, skin
puncture should be performed again. The maximum number of skin puncture
should be 6 times, and the cumulative redirection of each skin puncture should
not exceed 6 times. If six skin piercings are unsuccessful, traditional palpation,
replacement of puncture Spaces, or general anesthesia are considered and
recorded.
In the US-RTG group, the optimal puncture section considered by the operator
was selected and recorded directly in the plane of the paracentral transverse
section, out of the plane of the paracentral sagittal section or in the plane of the
paracentral sagittal section for real-time ultrasound guided lumbar epidural
anesthesia. The positioning time, the depth and width of the retrodural complex,
the first successful attempt (first skin piercing without redirection), the number
of skin piercings, the number of redirects, and the operation time (probe
touching the skin until the end of the operation) were recorded. After
successful epidural puncture, 25G lumbar anesthesia needle was inserted (if
CSF outflow was not smooth, the epidural needle could be rotated in place and
then re-inserted into the epidural puncture). Subarachnoid block
(2.5mL/12.5mg of 0.5% ropivacaine without high glucose) was performed
immediately after CSF outflow was smooth, followed by epidural catheter. If
there is no CSF after withdrawal, skin puncture should be performed again.

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The maximum number of skin puncture should be 6 times, and the cumulative
redirection of each skin puncture should not exceed 6 times. If six skin
piercings are unsuccessful, traditional palpation, replacement of puncture
Spaces, or general anesthesia are considered and recorded.
Whether the patient was in the left or right decubitus position, the operator
used the puncture needle manually and the ultrasound probe non-manually.
Adverse reactions and complications were recorded in both groups, including
radicular pain, bloody cerebrospinal fluid puncture, headache after dural
puncture, paresthesia, back pain, whether traditional palpation was used, the
puncture space was changed, or general anesthesia was used. Patient
satisfaction score: Patients were asked to use a 5-point numerical rating scale
to evaluate their satisfaction (1, very dissatisfied; 5, very satisfied). The VNRS,
verbal numerical rating scale (0-10) and whether to add analgesic drugs were
recorded in the two groups.
3. Outcomes
Primary outcomes: first attempt success rate (first skin piercing, no redirection);
Secondary outcomes: operation time (seconds), positioning time, depth and
width of posterior dural complex, skin puncture number, redirection number;
Patient satisfaction score: Patients were asked to use a 5-point numerical rating
scale to evaluate their satisfaction (1, very dissatisfied; 5, very satisfied).
Operation difficulty score: After the operation, the anesthesiologist will score
the difficulty of this operation (1, very dissatisfied; 5, very satisfied). Change
of anesthesia method (traditional blind method, USAS or USRTG, change of
puncture space, general anesthesia).
Adverse reactions and complications: include radicular pain, bleeding, puncture,
headache after dural puncture, paraesthesia, and back pain.

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