Automated Ultrasound Guidance Streamlines Epidural Placement for Challenging Patients in Labor

It’s no secret that childbirth hurts. For most women, it is characterized by intense pain and
pressure in the lower abdomen and back – and for some, this can be overwhelming. Many
patients choose relief through epidural analgesia, which involves injection of a local
anesthetic near nerve roots in the lumbar spinal region. This inhibits nerve conduction,
decreasing sensation in the lower half of the body.

But pain relief itself can hurt. Physicians must caution patients that epidural analgesia can
lead to complications and some pain may be associated with the epidural procedure itself,
adding to anxiety during an already anxious time. These complications can include spinal
headache, which can be severe, and soreness at the site of the epidural. While the risk is
minimal for the average patient, in certain populations – among them women with high body
mass index (BMI) and scoliosis or other spinal deformities – it may be greater due to
technical difficulties associated with the epidural delivery. In addition, problematic anesthesia
delivery is painful to the medical system due to increased costs of prolonged procedures and
patient discomfort and dissatisfaction.

BACKGROUND

Even in today’s advanced healthcare age, epidural delivery can be difficult because many
anesthesiologists continue to perform the procedure as if they had virtual blinders on. When
attempting to pinpoint the optimal site for injection of a powerful drug, they still rely on their
sense of touch to assess spinal anatomy. In obese patients and those with spinal anomalies,
needle placement is challenging because physicians cannot successfully palpate the spine to
determine the appropriate injection site.

Image guidance for epidural placement would remove the physician’s virtual blindfold to
improve accuracy. However, many imaging modalities involve X-ray exposure, which should
be avoided in a woman carrying a fetus.

Ultrasound, however, involves no radiation, and research has shown the technology helpful
in accurately identifying the appropriate epidural injection site. But performing and
interpreting ultrasound requires specialized training and experience that is not in some
anesthesiologists’ skill set.

MODERN TECHNOLOGY

Modern technological advances have led to the development of a range of specialized
ultrasound devices, including the novel Accuro device by Rivanna Medical (Charlottesville,
Virginia). The device applies automated 3D-navigation to spinal ultrasound imaging,
eliminating the steep learning curve of interpreting and using ultrasound images to support
epidural anesthesia administration. Accuro provides anesthesiologists, regardless of their
ultrasound experience, with a clear route to the appropriate epidural site.

Accuro’s image-guidance platform automates measurements of the spinal midline and
epidural depth and trajectory in real time. Additionally, the device uses a new bone-specific
image reconstruction technology called BoneEnhance. According to a study published
recently in Investigative Radiology, Accuro was shown to deliver a five- to 10-fold increase
in bone-to-tissue contrast compared to traditional ultrasound.

By contrast to unwieldy, complex, traditional ultrasound technology, Accuro is pocket-sized,
portable and battery-powered. It can be carried right to the bedside, making it easy and
practical to use in Labor and Delivery, and in a crowded operating room.

At University of Kentucky College of Medicine, we have been using Accuro in Labor and
Delivery for about a year. The hospital serves a significant population of obese patients on a
busy Labor and Delivery floor. Given that, epidural administration may be uncomfortable and
potentially problematic for these patients and a bottleneck for anesthesiologists. In many
cases, anesthesiologists are simply unable to palpate a woman’s spine to identify the
anatomical landmarks necessary to efficiently perform epidural analgesia.

Without palpation, anesthesiologists have no anatomical information as the basis for epidural
placement – and experience, experimentation and guesswork come into play. As a result, the
process can sometimes take as long as 30 to 40 minutes, compared to five to 10 minutes for
typical patients. During that time, pregnant women sit hunched over and may have to endure
several needle sticks until insertion is successful. If the needle hits bone, the result is more
pain.

CONCLUSION

Accuro’s automated ultrasound guidance helps eliminate many of the problems of epidural
placement for these difficult patients, as illustrated by two cases that I recently observed. In
one, a resident and junior anesthesiology attending were attempting to administer an epidural
to a C-section patient with a body mass index (BMI) of almost 50, who weighed about 270
pounds. Unable to feel the required spinal landmarks, they struggled for a long time to place
the needle blindly. Then the resident suggested using the Accuro. Together they were able to
successfully perform epidural anesthesia on the first attempt with the Accuro. This was the
first time the attending had used the device and only the second time for the resident.

SECOND CASE

A second case involved a laboring woman with a BMI of 60 who also presented difficulties
with spinal palpation. After numerous attempts at blind needle placement, the Accuro was
employed to identify the spinal midline and interlaminar space at the correct vertebral level.
The epidural catheter was then placed in just a few minutes.

Unlike traditional ultrasound, the Accuro learning curve is minimal. Our physicians simply
move the device along the patient’s back to identify the midline and interlaminar space.
These landmarks appear as dotted red and orange overlays on the device. In addition, the
estimated depths to the spinous process and the epidural space are displayed instantaneously
on the Accuro screen. Users mark this location and then proceed with epidural placement.
Accuro is so intuitive and friendly that it can be mastered by many within 10 minutes and
operated with ease, even with only occasional use.

In addition to Labor and Delivery, a second Accuro device is in use at our hospital by the
Acute Pain Service. The device has also been employed occasionally at our institution by
pediatric oncologists who encountered difficult lumbar punctures.

Before learning about the Accuro technology, I had been considering purchasing a more
traditional ultrasound for Labor and Delivery. However, the use of a traditional ultrasound
machine would have been much more cumbersome, as well as being more difficult to use for
those anesthesiologists who lacked ultrasound experience. Accuro’s sophisticated algorithms
make image-guided epidural placement a reality for our anesthesia team at the University of
Kentucky.

“The Accuro learning curve is minimal. Our physicians simply move the device along the patient’s back to identify the midline and interlaminar space […] In addition, the estimated depths to the spinous process and the epidural space are displayed instantaneously on the Accuro screen […] Accuro is so intuitive and friendly that it can be mastered by many within 10 minutes and operated with ease, even with only occasional use.”