Automated Ultrasound Guidance Streamlines Epidural Placement for Challenging Patients in Labor and Delivery

By Regina Fragneto, MD, Professor of Anesthesiology, Division Chief, Obstetric Anesthesia, University of Kentucky College of Medicine

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. Most patients choose relief thought epidural anesthesia, which involves injection of a local anesthetic into the spinal column nearby the spinal cord and nerve roots. This acts on nerve impulses in the lower spinal section, blocking sensation in the lower half of the body.

But, pain relief also can hurt. Physicians must caution patients that epidural anesthesia can lead to more pain and complications—adding to anxiety during an already anxious time. These complications include possible long-term headaches, backaches and in rare cases paralysis. While for the average patient the risk is minimal, in certain populations, it is much greater—among them women with high body mass index (BMI) and scoliosis or other spinal deformities. In addition, problematic anesthesia delivery also is painful to the medical system due to increased costs of prolonged procedures and patient discomfort and dissatisfaction.

Even in today’s advanced healthcare age, epidural delivery is difficult because, 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, most imaging modalities involve x-ray exposure and cannot be used on 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 often not in the anesthesiologist’s skillset.

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

Accuro’s innovative image-guidance platform automates measurements of the spinal midline and epidural depth and trajectory with its innovative SpineNav3D technology. The device’s BoneEnhance technology is optimized for visualization of bony spinal anatomy, while traditional ultrasound is inherently more suited for soft tissue imaging. According to Rivanna, Accuro delivers 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 a crowded operating room.
At University of Kentucky College of Medicine, we have been using the device 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 had been 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 for epidural delivery.

Without palpation, anesthesiologists have no anatomical information as the basis for epidural placement– and experience, experimentation and guess-work comes into play. As a result, the process often can take 30 to 40 minutes, compared to five minutes for typical patients. During that time, pregnant women wait hunched over and must often endure several needle sticks until insertion is successful. If the needle hits bone, the result is more pain.

Accuro’s automated ultrasound guidance helps eliminate many of the problems of epidural delivery for these difficult patients, as illustrated by two recent cases. In one, a junior anesthesiology attending was 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, the attending struggled to place the needle blindly and eventually called in her resident for assistance. Using the Accuro, together the doctors were able to deliver the anesthesia. This was only the second time the resident had used the device.

A second case involved a laboring woman of similar weight who also presented with difficulties in 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 placed in 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 overlays on the device and the depth to the spinous process, and the epidural space is calculated displayed. Users mark this location and proceed with anesthesia placement. Accuro is so intuitive and friendly that it can be mastered 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 the hospital for acute post-op pain. The device also is employed by pediatric oncologists and other physicians who deliver procedures involving lumbar punctures.

Before learning about Accuro technology, I had been considering purchasing a more traditional ultrasound for the department. However, images would have been difficult to read for many anesthesiologists who lacked ultrasound experience. Accuro’s sophisticated algorithms make image guidance epidural a reality for our anesthesiologists.