Author: Bob Kronemyer
An Italian study has found that in obese patients undergoing orthopedic surgery, a hand-held neuraxial guidance instrument (Figure) significantly reduced the number of needle redirections and passes through the skin when performing spinal anesthesia, compared with conventional palpation for spinal anesthesia.
The randomized study, published in Regional Anesthesia & Pain Medicine (2020;45:63-66), also concluded that the procedural time was increased when using the device (Accuro, Rivanna Medical).
In addition, despite the many benefits of spinal anesthesia in this patient population, there are numerous technical difficulties that occur. “Our daily challenge is to be able to perform neuraxial blocks in these [obese] patients when indicated, without increasing the complication rate,” Dr. Ghisi said. “The safety of the spinal block is in fact affected by the number of needle insertions through the skin and the number of redirections in the deep tissues.”
Quantification of Needle Redirections, Passes
A total of 130 men and women with a BMI of at least 30 kg/m2 and scheduled for lower limb surgery under spinal block were randomized at the hospital between March 2017 and April 2018 to a control group (spinal block after palpation of cutaneous landmarks) or another group scanned with the battery-operated Accuro.
Of the 99 patients who completed the study, the median number of redirections in the Accuro group was three (range, zero to nine) and median number of needle passes through the skin was one (range, one to two), versus six (range, one to 16) and one (range, one to three) in the control group (P=0.008 and P=0.019, respectively).
The study also found that the time needed to scan using the Accuro was 558 (±232) seconds, compared with 348 (±255) seconds for palpation-guided spinal anesthesia. The number of failed blocks and degree of procedural pain were similar for the two techniques.
“We expected that a preprocedural ultrasound scan with an ultrasound probe would provide many advantages in a population of obese patients undergoing spinal anesthesia for orthopedic procedures,” Dr. Ghisi said. “We found Accuro particularly easy to use by clinicians who were not expert in scanning the vertebral column.”
Dr. Ghisi and her colleagues said a significant reduction in the performance time of Accuro can be achieved if the ultrasound probe is first applied on the skin in a nonsterile fashion, thus saving time covering the probe.
The study authors also noted that Accuro performs well when the obese patient is in the lateral decubitus position, “which is the position of choice at our institution when performing spinal anesthesia,” Dr. Ghisi said. “Moreover, the device can be used for counting the vertebral level, upward from the sacrum, to confirm that the expected metameric level to perform the spinal block corresponds to the level palpated blindly.”
A Shift Away From Blind Palpation
The safety of any ultrasound probe has already been well established, according to Dr. Ghisi. “However, in Italy, the hand-held Accuro costs as much as a standard, cart-based ultrasound machine, which is much more multipurpose,” she said. In the United States, Accuro pricing begins at a fraction of the cost of a typical cart-based system. Rivanna is working with its Italian partners to reduce the price in Italy, the company noted.
“It would be interesting to compare Accuro with a traditional U.S. device for preprocedural scan of the column to guide spinal blocks in the same obese population, with the primary end point being the time to perform a spinal block,” Dr. Ghisi said.
Accuro, which began selling commercially in the United States in 2016, “is leading a shift in clinical practice away from the conventional ‘blind’ palpation-based approach and toward an image-guided standard of care,” said Will Mauldin, PhD, the co-founder and CEO of Rivanna.
Dr. Mauldin, who also is the co-inventor of the device, noted there are now clinical studies demonstrating that Accuro is superior to palpation, regardless of provider training, experience and type of neuraxial anesthesia.
“While much of the neuraxial ultrasound literature has focused on trainee performance, this new study is particularly notable because it demonstrates improvements gained by experienced providers,” Dr. Mauldin said. “Unlike conventional ultrasound equipment, Accuro is hand-held with automated image guidance technology, which makes the clinical benefits more easily accessible and attainable.”