Ultrasound-Guided Nerve Blocks Improve Fracture Pain

Nancy A. Melville

August 16, 2022

Ultrasound-guided nerve blocks for preoperative pain management after hip fracture provide improvements over conventional anesthesia including greater pain reduction and fewer adverse events, results from a meta-analysis published in BMC Anesthesiology show.

With the caveat that the quality of evidence in most trials in the analysis is low owing to a lack of blinding and other factors, "our review suggests that among patients suffering from a hip fracture, a preoperative ultrasound-guided peripheral nerve block is associated with a significant pain reduction and reduced need for systemic analgesics compared to conventional analgesia," report the authors.

"Our results may also indicate a lower risk of delirium, serious adverse events and higher patient satisfaction in patients receiving an ultrasound-guided peripheral nerve block," they add.

Because hip fractures commonly affect older populations and those who are frail, treatment of the substantial pain that can occur perioperatively is a challenge.

Peripheral nerve blocks have been shown to reduce pain within 30 minutes of the block placement; however, most studies have primarily included blocks that use anatomic landmarks or nerve stimulation for guidance. However, the use of ultrasound guidance with the nerve block should improve efficacy, the authors note.

"It seems intuitive that using ultrasound-guidance should be more effective than using a blind technique, since it allows a trained physician to deposit the local anaesthetic with much more precision," they write.

To evaluate the data from studies that have looked at ultrasound-guided peripheral nerve blocks, Oskar Wilborg Exsteen, of the Department of Anesthesiology and Intensive Care, Copenhagen University Hospital, Nordsjællands Hospital, Hillerød, Denmark, and colleagues identified 12 randomized controlled trials, involving a combined total of 976 participants, for the meta-analysis.

The studies included 509 participants who received ultrasound-guided peripheral nerve blocks, specifically the femoral nerve block and fascia iliaca block, and 476 who were randomly assigned to control groups.

Overall, those treated with the nerve blocks showed significantly greater reductions in pain measured closest to 2 hours of block placement compared with conventional analgesia, with a mean reduction of 2.26 points on the Visual Analogue Scale (VAS) (range, from 0 to 10; P < .001).

Ultrasound-guided peripheral nerve block use was associated with lower preoperative usage of analgesic intravenous morphine equivalents in milligram, reported in four of the trials (random effects model mean difference of -5.34; P = .003).

Delirium was also significantly lower with the nerve blocks (risk ratio [RR], 0.6; P = 0.03), as were serious adverse events, compared with standard analgesia (RR, 0.33; P = .006), whereas patient satisfaction was significantly higher with the nerve blocks (mean VAS difference, 25.9 [score 0-100]; P < .001).

Seven of the studies had monitored for serious adverse events or complications related to the nerve blocks, but none reported any complications directly related to the ultrasound-guided peripheral nerve blocks.

Owing to the inability to conduct blinded comparisons, clinical heterogeneity, and other caveats, the quality of evidence was ultimately judged to be "low" or "very low"; however, the observed benefits are nevertheless relevant, the authors conclude.

"Despite the low quality of evidence, ultrasound-guided blocks were associated with benefits compared to conventional systemic analgesia," they say.

Key caveats include that the morphine reductions observed with the nerve blocks were not substantial, they note. "The opioid-sparing effect seems small and may be of less clinical importance," they write. The decreases in opioid consumption, as well as pain reduction in the analysis, are in fact similar to those observed with conventional, peripheral nerve blocks that did not use ultrasound guidance compared with standard pain management.

No trials were identified that directly compared ultrasound-guided peripheral nerve blocks with nerve block techniques that didn't use ultrasound.

However, the other noted improvements carry more weight, the authors say.

"The potential for higher patient satisfaction and reduction in serious adverse events and delirium may be of clinical importance," they write.

Ultrasound-Guided Peripheral Nerve Blocks Not Always Accessible

Of note, the use of ultrasound-guided peripheral nerve blocks appears to be somewhat low, with one observational trend study of national data in the United States showing that among patients receiving a peripheral nerve block for hip arthroplasty, only 3.2% of the procedures were performed using ultrasound guidance.

Stephen C. Haskins, MD, a co-author on that study, said that the low utilization underscores that in real-world practice, an ultrasound-guided approach isn't always convenient.

"I think our findings demonstrate a common misconception that exists for those of us that work at academic institutions and/or within the ivory towers of regional anesthesia, which is that everyone is performing cutting edge ultrasound-guided techniques for all procedures," Haskins, an associate attending anesthesiologist and chief medical diversity officer with the Department of Anesthesiology, Critical Care & Pain Management at the Hospital for Special Surgery in New York, told Medscape Medical News.

However, "there are many limitations to use of ultrasound for these blocks, including limited access to machines, limited access to training, and limited interest and support from our surgical colleagues," he explained.

"Ultimately, the best nerve block is the one performed in a timely and successful fashion, regardless of technique," he said. "But we will continue to see a trend towards ultrasound use in the future due to increasing access in the form of portability and affordability."

Haskins noted that newer ultrasound-guided nerve blocks that were not reviewed in the study, such as the pericapsular nerve group block, regional block, and supra-inguinal fascia iliaca block, which provide additional benefits such as avoiding quadriceps weakness.

If anything, I would expect the findings of this analysis to undersell the benefits of peripheral nerve blocks in this population. Jeff Gadsden, MD

Jeff Gadsden, MD, chief of the Orthopaedics, Plastic and Regional Anesthesiology Division at Duke University Medical Center, in Durham, North Carolina, agreed, noting that much has changed since some of the older studies in the analysis, that date back to 2010.

"A fascia iliaca block done in 2022 looks a lot different than it did in 2012, and we would expect it to be more consistent, reliable and longer-lasting with current techniques and technology," he told Medscape Medical News.

"So, if anything, I would expect the findings of this analysis to undersell the benefits of peripheral nerve blocks in this population."

Although the quality of evidence in the meta-analysis is described as "low," the downsides of the procedures are few, and "the potential benefits [of ultrasound-guided peripheral nerve blocks] are just too good to ignore," Gadsden emphasized.

"If we can avoid or reduce opioids in this population and at the same time reduce the acute pain from the injury, there is no question that the incidence of delirium will go down," he said. "Delirium is associated with a number of poor outcomes following hip fracture, including increased mortality."

"The bottom line is that the risk/benefit ratio is so far in favor of performing the blocks that even in the face of 'modest' levels of evidence, we should all be doing these."

The authors, Haskins, and Gadsden had no disclosures relating to the study to report.

BMC Anesthesiology. Published June 21, 2022. Full text

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