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,” reported 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 added.
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 noted.
“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 anesthetic with much more precision,” they wrote.
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 and 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, 0-10; 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, –5.34; P = .003).
Delirium was also significantly lower with the nerve blocks (risk ratio, 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 concluded.
“Despite the low quality of evidence, ultrasound-guided blocks were associated with benefits compared to conventional systemic analgesia,” they said.
Key caveats include that the morphine reductions observed with the nerve blocks were not substantial, they noted. “The opioid-sparing effect seems small and may be of less clinical importance.” 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 said.
“The potential for higher patient satisfaction and reduction in serious adverse events and delirium may be of clinical importance,” they wrote.