Risk, Not Pain Relief, Increased by Pre-Nerve Block Sedation

BALTIMORE – When patients are sedated before a nerve block to diagnose or treat chronic pain, costs and the risks of unnecessary surgery increase without improving patient satisfaction or pain control in the long term.

That’s according to a report published recently in the journal Pain Medicine. The study was led by Johns Hopkins School of Medicine researchers with participation from Uniformed Services University of the Health Sciences in Bethesda, MD, and other medical facilities.1

“Sedation doesn’t help, but it does add expense and risk,” said study leader Steven P. Cohen, MD, a professor of anesthesiology and critical care medicine. “In some places, every patient is being sedated. Our research shows it should be used very sparingly.”

Nerve blocks are among the procedures performed ahead of surgery to help determine the source of pain; if the nerve block fails to numb pain, surgery or nerve ablation might not help. To ease anxiety and pain while the injection is given, clinicians increasingly have used sedation, light or deep, according to the report.

The Johns Hopkins study indicates, however, that sedation before a nerve block significantly increases false-positive results and raises overall surgical risks.

For the study, researchers recruited 73 patients with back or limb pain who were scheduled to receive multiple nerve blocks. With about half of the group receiving the first injection with sedation and the second without, the remaining patients received injections in the opposite order.

The research asked patients to keep six-hour pain diaries and then a month later to report whether the injections brought relief and to rate their satisfaction with the treatment. Although the sedated patients reported less pain immediately after the nerve block injection, on every other measure — from 30-day pain assessments to overall patient satisfaction — the results were the same, regardless of whether they were sedated.

“A lot of cost for very little benefit,” Cohen suggested, pointing out that the sedative can relax muscles and have pain-relieving properties while it also increases recovery time.

If patients report that the nerve block eased their underlying pain, spinal fusion or radiofrequency ablation often is performed but might not have been warranted. The result, Cohen pointed out, is that the patients end up still in pain but having gone through an unnecessary procedure.

1Cohen SP, Hameed H, Kurihara C, Pasquina PF, Patel AM, Babade M, Griffith SR, Erdek ME, Jamison DE, Hurley RW. The effect of sedation on the accuracy and treatment outcomes for diagnostic injections: a randomized, controlled, crossover study. Pain Med. 2014 Apr;15(4):588-602. doi: 10.1111/pme.12389. Epub 2014 Feb 13. PubMed PMID: 24524866.


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