Rated #1

< Back

Medical News

Study: Peripheral Nerve Blocks Lower Opioid Use Post-TKA

Toronto—Peripheral nerve blocks (PNBs) following discharge after total knee arthroplasty (TKA) surgery reduce reliance on medications like opioids.

 

Arguing against the contention that PNBs are no longer indicated for total joint replacement surgery, Colin McCartney, MBChB, associate scientist, Sunnybrook Research Institute, Toronto, Ontario, Canada, argued that PNBs provide “profound analgesia for our patients.”

 

Dr. McCartney, speaking at the International Symposium of Ultrasound for Regional Anesthesia, Pain Medicine & Perioperative Applications, maintained that the impact of local infiltration anesthesia is transient and the evidence for its use is lacking. “It has generally been compared to placebo,” said Dr. McCartney, who is a professor in the Department of Anesthesia at the University of Toronto.

 

A key advantage of PNBs is that they produce postoperative opioid sparing, said Dr. McCartney, citing a meta-analysis of randomized trials (Anesth Analg 2005;101:1634-1642).

 

The root problem of why PNBs are perceived as being ineffective lies in inadequate training of anesthesiologists, said Dr. McCartney. “Our training of anesthetists to do PNBs is poor,” he said. “Doing 40 or 50 blocks in training is not sufficient.”

 

Dr. McCartney challenged the notion that PNBs are a risk factor for postprocedure falls. He cited research (Anesthesiology 2014;120:551-563) that failed to find a relationship between the use of continuous PNBs and the risk for falls after TKA. The study found TKA patients who experienced falls while in hospital were older and had more major complications, including 30-day mortality.

 

“The bottom line is that PNBs don’t cause patients to fall,” said Dr. McCartney. “It’s other factors, like age.”

Local infiltration anesthesia is generally thought to improve postoperative rehabilitation and accelerate recovery, whereas PNBs are regarded as slowing functional recovery. But Dr. McCartney said continuous nerve blocks do not necessarily mean a slower functional recovery for patients.

 

Pointing to a randomized study of patients who underwent TKA (Br J Anaesth 2010;105:185-189) that compared postoperative analgesia with either periarticular infiltration of local anesthetic or continuous femoral nerve block, Dr. McCartney said patients who received the femoral nerve block experienced better recovery than those who received periarticular infiltration.

 

Local Infiltration Anesthesia?

Effective nerve blocks should meet several criteria, said Sanjay Sinha, MD, director of regional anesthesia at St. Francis Hospital and Medical Center in Hartford, Conn., and assistant clinical professor of anesthesiology at the University of Connecticut School of Medicine, Farmington.

“The ideal nerve block should be simple to perform, so simple that even surgeons can do it,” said Dr. Sinha. “It should not produce motor weakness, so ambulation can be started sooner and physiotherapy can be started sooner. The cost of doing the block should be minimal. It sounds to me like local infiltration anesthesia meets all these criteria.”

 

One of the disadvantages of the PNB is that it demands “a higher skill set and is technically challenging,” said Dr. Sinha, who added that risk for infection is also a consideration with PNBs and their associated use of catheters, and that use of PNBs demands greater manpower resources.

 

The use of local infiltration anesthesia can produce sufficient pain control for patients undergoing TKA. Dr. Sinha referred to one study (Acta Anaesthesiol Scand 2008;52:1331-1335) involving 12 patients who underwent bilateral TKA. Ropivacaine was administered in one knee and saline in the other, so patients served as their own controls, and patients received multimodal medications postoperatively.

 

“They [researchers] found pain control was superior in the knee that had local anesthesia as opposed to placebo,” said Dr. Sinha.

 

Dr. Sinha also pointed to a meta-analysis that looked at local infiltration anesthesia directly into the knee (J Bone Joint Surg Br 2012;94:1154-1159). The authors concluded that local infiltration produced a reduction in postoperative pain.

 

The emergence of agents like liposomal bupivacaine may assist in prolonging postoperative analgesia and potentially decreasing use of opioids post-discharge, according to Dr. Sinha.

 

One of the potential risks associated with PNB is nerve damage, said Dr. Sinha. “Anytime you do a nerve block, there is a risk for nerve injury.”

 

However, a review of 32 studies (Anesth Analg 2007;104:965-974) found the rate of neuropathy after PNB to be 3%, but investigators found the occurrence of permanent post-PNB neuropathy to be very rare.

 

Source: Pain Medicine News