Adding Quadratus Lumborum Block To Post-Cesarean Analgesia Found Ineffective

Author: Michael Vlessides

Anesthesiology News

Although the quadratus lumborum block has proved effective in abdominal surgery, the benefit was not seen in women who had undergone cesarean delivery, according to a Canadian research team. Their study found that although adding the block to an intrathecal morphine–based multimodal analgesic regimen was associated with increased time to first opioid use, it did not reduce analgesia use or decrease pain scores compared with women who received intrathecal morphine alone.

“The gold standard for postoperative pain control after cesarean delivery is typically intrathecal morphine paired with multimodal analgesia,” said Richard Roda, MD, an anesthesiology resident at Dalhousie University in Halifax, Nova Scotia. “However, we still see approximately 30% of women experiencing severe postoperative pain on movement after cesarean delivery, which can then put them at risk of developing chronic pain. So what can we do?”

Enter the quadratus lumborum block, which has been shown in previous research to extend analgesia when it is included in a multimodal regimen with intrathecal morphine. Nevertheless, no study to date has looked into the benefits of adding the novel block to intrathecal morphine–based multimodal analgesia in women who had a cesarean delivery.

A total of 50 women received the quadratus lumborum block with 15 mL of 0.5% ropivacaine per side, along with intrathecal morphine. “The quadratus lumborum muscle originates at the internal lip of the iliac crest, inserts into the interior border of the 12th rib, and also inserts into the L1-L4 transverse processes,” Dr. Roda explained. “So with the patient supine and the ipsilateral hip rolled, we can track down the transverse abdominis under ultrasound guidance until the quadratus lumborum comes into view. Then we inject the local anesthetic based on the lateral quadratus lumborum block approach, just posterior to the quadratus lumborum, as well as the thoracolumbar fascia.”

The 50 study patients were frequency-matched based on body mass index, parity, previous cesarean delivery and maternal age with 100 women who received intrathecal morphine only. All participants received identical postoperative multimodal analgesic regimens comprising scheduled naproxen/acetaminophen, with oxycodone on request.

Trend, but Not Significant

As Dr. Roda reported at the 2018 Joint World Congress on Regional Anesthesia and Pain Medicine and annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 5507), no significant differences were found between the two groups for 24- and 48-hour oxycodone use, median and maximum 24- and 48-hour pain scores, or antiemetic use. Furthermore, no obstetric or anesthetic adverse events were recorded in either group.

“We did find a difference, however, between the time to first oxycodone use in the quadratus lumborum block patients,” Dr. Roda said. The quadratus lumborum block patients did not request their first dose until 10.6 hours (range, 3.9-22.4 hours) compared with 2.9 hours (range, 1.8-18.6 hours) (P=0.009) postoperatively among those who did not receive the block.

“In conclusion, this was the first study of its kind to compare quadratus lumborum block and intrathecal morphine with intrathecal morphine alone on postoperative outcomes,” Dr. Roda said. “Although we didn’t find a difference in the 24-hour oxycodone consumption, the trend did favor the block group. It’s possible that by adding the quadratus lumborum block to intrathecal morphine we’re seeing diminishing returns, so we may need to increase our sample size to detect a smaller effect size.

“We think it’s possible that we might see a difference at 12 hours,” he added. “But as the block starts to wear off and we get toward 24 and 48 hours, the intrathecal morphine group catches up to the point where we don’t see a difference.”

The study left some of Dr. Roda’s audience questioning technical challenges the block may present. An attendee asked, “How difficult is it to perform this procedure in a recently performed cesarean delivery, with having to put the patient in the necessary position?”

“We don’t flip the patient,” Dr. Roda answered. “We finish the cesarean delivery, the drapes come off, and the woman has the baby on her chest. Then we put a roll under her hip to prop it up, and then we can scan posteriorly with the ultrasound.

“It was generally well tolerated,” Dr. Roda added. “Usually we finish both sides in seven to 10 minutes.”

Another attendee asked whether there were any complications associated with doing bilateral quadratus lumborum blocks. “We looked at overall anesthetic complications and postoperative complications, which we didn’t see,” Dr. Roda replied. “As far as anticipated complications, in addition to typical complications for any peripheral nerve block, you can actually get quite close to the fat around the kidney with this block.”