The largest study of its kind to date has concluded that transversus abdominis plane (TAP) blocks with liposomal bupivacaine (Exparel, Pacira BioSciences) produce comparable analgesia to epidural analgesic approaches in adults undergoing abdominal surgery, and resulted in significantly less postoperative hypotension.

However, the study found that patients receiving TAP blocks used more postoperative opioids.

“We started using TAP blocks several years ago,” said Alparslan Turan, MD, a professor and the vice chair of the Department of Outcomes Research at Cleveland Clinic in Cleveland. “At first, we did them with normal local anesthetic, but the effect is relatively short. Because we were looking for prolonged analgesia, we started using liposomal bupivacaine in our TAP blocks.

“While we had promising results, the literature is very limited in this field, particularly since liposomal bupivacaine is not approved for all blocks yet,” Turan said. “So we wanted to compare this approach with the gold standard, which is epidural analgesia.”

The randomized, open-label, multicenter clinical trial—dubbed the EXPLANE trial by the researchers—comprised adult patients undergoing either open or laparoscopic-assisted abdominal surgery. Participants were randomized to receive either four-quadrant or bilateral TAP blocks with a mixture of 100 mg of bupivacaine and 266 mg of liposomal bupivacaine, or a continuous epidural infusion or patient-controlled analgesia with 0.1% bupivacaine without epidural opioids.

The trial’s primary outcome was postoperative analgesia, which was defined as noninferiority in both average pain scores (0-10 scale; noninferiority difference, 1 point) and opioid consumption (noninferiority difference, 25%) during the first 72 hours after surgery.

Hypotension a Key Finding

As the researchers reported in a presentation at the virtual Euroanaesthesia 2020 (abstract 5999), the study was concluded at its third interim analysis after crossing a predefined futility boundary. At that point, they analyzed data from 477 participants presenting to seven different sites.

It was found that the estimated difference in average pain scores between patients receiving the TAP block and epidural was 0.08 (95% CI, –0.22 to 0.38; noninferiority, P<0.001).

“This was not unexpected,” Turan said in an interview with Anesthesiology News. “Most of the time, nurses target patients to a certain pain score of 4 or less, which is very common in pain studies. As a result, the pain score does not give you much information.”

For this reason, the researchers also examined opioid consumption. The analysis revealed that opioid consumption in the TAP block group was not noninferior to the epidural group (estimated ratio of geometric means, 1.4; 95% CI, 1.0-1.96; noninferiority, P=0.80).

“The difference was a total of 21 mg of morphine equivalents over the three days,” Turan explained. “So, basically, the difference between an epidural and a TAP block with Exparel was only 7 mg per postoperative day, which is not very much. Nevertheless, we wanted to see if this made any difference in terms of other outcomes.”

The analysis found no notable differences between groups with respect to opioid-related side effects, quality of recovery or hospital length of stay on postoperative days 1 to 3.

With respect to blood pressure, the study found that the risk for having mean arterial pressure (MAP) less than 65 mm Hg was significantly lower in TAP patients (31%) than among the epidural group (48%). The estimated relative risk was 0.64 (99% CI, 0.42-0.98; P=0.006). Moreover, as many as 22% of patients in the epidural group had at least 10 minutes with MAP less than 75 mm Hg on average during every monitoring hour, compared with 15% of their counterparts in the TAP group.

These findings, the investigators concluded, demonstrate that TAP blocks with liposomal bupivacaine present a viable alternative to epidural analgesia in patients undergoing abdominal surgery. “The TAP block works well, and is a reasonable way to take care of the pain.

“It might cause a bit more opioid consumption, though I am not sure if it’s clinically meaningful or not,” Turan continued. “But importantly, hypotension was much more common in epidural patients. And we know that hypertension is related to a series of ischemic complications.”

Given the varying benefits offered by each analgesic approach, patient characteristics will likely determine which one clinicians choose. “If you have a patient in whom pain control will be difficult, then I would stick with the epidural,” Turan said. “On the other hand, if you have a patient who is cardiovascularly compromised and at risk of things like myocardial infarction or stroke, it might be advisable to avoid the epidural and stick with the TAP block with Exparel.”

James K. Kim, MD, an assistant professor of clinical anesthesiology and critical care at the University of Pennsylvania Health System, in Philadelphia, agreed that the decision to use either technique is largely patient dependent. “If analgesia is your primary focus and you want to give your patient the ‘Cadillac’ of analgesia, I’m a huge proponent of thoracic epidurals,” Kim said. “However, if a patient has contraindications to neuraxial techniques or even a thoracic epidural that was prematurely dislodged/intentionally removed due to anticoagulation status or refractory hypotension, I think this approach represents a fantastic alternative as a component of multimodal analgesia.”

As Kim discussed, he regularly uses liposomal bupivacaine when performing fascial plane blocks. “It prolongs the duration of action compared to plain local anesthetic, though I’m not convinced for as long as 72 hours,” he explained. “In addition, postoperative hypotension is a big factor that many clinicians don’t take into consideration when performing neuraxial techniques, which can be avoided with fascial plane blocks.”

—Michael Vlessides

Turan and Kim reported no relevant financial disclosures.