Effect of TLIP block on analgesic needs in people undergoing spine surgery under general anesthesia

In people undergoing lumbar spinal surgery, the combination of thoracolumbar interfascial plane (TLIP) block and general anesthesia decreased both postoperative and intraoperative analgesic requirements, lowered intra-operative hemodynamic response to surgery, and attained good postsurgery pain control.

Spinal surgeries are usually linked with significant postsurgery pain that takes approximately three days to recede. For encouraging early mobilization and minimizing postsurgery noxious events, appropriate perioperative pain control is vital. The most commonly performed spinal surgical procedures are laminectomy, discectomy, and spinal fixation.

Extensive dissection of bones, tissues, and ligaments is often carried out during spinal surgeries, leading to a considerable degree of postsurgery severe pain. It is a significant challenge for doctors to adequately manage pain in such patients. This is because most of the patients have already been given ordinary analgesics and/or opioids for improving the preexistent chronic back pain.

The pain following spine surgery can arise from mechanical irritation, nerve compression, or postsurgery inflammatory processes. Also, it can be originated from distinct structures like ligaments, muscles, vertebrae, dural sleeves, discs, and capsules of the facet joint. Innervation of these pain generators is notably from dorsal rami of spinal nerves. For managing severe pain disorders, opioids are usually utilized as effective analgesics.

But, their widespread usage is limited due to their adverse effects like respiratory distress, vomiting, nausea, and acquired tolerance. The preemptive multimodal pain-relieving regimens that depend on the synergistic action of nonopioids administered in reduced doses have been utilized to enhance postsurgery pain control and minimize the intake of opioids. The protocols to decrease pain following lumbar surgery suggest the usage of regional anesthesia techniques for reducing opioid analgesic use to the minimum.

The interfascial plane block exhibits an immense potential to offer extended postsurgery analgesia and to decrease opioid intake and neuraxial-associated motor block to a minimum. In case of transversus abdominis plane (TAP) block, the local anesthetic agents target the ventral rami of the thoracolumbar nerves, thus offering anesthesia to anterior abdominal wall. The TLIP block was initially elucidated by Hand et al. This regional anesthetic technique is comparable to the TAP block but it targets the back.

During TLIP block, injection of local anesthetics is done into fascial plane lying between multifidus and longissimus muscles at level of the 3^rd lumbar vertebra. By targeting the posterior rami of the thoracolumbar spinal nerves, it helps to attain a reproducible area of anesthesia having a predictable spread. But, some studies have stated that the ultrasound-guided TLIP block can be utilized during lumbar spine surgery to offer good perioperative pain control.

RATIONALE BEHIND RESEARCH

Till now, none of the prior studies has explored the impact of TLIP block analgesia on perioperative hemodynamics. With the aim to enhance the quality of anesthesia and to minimize the need for perioperative analgesics, this randomized controlled double-blinded clinical trial was carried out.

OBJECTIVE

A study was performed to examine the pain-relieving effect of combination of general anesthesia and TLIP block versus general anesthesia alone in people scheduled for elective spinal surgery 

Study outcomes

• The major endpoint was postoperative analgesic consumption in the initial 24 hours.
• Pain scores, intraoperative additional need for analgesic agents, and time to the 1st  request of postsurgery analgesia were the secondary outcomes. 

Outcomes

Baseline: There were no vital differences reported at baseline.

Study outcomes

• Compared to the control group, morphine consumption was reduced in the TLIP group (14.33±2.58 mg vs. 5.13±1.55 mg) at 24 hours after surgery (Figure 1).
• The intraoperative fentanyl consumption was reduced in the TLIP arm (15±35.11 mcgs) in comparison with the control arm (105±62.08 mcgs).
• The postsurgery 1st  request for analgesia was noted to be delayed in the TLIP arm (7.30±2.69 h) when compared to the control arm (0.92±1.23 h).
• The postoperative pain scores at rest were 2.53 ± 0.97 and 3.43 ± 0.50 at twenty-four hours in the TLIP arm and the control arm, respectively.
• At twenty-four hours, the postsurgery pain scores at passive flexion of the spine were reported to be 2.73 ±0.87 and 3.93 ±0.78 in the TLIP arm and the control arm, respectively.
• Participants in the TLIP group exhibited reduced perioperative hemodynamic responses to surgical stimulation vs. the control group. 

This randomized controlled trial was carried out for testing the hypothesis that the combination of TLIP block and general anesthesia can alleviate pain and minimize the perioperative analgesic needs in people undergoing spinal surgery. Lumbar spine surgery generally causes considerable postsurgery pain. Appropriate pain management expedites patient mobility, enhances satisfaction, and decreases postsurgery complications.

Along with systemic analgesics, the neuro-axial regional anesthetic techniques like subarachnoid, paravertebral, or epidural blocks can be utilized for postsurgery pain management.  Recently, the ultrasound-guided TLIP block has been stated in numerous studies to manage acute pain following lumbar spinal surgery as well as a possibility to manage chronic low back pain. Since the TLIP block is administered more superficially, it is easy to perform and also very safe.

Compared to the control group, the TLIP group exhibited reduced analgesic consumption in the initial 24 hours after surgery. This finding was noted to be consistent with a study carried out by Ueshima et al. that determined TLIP effect on perioperative analgesic needs for people undergoing primary lumbar laminoplasty under general anesthesia.

Compared to the control group, the TLIP group illustrated decreased intake of postsurgery patient-controlled analgesia fentanyl for the next 48 hours after surgery. Likewise, Chen et al. reported decreased intake of postsurgery patient-controlled analgesia sufentanil for people scheduled to undergo lumbar spine fusion surgery in the TLIP arm in comparison with the control arm.

Furthermore, Ozmen et al. noted reduced postsurgery patient-controlled analgesia fentanyl intake for 24 hours after single-level lumbar disc surgery in individuals who were given a TLIP block when compared to general anesthesia alone. Ekinci et al undertook a study to investigate the pain-relieving impact of modified TLIP vs wound infiltration in people scheduled for an endoscopic single-level lumbar discectomy and partial laminectomy.

Decreased postsurgery opioid intake was witnessed in the modified TLIP arm when compared to the wound infiltration arm. Ahiskalioglu et al. determined the pain-relieving effect of ultrasound-guided modified TLIP block for postsurgery pain after spinal surgery and found an elevated postsurgery need for analgesics in the control arm when compared to the modified TLIP arm. A substantial difference was noted in the requests for supplementary analgesia that was highly common in the control arm vs. the modified TLIP arm.

In this trial, the intraoperative extra fentanyl intake was found to be reduced in the TLIP group when compared to the control group. In a study carried out by Ke et al. that recruited people undergoing lumbar spine fusion surgery, the intraoperative remifentanil intake was found to be reduced in the TLIP group vs. the control group. Notably, no previous studies assessed the influence of TLIP block versus control on the intrasurgery or postsurgery hemodynamic parameters.

Numerous studies investigated the impact of combined neuraxial anesthesia vs general anesthesia alone on intraoperative and postoperative hemodynamics in people undergoing lumbar spine surgery. Similar to these study results, they stated that the intraoperative and postoperative blood pressure or heart rate  were remarkably greater in individuals who received general anesthesia alone.

A considerably reduced pain score at rest and during passive flexion of the spine was witnessed in the TLIP arm in comparison with the control arm at all-time points during the initial 24 postsurgery hours. This showed consistency with numerous studies that indicated minimized postsurgery pain scores in the study arms that received TLIP or modified TLIP blocks for single level lumbar discectomy, lumbar spine fusion surgery, and primary lumbar laminoplasty when compared to the control arms.

A study by Ammar and Taeimah investigated the combination of TLIP block with general anesthesia versus general anesthesia alone for 70 people scheduled for lumbar disc surgery. The TLIP group exhibited a profound decline in postsurgery pain scores, and 24 hours postsurgery morphine consumption was also considerably reduced in the TLIP group when compared to the control group, along with a delayed first request for postsurgery analgesia in the TLIP group when compared to the control group.

When compared to the outcomes of the study carried out by Ammar and Taeimah, the findings of this study showed comparable postsurgery pain scores and the time to first analgesic request. However, postsurgery morphine consumption was reduced. The TLIP block targets the dorsal ramus of the spinal nerve. On the other hand, erector spinae plane block (ESPB), a new regional anesthetic technique, targets both dorsal rami and ventral rami of spinal nerves, and it spreads over epidural and paravertebral spaces.

Numerous studies have evaluated the perioperative pain-relieving effect of ESPB for spinal surgery carried out under general anesthesia and concluded that people who received ESPB have reduced postsurgery pain scores and less postsurgery opioid consumption when compared to those who received general anesthesia alone. 

In a study by Ciftci et al, 90 people scheduled for lumbar discectomy surgery under general anesthesia were segregated into the ESPB arm, the modified TLIP block arm, and the control arm. In comparison with the control group, both ESPB and modified TLIP groups displayed considerably reduced postsurgery opioid intake, postsurgery passive and active pain scores, and the utilization of rescue analgesia. Non-superiority was noted between both regional techniques.

More large-sample and high-quality randomized controlled trials are required in the future to show the safety and efficacy of the TLIP block in comparison with other regional blocks and to determine the effect of different drug adjuvants to alleviate pain in individuals undergoing spine surgery under general anesthesia.