Comparative efficacy of levobupivacaine alone and in combination with dexmedetomidine for thoracic paravertebral block in people undergoing laparoscopic cholecystectomy

In individuals undergoing laparoscopic cholecystectomy, thoracic paravertebral block using dexmedetomidine added to levobupivacaine considerably lowered the total analgesic consumption in the first 48 hours. It also offered a longer duration of analgesia postsurgery in comparison with levobupivacaine alone.

One of the most common surgeries carried out in individuals with gall ball disease is laparoscopic cholecystectomy. Individuals undergoing this surgery may suffer from severe post-surgery pain if the management of analgesia is not done suitably. The presence of acute post-surgery pain causes severe discomfort to the patient, limits early recovery of the patient, and extends post-anesthesia care unit stays.

Over the past years, there has been a rise in the use of paravertebral blocks for offering pain relief after surgery. Using ultrasound to administer thoracic paravertebral block has remarkably declined the occurrence of complications. In literature, the usage of thoracic paravertebral block for offering post-laparoscopic cholecystectomy analgesia has been elucidated.

Rationale behind research

Although numerous local anesthetics combinations have been utilized for offering thoracic paravertebral block, there is a paucity of studies on adjuvants in the thoracic paravertebral block in laparoscopic cholecystectomy. Therefore, this large study was performed.

Objective

A randomized, prospective, double-blind clinical trial was carried out to explore further analgesic needs in individuals undergoing laparoscopic cholecystectomies following preoperative unilateral thoracic paravertebral blocks utilizing two distinct analgesic combinations (levobupivacaine vs. its combo with dexmedetomidine). 

Study outcomes

• The primary endpoint was the estimation of the total analgesic intake in the first 48 hours postsurgery period
• The secondary endpoint was  pain scores, time to initial request for rescue analgesic, and side-effects in the postsurgery period

Outcomes

Baseline: There were no significant differences reported at baseline.

Study outcomes

• The total amount of rescue analgesia (injection tramadol plus injection tramadol intravenous equivalent dose) used during 48 hours postsurgery was higher in Group I (146.55 mg) vs. Group II (111.30 mg)
• The mean time for demanding rescue analgesia was greater in Group II (340 min) compared to Group I (273 min)
• The number of participants who needed first rescue analgesia (injection tramadol IV) was similar in both arms. However, the number of participants needing second rescue analgesia (injection morphine IV) differed significantly (Group I: 13/35 subjects, Group II: 5/35 subjects)

In this trial, substantial improvements were witnessed in the pain-relieving efficacy of dexmedetomidine and levobupivacaine combination in comparison with levobupivacaine alone in paravertebral blocks in individuals undergoing laparoscopic cholecystectomy.

The postsurgery analgesic intake was lowered during the entire 48 hours postsurgery observation period in subjects receiving a combo of dexmedetomidine and levobupivacaine in paravertebral blocks. Also, the Numerical Rating Scale (NRS) pain scores at rest and in the movement were found to be reduced in these subjects, and the time to first rescue analgesic was also considerably greater.

Subjects who were given a combo of levobupivacaine and dexmedetomidine had reduced occurrence of postoperative nausea and vomiting (PONV), declined sedation scores, and improved participant comfort score. Laparoscopic cholecystectomy is now being conducted more on an outpatient basis. Thus, to expedite postsurgery recovery,  effective analgesia with opioid-sparing attributes is usually favored.

Laparoscopic cholecystectomy is linked with a vital component of visceral pain, and the occurrence of shoulder pain may reflect a component of diaphragmatic referred pain. The chronic post-surgery pain risk has been noted to be 10-40% following laparoscopic or traditional open cholecystectomy.

Both high-quality afferent somatic and visceral pain blockade is crucial to effectively manage chole-cystectomy pain. The paravertebral blockade has been witnessed to yield high-quality afferent blockade with the elimination of somatosensory elicited potentials. Furthermore, it has also been found capable of mitigating the postoperative stress response related to traditional cholecystectomy.

A study conducted by Naja et al. examined the efficacy of nerve stimulator-guided bilateral paravertebral blockade (with a combo of clonidine, lignocaine, fentanyl, and bupivacaine) in combination with the general anesthesia vs. general anesthesia alone to minimize post-surgery pain after laparoscopic cholecystectomy. It was noted that when utilized as a complement to general anesthesia, the paravertebral blockade with bupivacaine, lidocaine, fentanyl, and clonidine improved postsurgery pain relief.

Aggarwal et al. carried out an analysis to assess the efficiency of paravertebral block utilizing bupivacaine in laparoscopic cholecystectomy. It was noted that subjects receiving paravertebral blocks needed 38% less patient-controlled analgesia morphine vs. the control arm. The intrasurgery supplemental fentanyl need in their study arm was 54% reduced compared to the control arm.

In a meta-analysis performed by Junior et al., the thoracic epidural was compared with paravertebral block for postsurgery pain in individuals undergoing thoracotomy. No substantial differences in pain relief were noted between paravertebral and thoracic epidural block. However, the paravertebral block was witnessed to be linked with a substantially less incidence of urinary retention and hypotension.

Dexmedetomidine has remarkably emerged as a promising adjuvant illustrating a facilitatory effect with local anesthetic. In a wide array of research, dexmedetomidine has been utilized as an adjuvant to local anesthetics for peripheral nerve blockade.

In most studies, dexmedetomidine demonstrated improved efficacy of the block without any reports of neurological adverse events. Prior studies have also depicted the efficiency of paravertebral block utilizing local anesthetics with or without opioids.  But, none of the studies have determined dexmedetomidine's role along with local anesthetics for offering thoracic paravertebral blocks in laparoscopic cholecystectomy.

In this trial, paravertebral blocks were administered to both arms but utilized different combos of drugs (levobupivacaine-dexmedetomidine/levobupivacaine) for giving the blocks. It was witnessed that the combo of dexmedetomidine and levobupivacaine when utilized to offer paravertebral block in laparoscopic cholecystectomy led to a considerable decline in the postsurgery pain, in comparison with using levobupivacaine alone.

One of the most obnoxious symptoms witnessed by the patients after laparoscopic cholecystectomy is PONV. The opioid-sparing effects of different regimens were extensively reviewed by Kehlet et al. and remarked that about 30% decline in opioid need was clinically significant.

An opioid-sparing analgesic approach should also lead to the lowered occurrence of opioid-associated adverse events. Therefore, the incidence of opioid-associated side effects like respiratory depression, nausea, constipation, dizziness, and vomiting was determined between the arms. Compared to Group I, the participants in Group II reported less PONV in the postsurgery period.

The number of participants who complained of PONV and who needed rescue antiemetic was 3 out of 35 subjects in Group II post-surgery vs. 8 out of 35 subjects in Group I. This difference displays a considerable opioid-sparing advantage of paravertebral blocks in terms of decreased PONV but did not reach statistical significance, perhaps due to the small sample size.

The sedation score was considerably low in Group II than Group I at 30 and 60 minutes in the postsurgery period. This may have been due to adding dexmedetomidine to levobupivacaine for administering paravertebral blocks in Group II. An analysis carried out by Jung HS et al. determined the impact of intrasurgery infusion of dexmedetomidine with remifentanil on perioperative hemodynamics, sedation, hypnosis, and postsurgery pain control.

After arrival in the postanesthetic care unit, the sedation score was remarkably reduced in the dexmedetomidine arm compared to the remifentanil arm. Dexmedetomidine exhibits analgesia-sparing and sedative effects through central actions in the dorsal horn and locus coeruleus of the spinal cord. It suppresses the release of noradrenaline, thus decreasing excitation in the CNS, specifically in the locus coeruleus.