Clinical Efficacy and Safety of Dexmedetomidine as an Adjuvant to Bupivacaine in Ultrasound-guided Quadratus Lumborum Versus Epidural Block for Postoperative Analgesia in Lower Abdominal Cancer Surgeries.

One of the main concerns of patients presenting for major abdominal surgery and anesthesiologists who are involved in postoperative care is postoperative analgesia[1].

Despite improvements in surgical technique and perioperative care, complications in the immediate post-operative period remain significant [2]. The patients often experience significant post-operative pain and functional impairment and need 5-10 days to recover [3], [4].

Poor postoperative pain control leads to longer postoperative care, longer hospital stay and decreased patient overall satisfaction [5]. Opioids remain the mainstay of postoperative pain relief but have their own side effects. Therefore, the use of a multimodal analgesic strategy is nowadays preferable in most clinical settings to minimize the need for opioids. The use of regional anesthetic techniques provides excellent analgesia, as their effect can extend beyond the perioperative period [6].

As an important element of multimodal analgesia, regional blocks can reduce the dosage of opioids, minimize side effects, and enhance the quality of recovery after surgery [7].

Ultrasound-guided Quadratus Lumborum Block (QLB) is a relatively new regional anesthetic technique that was first described by Professor R. Blanco in 2007 at the annual scientific meeting of the European Society of Regional Anesthesia [8], it is relatively easily performed, the block effect lasts 24 - 48 h and up till now, no complications have been described during or after the block performance. QLB is safe and has found its place in multimodal postoperative pain strategy in patients undergoing abdominal surgery [9]. Quadratus lumborum block (QLB) is an emerging truncal block technique, [10] which includes injecting local anesthetic (LA) into the thoracolumbar fascia (TLF) surrounding the quadratus lumborum (QL) muscle. The analgesic effect is produced by the LA spreading along the TLF into the thoracic paravertebral space and transversalis fascia. QLB is an effective analgesic method for patients undergoing abdominal and hip surgeries [11,12 ,13 ,14]. Based on the different injection sites, there are four types of QLB, namely, lateral QLB, posterior QLB, transmuscular QLB, and intramuscular QLB. Transmuscular QLB includes the injection of LA between the QL muscle and the psoas major (PM) muscle. Transmuscular QLB can be implemented at the L4 and L2 levels using the subcostal approach [15]. Hesham et al. [16] have reported that the use of the subcostal approach to Transmuscular QLB can provide appropriate sensory blockade for open urological surgeries.