The quadratus lumborum block is a novel truncal block, gaining popularity among perioperative analgesic technique in many abdominal surgeries nowadays. In particular, the quadratus lumborum block is fast becoming an appealing replacement to epidural as it lacks central neuraxial block side effects. It has been well proved in caesarean sections, hip arthroplasty and gynecologic surgery. It’s the latest addition to this line was open and lapnephrectomies. This article deals with various approaches of QLB and the analgesic effectiveness in nephrectomies.
Four types of approaches were described for quadrates lumborum blocks namely anterior, lateral, posterior, and intramuscular approaches. Among these the most studied and performed technique was anterior quadratus block.
The anterior quadratus lumborum block is between the quadratus lumborum muscle and the psoas major muscle at the level of the L4 transverse process.
The lateral quadratus lumborum block is on the lateral side of the quadratus lumborum muscle where it contacts the transversalis fascia.
The posterior quadratus lumborum block is on the posterior side of the QLM between the QLM and the middle layer of the thoracolumbar fascia.
The intramuscular quadratus lumborum block is involved directly into the quadratus lumborum muscle itself.
Regarding the mechanism of anterior quadratus lumborum block specifically targets the roots and upper branches of the lumbar plexus. Another possible mechanism involved was thoracolumbarfascia nociceptors. The thoracolumbar fascia is a complex connective tissue structure, which connect the anterolateral abdominal wall with the lumbar paravertebral region and it has dense sensory structures like A- and C-fiber nociceptors and mechanoreceptors. These nociceptors and mechanoreceptors blockade by local anaesthetics provide good analgesia. Apart from above mentioned mechanisms, there were many cadaveric studies showed that the relationship between the amount of drug and the level of injections could affect the analgesic levels.
In open nephrectomies, epidural was the preferred mode of analgesia. Now a days many studies proved that the extend of analgesiain QLB was from T5 to L2 level and the effectiveness was also equal to epidurals. For laparoscopic nephrectomies also the port sites were well within the boundaries of the above mentioned dermatomal levels and the pain was very well controlled by QLB. In compare to epidural analgesia, quadratus lumborum blocks appear to provide equivalent analgesia with less hemodynamic compromise, and less postoperative nausea and vomiting, due to less opioid usage. It also provides enhanced postoperative recovery by means of early mobilization, shorter urinary catheterization time and early return of bowel function.
Reduction in opioid usage and enhanced recovery in QLB a excellent choice of analgesic technique in intraabdominal surgeries especially nephrectomies. But compare to epidural and other modes of analgesia, QLB needs sound knowledge in ultrasound anatomy, because this block solely performed only under ultrasound guidance.
Dr. Karthick Raja Velayutham Consultant Anaesthesiologist Kauvery Hopsital Chennai
