Gaurav Sindwani1, Aditi Suri2, Sandeep Sahu3. 1. Department of Anesthesia, Institute of Liver and Biliary Sciences, New Delhi, India. 2. Department of Oncoanesthesia, AIIMS, New Delhi, India. 3. Department of Anaesthesia, SGPGI, Lucknow, Uttar Pradesh, India.
Sir,We thank the readers for their critical comments.[12] In response to the first question, quadratus lumborum block (QLB) can be given in four different approaches which are anterolateral or lateral QLB (type 1), posterior QLB (type 2), and anterior or transmuscular QLB (type 3). Recently, an intramuscular approach for QLB has been described which we referred to as the fourth approach.[3] In response to the second question, in the figure, we tried to keep the anatomy of ultrasound-guided QLB clear for the readers. One of the major landmarks for the ultrasound-guided QLB is the tapering of the transverse abdominis muscle and the beginning of the thoracolumbar fascia (TLF). Therefore, it is easy for the readers to understand the anatomy when all the three anterior abdominal wall muscles are seen along with the beginning of TLF and quadratus lumborum muscle in the same figure.In response to the third query, ideally, the needle tip or catheter should be placed in between the quadratus lumborum muscle and the TLF,[4] and not in the deep recess covered by the peritoneum as the readers suggested. This is because there is considerable amount of fat in between the peritoneum and TLF. Moreover, there is no continuity of this space with that of the QLB space. Therefore, drug deposited in the deep recess cannot spread along the fascial plane. In type 3 QLB, drug is injected very near to the paravertebral space in between the quadratus lumborum muscle and psoas major muscle. Moreover, TLF also has a rich nerve supply. Therefore, it is still possible that type 3 QLB would still result in good analgesia even when type 1 QLB fails as the natural tendency of the drug is to spread more medially rather than laterally.