We would be glad to address the concerns raised by Hansen et al.1 regarding the “anterior approach” of quadratus lumborum block (QLB) described by Chakraborty et al.2 We also elaborate on the advantages and drawbacks of our technique.
QLB is a recently developed technique and needs further evaluations to encourage its use among the Anesthesia community. While administering QLB in children, we perceived a need for change in the technique for the reasons given below.
Although in adults usually the block is given in an awake patient, children have to be anesthetized before administering the block. Turning and positioning a child under anesthesia has risks. Accessing the anterior surface of quadratus lumborum muscle from an anterior approach can avoid those risks because we can keep the child in supine position, draw him/her to the edge of the table, and hold the probe from below.
Second, our technique uses a linear array high-frequency ultrasound transducer, which gives a sharper image, thus avoiding inadvertent trauma to any important structures, such as blood vessels. Although the ultrasound beam from a linear array transducer has a lesser penetration compared with a curvilinear one, in small children it is often sufficient, as noted and reported by us.
The lower thoracic and upper lumbar nerves travel through the psoas major muscle (PMM), emerge at the lateral border of PMM and travel along the anterior surface of QLM, between the thoracolumbar fascia and the fascia transversalis, and then enter the transversus abdominis plane.3 In our technique, the block needle enters the plane between the thoracolumbar fascia and the fascia transversalis (or renal fascia) just lateral to the anterolateral margin of QL and advances further through hydrodissection (Fig. 1). By the time it reaches the area between QL and PMM, already considerable length of the needle is in the plane. At this point, if a catheter is introduced and advanced even by a centimeter or 2, by withdrawing the needle gently, holding the catheter in place can ensure sufficient length (4–5 cm) of the catheter in the desired plane. Thus, placing a catheter is easier; there is lesser chance of catheter kink or migration. Our technique as one can see is similar to the original “QLB 1” technique used by Blanco.4
However, in the transmuscular approach, the needle enters the plane at a right angle, and advancing the catheter can be difficult. The catheter may be displaced because of the movement of the patient in the postoperative period as it traverses through the QL muscle and any movement of the muscle displaces the catheter.
Borglum et al. have expressed their concern that in the anterior approach, the needle may enter the peritoneum, which we do not agree with. Fascia transversalis is continued posteriorly as the renal fascia, encompassing the kidneys and perirenal fat. Between renal fascia and the anterior layer of lumbar fascia (also known as thoracolumbar fascia) lie variable amount of adipose tissue known as pararenal fat.5 Because of this fatty tissue, this plane is easily dissectible by saline injection. Between the peritoneum and the renal fascia lie the kidney and perirenal fat. Even if the needle were to pierce the renal fascia, it would enter the perirenal fat, where no major structure lies in near vicinity.
The major drawback of our technique is that it is difficult to perform in adult patients. We hope that with progress of ultrasound technology, the anterior approach of QLB can soon be performed in adult patients as well.
Arunangshu Chakraborty, MBBS, MD
Taniya Datta, MBBS, MD
Rakhi Khemka, MBBS, MD
Department of Anaesthesiology, Critical Care and Pain
Tata Medical Center
1. Hansen CK, Dam M, Bendtsen TF, Børglum J. Ultrasound-guided quadratus lumborum blocks: definition of the clinical relevant endpoint of injection and the safest approach. A A Case Reports. 2016;6:39
2. Chakraborty A, Goswami J, Patro V. Ultrasound-guided continuous quadratus lumborum block for postoperative analgesia in a pediatric patient. A A Case Rep. 2015;4:34–6
3. Snell RS Clinical Anatomy by Regions. 20078th ed Philadelphia, PA Lippincott Williams & Wilkins:153
5. Snell RS Clinical Anatomy by Regions. 20078th ed Philadelphia, PA Lippincott Williams & Wilkins:261