Quadratus lumborum block failure: "A must know complication".

Sir,

Quadratus lumborum block (QLB) is a type of abdominal wall block which has shown promising results in managing the post-operative pain of patients undergoing abdominal and retroperitoneal surgeries.[12] We report a case where the correctly placed ultrasound guided continuous type 1 QLB failed to provide analgesia in a patient undergoing laparoscopic nephrectomy. This failure occurred secondary to damage to thoracolumbarfascia (TLF) during the surgical dissection.

A 45-year-old male, weighing 75 kg, belonging to the American Society of Anesthesiologists (ASA) physical status 1, was posted for left laparoscopic radical nephrectomy by transperitoneal approach under general anaesthesia. Ultrasound-guided continuous type 1 QLB was planned for post-operative analgesia. Written informed consent was obtained. Electrocardiogram (ECG), pulse oxymeter and non invasive blood pressure monitors were attached. General anaesthesia was given. Under strict aseptic precautions, an experienced anaesthetist performed the ultrasound-guided block in the right lateral position. Using an in-plane technique, an 18- gauge Tuohy's needle was inserted. The needle tip was placed precisely in between the quadratus lumborum muscle and TLF. Correct needle position was confirmed by injecting 5 ml of normal saline. After injecting another 5 ml of normal saline, a 20-gauge polyurethane catheter was inserted into the space without any difficulty. Catheter was fixed in situ using transparent dressing. After creating pneumo-peritoneum, surgery was started. Lateral peritoneal reflection was incised along the line of Toldt to reach the retroperitoneal space. While doing surgical dissection, the anterior layer of TLF got damaged and the catheter was seen lying over the QL muscle in the laparoscopic monitor. Surgery was uneventful. Before extubation, catheter was removed. Ultrasound-guided continuous type 3 QLB was performed to manage the post-operative pain [Figure 1].[3] Ropivacaine (0.2%) 20 ml bolus was given after negative aspiration for blood. The trachea was extubated. Continuous infusion of 0.1% ropivacaine started at 5 ml/h in the recovery room. Catheter was removed on the third post-operative day. Maximum visual analogue scale score on day 1 was 3, whereas on day 2, it was 2. Sensory level achieved was from T6-L1. Injection paracetamol 1 g intravenous (IV) was given every 6 hourly as a part of multimodal approach. Injection tramadol 100 mg IV was used as a rescue analgesic. No other analgesics were rquired.

Figure 1

Ultrasound guided quadratus lumborum block. EO: External oblique muscle, IO: Internal oblique muscle, TA: Transverse abdominis muscle, QL: Quadratus lumborum muscle, TLF: Thoracolumbar fascia

QLB can be given by four different approaches. In type 1, QLB drug is deposited anterolateral to the QL muscle, in between TLF and QL muscle. In type 2, QLB drug is deposited posteriorly to QL muscle, and in type 3, QLB drug is deposited in between QL and psoas muscle. TLF is a thin layer of fascia which gets divided into the three layers. The anterior layer blends laterally with transversalis fascia and medially with the fascia of psoas major muscle.[4] Drug deposited in this plane spreads medially, under lateral arcuate ligament to reach the thoracic paravertebral space. Therefore, the drug spread to paravertebral space after type 2 and type 3 QLB is better when compared to type 1 as drug is deposited more medially and posteriorly. Afterward, this drug can spread in the craniocephalic direction to produce sympatholysis. TLF also has high-density network of sympathetic fibres which can be the another mechanism for the effects produced by the QL block.[5]

In our case, damage to the TLF would probably have caused the drug to spread beyond the plane, resulting in block failure. Preoperatively, the patient was explained regarding both QLB and epidural analgesia and he chose the former. Therefore, after observing the damaged TLF, it was decided to perform type 3 QLB, since transversus abdominis plane (TAP) block would have resulted in inadequate analgesia. As per our literature search, this is the first case report describing a complication of QLB which could potentially result in its failure. To conclude, type 1 QLB can fail to provide post-operative analgesia if surgery involves dissection in the retroperitoneal area as there are high chances of damaging the TLF.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.