Postoperative Analgesic Effects of Various Quadratus Lumborum Block Approaches Following Cesarean Section.

Patients fulfilling the eligibility criteria were approached prior to delivery. The attending physician explained the nature of the study and all patients signed an informed consent then patients were divided in to four groups as follows (equal sample size in each group): the QLB type 2 (QL2 group), QLB type 3 (QL3 group), QLB type 2 +3 (QL2+3 group) and EA only group.

A 16-gauge intravenous cannula pathway was established in the non-dominant hand or arm in the operation unit. All parturient with standard monitoring including electrocardiogram, pulse arterial oxygen saturation, respiratory rate and non-invasive blood pressure (NIBP) was performed combined with spinal and epidural anesthesia before C-section in the left lateral position and peripheral nerve block at the end of surgery by an experienced doctor (A.M.A). The epidural needle was inserted into the lumbar epidural space at the level of L2-3 intervertebral space.

After finding the epidural space using loss of resistance to saline technique, the tip of a spinal needle passed through the epidural needle. To achieve a sensory block height to the level of the sixth thoracic dermatome, every parturient received intrathecal anesthesia of 0.75% bupivacaine (1.3-1.7 )mL. Then, the needle was withdrawn and then an epidural catheter was inserted through the epidural needle in case the failure of intrathecal anesthesia. All surgical treatments were performed successfully in the usual manner.

Immediately after surgery, all subjects were transferred to the post-anesthesia care unit (PACU) and administered pre-determined analgesia, All parturient were lift in the supine position, tilting 45 degrees to the opposed side in order to place the low-frequency convex probe properly and see the sonography clearly. Bilateral QLB was performed using the atraumatic needle (22-G, 120-mm needle for peripheral nerve blocks) advanced in-plane under the guidance of an ultrasound machine. The ultrasonogram of the abdominal wall was displayed clearly through probe moving or tilting. Pillows helped to relieve the tension along the abdominal wall of parturient. The whole procedure was performed strictly according to clinical protocol.

In this study, QL2 or QL3 were conducted through an anterolateral approach with the supine position as mentioned in (Sato et al, 2017). The ultrasound transducer was placed transversely on both flanks at the horizontal level of L2-3 and adjusted until the "Shamrock sign" formed of QL muscle, psoas major and erector spinae was visualized, with imaging depth set between 0 and 9.9 cm. Needles will be penetrated in an anterolateral to posteromedial direction. Local anesthetic will be injected posterior to QL muscle in QL2, while in QL3, it will be located between QL muscle and psoas major. QL2+3 block was conducted in the same plane with only one puncture on each side.