Evaluation of Sensory Loss and Postoperative Analgesia Obtained by Diaphragmatic Apposition Zone Block Under Direct Laparoscopic Visualization in Patients Undergoing Nephrectomy: A Descriptive Study.

Purpose: Local anesthetics can spread into the subendothoracic fascia compartment via the arcuate ligament and apposition zone of the diaphragm after the anterior quadratus lumborum blocks. Therefore, a new block may be achieved if local anesthetic is administered into the diaphragmatic apposition zone (DAZ) under direct laparoscopic visualization by surgeons. Therefore, we evaluated the sensory loss and postoperative analgesic efficacy of this new block in patients receiving laparoscopic nephrectomy.

Methods: A total of 28 patients scheduled to receive elective laparoscopic nephrectomy under general anesthesia were enrolled in this study. The DAZ blocks were performed in patients under direct laparoscopic visualization with 20 mL of 0.5% ropivacaine before the dissected kidneys or renal tumors were taken out from the incision. All patients received the intravenous patient-controlled analgesia after surgery. The dermatomes of sensory loss and the muscle weakness of quadriceps femoris were assessed at 2 h post-surgery in the wards. The postoperative pain was scored. The opioid consumption in the first 24 h after surgery was recorded.

Results: The average number of dermatomes of sensory block was 8.6 ± 1.2. The highest level of sensory loss was T6 (T5-T6) [median (interquartile range, IQR)], and the lowest level of sensory block was L1 (L1-L2). The postoperative pain scores at rest or on movement at 2 h, 6 h, 12 h, 24 h and 48 h were kept at the low levels (less than 4). The muscle strength of the quadriceps femoris evaluated was 5 (5-5) points [median (IQR)]. Total dose of intravenous morphine equivalent consumption in the first 24 h after surgery was 21.2 ± 4.1 mg.

Conclusion: The DAZ block manifests a wide dermatomal coverage of sensory loss and is associated with the low levels of postoperative pain intensity and opioid use. It provides a new postoperative analgesia option for patients undergoing laparoscopic nephrectomy.