Pararectus Block for Open Abdominal Surgery

Abstract

To the Editor: The midline incision in open abdominal surgery is mainly innervated by the intercostal and subcostal nerves. They usually pass between the internal oblique muscle and transversus abdominis muscle, and perforate the sheath of the rectus abdominal muscle. After supplying the rectus abdominis muscle, these nerves become the anterior cutaneous branches of the rectus abdominis nerve, supplying the anterior abdominal skin (1). We hypothesized that bilateral blockade of the intercostal nerves on the lateral linea alba, a “pararectus” block, could provide surgical analgesia for midline incision and relaxation of the rectus abdominis muscle. We performed pararectus blocks in seven patients undergoing open abdominal surgery. Pararectus block was performed after induction of anesthesia. For this block, four or five injection points one each side were determined on the lateral linea alba (Fig. 1). A short-bevel 23-gauge 2.54- cm needle was inserted and advanced in the cephalad direction along the lateral linea alba. Two milliliters of ropivacaine 0.375% was infiltrated subcutaneously. While gently advancing the needle, an additional 3–4 mL of ropivacaine (0.375%) was infiltrated. Sometimes, a “pop” was felt when the needle passed through the aponeurosis into the peritoneal cavity. This sensation was not required to complete this technique, and we generally stopped short of this to minimize the risks of peritoneal penetration. We only injected the ropivacaine after a negative aspiration test.Figure 1.: Injection points (X). 1 and 2 = Lateral linea alba, 3 = Umbilicus. Arrows indicate needle direction.Anesthesia was maintained with 50%–66% nitrous oxide in oxygen, 1% sevoflurane, and fentanyl 2–4 μg/kg. No patients responded when the abdominal incision was made. However, four patients had transient increases in heart rate and six patients had transient increases in arterial blood pressure during the intraabdominal procedure. The abdominal wall was relaxed without muscular relaxants. No patients complained of postoperative pain immediately after awakening from anesthesia. Postoperative pain management consisted of a continuous IV infusion of fentanyl (20 μg/h) for the first day, supplemented with flurbiprofen on the second day in three patients. The averages of visual analog scale (VAS) scores on each day were 23, 49, and 31 on the first, second, and third postoperative days, respectively. The clinical course in these patients suggests that the intercostal nerves were effectively blocked by this technique. The bilateral rectus abdominis muscles were relaxed, no patients showed signs of poor analgesia on the abdominal incision, and VAS scores on the first postoperative day suggested reasonable levels of analgesia. We suggest that this technique may merit further evaluation in clinical trials. Satoki Inoue, MD Masahiro Takahashi, MD Hitoshi Furuya, MD Department of Anesthesiology Nara Medical University Kashihara, Nara, Japan [email protected]