A new neurostimulator guided technique of rectus sheath block: study of feasibility and local anesthetic spread in children

Background
Rectus sheath block (RSB) is a valuable regional technique for abdominal wall midline analgesia. It can be used for a variety of surgical procedures such as midline laparotomy, umbilical and paraumbilical hernia repair, and laparoscopic surgery. Not all operating theatres, especially in low income countries, are equipped with ultrasound (US) scanners for carrying out US guided regional blocks. In cases of total absence of objective control, neurostimulator (NS) guided technique of RSB can be useful. The aim of the study was to assess the feasibility of performing NS guided RSB.

Methods
US guided RSB with NS was performed on patients in group 1. NS guided RSB was performed on patients in group 2. US scanning of block area and clinical efficacy assessment were performed in group 2.

Results
In group 1 in all cases of US guided RSB with NS, needle entry into the rectus abdominis muscle resulted in its contractions and needle contact with the posterior sheath resulted in cessation of these contractions. In group 2 optimal spread of local anesthetic was achieved in 86 cases (74.14%), and suboptimal spread in 30 cases (25.86%) of NS guided RSB. There were no cases of non-optimal local anesthetic spread. In all cases NS guided RSB had high clinical efficacy (there was no motor response to incision and no need for fentanyl administration).

Conclusions
Rectus sheath block can be performed under neurostimulator guidance. Neurostimulator guided rectus sheath block results in optimal or suboptimal local anes­thetic spread. Clinical efficacy of neurostimulator guided rectus sheath block is high. The trial is registered as ACTRN12618000553279 (http://www.ANZCTR.org.au/ACTRN12618 000553279.aspx).