The rectus sheath block for laparoscopic surgery in adults: a comparison between the loss of resistance and ultrasound guided techniques

Abstract

The rectus sheath block has been shown to be beneficial in providing analgesia in patients undergoing laparoscopic surgery [1]. However, potential complications include peritoneal injection and bowel perforation. This study investigates the accuracy of blind rectus sheath block using loss of resistance (LOR) compared to ultrasound guidance (US). After approval from the Local Research Ethics Committee, consenting patients admitted for laparoscopy were randomly allocated to receive rectus sheath block by either LOR or US. Five anaesthetic trainees were randomly assigned to perform rectus sheath block by LOR while another five trainees performed rectus sheath block by US using the Sonosite 180 Plus (Sonoma Health Products Inc, Forestville, CA, USA). Rectus sheath blocks were placed bilaterally above and below the umbilicus using a regional block needle, and the distance to the anterior layer of the rectus sheath, width of the rectus sheath muscle, and body mass index (BMI) were recorded. The accuracy of placement of 10 ml levobupivacaine 0.25% was recorded. Eight-three patients (332 placements of levobupivacaine) were studied, with a mean (SD) age of 43 (14) years. Mean BMI was 26.5 (5.0) kg.m−2. Age and BMI were similar between LOR and US groups. The mean (SD) distance from the skin to the anterior layer of the rectus sheath was 2.3 (0.9) cm and 2.7 cm (0.9) cm above and below the umbilicus, respectively. The correlation coefficient (r) between BMI and the distance from the skin to the anterior layer of the rectus sheath, both above and below the umbilicus, was 0.68 (p < 0.01) and 0.75 (p < 0.01), respectively. Mean (SD) width of the rectus muscle was 1.0 cm (0.1) and correlated with BMI (r = 0.29; p < 0.05). The accuracy of placement of levobupivacaine is shown in Table 1. The results of this study suggest that, with respect to RSB in adult patients, improved accuracy and a reduction in potential complications are best achieved using US guidance. A fascial plane lying at a variable distance above the anterior layer of the rectus muscle was commonly observed. Blind puncture of this fascial plane may be wrongly interpreted as that of the anterior layer of the rectus sheath muscle. US guidance may also be useful in improving the accuracy of other regional techniques normally reliant on LOR through fascial planes. We gratefully acknowledge the assistance provided by the Departments of Anaesthesia, Surgery and Gynaecology, Royal Alexandra Hospital, Paisley, UK.