Combining micro-endoscopy and ultrasound guidance for transversus abdominal plane catheter insertion: a feasibility cadaveric study

BACKGROUND AND OBJECTIVES: Continuous transversus abdominis plane could represent a valid alternative for postoperative analgesia after open abdominal surgery. Unfortunately, placing catheters along the transversus abdominis plane is challenging even with ultrasound guidance. Coupling conventional ultrasound guidance with direct vision via micro-endoscopy could potentially improve visualization of the tissue plane and reduce unintended intramuscular catheter placement and intramuscular infusion. METHODS: After institutional approval, transversus abdominis plane catheters were placed in anatomical bodies under combined ultrasound guidance and micro-endoscopic vision. After colored dye injection through the catheters, anatomical dissection was performed to objectively determine spread. RESULTS: Four catheters showed a successful intended-plane dye spread into transversus abdominis plane in three anatomical bodies. For all catheters, adjunction of micro-endoscopic vision was needed to obtain catheter progression along the transversus abdominis plane. Successfully spread covered T8 to T12 segmental levels. CONCLUSIONS: This preliminary cadaveric study suggests that correct positioning of catheters into the transversus abdominis plane could be facilitated by micro-endoscopy vision coupled with ultrasound guidance. Additional studies are needed to confirm these results.