Factors influencing postoperative abdominal pain in DIEP flap breast reconstruction

Identification of a subgroup of patients with severe postoperative pain is important for adequate pain management for enhanced, fast recovery after deep inferior epigastric artery perforator (DIEP) flap breast reconstruction. The purpose of this study was to identify factors influencing postoperative abdominal pain in patients undergoing DIEP flap breast reconstruction.

Consecutive patients who underwent unilateral breast reconstruction using DIEP free flaps from October 2018 to July 2020 were included in this study. Visual analog scale (VAS)-guided postoperative pain scores were documented every 3 hours until 48 hours postoperatively. Factors affecting patient-reported pain scores were analyzed using a linear mixed-effects model. Independent variables included patient characteristics, history of previous open abdominal surgery, and operative factors including the flap size, flap weight, use of a unipedicled or bipedicled flap, number of perforators, timing of reconstruction, and use of a catheter-based subcutaneous plane block in the abdomen. A catheter was placed above the rectus fascia during closure, and analgesics were continuously infused during the 48 hours using an ON-Q Pain Relief System (I-Flow Co., Lake Forest, CA, USA).

Fifty-five patients were included in the analysis. In the linear mixed effect model using multiple clinical variables, the harvested flap weight was significantly associated with the degree of pain (β coefficient =0.157, P=0.008). The pain degrees significantly decreased according to postoperative days (β coefficient =-0.649, P<0.001). The flap type (unipedicle or bipedicle), number of perforators, timing of reconstruction, and history of previous abdominal surgery did not influence pain degrees. The use of subcutaneous plane block did not affect the degree of pain or dose of analgesics used.

A larger flap weight is associated with an increased degree of pain in patients undergoing DIEP flap breast reconstructions. Vigorous pain management might be necessary when a large flap is elevated.