Inguinal pain syndrome. The influence of intraoperative local administration of 0.5% bupivacaine on postoperative pain control following Lichtenstein hernioplasty. A prospective case-control study.

Abstract

During the period between December 2015 and May 2016, 133 patients with preoperative diagnosis of an inguinal (81.95%, n=109), scrotal (13.53%, n=18) or recurrent hernia (4.51%, n=6) underwent an elective intervention and were randomly allocated to the group, which intraoperatively received 20 mL of 0.5% bupivacaine locally in selected anatomical points of the inguinal canal. In the group with preoperative diagnosis of an inguinal hernia, this intervention was applied in 56.88% of cases (n=62). In the case of scrotal or recurrent hernia, a similar intervention was applied in 41.67% (n=10) of patients. During the hospital stay, pain was assessed four times a day using the NRS numeric scale. All patients received preoperative antibiotic prophylaxis, and, during observation, analgesics and low-molecular-weight heparin were used. In the studied group, risk factor were identified, which affect the pain level associated with surgical treatment of an inguinal hernia. Mean pain level score according to the NRS scale (0-10) for an inguinal hernia was 4.17 on day 0 (standard deviation 2.22; minimum 0; maximum 10). On day 1 - 2.86 (standard deviation 1.86; minimum 0; maximum 8). On day 2 - 0.84 (standard deviation 1.21; minimum 0; maximum 5). The values of those parameters for a scrotal and recurrent hernia were as follows: on day 0 - 3.67 (standard deviation 1.76; minimum 0; maximum 7). On day 1 - 3.79 (standard deviation 1.67; minimum 0; maximum 7). On day 2 - 2.25 (standard deviation 1.54; minimum 0; maximum 4). Intraoperative application of 20 mL 0.5% bupivacaine did not reduce the postoperative pain on the postoperative day 0, 1, 2. Among independent risk factors exacerbating pain, the following variables were identified: local complications of the operated site including edema, ecchymosis and hematoma of the inguinal region. More frequent dressing changes were directly correlated with an increased pain sensation. Postoperative urethral catheterization due to urinary retention was associated with an increased pain immediately after surgery. In the case of intraoperative diagnosis of concurrent direct and indirect hernia (so-called pantaloon hernia), less intense pain was observed on postoperative day 0. Other parameters such as age, sex, duration of operation, duration of hospitalization and wound drainage did not influence the pain sensation. Local injection of an analgesic into the operated site was not associated with the reduction of pain assessed on postoperative day 0, 1 and 2 after an isolated inguinal, scrotal or recurrent hernia repair. Pathologies of the operated site such as edema, ecchymosis or hematoma were associated with an increased pain sensations on observation. Also, postoperative urinary retention and urethral catheterization increased the pain sensation after an inguinal hernia repair. A lack of wound complications significantly decreased the pain sensation during the immediate postoperative period after hernia repair.