Anal Fistula refers to an abnormal infectious fistula tract between the anorectum and the perianal skin. The prevalence of anal fistula is approximately 8.6 cases per 100,000 individuals. It can occur at any age but is relatively more common in individuals aged 20-40 years, with a higher incidence in males than females.
Postoperative wound management is a critical component of the overall treatment for anal fistula patients. Regular postoperative wound care, such as dressing changes, can reduce recurrence rates, alleviate pain, and shorten hospitalization time. However, postoperative pain remains a major challenge in wound management following anal fistula surgery. This is largely attributed to inadequate current postoperative analgesic protocols.
With ongoing advancements in local anesthetics, liposomal bupivacaine has been applied for postoperative analgesia. It offers higher bioavailability and a prolonged half-life, providing up to 72 hours of sustained analgesic effect. Given the limitations of existing analgesic strategies for post-anal fistula surgery, developing more effective pain management approaches to reduce postoperative pain holds significant clinical importance.
Therefore, the investigators propose that a repeat-dosing strategy based on liposomal bupivacaine may provide superior postoperative pain control for anal fistula patients. To investigate this, the investigators designed a prospective, multicenter, randomized, open-label, controlled clinical trial. This study aims to evaluate the efficacy and safety of repeat-dose liposomal bupivacaine for postoperative analgesia following anal fistula surgery, thereby generating high-level evidence to support its clinical application in this context.
Diagnosed with anal fistula and scheduled to undergo anal fistula surgery;
Aged between 18 and 60 years;
ASA (American Society of Anesthesiologists) physical status class I-II;
Patient provides written informed consent after understanding the study protocol.
Anal fistula caused by specific etiologies (e.g., tuberculosis);
Concurrent acute perianal skin infection;
Poorly controlled diabetes (HbA1c >9%);
Chronic use of corticosteroids;
Parallel
A single dose of liposomal bupivacaine is administered at the conclusion of surgery without adjunctive analgesics, followed by a supplemental dose 72 hours postoperatively.
DrugAt surgical closure, a single dose of undiluted liposomal bupivacaine (266 mg/20 mL) is administered without concurrent analgesics. The total 20 mL volume is divided into six equal aliquots (≈3.3 mL each) and infiltrated circumferentially around the incision using a 25-gauge or larger-bore needle. Injections target tissue layers above and below the fascia and within the subcutaneous plane, with frequent aspiration during administration to mitigate intravascular injection risk. Seventy-two hours postoperatively, a repeat dose of undiluted liposomal bupivacaine (266 mg/20 mL) is administered. Prior to infiltration, topical lidocaine cream is applied to the per-incisional skin for ≥20 minutes. The full 20 mL volume is then injected uniformly around the incision via circumferential needle advancement into pericicatricial tissues.
Area Under the Curve (AUC) of the Numerical Rating Scale (NRS) for pain within 7 Days postoperatively (NRS-AUC0-168h)
Numerical rating scale, a numerical rating scale where participants select a number from 0 to 10 based on their subjective pain experience. On this scale: 0 represents no pain; 10 represents the most severe pain imaginable.
Numerical Rating Scale (NRS) for pain during wound dressing changes within 7 days postoperatively
Numerical rating scale, a numerical rating scale where participants select a number from 0 to 10 based on their subjective pain experience. On this scale: 0 represents no pain; 10 represents the most severe pain imaginable.
Area Under the Curve (AUC) of the Numerical Rating Scale (NRS) for pain from 96 to 168 hours postoperatively (NRS-AUC96h-168h)
Number of breakthrough pain episodes and corresponding Numerical Rating Scale (NRS) scores during episodes
Numerical rating scale, a numerical rating scale where participants select a number from 0 to 10 based on their subjective pain experience. On this scale: 0 represents no pain; 10 represents the most severe pain imaginable.
Postoperative 7-day cumulative consumption of all analgesic drugs (calculated as morphine equivalents)
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Sixth Affiliated Hospital, Sun Yat-sen University
Lead sponsor
The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine
Collaborator
Maoming People's Hospital
Collaborator
Dongguan Hospital of Traditional Chinese Medicine
Collaborator
Xingyi People's Hospital
Collaborator
Nanjing Hospital of C. M.
Collaborator
People's Hospital of Xinjiang Uygur Autonomous Region
Collaborator
