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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
408
At 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.
The Sixth Affiliated Hospital of Sun Yat-sen University
Guangzhou, Guangdong, China
RECRUITINGArea 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.
Time frame: 7 days postoperatively
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.
Time frame: 7 days postoperatively
Area Under the Curve (AUC) of the Numerical Rating Scale (NRS) for pain from 96 to 168 hours postoperatively (NRS-AUC96h-168h)
Time frame: 96 to 168 hours postoperatively
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.
Time frame: 7 days postoperatively
Postoperative 7-day cumulative consumption of all analgesic drugs (calculated as morphine equivalents)
Time frame: 7 days postoperatively
Postoperative 7-day cumulative consumption of rescue analgesic drugs (calculated as morphine equivalents)
Time frame: 7 days postoperatively
Safety (including incidence of postoperative adverse events and serious adverse events): Adverse events and serious adverse events occurring within 14 days after medication were assessed
Time frame: 14 days after medication were assessed
Postoperative heart rate monitoring: Heart rate at 24h, 48h, 72h, 96h, 120h, 144h, and 168h postoperatively.
Time frame: At 24, 48, 72, 96, 120, 144, and 168 hours postoperatively.
Postoperative blood pressure monitoring: systolic blood pressure, and diastolic blood pressure at 24h, 48h, 72h, 96h, 120h, 144h, and 168h postoperatively.
Time frame: At 24, 48, 72, 96, 120, 144, and 168 hours postoperatively.
SF-12 scores at preoperative, 1 week, 1 month, and 2 months postoperatively.
The 12-Item Short Form Health Survey (SF-12) is a widely used concise instrument developed by the Medical Outcomes Study (MOS) to assess an individual's health-related quality of life (HRQoL), derived as an abbreviated version of the SF-36 scale. Overall scores range from 0 to 100, with higher scores representing better health status.
Time frame: 1 week, 1 month, and 2 months postoperatively.
Preoperative, 14-day postoperative, and 1-month postoperative Wexner Incontinence Scores
The Wexner Incontinence score, also termed the Cleveland Clinic Fecal Incontinence Severity Scoring System (CCIS) is a fecal incontinence score from 0-20; where 0 is perfect continence and 20 is complete incontinence.
Time frame: Prior to surgery; 14 days after surgery; 1 month postoperatively.
Analgesia satisfaction: Postoperative analgesic satisfaction was assessed using a 5-point categorical scale at 24h, 96h, and 168h postoperatively.
The Postoperative Analgesia Satisfaction Scale is an investigator-developed instrument where participants select a number from 0 to 4 based on their subjective experience, with higher scores representing greater satisfaction.
Time frame: At 24, 96, and 168 hours postoperatively.
Wound healing rate within 8 weeks postoperatively.
Wound Healing Rate: The wound area on postoperative day 1 is defined as the initial wound area. Measure the maximum length and perpendicular width of the wound to calculate the wound area. Formula: Wound Healing Rate = \[(Initial Area - Current Area) / Initial Area\] × 100%.
Time frame: 8 weeks postoperatively
Wound healing time within 8 weeks postoperatively.
Wound Healing Time: The duration from initial dressing change until complete wound epithelialization is achieved.
Time frame: 8 weeks postoperatively
Wound Edema Score within 8 weeks postoperatively.
Wound Edema Scoring Criteria: 3 points: Severe edema with gross elevation beyond wound margins, requiring surgical intervention; 2 points: Significant edema extending beyond wound margins, managed with dressing changes; 1 point: Mild localized edema; 0 points: No detectable edema.
Time frame: 8 weeks postoperatively
Wound granulation tissue color score within 8 weeks postoperatively.
Granulation Tissue Color Scoring: 1. point: Bright red; 2. points: Pale red; 3. points: Purple.
Time frame: 8 weeks postoperatively.
Whether the wound is infected within 8 weeks postoperatively.
Time frame: 8 weeks postoperatively.
Whether the wound is bleeding within 8 weeks postoperatively.
Whether bleeding is present (none, oozing, active)
Time frame: 8 weeks postoperatively.
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