Combination Therapy of Vacuum Sealing Drainage and Counter-Current Irrigation for Refractory Perianal Wounds

Summary

This prospective clinical study evaluated the efficacy of closed negative-pressure antegrade irrigation and drainage (a vacuum-sealing drainage-based combination therapy) in the management of refractory perianal wounds. The primary goals were to improve wound drainage, alleviate postoperative pain, and accelerate healing time.

Abstract

Perianal refractory wounds refer to long-term non-healing wounds of the skin and soft tissues surrounding the anus, often resulting from surgery or complications of chronic diseases. Current treatment mainly focuses on maintaining an open wound environment and allowing healing to follow its natural course. Due to the specific anatomical location, susceptibility to secondary infection, and the local wound environment, healing often requires more than 4 weeks. Vacuum-sealed drainage (VSD), combined with counter-current irrigation technology, has been widely adopted and demonstrated significant efficacy in specialties such as burn and plastic surgery, orthopedics, and general surgery. This non-invasive negative-pressure technology offers new approaches for treating refractory perianal wounds, promoting active intervention in the healing process, accelerating healing speed, improving healing quality, and reducing patient discomfort. This article describes the management and application details of this technology for refractory perianal wounds, including methods of outer-film application at different positions, differences in negative-pressure settings based on wound distance from the anal margin, and strategies to avoid secondary contamination. This methodology may facilitate broader clinical adoption of VSD for perianal refractory wounds and presents new therapeutic opportunities for managing such challenging non-healing wounds.

Introduction

Refractory wounds are generally defined as those that fail to heal after more than four weeks of standardized treatment due to various external or internal factors¹. The perianal region presents unique anatomical challenges, making postoperative wounds difficult to keep clean and dry. These conditions often perpetuate the inflammatory phase, leading to chronic low-grade inflammation and delayed healing². Perianal refractory wounds are characterized by prolonged treatment cycles, high recurrence rates, significant healthcare costs, and considerable physical and psychological burdens for patients³. Conventional oral and topical pharmacotherapies frequently yield unsatisfactory outcomes. Therefore, the development of safe and efficient treatment strategies is a current research priority.

Conventional wound healing results from a coordinated interplay of cells, growth factors, structural proteins, and proteolytic enzymes. The process is typically divided into three overlapping phases: inflammatory, proliferative, and tissue remodeling^4,5,6. The inflammatory phase initiates immediately after injury, where cellular and vascular responses act to clear necrotic tissue and foreign material. This phase is marked by increased capillary permeability, leukocyte infiltration, platelet adhesion, and the release of growth factors and bioactive substances, which collectively stimulate fibroblast activity and transition to the proliferative phase⁷. Fibroblasts synthesize essential components for healing, such as glycosaminoglycans (GAG) and collagen. GAG is a crucial element of the extracellular matrix, facilitating collagen deposition and aggregation⁸. Collagen content is positively correlated with wound tensile strength. If fibroblasts remain in a state of replication and migration without sufficient collagen synthesis, wound strength is compromised, and healing stagnates. When collagen degradation and synthesis reach equilibrium, the wound enters the remodeling phase. Chronic wound healing also involves granulation tissue formation and wound contraction, which reduces wound area but may disrupt structural integrity if disorganized¹⁰. As healing progresses, granulation tissue undergoes cellular and vascular changes, with superfluous cells removed via apoptosis. Delayed apoptosis can result in excessive scarring^5,6,10.

The pathogenesis of perianal refractory wounds follows these general principles but is further complicated by unique physiological and local environmental factors, resulting in a more complex healing mechanism^11,12,13. Additional factors impairing perianal wound healing include high bacterial load, persistent infection, residual necrotic tissue, inadequate tissue perfusion, reperfusion injury, malnutrition, and bacterial biofilm formation^14,15. The perianal area is particularly susceptible because postoperative wounds are often open and contiguous with the anal canal. The loose surrounding soft tissue and interconnected potential spaces facilitate infection spread¹⁶. Postoperative exudate and necrotic tissue provide an ideal medium for bacterial proliferation, increasing infection risk. Inadequate initial debridement may leave necrotic material that forms a fibrin network, sequestering growth factors and impeding healing¹⁷. Bacterial overgrowth prolongs inflammation through the release of inflammatory toxins and proteases, exacerbating tissue necrosis¹⁸. Poor tissue perfusion contributes to ischemia, hypoxia, metabolite accumulation, and impaired neutrophil function, all of which delay healing¹⁹. Tissue regeneration requires adequate nutrition; deficiencies in protein, trace elements, and energy due to poor perfusion can prolong the healing process. Malnutrition not only compromises the patient's systemic condition but also predisposes acute wounds to chronicity²⁰. Bacterial biofilm-structured communities of bacteria embedded in an extracellular matrix mixed with necrotic tissue protect bacteria from antibiotics and host defenses, leading to clinical signs such as redness, swelling, heat, pain, and local tissue hypoxia²¹.

Traditional management of perianal refractory wounds emphasizes thorough debridement, maintaining an open wound, ensuring adequate drainage, and treating underlying conditions. Advances in the understanding of wound healing pathophysiology, coupled with the development of novel biomaterials and technologies, have enabled more effective and targeted therapies aimed at shortening healing time and improving outcomes²².

Modern wound dressings address limitations of traditional gauze. For instance, silver-ion dressings containing sodium carboxymethyl cellulose utilize silver ions to disrupt bacterial cell walls, providing broad-spectrum antibacterial or bactericidal effects²³. Advanced nanomaterials like nano-silver dressings or nano-hydrogels demonstrate enhanced bacterial clearance, reduced post-healing scarring, and potential for delivering reparative cells, offering greater therapeutic promise^24,25,26. These advanced dressings are particularly considered for wounds with high exudate or signs of local infection.

Clinical investigation into biological products for perianal refractory wounds is ongoing, with platelet-rich plasma (PRP) and adipose-derived stem cells (ADSCs) being prominent examples²⁷. Autologous PRP, prepared by centrifuging fresh whole blood, is enriched with platelets, fibrin, and bioactive factors that can inhibit inflammation and accelerate healing²⁸. As an autologous product, PRP minimizes immunogenic reactions. ADSC therapy for refractory wounds is increasingly reported²⁹. While stem cells hold significant regenerative potential, challenges related to cell sourcing, characterization, cultivation protocols, regulatory approval, and ethical considerations remain³⁰. These biological therapies are often explored for complex cases, such as wounds that fail conventional care or those associated with systemic conditions like diabetes.

Surgical advancements for refractory perianal wounds include techniques such as vacuum sealing drainage (VSD) and flap transfer³¹. VSD applies controlled negative pressure to the wound, isolating it from the external environment while actively removing necrotic material and exudate. This helps prevent secondary infection and biofilm formation^32,33,34, thereby promoting granulation tissue growth and accelerating healing. VSD is especially suited for large (>15 cm²), exudating wounds or those with irregular cavities, where traditional dressing management is challenging. Although VSD has a well-established history in managing various wound types, its application specifically for perianal wounds is less frequently documented. This study adapted and refined VSD techniques for the perianal region and herein summarizes the key application principles.

Protocol

This study protocol was approved by the Ethics Review Committee of Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine (Approval No. KY2018039). All participants provided written informed consent prior to enrollment. Details of the materials used are mentioned in the Table of Materials.

1. Patient selection

1. Inclusion criteria
   1. Diagnosis of a severe perianal or perineal wound, including high-complex anal fistula (suprasphincteric or extrasphincteric types per the Parks classification) or perineal necrotizing fasciitis.
   2. Absence of significant abnormalities in routine preoperative examinations (e.g., complete blood count, coagulation profile, electrocardiogram) and no uncontrolled major comorbidities (e.g., cardiovascular, cerebrovascular, or hematologic diseases).
   3. Presence of a postoperative open wound with a surface area exceeding 15 cm², confirmed by measurement using a sterile ruler.
   4. Provision of signed informed consent for the described technique and treatment regimen, coupled with expressed willingness to comply with scheduled follow-up assessments.
2. Exclusion criteria
   1. Wounds anatomically unsuitable for negative pressure wound therapy (NPWT), including wounds in direct proximity to major unprotected blood vessels or nerves, or wounds with exposed organs or communication with the peritoneal cavity.
   2. Presence of severe systemic conditions: active malignancy, chronic use of therapeutic anticoagulants (e.g., warfarin, direct oral anticoagulants), diagnosed hematologic disorders, or severe hepatic/renal dysfunction (e.g., Child-Pugh class C or eGFR < 30 mL/min/1.73 m²).
   3. Perianal/perineal lesions of specific etiologies such as confirmed tuberculous infection or active inflammatory bowel disease (e.g., Crohn's disease flare).
   4. Pregnancy or lactation.
   5. Documented psychiatric disorder impairing legal capacity to provide consent.
3. Discontinuation criteria
   1. Occurrence of NPWT-related complications necessitating device removal: active bleeding not controlled by pressure, signs of progressive systemic infection (e.g., worsening sepsis), extensive contact dermatitis or skin necrosis related to the dressing materials, or severe pain intolerance.
   2. Voluntary patient withdrawal or non-compliance with the prescribed treatment protocol.

2. Combined negative pressure and countercurrent irrigation procedure

1. Preoperative preparation
   1. For wounds communicating with the anorectum, implement a full mechanical bowel preparation (e.g., polyethylene glycol solution) one day prior to surgery.
   2. Establish intravenous access. Institute fasting for a minimum of 8 h preoperatively for solids and 2 h for clear fluids.
   3. Consider a diverting colostomy in cases of extensive contamination to protect the postoperative wound field. This decision should be made preoperatively by the surgical team.
2. Anesthesia and positioning
   1. Administer a subarachnoid block (spinal anesthesia) as the primary anesthetic technique.
   2. Position the patient in the prone jackknife, lithotomy, or lateral decubitus position based on the precise location and extent of the perianal lesion.
   3. Provide supplemental intravenous sedation (e.g., midazolam, propofol infusion) for patients experiencing intraoperative anxiety.
3. Stepwise operative procedure
   1. Step 1: Preoperative skin preparation
      1. Shave all hair from the perineal and perianal region, extending at least 20 cm beyond the anticipated wound margins.
      2. Thoroughly cleanse the shaved skin with 75% ethanol-soaked gauze to remove cutaneous oils and sweat.
      3. Follow with standard surgical disinfection using 10% povidone-iodine solution, applied in concentric circles from the wound periphery outward.
         NOTE: The prepared skin should be completely hair-free, dry, and free of oily residue to ensure subsequent airtight adhesion of the drape.
   2. Step 2: Surgical debridement and hemostasis
      1. Perform radical debridement to excise all non-viable, necrotic tissue. Explore interconnected tissue planes and spaces using blunt dissection.
      2. Preserve functionally critical structures (e.g., external anal sphincter fibers, testicular tissue). Immediately cover exposed viable structures with moist saline gauze.
      3. Achieve complete hemostasis. Use precise suture ligation (e.g., 3-0 or 4-0 absorbable suture) for bleeding points within muscle or deep tissue. Minimize the use of electrocautery in highly vascular areas to reduce the risk of delayed hemorrhage.
      4. Irrigate the wound cavity copiously with warm sterile 0.9% saline solution (minimum 1000 mL) until the effluent is clear.
         NOTE: The wound bed should consist entirely of viable, bleeding tissue with no active bleeding points.
   3. Step 3: NPWT device configuration and placement
      1. Trim a sterile, open-cell polyurethane foam dressing to conform precisely to the three-dimensional geometry of the wound cavity. Avoid overpacking.
      2. Fenestrate a dedicated irrigation tube (e.g., 8 Fr Nelaton catheter) along its distal 5-7 cm segment.
      3. Position this tube beneath the foam dressing, ensuring the fenestrated segment lies within the wound cavity.
      4. Place a single, non-fenestrated silicone drainage tube connected to the NPWT pump on top of the foam.
      5. Apply a transparent, adhesive polyurethane film drape over the entire construct.
      6. Extend the drape a minimum of 5 cm onto intact, dry surrounding skin in all directions.
      7. Smooth out all wrinkles and creases by hand to eliminate channels for air leaks.
         NOTE: Apply manual negative pressure (e.g., using a 60 mL syringe) to the drainage tube. The film should depress uniformly against the foam, and the system should hold suction for at least 15 s, confirming an airtight seal.
   4. Step 4: Initiation of combined therapy
      1. Connect the drainage tube to a programmable NPWT pump capable of intermittent or continuous suction modes.
      2. Set the negative pressure parameters based on wound location: 100-120 mmHg for anterior perineal and scrotal regions; up to 150 mmHg for perianal and gluteal regions. Initiate therapy in continuous mode.
      3. Connect the irrigation tube to a separate infusion line. Administer the irrigation solution (typically 0.9% saline or a prescribed antiseptic solution) as a **slow, continuous trickle at a rate of 10-20 mL/h, or as intermittent boluses of 50-100 mL every 4-6 h, depending on exudate viscosity.
         NOTE: Within the first hour, confirm effective operation: the foam should remain collapsed under the film, and fluid should be visibly moving into the drainage canister. No persistent air leak alarms should be active on the pump.
4. Postoperative management and monitoring
   1. Maintain systemic antibiotic therapy based on preoperative wound culture and sensitivity results.
   2. Aggressively manage underlying comorbidities (e.g., glycemic control in diabetics, blood pressure stabilization).
   3. Inspect the NPWT system at least every 8 h. Document: 1) integrity of the airtight seal, 2) patency and character of effluent in the drainage tubing, 3) pump function and pressure setting, and 4) condition of the peri-wound skin.
   4. Change the entire NPWT dressing (foam, tubes, drape) every 72 to 96 h, or sooner if the canister is full, a leak occurs, or clinical signs of infection worsen.
      NOTE: During each change, assess wound progress. Healthy granulation tissue appears pink/red, beefy, and fills the wound bed from the base upwards.
5. Termination of NPWT and secondary healing
   1. Discontinue NPWT when the wound cavity is shallow (<1 cm depth) and uniformly covered with healthy granulation tissue, with minimal exudate and no signs of infection.
   2. For large wounds with robust granulation, proceed to secondary surgical closure (e.g., split-thickness skin grafting, local flap advancement) promptly after NPWT cessation to expedite final healing.
6. Precautions and discontinuation
   1. Discontinue NPWT immediately and reassess the patient if any of the following occur:
      1. Active, fresh bleeding through the tubing.
      2. Clinical deterioration suggestive of spreading infection (increased pain, erythema, fever, purulent discharge).
      3. Failure to maintain target negative pressure due to an unsealable leak, tube blockage, or pump malfunction.
      4. Evidence of significant skin maceration, erosion, or new necrosis at the dressing periphery.
      5. Patient reports severe, uncontrolled pain attributed to the therapy.

Results

This clinical study evaluated closed negative pressure antegrade irrigation-drainage for refractory perianal wounds. Forty patients were randomized into an experimental group (NPWT, n = 20) and a control group (conventional care, n = 20).

Postoperative wound exudate volume
Postoperative drainage showed a clear improvement trend in the experimental group, with exudate volume significantly reduced from day 7 onward (Figure 1), indicating more ef...

Discussion

This randomized controlled trial demonstrates that a combined regimen of VSD with countercurrent irrigation significantly accelerates healing, reduces wound exudate, and alleviates pain in patients with refractory perianal wounds compared to conventional dressing changes. The findings corroborate and extend the growing body of evidence supporting active management of the wound environment in complex surgical sites.

Our primary finding -- a reduction in median healing time by approximately 14 d...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Enclosed Injection-Suction Vacuum Circle IVC Technology	Guangdong Meijie Weitong Biotechnology Co., Ltd.	MJ-03c	None