Wound management remains a significant clinical challenge, particularly in patients with chronic ulcers, surgical wounds, and traumatic injuries. Delayed wound healing can lead to severe complications, including infections, prolonged hospitalization, and increased healthcare costs.¹ Among the advanced wound care modalities, Negative Pressure Wound Therapy (NPWT) has emerged as a widely adopted intervention due to its ability to accelerate healing through mechanical and biological mechanisms.

NPWT applies controlled sub-atmospheric pressure to the wound bed, facilitating fluid removal, reducing edema, and promoting granulation tissue formation.² The therapy also enhances local blood flow and exerts mechanical forces that stimulate cell proliferation, contributing to faster wound contraction.³ Originally developed for complex and non-healing wounds, NPWT is now used in various clinical settings, including diabetic foot ulcers, pressure injuries, and post-operative wound complications.

Despite its widespread adoption, the evidence on NPWT's efficacy varies across different wound types and patient populations. While large-scale randomized controlled trials (RCTs) have demonstrated its benefits, smaller studies have reported inconsistent outcomes, particularly regarding infection control and time to complete healing.⁴ Additionally, most existing research focuses on specific wound etiologies, leaving gaps in understanding its effectiveness across diverse wound presentations.

This study aims to evaluate the efficacy of NPWT in patients with acute and chronic wounds, assessing key outcomes such as wound size reduction, infection rates, and granulation tissue formation. By analyzing a heterogeneous group of wound types, this research provides insights into the broader applicability of NPWT in real-world clinical settings. The findings will contribute to the growing body of evidence supporting NPWT while addressing variability in smaller patient cohorts.

Methodology

Research Design, setting

This comparative pre & post intervention study evaluated the efficacy of NPWT in wound healing. Patients receiving NPWT were monitored over 12 weeks, with periodic assessments of wound progression, infection rates, and healing outcomes.  The study was conducted at Birpara State General Hospital.

Inclusion Criteria

• Wound size ≥2 cm²
• Duration of wound >4 weeks
• Adequate tissue perfusion (ABI ≥0.6)
• Informed consent provided

Exclusion Criteria

• Active systemic infection (e.g., sepsis)
• Non-compliance with NPWT protocols
• Allergy to NPWT dressing components
• Life expectancy <6 months (palliative care)

Sample Size Calculation

The sample size (*n* = 88) was determined using G*Power 3.1, based on:

• Effect size: 0.35 (derived from prior NPWT studies with wound size reduction as the primary outcome).
• Power: 80% (β = 0.20).
• Significance level (α): 0.05.
• Attrition rate: 10% (final target = 88 analyzable cases).

Procedure for Data Collection

Baseline Assessment:

• Wound dimensions (length × width × depth).
• Photographic documentation + microbiological swabs.
• Comorbidity profiling (HbA1c, ABI, nutritional status).

Intervention:

• NPWT applied per manufacturer guidelines; dressings changed every 48–72 hours.

Follow-Up:

• Weekly evaluations for 12 weeks:
• Wound measurement (digital planimetry).
• Infection screening (clinical signs + cultures).
• Pain assessment (VAS).

Statistical Analysis:

Collected in a structured proforma and entered into Microsoft Excel. Continuous variables (wound size, pain scores): Paired *t*-tests. Categorical variables (infection rates): Chi-square/Fisher’s exact test. Significance threshold: *p* < 0.05 (SPSS v26).

Table 1: Baseline Demographic and Clinical Characteristics of Participants (N=88)

The study enrolled 88 patients (mean age: 58.4 ± 12.3 years; 59.1% male). Diabetic ulcers (42%) and pressure injuries (28%) were the most common wound types, with a mean wound duration of 6.2 ± 3.1 weeks. Comorbidities included diabetes mellitus (70.5%), hypertension (51.1%), and peripheral artery disease (33%).

Table 2: Primary Outcomes of NPWT Over 12 Weeks

NPWT significantly reduced wound size by 65% (8.5 ± 4.2 cm² to 3.0 ± 1.8 cm²; *p* < 0.001), with complete closure achieved in 45.5% of cases. Granulation tissue formation increased from 13.6% at baseline to 78.4% at Week 12 (*p* < 0.001).

Table 3: Secondary Outcomes: Infection and Pain Scores

Infection rates declined from 34.1% to 12.5% post-NPWT (*p* = 0.002). Patient-reported pain scores improved markedly (VAS: 6.2 ± 1.5 to 2.8 ± 1.2; *p* < 0.001).

Table 4: Subgroup Analysis by Wound Type

*p < 0.05

Surgical wounds showed the highest size reduction (70.1 ± 9.5%; *p* < 0.05 vs. other types) and infection resolution (88.9%). Traumatic wounds had the highest granulation rate (87.5%).

Discussion

The present study demonstrated significant improvement in wound healing parameters with NPWT, showing a 65% reduction in wound size and complete wound closure in 45.5% of cases within 12 weeks. These findings strongly support the growing body of evidence on NPWT's effectiveness. Our results are particularly noteworthy when compared to the landmark V.A.C. Therapy Clinical Guidelines⁵ which reported similar wound size reductions of 60-70% in complex wounds. The consistency between our findings and larger studies suggests that NPWT delivers reliable outcomes even in smaller, more diverse patient cohorts. Notably, our granulation tissue formation rate of 78.4% exceeds the 50-60% rates typically reported with conventional moist wound therapy⁶, highlighting NPWT's superior ability to promote tissue regeneration.

When examining infection control, our data showed a remarkable 63.6% reduction in wound infections post-NPWT. This aligns closely with findings from Armstrong et al.⁷ who documented a 58% decrease in infection rates among diabetic foot ulcer patients receiving NPWT. However, our infection resolution rates were slightly better (12.5% vs 15% in Armstrong's study), possibly due to our standardized dressing change protocol every 48-72 hours. The pain reduction outcomes (VAS scores decreasing from 6.2 to 2.8) were particularly striking and more pronounced than those reported by Liu et al.⁸ in their meta-analysis, where average pain reduction was only 2.5 points on the VAS scale. This difference may be attributed to our institution's comprehensive pain management protocol used alongside NPWT.

The subgroup analysis revealed important variations in treatment response. Surgical wounds showed the best outcomes with 70.1% size reduction and 88.9% infection resolution, supporting the findings of Kim et al.⁹ who reported superior NPWT results in post-operative wounds. However, our diabetic ulcer subgroup, while showing good response (58.3% reduction), had slightly lower outcomes than pressure injuries (62.4%). This contrasts with Blume et al.¹⁰ findings where diabetic ulcers responded equally well, suggesting that our patient population may have had more advanced disease at baseline. These variations emphasize the need for tailored NPWT protocols based on wound etiology and patient comorbidities.

The superior performance of NPWT in our study can be attributed to its multifaceted mechanism of action. The constant negative pressure not only removes exudate and reduces edema but also promotes angiogenesis through mechanical stress on wound bed microvasculature, as demonstrated in experimental studies by Huang et al.¹¹ This explains the robust granulation tissue formation we observed. Additionally, the closed wound environment created by NPWT dressings likely contributed to our impressive infection control rates by preventing bacterial contamination, supporting the "barrier hypothesis" proposed by Orgill and Bayer.¹²

While our results are encouraging, several limitations must be acknowledged. The single-arm design prevents direct comparison with standard therapies, and our 12-week follow-up may not capture long-term recurrence rates. Future studies should incorporate randomized controlled designs with longer follow-up periods. Additionally, cost-effectiveness analysis was beyond our scope but would be valuable for healthcare policy decisions. Emerging technologies like single-use NPWT systems warrant investigation as potential alternatives to traditional systems.

Conclusion
This study strengthens the evidence base for NPWT as an effective treatment modality for complex wounds. Our findings, consistent with larger trials yet providing novel insights into smaller cohort dynamics, support the wider adoption of NPWT in clinical practice. The therapy's ability to accelerate healing, control infection, and reduce pain makes it particularly valuable for challenging wound cases. Future research should focus on optimizing protocols for specific wound types and expanding access to this beneficial technology.

References

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