Negative pressure wound therapy (NPWT) is a non-invasive technique that employs negative pressure within a sealed suction system, applied to acute or chronic wounds, and promotes wound healing process through the elimination of exudate, mechanical contraction of wound edges, and stimulation of angiogenesis.

1. Negative Pressure
Wound Therapy in
Diabetic Foot Ulcer
Adhithya Mullath Ullas
MSc Diabetes
Assessment Number: J105851

2. Introduction
• Global diabetes prevalence exceeds 400 million
individuals, with approximately 15% of this population
expected to develop Diabetic Foot Ulcer (DFU) during
their lifetime (Cho et al., 2018).
• DFU encompass ulcers, infections and tissue damage
of the foot below the medial malleolus (Maranna et al.,
2021).
• Major impact on morbidity, mortality and quality of life
of patients as well as economic burden on society
(Maranna et al., 2021).
• Negative pressure wound therapy (NPWT) is a non-invasive technique that employs negative pressure
within a sealed suction system, applied to acute or chronic wounds, and promotes wound healing process
through the elimination of exudate, mechanical contraction of wound edges, and stimulation of
angiogenesis (Ari et al., 2023).

3. Pathogenesis of DFU
Main factors involved:
• Persistent hyperglycaemia
• Diabetic neuropathy
• Peripheral artery disease
• Local infection
(Ari et al., 2023).
Figure 1: The mechanisms of diabetic non-healing wound
development (Deng & Chen, 2022)

4. Mechanism of NPWT
Negative Pressure Wound Therapy (NPWT) is a biophysical tool with a mechanical apparatus linked to a
dressing via a plastic tube and, when connected to a suction device, this setup facilitates the generation of
sub-atmospheric pressure at the location of a wound (Nain et al., 2011).
• Wound perfusion → stimulates angiogenesis
• Increase growth factor expression – transforming
growth factor – β, pro-healing growth factors
Figure 2: NPWT diagram (Gilero, 2023) Figure 3: Mechanism of NPWT (Triage Meditech, 2020).

5. Components of Vacuum Assisted Closure therapy
A. Showing the polyurethane foam applied over the diabetic foot
ulcer.
B. Showing the canister into which the effluents from the wound
are collected.
C. VAC therapy unit from which a continuous negative pressure of
125 mm Hg was applied (Maranna et al., 2021)

6. Current Research on NPWT in DFU
DiaFu study (Seidel et al., 2020) Wu et al. (2023) Maranna et al. (2021)
To evaluate effectiveness and safety of
NPWT compared to standard moist
wound care in DFU in clinical practice.
To compare the efficacy of NPWT
and alginate dressings on wound
bed preparation prior to split
thickness skin graft (STSG) surgery
in chronic DFUs
To compare NPWT and conventional
saline dressings
in DFU healing
Adult patients (age >18 years);
chronic DFUs (≥ 4 weeks);
Wagner grade 2–4
Adult patients (age >18 years);
chronic DFU wounds (≥2 weeks),
ankle brachial index (ABI) 0.5~0.9,
wound area 8~20 cm2, Wagner
grade 2-3
Adult patients (age >18 years);
chronic DFU wounds (≥3 months),
Wagner 1-2; ulcer size 5-20cm

7. Methods
DiaFu study (Seidel et al., 2020) Wu et al. (2023) Maranna et al. (2021)
Patients underwent amputation,
debridement, or thorough wound
cleansing up to 6 hours before
randomization.
Wound Bed Preparation :
NPWT group: commercially available
CE-marked NPWT devices;
intermittent & continuous NPWT with
negative pressure adapted to dressing
type and wound needs.
Control Arm: any local wound
treatment standard except NPWT.
Follow-up – 6 months
Radical surgical debridement
→ antibiotics for infections / insulin
pumps for glycemic control →
offloading therapies.
Wound Bed Preparation :
NPWT group: Utilized Vacuum-
Assisted Closure (VAC) system with
specific protocols negative pressure
of -125 mmHg (continuous mode).
The VAC foams were changed once
every 72 hours (h)
Control group: Used alginate
dressings with fabric dressings
STSG surgery
Initial assessments/surgical
debridement
NPWT Group: VAC therapy -
Polyurethane foam applied, secured
airtight by the TRAC system,
continuous negative pressure of -125
mm Hg to the wound.
Dressings changed after 72 hours
with aseptic precautions.
Control group: normal saline-soaked
gauze dressing, changed daily with
aseptic precautions.
Follow-up – 3 months
TRAC- therapeutic regulated accurate care

8. Result | DiaFu study (Seidel et al., 2020)
Primary outcome:
• Wound closure within 16 weeks – no significant difference
(difference: n=4 (2.5% (95% CI−4.7% – 9.7%); p=0.53))
• NPWT group completed treatment in a shorter duration
compared to SMWC (33.3±25.0 days vs. 40.0±25.5 days).
Secondary Outcomes:
• Recurrence rate after complete wound closure was slightly
higher for NPWT (4.0%) compared to SMWC (0%), but the
difference was not significant.
• After 6 months, the number of participants with closed wounds
was higher in the SMWC arm (20.7% vs. 14.0%),
but the difference was not significant.
Safety:
• Incidence of Adverse Events (AEs) in the NPWT arm compared to
SMWC - 56.1% vs. 41.4%. No significant difference in Serious
Adverse Events (SAEs) between
the treatment arms.
Figure 4: Time until complete, sustained and verified
wound closure in the ITT population. NPWT, negative
pressure wound therapy; SMWC, standard moist wound
care.

9. Result | Wu et al. (2023)
• NPWT group had a shorter time to STSG surgery compared to the
control group (mean days: 7.2 vs. 13.6, p=2.2×10^-24).
• NPWT group had significantly reduced hospital days compared to
the control group (mean days: 15.0 vs. 24.1, p=1.2×10^-53).
• Skin graft survival rate was 100% in the NPWT group and 76% in
the control group (mean difference: 24%, p=3.1×10^-19).
• NPWT group showed a significantly reduced number of
Neutrophil Extracellular Traps (NETs) compared to the control
group.
• NPWT group exhibited a shift from M1 to M2 macrophage
phenotypes.
Safety:
• Incidence of Adverse Events (AEs) in the NPWT arm compared to
SMWC - 56.1% vs. 41.4%. No significant difference in Serious
Adverse Events (SAEs) between
the treatment arms.
Figure 5: Kaplan‒Meier plot demonstrated that
patients in the NPWT group had less time to STSG
surgery. X axis: time to STSG surgery (day), Y axis:
cumulative event.

10. Result | Maranna et al. (2021)
Figure 6. Graph showing the change in ulcer size
(cm2) between the two groups on day 1 and day 14.
X-axis depicting size of the ulcer (cm2) and Y-axis
showing time period (days). The mean size of ulcers
after NPWT was 29 cm2 and after conventional
dressings was 37.57 cm2 and was statistically
significant (p = 0.037).
NPWT Group
Conventional saline
dressing group
Reduction in Ulcer Size by
Day 14
40.78 ± 10.12%
(p = 0.008)
21.18 ± 7.11%
Granulation Tissue
Formation on Day 14
91.14 ± 6.53%
(p < 0.001)
52.61 ± 9.64%
Time for 100% Granulation
Tissue Formation
14.82 ± 7.30 days
(p < 0.001)
44.57 ± 9.29 days
Duration of Hospital Stay
15.68 ± 2.02 days
(p < 0.001)
29.00 ± 7.11 days
Complete Healing at
3 Months
90.9% 26.1%

11. Conclusion
• The DiaFu study did not support the use of NPWT in patients with ischemic Diabetic Foot Ulcers
(DFUs) based on the lack of significant differences in primary and secondary outcomes. The
results may not be applicable to non-ischemic DFUs (Seidel et al., 2020).
• According to Wu et al. (2023), for patients with chronic DFUs, NPWT outperforms conventional
moist dressings in wound bed preparation prior to STSG surgery.
• According to Maranna et al. (2021), NPWT led to early reduction in ulcer size, more granulation
tissue formation, shorter hospital stay and complete wound healing. In lower- and middle-
income countries like India with high prevalence of DFUs, early recovery is beneficial to the
patients to resume their daily activities.
• For Wagner 1-2 DFU if appropriate care is given at the right time, progression can be prevented.
• NPWT showed a significant superiority in optimal wound bed preparation compared to
conventional methods.

12. References
Ari, D., Zaenal Muttaqien Sofro, Heny Suseani Pangastuti, & Ishandono Dachlan. (2023). The Efficacy of Negative Pressure Wound Therapy (NPWT) on Healing of Diabetic Foot Ulcers:
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and projections for 2045. Diabetes Research and Clinical Practice, 138(1), 271–281. https://doi.org/10.1016/j.diabres.2018.02.023
Deng, H., & Chen, Y. (2022). The role of adipose-derived stem cells-derived extracellular vesicles in the treatment of diabetic foot ulcer: Trends and prospects. Frontiers in Endocrinology,
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Gilero. (2023, December 15). Negative Pressure Wound Therapy (NPWT) Device - Gilero. Gilero. https://www.gilero.com/case-study/negative-pressure-wound-therapy-npwt-device/
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