Hydromechanical Debridement With NPWTi-d for Limb Salvage
Medical education note: This article is for healthcare professionals and not a substitute for device IFUs or clinical judgment.
Overview
Lower-extremity ulcers in patients with diabetes are difficult to heal because of neuropathy, ischemia, infection, and necrotic tissue; they carry a high risk of lower-extremity amputation when not optimally treated. Large reviews estimate that 50–60% of diabetic foot ulcers (DFUs) become infected and that a substantial proportion of these infections progress to major amputation if not controlled. (1,2)
A recent case series by Alonso and colleagues describes the use of Negative Pressure Wound Therapy with Instillation and Dwell (NPWTi-d) using hypochlorous acid (HOCl) instilled through a reticulated open-cell foam dressing with through-holes (ROCF-CC) as an adjunctive limb-salvage strategy for complex diabetic lower-extremity ulcers. In this protocol, NPWTi-d was integrated into a structured diabetic limb-salvage pathway rather than used in isolation. (3,4)
Study Snapshot
(Patients A, B and B on right, initial visits)
This case series was conducted as part of a hospital-based diabetic limb-salvage protocol in which three patients with diabetes and nine complex lower-extremity ulcers were treated with NPWTi-d and HOCl via ROCF-CC. The limb-salvage protocol also included glycemic control, offloading, revascularization when indicated, nutritional support, smoking cessation, systemic antibiotics, and sharp debridement. (3,5)
Following sharp surgical debridement, NPWTi-d was applied using a ROCF-CC dressing. Settings included instillation of hypochlorous acid every 2–3.5 hours, a dwell time of 10–20 minutes, continuous negative pressure at −125 mmHg, and dressing changes three times per week. These parameters are consistent with published NPWTi-d protocols using ROCF-CC in complex wounds. (3,6)
At each dressing change, the team used non-contact real-time fluorescence wound imaging to visualize regions of high bacterial load and non-contact near-infrared spectroscopy (NIRS) to measure perfusion/oxygenation (StO₂) in and around the wound. This combined imaging approach is supported by growing evidence showing that fluorescence imaging improves detection of clinically significant bacterial burden in DFUs and that NIRS can non-invasively quantify tissue oxygenation in ischemic wounds. (7,8)
Results: Fast Conversion, Zero Amputations
(Patient B Re-epithelialized after 18 weeks)
At baseline, wound volumes ranged from 4.6 to 49.2 cm³, with nonviable tissue covering between 15% and 100% of the wound surface. (3)
Under NPWTi-d with HOCl and ROCF-CC, all nine wounds converted to at least 90% coverage with clean granulation tissue in an average of 24.1 days. No patient required amputation during the observation period, and all limbs were salvaged. (3,4)
These findings align with other case series and retrospective analyses in which NPWTi-d with ROCF-CC has been associated with accelerated wound-bed preparation, earlier readiness for grafting, and limb preservation in high-risk diabetic and lower-extremity wounds. (4,5)
Mechanism: Hydromechanical Tissue Removal
NPWTi-d combines the mechanical benefits of negative pressure with cyclical instillation and dwell of a wound solution. During the instillation phase, the HOCl solution saturates the wound bed and helps loosen slough, fibrin and biofilm; during the dwell time, it interacts with devitalized tissue and bacteria; and during suction, the solution and solubilized debris are evacuated through the ROCF-CC’s through-holes. This cycle promotes hydromechanical removal of nonviable tissue while maintaining an optimally moist wound environment. (6,9)
The SAWC case series emphasizes that this hydromechanical effect, delivered through the ROCF-CC contact layer, can decrease the need for repeated operative debridement and rapidly convert an infected, stalled wound into a clean, granulating base suitable for cellular, acellular or matrix grafting materials. (3,10)
Clinical Implications
For diabetic patients at high risk of limb loss, rapidly converting infected, necrotic ulcers into healing wounds is critical for avoiding major amputation. Integrating NPWTi-d with HOCl and ROCF-CC into a multidisciplinary limb-salvage protocol may reduce amputation risk by combining aggressive bioburden control, ongoing wound-bed preparation, and optimized perfusion. (3,5)
The use of fluorescence imaging to identify areas of high bacterial load and NIRS to assess tissue oxygenation provides actionable, point-of-care data to guide escalation or de-escalation of treatment. Clinical studies suggest that routine fluorescence imaging reduces unnecessary antimicrobial use while improving healing, and that NIRS-derived oxygenation metrics correlate with wound-healing trajectories in ischemic limbs. (7,8)
Workflow-wise, scheduled instillation every 2–3.5 hours automates wound cleansing between nurse visits, while dressing changes three times per week balance staff workload with close clinical monitoring. Published NPWTi-d protocols using similar parameters have reported improved granulation tissue formation and reduced signs of local infection compared to NPWT alone. (4,6)
Visual and Practical Insights
A summarized table on the poster lists each wound’s initial size, percentage of nonviable tissue, and time to 90% granulation, illustrating how even wounds with extensive necrosis (up to 100% nonviable tissue) can be converted to healthy granulation within roughly one month when NPWTi-d is combined with systemic and local limb-salvage measures. These observations are consistent with other NPWTi-d series in complex diabetic foot and lower-extremity wounds. (4,5)
Summary
This case series demonstrates that NPWTi-d with hypochlorous acid delivered via ROCF-CC can function as a form of automated hydromechanical debridement within a structured diabetic limb-salvage protocol. In nine high-risk diabetic lower-extremity ulcers, wounds transitioned from heavily colonized and necrotic to ≥90% clean granulation in an average of 24.1 days, with no amputations required. These early data, together with growing literature on NPWTi-d, fluorescence imaging, and NIRS, support considering this combined approach for select complex diabetic limb-threatening wounds. (3,6)
References
Armstrong DG, Boulton AJM, Bus SA. Diabetic foot ulcers: a review. N Engl J Med. 2023;389(2):e3. (High infection and amputation risk in DFUs.)
Link: https://pubmed.ncbi.nlm.nih.gov/37395769/McDermott K, Fang M, Boulton AJM, Selvin E, Hicks CW. Etiology, epidemiology, and disparities in the burden of diabetic foot ulcers. Diabetes Care. 2023;46(1):209–221. (Epidemiology and amputation burden in DFU.)
Link: https://diabetesjournals.org/care/article/46/1/209/148198/Alonso MC, Singh J, Key D. Hydromechanical removal of nonviable tissue with negative pressure wound therapy and instillation to assist limb salvage. SAWC Spring 2025, Abstract CS-008. (Three-patient, nine-ulcer NPWTi-d limb-salvage case series.)
Link: https://sawcs2025posters.eventscribe.net/ajaxcalls/PosterInfo.asp?PosterID=731826McElroy EF, et al. Use of negative pressure wound therapy with instillation and dwell time using a reticulated open-cell foam dressing with through holes. Int Wound J. 2019;16(5):1188–1194. (NPWTi-d with ROCF-CC in complex wounds.)
Link: https://pubmed.ncbi.nlm.nih.gov/30784210/Ioannidis O, et al. Tailored negative pressure wound therapy with instillation in patients with microangiopathy. World J Emerg Surg. 2025;20:xx. (NPWTi-d and ROCF-CC as key elements for complex wound healing.)
Link: https://wjes.biomedcentral.com/articles/10.1186/s13017-025-00605-7Kim PJ, Attinger CE, Steinberg JS, et al. Negative pressure wound therapy with instillation: international consensus guidelines update. Int Wound J. 2019;16(1):19–24. (Mechanisms and parameters for NPWTi-d.)
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC7003930/Armstrong DG, et al. Point-of-care fluorescence imaging reveals extent of bacterial load in diabetic foot ulcers. Int Wound J. 2023;20(2):554–566. (FL imaging for quantifying bacterial load in DFUs.)
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC9885466/Račytė A, et al. Oxygen saturation increase in ischemic wound tissues during therapy monitored by NIRS. Biomedicines. 2024;12(8):1805. (NIRS for monitoring wound perfusion.)
Link: https://www.mdpi.com/2227-9059/12/8/1805Téot L, Boissiere F, Fluieraru S. Novel foam dressing using NPWT with instillation to remove thick exudate. Int Wound J. 2017;14(5):842–848. (Describes hydromechanical cleansing with NPWTi-d.) Amazon Web Services, Inc.
Link: https://s3.amazonaws.com/HMP/hmp_ln/imported/transfer/Acelity_March2018_Supp.pdfPrice N, et al. Routine fluorescence imaging to detect wound bacteria reduces antibiotic use and antimicrobial dressing expenditure while improving healing rates: retrospective analysis of 229 foot ulcers. Diagnostics (Basel). 2020;10(11):927. (Impact of routine fluorescence imaging on DFU management.) MolecuLight
Link: https://www.mdpi.com/2075-4418/10/11/927
