Negative Pressure Wound Therapy Revolutionized Wound Care

Negative pressure wound therapy (NPWT) revolutionized wound care when it was introduced in the 1990s as one of the first widespread advanced wound therapies. Since its debut, NPWT has been diversified to include options for the management of closed incisions, disposable single-use devices, and formalized mechanisms for instillation and dwell time (NPWTi-d).

When used for wound management NPWT delivers sub-atmospheric pressure at the wound site, which exerts multiple beneficial effects. Sub-atmospheric pressure causes microstrain on cells, stimulating them to divide. This concept is being studied in the developing field of mechanobiology, which connects the fields of biology, engineering, and physics. Mechanical or physical forces can induce microstrain and associated cellular deformation which contribute to biological responses. For example, fibroblasts are important cells in the healing process: they synthesize and remodel collagen, tumor necrosis factor alpha (TNF-a), matrix metalloproteinases (MMPS), and growth factors. Fibroblasts are also known to respond to mechanical cues like tension, compression, and shear.¹ The microstrain exerted during NPWT is thought to contribute to the expedited healing observed. Additionally, macrostrain occurs during the delivery of properly applied NPWT, whereby the dressing supports the wound edges and aids in contraction of the wound. An additional mechanism of action of NPWT is its assistance with drainage management by drawing and containing drainage away from the wound bed. Wound drainage can contain high levels of inflammatory cytokines and bacteria which potentiate the inflammatory cycle, contributing to wound stagnation and delayed wound healing. Another benefit associated with the use of NPWT is the improved perfusion that results from removal of subcutaneous and interstitial edema. When compared to standard wound dressings NPWT is contributes to improved granulation tissue, decreased time to healing, and reduced overall cost of treatment.²

Mechanical negative pressure wound therapy (mNPWT) delivers positive wound outcomes utilizing these same mechanisms of action.^3,4 Unlike traditional NPWT (tNPWT), mNPWT is disposable and does not require electrical power to provide sub-atmospheric pressure at the wound site. Its use in wound management is similar to tNPWT, and it can also be used as a bolster for cellular and tissue product grafts. When adding this therapy as an option for patient care, it is important to know that comparative effectiveness research has demonstrated similar wound healing and adverse event outcomes between tNPWT and mNPWT.^2,5 Considerations when selecting mNPWT versus tNPWT are primarily related to drainage and wound size, and occasionally include wound location. Wounds with excessive drainage, significant depth, undermining, or difficult locations can still benefit from tNPWT or NPWTi-d. Care setting can be an important consideration as well. Though mNPWT can be reimbursed in the home health setting, not all home health agencies are aware of this or have staff trained on application. Reimbursement is currently available in the clinic setting, hospital outpatient department, and the emergency room as a place of service.

mNPWT is especially convenient in the ambulatory setting, where it is touted as being ultraportable. The device is convenient as it does not need to be plugged in to charge, and patients do not need to carry additional baggage. With mNPWT the lightweight device is strapped near the wound site, limiting excessive tubing and eliminating electrical cords. This can decrease the risk of falls and associated injuries. Patients returning to work, especially with physical requirements, request mNPWT to increase mobility and return to work sooner. It is also important to consider other NPWT quality of life measures.  mNPWT is associated with increased comfort and decreased noise, impact on social interactions, and sleep disruption compared to tNPWT.²

mNPWT is a convenient tool to deliver healing outcomes comparable to tNPWT in patients, but with added improvements regarding wound-related quality of life. 

References

1. Tracy LE, Minasian RA, Caterson EJ. Extracellular matrix and dermal fibroblast function in the healing wound. Adv Wound Care. 2016;5(3):119–136. doi:10.1089/wound.2014.0561. ISSN 2162-1918.
2. Armstrong DG, Marston WA, Reyzelman AM, Kirsner RS. Comparative effectiveness of mechanically and electrically powered negative pressure wound therapy devices: a multicenter randomized controlled trial. Wound Repair Regen. 2012;20(3):332-341. doi:10.1111/j.1524-475X.2012.00780.x
3. Fong KD, Hu D, Eichstadt S, et al. The SNaP system: biomechanical and animal model testing of a novel ultraportable negative-pressure wound therapy system. Plast Reconstr Surg. 2010;125(5):1362-1371. doi:10.1097/PRS.0b013e3181d62b25
4. Fong KD, Hu D, Eichstadt SL, et al. Initial clinical experience using a novel ultraportable negative pressure wound therapy device. Wounds. 2010;22(9):230-236.
5. Marston WA, Armstrong DG, Reyzelman AM, Kirsner RS. A multicenter randomized controlled trial comparing treatment of venous leg ulcers using mechanically versus electrically powered negative pressure wound therapy. Adv Wound Care. 2015;4(2):75-82. doi:10.1089/wound.2014.0575