Introduction

Negative pressure wound therapy (NPWT) is a known adjunctive modality for healing wounds. The use of NPWT is well documented for the treatment of both acute and chronic wounds. NPWT is designed to remove fluid, decreasing the afterload to blood flow and resulting in increased localized tissue perfusion.¹ Use of negative pressure may also enhance the formation of granulation tissue by secondary intention.¹ Negative pressure wound therapy with instillation (NPWTi) is a modification of NPWT, gaining popularity in the past few years. NPWTi can irrigate the wound with various solutions between sessions of negative pressure treatment.² NPWTi has the same properties of standard NPWT with the added ability to cleanse a wound. NPWTi promotes wound cleansing, granulation tissue development, and overall healing in wounds that do not see enough improvement with the use of standard NPWT.³ NPWTi has shown promising results, specifically in decreasing bacterial bioburden.⁴

Functional Principles of NPWT With Instillation

Like NPWT, NPWTi has applications for both acute and chronic wounds. Unlike NPWT, adding instillation allows for the use of topical solutions such as cleansers, antiseptics, and antibiotics in the wound bed. Retrograde instillation releases the solution into the wound. While the vacuum pump is paused, an additional tubing device allows the solution to soak into the wound bed for a given time. After the allotted soaking time, the solution is removed. This process can be repeated as often as is required. The solution contacts the area between the foam and the wound surface. The process allows instillation of the chosen solution without burdening the staff or the patient. Using today’s technology, wound care clinicians can control the amount of fluid, instillation time, soak time, and frequency of the therapy cycle.

The History of NPWTi Use and Method of Action

When NPWTi was first proposed in 1998, 3 phases were included: irrigation, dwell, and drainage.⁵ In theory, alternations between NPWT and instillation can be programmed as desired.⁶ The process should be done in a controlled manner, including instillation or irrigation phase, dwelling period, and drainage or suction period. Typically, the instillation period of the solution takes about 10-30 seconds. The dwelling period is dependent on the time the solution needs to dwell to be effective. The suction period is typically 2-3 hours. Again, these 3 phases can be programmed and adjusted as needed.

The Phases of NPWTi Use

The first phase, the instillation phase, typically lasts 10-30 seconds.⁶ The vacuum closes, and the instillation apparatus opens. Solution moves from the solution container through the tubing to saturate both the foam and the wound bed. The intake of the solution to the wound is monitored through transparent drapes. The amount of solution required for the instillation system can be measured and programmed. The second phase involves soaking the solution within the wound bed. The instillation line is now closed. The inflow and outflow are blocked. The instilled fluid in this phase has access to the wound surface. Typically the soak time is around 5-30 minutes.⁶The third phase is the suction phase. In this phase, the NPWT is restored. The solution is evacuated from the wound along with wound exudate. The duration of the vacuum phase is programmable and based on clinical assessment. The standard setting is 3 hours. Each cycle is said to correspond to a standard dressing change.⁶ Since each cycle varies based on programmability, the amount of “dressing changes” using NPWTi varies. Reducing the number of dressing changes can benefit the staff and the patient. Dressing changes are often painful for the patient and time-consuming for the health care provider. The NPWT has an integrated reservoir of instillation fluid removed by the suction.

Usage: Indications for NPWTi

Application of NPWTi has been documented in literature for usage in:⁶

• Septic wounds (acute infection, post-operative infections, osteitis, osteomyelitis)
• General surgery
• Thoracic surgery
• Severe periprosthetic infection in breast reconstruction
• Trauma and orthopedics
• Necrotizing fasciitis
• Gangrene
• Chronic wounds such as diabetic lower limb ulcers
• Venous leg ulcers
• Uncomplicated wounds
• Painful wounds

Conclusion

The potential benefits of NPWTi in the treatment of our patients are numerous, especially in light of promising results available in current literature. However, to ensure appropriate patient and wound selection, further research is required to achieve consistency involving settings, standardization, and individualization of parameters. References

1. Mendonca DA, Papini R, Price PE. Negative-pressure wound therapy: a snapshot of the evidence. Int Wound J. 2006;3(4):261-271.
2. Yang C, Goss SG, Alcantara S, Schultz G, Lantis Ii JC. Effect of Negative Pressure Wound Therapy With Instillation on Bioburden in Chronically Infected Wounds. Wounds. 2017;29(8):240-246.
3. Kim PJ, Silverman R, Attinger CE, Griffin L. Comparison of Negative Pressure Wound Therapy With and Without Instillation of Saline in the Management of Infected Wounds. Cureus. 2020;12(7):e9047.
4. Giri P, Krishnaraj B, Chandra Sistla S, et al. Does negative pressure wound therapy with saline instillation improve wound healing compared to conventional negative pressure wound therapy? - A randomized controlled trial in patients with extremity ulcers. Ann Med Surg (Lond). 2020;61:73-80.
5. Fleischmann W, Russ M, Westhauser A, Stampehl M. Die Vakuumversiegelung als Trägersystem für eine gezielte lokale Medikamentenapplikation bei Wundinfektionen [Vacuum sealing as carrier system for controlled local drug administration in wound infection]. Unfallchirurg. 1998;101(8):649-654.
6. Apelqvist J, Willy C, Fagerdahl AM, et al. EWMA Document: Negative Pressure Wound Therapy [published correction appears in J Wound Care. 2018 Apr 2;27(4):253]. J Wound Care. 2017;26(Sup3):S1-S154.

About the Authors

Dr. Lenz is a Certified Wound Specialist Physician. He has a special interest in limb salvage and wound care including surgery to correct deformities causing lower extremity ulcerations. He uses the most technologically advanced wound healing treatments available. He has presented multiple research projects related to advanced wound care at national surgical conferences. He is a graduate of the New York College of Podiatric Medicine and completed a comprehensive medical and surgical residency at the Jesse Brown Veterans Affairs Medical Center in Chicago, Illinois, where he served as Chief Resident. Dr. Lenz completed advanced surgical training in Germany and England, where he worked with international experts in diabetic foot surgery. He is dual board certified by the American Board of Wound Management and the American Board of Podiatric Medicine. He is a member of the American Podiatric Medical Association (APMA). Dr. Lenz is certified in hyperbaric medicine by the Undersea and Hyperbaric Medical Society. Dr. Lenz is certified in foot surgery by the American Board of Foot and Ankle Surgery.

Dr. Hussain is a foot and ankle surgery resident at RWJBH-Community Medical Center in Toms River, New Jersey. Fahad received his bachelor’s degree in biology from The University of Houston, and his medical degree from Temple University School of Podiatric Medicine. Dr. Hussain is surgically inclined and has a devoted interest in reconstructive surgery, limb salvage, cosmetic surgery, trauma, and minimally invasive surgery.