Negative pressure wound therapy (NPWT) is a medical treatment that uses controlled suction to help heal difficult wounds. A sealed dressing covers the wound, and a pump draws air out to create a vacuum-like environment, typically at 75 to 125 mmHg of pressure. This gentle suction pulls the wound edges together, removes excess fluid, and stimulates new tissue growth in wounds that might otherwise take months to heal or not heal at all.
How It Works
The system has three basic components: a wound filler (foam or gauze placed inside the wound), an airtight adhesive film that seals everything in, and a pump connected by tubing. Once the pump turns on, it creates negative pressure inside the sealed space. That suction does several things simultaneously at both the visible and cellular level.
On the visible scale, the suction physically draws the wound edges inward, shrinking the overall wound size. Fluid that would otherwise pool in the wound, including bacteria-laden drainage, gets pulled out into a collection canister. This keeps the wound bed cleaner and reduces swelling in surrounding tissue.
At the cellular level, something more interesting happens. The wound tissue gets drawn into the tiny pores of the foam filler, creating microscopic stretching and compression across thousands of individual cells. Cells near the foam walls get squeezed, while cells in the spaces between pores stretch by roughly 5 to 20 percent. That mechanical tugging acts as a signal. Stretched cells ramp up production of growth factors that trigger new blood vessel formation and tissue repair. It’s the same basic principle behind how exercise strengthens muscle: controlled mechanical stress prompts the body to build.
The therapy can run continuously or cycle on and off at intervals. Intermittent cycling may enhance the stretching stimulus, though continuous therapy is more commonly used because patients tolerate it better.
What Wounds It Treats
NPWT is used across a wide range of wound types, particularly ones that resist healing with standard bandages alone. The most common applications include:
- Pressure ulcers at stage III or IV, where the wound extends into deeper tissue layers
- Diabetic foot ulcers and other neuropathic wounds
- Venous or arterial leg ulcers caused by poor circulation
- Surgical wounds that split open (dehiscence), especially when hardware or bone is exposed
- Open fractures where bone has broken through the skin
- Burns and skin grafts, where NPWT helps hold grafts in place and encourages them to take
- Post-surgical chest infections following heart surgery
In each case, the goal is the same: prepare the wound bed for eventual closure, whether that happens naturally or through a later surgical procedure like a skin graft or flap.
How Well It Works
A meta-analysis pooling data from eight randomized controlled trials (421 patients) and six retrospective studies (488 patients) on open fractures found that NPWT produced significantly lower infection rates, shorter time to wound coverage, faster overall healing, shorter hospital stays, and fewer amputations compared to conventional dressings.
These results reflect what clinicians see in practice: NPWT doesn’t just speed healing, it changes the trajectory of wounds that were stalled or deteriorating. An expert panel convened in late 2023 reinforced that wound closure should remain the definitive goal and that NPWT should be considered early, particularly for complex wounds with heavy bacterial loads, chronic infections, or wounds that struggle to develop new tissue.
What the Experience Looks Like
If you’re starting NPWT, a clinician will clean the wound and place a foam or gauze filler inside it, cut to fit. An adhesive film goes over the top to create an airtight seal, and a small tube connects the dressing to a portable pump. When the pump starts, you’ll feel a tightening or pulling sensation as the dressing contracts against the wound. Most people describe it as pressure rather than pain, though the first application or dressing change can be uncomfortable.
The pump is usually a compact, portable unit about the size of a small lunchbox. It can be carried in a bag or clipped to a belt, so you’re not confined to bed. Many people continue NPWT at home after an initial hospital stay. A collection canister attached to the pump holds the fluid drawn from the wound, and you or a caregiver will need to monitor it.
Dressing changes happen every two to three days on average. For clean wounds, changes every 48 to 72 hours are standard. Infected or contaminated wounds may need more frequent changes, sometimes daily, with close monitoring at each change. A large study of acute contaminated wounds found that an interval of roughly 1.7 to 4.1 days between the first and second dressing change was both safe and effective, with an average of about 3 days. Your care team will tailor the schedule to how your wound responds.
The therapy can last anywhere from a few days to several weeks depending on wound size, depth, and complexity. At every dressing change, clinicians reassess whether the wound is progressing, whether the pressure settings need adjusting, and whether it’s time to transition to a different treatment or proceed with surgical closure.
When NPWT Should Not Be Used
Certain wound conditions make NPWT unsafe. The FDA lists specific contraindications:
- Dead tissue with a hard, leathery covering (eschar) that hasn’t been removed
- Untreated bone infections (osteomyelitis)
- Abnormal connections between tissues (fistulas) that haven’t been fully evaluated
- Cancer present in the wound
- Exposed blood vessels, nerves, or surgical connection sites
- Exposed bone or tendons (without protective covering)
The concern with exposed blood vessels is straightforward: suction on a blood vessel can cause life-threatening bleeding. Similarly, placing negative pressure over cancerous tissue could theoretically stimulate its growth. Wounds with dead tissue need to be cleaned out (debrided) first, because the suction can’t do its job through necrotic material.
NPWT With Instillation
A newer variation called NPWT with instillation (NPWTi-d) periodically flushes the wound with a cleansing solution before resuming suction. The pump cycles between delivering fluid into the wound, letting it dwell for a set period, and then suctioning it back out along with debris and bacteria. This approach is recommended for wounds with heavy bacterial contamination, chronic infections, and wounds that have stalled in the healing process. Expert guidelines from 2023 suggest considering early initiation of instillation therapy for complex wounds, with reassessment of the chosen solution at each dressing change.