Wound VAC Care After Cancer Surgery

A wound vac is a pump that applies gentle suction to a wound through a sealed dressing. Its formal name is negative pressure wound therapy, shortened to NPWT. You may also hear vacuum-assisted closure, or VAC.

An AHRQ technology assessment quotes the definition used by the Centers for Medicare and Medicaid Services: "the application of subatmospheric pressure to a wound to remove exudate and debris, via an integrated system consisting of a suction pump, separate exudate collection chamber, and dressing, over specific wounds." Exudate is the fluid a wound weeps.

Four parts make up the system. A foam or gauze dressing sits in the wound. A clear adhesive film seals over it and onto the surrounding skin. Tubing runs from the dressing to a pump. A canister catches what comes out.

The seal is not packaging. It is the therapy. Without an airtight seal there is no negative pressure.

Call 911 for bright red blood filling the tubing or canister, or blood soaking through the dressing. Then follow the written bleeding instructions your wound team gave you. Many systems tell you to switch the pump off and leave the dressing in place while you wait for help, but the exact steps belong to your device and your wound team, so use theirs. If you were never given any written instructions, ask for them today.

This is not a remote risk. FDA lists "uncontrolled bleeding" among the risks to health for these devices, and says labeling should address "bleeding and hemorrhage." The AHRQ report cites FDA data of "174 reports of injury and 12 deaths that have occurred since 2007," noting that infection was the most common adverse event and bleeding the most severe.

Call your wound team or surgeon the same day for:

• A temperature of 100.4°F (38°C) or higher — call immediately, not later in the day. CDC's instruction for people having cancer treatment is to "call your doctor immediately if you have a temperature of 100.4ºF (38ºC) or higher." MedlinePlus uses 100.5°F (38°C) for surgical wounds. Use the lower number. CDC adds that "fever may be the only sign that you have an infection, and an infection during chemotherapy can be life-threatening."
• Drainage that "increases or becomes thick, tan, green, or yellow, or smells bad," which MedlinePlus says indicates pus.
• "More redness, pain, swelling, or bleeding at the wound site," in MedlinePlus's wording.
• A wound that "is larger or deeper, or it looks dried out or dark."
• A seal you cannot restore. If the pump keeps alarming and the dressing will not hold suction, that is a call, not a wait.
• Foam that cannot be accounted for. More on this below.

Ask your team for one specific number: how long the pump can safely be off. Then write it on the device. You do not want to be working that out during a power cut at 2am.

StatPearls describes the mechanism in two parts. Macrodeformation pulls the wound edges together, shrinking the open area. Microdeformation creates tiny stresses at the wound surface that stimulate new tissue. Alongside that, the therapy "actively removes excess inflammatory exudate from the wound site" and helps restore small-vessel blood flow.

The wounds it suits are "complex or deep wounds that are nonhealing, at risk of delayed healing, or likely to benefit from accelerated healing." StatPearls includes dehisced wounds — wounds that have opened up after being closed — and surgical wounds generally. Cancer operations often leave exactly this kind of wound: wide, deep, and reconstructed.

StatPearls lists "underlying malignancy" among the contraindications to NPWT, "due to the theoretical risk of tumor seeding." In other words, the therapy is not normally applied over tissue known to still contain cancer.

That is not a reason to refuse a wound vac after cancer surgery. It is used on wounds where the tumor has been taken out. But if you know or suspect cancer remains in or near the wound bed, raise it and get a clear answer.

The other contraindications StatPearls lists are exposed blood vessels, bowel or vulnerable abdominal structures; untreated active infection; and necrotic tissue that has not been properly removed. On bone infection StatPearls is narrower: case reports describe NPWT over wound beds with active osteomyelitis without harm, but "this approach is not considered standard of care."

Suction may be continuous, meaning constant, or intermittent, cycling on and off. Which one you are on, and at what pressure, is set by the wound team for your wound and your device, and the settings differ between systems. Those numbers are on your own prescription and in the instructions that came with the pump.

The foam itself is chosen too. StatPearls notes it is "derived from either polyurethane (black) or polyvinyl alcohol (white)" and may be impregnated with silver for infection control. Black and white foam behave differently. They are not interchangeable.

Do not change the pressure, do not switch foam types, and do not remove foam unless your wound team has told you to.

Retained foam is a known and serious problem. StatPearls says the total number of foam pieces placed "must be documented to prevent inadvertent retention within the wound bed." FDA's special-controls guidance says device labeling should address "dressing being retained in wound."

The protection is simple arithmetic. At every dressing change, know how many pieces of foam went in. Confirm the same number comes out. Ask whoever changes the dressing to say the count out loud, and write it down. If a piece is unaccounted for, say so before the new dressing goes on.

Air leaks are the most common day-to-day problem. You may hear a faint hiss, or the pump may alarm. Intact foam under working suction feels firm and looks collapsed and wrinkled. Foam that is soft and puffy means the vacuum has gone.

Before you go home, get answers to four things: which alarms you may troubleshoot yourself, which mean you call, how the tubing should be routed, and how long the battery lasts.

FDA lists "reflux of waste exudate to wound" among improper-function risks. That is fluid running backwards into the wound. It is why the canister and tubing have to sit where you were shown, not tucked wherever is convenient.

FDA lists device incompatibility with MRI, hyperbaric chambers and defibrillation among the risks. Tell any team about to scan you that you have a wound vac. Put it on the same card as your allergies.

Second, dressing changes have no universal schedule. StatPearls says frequency depends on "the wound etiology and the patient's overall clinical status." Your interval is yours. Ask for it in writing, with the name and number of who does it.

Watch three things and record them.

The canister: how much fluid, and what it looks like. Thick tan, green or yellow fluid that smells bad is pus, and MedlinePlus says to report it.

The wound: it should be getting smaller and shallower, with healthy pink tissue filling in. MedlinePlus names the opposite as a warning sign — a wound that is "larger or deeper, or it looks dried out or dark."

The skin around the seal: the adhesive film covers healthy skin, and that skin can become sore or waterlogged. StatPearls lists maceration and hypersensitivity reactions among complications. Report skin breakdown under the film rather than trying to re-tape around it.

• FDA — Non-powered Suction Apparatus Device Intended for Negative Pressure Wound Therapy (NPWT): Class II Special Controls Guidance — note that this FDA guidance covers non-powered NPWT devices; most wound vacs used after cancer surgery are powered systems, and the manufacturer's instructions for your exact pump are the document that governs your care.
• NIH StatPearls (NCBI Bookshelf) — Negative Pressure Wound Therapy
• AHRQ (NCBI Bookshelf) — Negative Pressure Wound Therapy Technologies for Chronic Wound Care in the Home Setting
• MedlinePlus — Surgical wound care: open
• CDC — Watch Out for Fever (Preventing Infections in Cancer Patients)