Emerging Concepts With NPWT In The Lower Extremity

Negative pressure wound therapy (NPWT) has a proven track record for lower extremity wounds. These experts explore when to utilize NPWT, the use of the modality over incisions and grafts, the merits of instillation NPWT and advantages of disposable devices.

Q:

When do you use NPWT in lower extremity wounds? Has your usage changed over the years?

A:

Gary Rothenberg, DPM, calls NPWT an “excellent” adjunct advanced wound care modality that evidence-based medicine has proven to be clinically and cost-effective. He cites the fact that usually, NPWT is not an “either/or” but he can add negative pressure to what he is already doing, and the technology works synergistically with other advanced care such as skin substitutes. Similarly, Kazu Suzuki, DPM, CWS, will use NPWT over skin grafting and skin flaps in the operating room setting.

Dr. Rothenberg gleaned knowledge on NPWT through experience with vacuum-assisted closure (VAC therapy, KCI/Acelity) but he notes his philosophy for using NPWT has certainly changed over the years. Originally, Dr. Rothenberg says it was common to use NPWT on deep wounds and use the technology until wound closure. Now he chooses NPWT for all types of wounds. Dr. Rothenberg says this includes using it over closed incisions to prevent dehiscence. Additionally, Dr. Rothenberg offers that most users would agree that on open wounds, the NPWT endpoint is different. He notes it is common now to fill wounds using negative pressure and then move on to other modalities for closure.

Both Dr. Suzuki and Adam Isaac, DPM, use NPWT in large and deep wounds. In particular, Dr. Isaac says this includes wounds that have exposed deep structures and require rapid formation of granulation tissue. Assuming the wound is debrided of non-viable tissue and he has thoroughly addressed any infection, Dr. Isaac says NPWT is a useful adjunctive therapy for lower extremity wounds.

After properly debriding a wound of all nonviable tissue, mitigating infection and optimizing vascularity, NPWT can be of great benefit, according to Tammer Elmarsafi, DPM. As he says, one can apply NPWT between serial debridements or as a final step for increasing granulation tissue to fill large post-debridement soft tissue deficits.

Initially, Dr. Elmarsafi says the primary indications for NPWT were filling large wound voids and temporary wound coverage for patients who needed further surgery but required medical optimization or other procedures such as cardiac interventions. Today, he notes the utility of NPWT has “dramatically widened.”  

Dr. Suzuki’s usage of NPWT has decreased in the outpatient setting and increased in the acute care setting over the last few years. He believes the latest skin substitute grafts are so effective that one can treat most lower extremity wounds in outpatient clinics. On the other hand, Dr. Suzuki says one can best manage severely infected or large and deep wound cases in the hospital, often in conjunction with NPWT or instillation NPWT.

Dr. Isaac uses NPWT regularly in inpatient and outpatient settings. Perhaps the most significant change in his practice has been how often he initiates NPWT in ambulatory surgery centers (ASCs). As he notes, portable NPWT systems are available for off-the-shelf use at his ASCs.

“The ability to begin this therapy in the immediate postoperative period has been a tremendous asset in managing these wounds,” emphasizes Dr. Isaac.

The biggest learning curve for Dr. Rothenberg with NPWT over the years has been in patient selection. He says patients must demonstrate the ability to troubleshoot cognitively with him before he uses NPWT. With many of the negative pressure systems, he notes if there is a break in the seal or the system becomes dysfunctional for some reason, the patient has to be able to troubleshoot at home. A non-functional NPWT system can often cause significant problems with periwound maceration and cause worsening of the wound, emphasizes Dr. Rothenberg.

Dr. Rothenberg acknowledges having a hard time with NPWT and home health care. He also notes that he has “never been a fan” of NPWT on the plantar foot, adding that he has had minimal success and more complications when using NPWT for plantar foot wounds.

Q:

Do you use NPWT over incisions or grafts? When do you use them?

A:

All four panelists use NPWT with incisions and grafts. Dr. Suzuki prefers to use NPWT in almost all skin graft cases and skin flap cases. He says NPWT does a nice job of decreasing hematoma and seroma, and facilitating the healing process. Dr. Suzuki also believes the NPWT dressing under pressure has a bolster effect to mechanically stabilize the skin grafts and flaps, and counter the shearing forces that may disrupt the healing process.

Dr. Isaac says NPWT can form a “splint” for high-risk incision and amputation sites, and obviates the need for numerous postoperative dressing changes. Dr. Isaac also applies NPWT as a postoperative bolster for many of his grafts. With ultra-portable, disposable-type NPWT devices, he says patients can spend the immediate postoperative period at home while receiving virtually the same treatment as they would in the hospital setting.   

“Application of NPWT over a skin graft provides adequate control drainage and shear, and thus is a good adjunctive tool,” says Dr. Elmarsafi.

Dr. Rothenberg feels NPWT works synergistically with incisions and grafts. He has anecdotally seen wounds heal much faster after using NPWT and skin substitutes together. Additionally, he has used NPWT over incisions in high-risk patients, citing the use of the modality over closed transmetatarsal amputation incisions as an example. Dr. Rothenberg says with non-powered NPWT systems, such as SNAP (Acelity) and PICO (Smith and Nephew), the use of negative pressure over closed incisions has become easier and more common.

“To me, NPWT over a closed incision in a high-risk patient is like adding an insurance policy onto the surgery,” says Dr. Rothenberg. “Often, we have this one chance to heal a patient and a small investment of time and money in these high-risk patients can prevent wound dehiscence, infections, prolonged hospitalizations and further surgeries.”

Dr. Elmarsafi notes it is best to reserve incisional NPWT for patients with a proven history of poor healing potential or wounds with potential tension. He advises clinicians to avoid using foam that is too narrow and avoid using NPWT in patients with unresolved ischemia. Although Dr. Elmarsafi discourages closing under tension, he notes it is sometimes unavoidable. In these instances, NPWT can help mitigate the risk of dehiscence. After applying a split-thickness skin graft, he says it is important to protect against the formation of seroma or hematoma and shearing forces as doing so will increase graft take.

Q:

Do you use instillation NPWT? What kind of cases are most appropriate for instillation NPWT?

A:

“Instillation NPWT has changed the state of play in our inpatient management of complex wounds,” says Dr. Isaac. He emphasizes that one should consider instillation therapy for any wound in which one is using NPWT. He notes even the addition of normal saline can promote wound healing. In wounds in which there is some question over residual necrotic tissue or heavy bioburden, Dr. Isaac says instillation therapy can be quite useful.

Instillation of saline that dwells over a preselected time before continuous suction allows irrigation of the wound while still promoting granulation formation, says Dr. Elmarsafi. He notes very few contraindications for the use of saline. Accordingly, Dr. Elmarsafi says most wounds can accept NPWT with instillation and cites several instances when instillation therapy results in the highest success. When there is premature removal of hardware, Dr. Elmarsafi says instillation therapy with a surfactant such as polyhexanide can greatly decrease biofilm. He notes it is best to use NPWT with instillation between surgical debridements.

Dr. Suzuki uses instillation NPWT whenever he is facing moderate or severely infected wounds. He finds instillation decreases the need for repeat wound washout in the operating room. Dr. Suzuki adds that a recent study has found that instillation NPWT decreases the length of stay in the hospital and hastens wound closure.¹ He sees no reason not to use instillation NPWT when it is indicated.

Dr. Rothenberg does not have any experience with instillation therapy. While he says the technology has great indications and solid evidence, his institution has yet to add it to the formulary.

Q:

Do you use disposable-type NPWT?

A:

Dr. Rothenberg cites non-powered, disposable systems as “game-changers in the NPWT world.” As he notes, disposable negative pressure devices are often cheaper, easier and faster to apply, extremely patient friendly, and have similar efficacy to the powered systems. Dr. Rothenberg adds that disposable systems have changed the game for transition of care from inpatient to outpatient status. Many times, the powered systems are appropriate for acute wounds with more drainage but he has discharged patients earlier and safely by transitioning them to non-powered systems while still delivering the benefits of NPWT.

“The patient and provider satisfaction with these systems are true in my experience as well,” says Dr. Rothenberg.

“Ultra-portable, disposable-type NPWT has transformed my practice,” says Dr. Isaac. “It allows for rapid initiation of NPWT in the outpatient setting and reduces the length of stay in our hospitals.”

Typically, Dr. Isaac applies a disposable-type NPWT device over grafts and allows the patient to go home in the immediate postoperative period. In past years, he notes the same patient may have required four or five days in the hospital. Many disposable-type systems are just as effective as standard NPWT devices, asserts Dr. Isaac.  

Dr. Suzuki has used disposable NPWT systems, specifically PICO as well as SNAP and VAC Via (Acelity). He says those devices are valuable in his practice as they are lightweight and patients tolerate them much better. As he explains, elderly and frail patients may not have the strength or tolerance to carry a conventional battery-powered NPWT machine that weighs 10 pounds.

Dr. Elmarsafi notes some disposable NPWT devices on the market automatically turn off after one week while others are driven by mechanical springs rather than batteries. He is currently investigating the utility of disposable devices over incisions and on split-thickness skin grafts. Although disposable NPWT devices have advantages, Dr. Elmarsafi says studies are necessary before one can make any recommendations or form conclusions.

Dr. Elmarsafi is a Diabetic Limb Salvage Fellow at Medstar Georgetown University Hospital in the Center for Wound Healing in Washington, DC.

Dr. Isaac oversees the Complex Foot Wound Clinic within the Department of Podiatric Surgery at Kaiser Permanente Mid-Atlantic States, in Washington, DC.

Dr. Rothenberg is a Clinical Assistant Professor of Internal Medicine with the University of Michigan School of Medicine in Ann Arbor, Mich.

Dr. Suzuki is the Medical Director of the Tower Wound Care Centers at the Cedars-Sinai Medical Towers. He is also on the medical staff of the Cedars-Sinai Medical Center in Los Angeles and is a Visiting Professor at the Tokyo Medical and Dental University in Tokyo. He can be reached at Kazu.Suzuki@cshs.org.

Reference

1. Sibaja P, Sanchez A, Villegas G, et al. Management of the open abdomen using negative pressure wound therapy with instillation in severe abdominal sepsis: a review of 48 cases in Hospital Mexico, Costa Rica. Int J Surg Case Rep. 2016; epub Nov. 17.