Use of Mechanically Powered NPWT: A Clinical Case Study Series

  Today's Wound Clinic takes you through each patient's care trajectory in an exclusive series of photos. Be sure to check out the slideshow here: https://www.todayswoundclinic.com/slideshow/mechanical-npwt   The goal of care with any of our patients in the outpatient wound clinic is to get the wound healed as rapidly as we possibly can. This means attempting to make an early, accurate diagnosis and, with few exceptions, simultaneously concentrating on improving the wound bed to prepare it for healing as that diagnosis is being made. Preparing a wound bed for healing includes debridement, reducing bioburden and edema, and managing moisture in order to promote a granular wound bed. This is accomplished by a careful and detailed wound assessment in order to identify the barriers to healing and the needs of the wound. Wound specifics such as location, size, amount of exudate, current tissue type, and bacterial burden drive wound care clinicians toward a treatment decision, along with the support needs required (compression, offloading, nursing care). The result of this assessment allows us to set goals based on patients’ needs. Wounds are dynamic and change frequently, so our assessments must be performed at routine intervals in order to adjust the treatment plan as the wound bed changes and evolves.   One tool that we have to enhance the process of wound bed preparation as well as the promotion of granulation tissue is negative pressure wound therapy (NPWT). Many years of use have allowed wound clinicians to easily identify those patients who would benefit from this therapy, and we have become exceptionally skilled at the creative “art” of application for this therapy. NPWT enables us to remove deleterious wound exudate and reduce periwound edema, thereby improving perfusion and promoting granulation tissue. The often-predictable wound bed changes set the stage for either complete healing or preparation for other treatments such as cell-therapy products or skin grafting.

NPWT Delivery

  In recent years, there have been advancements made in the delivery of NPWT, such as using smaller devices that need no electrical power source. There are still some methods available that are battery operated (with exudate transferred to a foam dressing or a replaceable canister) and that have audible alarms should the seal be lost. There is also one that uses mechanical power generated by a constant-force spring mechanism that delivers the same negative pressure to the wound surface as powered systems, but uses a cartridge that is easily hidden away in pockets or strapped to the patient’s arm or leg. This small and silent device can have a dramatic impact on the quality of life for those who would benefit from NPWT, yet who have the desire to work, engage in social activities, and/or require safe ambulation that enables active participation in therapy. For those living with lower extremity wounds on the, the risk of falls is reduced by eliminating the need for tubing that might extend from the foot or leg to a suction unit carried on the shoulder. With no audible alarms, visual cues are instead provided should a seal or suction be lost, again making use in social situations more acceptable, as well as eliminating disruption during sleep.   Additionally, there is now reimbursement for use of these devices in the outpatient clinic and physician offices, both from the Centers for Medicare & Medicaid Services (CMS) and, in most cases, there has been excellent acceptance and reimbursement from managed care and private insurers. These mechanically powered negative pressure wound therapy (MPNPWT) options are also unique in that they use a thin hydrocolloid dressing used over either foam or gauze that is “kind” to skin, easy to seal, and compatible with the additional supplies often used in hard-to-seal areas such as pectin rings, pectin paste, and hydrocolloid dressings.   Use of these devices will not replace our need for larger powered units. For wounds with greater amounts of exudate, the larger units are still required. But as wounds become smaller and less exudative, the transition to the smaller units is a natural progression. For wounds that are thought to only require NPWT for a shorter period of time, the off-the-shelf convenience for beginning and ending therapy has also been impactful. There is also considerable cost savings because charges are generated for just as long as the therapy is required, eliminating the need for a monthly rental for short-term usage when used for wound bed preparation or other brief therapy durations such as bolstering skin grafts. The impact on patient satisfaction has been demonstrated in a randomized controlled trial comparing MPNPWT to a powered system. (See Table 1.) This improvement in quality of life has been replicated in clinical usage of MPNPWT conducted by the author. (See box at right.) The first patient experienced a deep wound to his lateral calf that failed to respond to powered NPWT. When queried if he was using the therapy as required, he explained that he “worked two jobs, one at a theme park and another at a convenience store.” He couldn’t have the device exposed to the public at either job, so he only connected for the few hours he was home to sleep. MPNPWT was initiated and the wound was closed in four weeks. This set the stage for the realization that the utility of MPNPWT in the working population is evident. What follows is a summary of case study results using MPNPWT. For extensive photos relating to each patient’s care, refer to the online version of this article at www.todayswoundclinic.com. Dot Weir is co-editor and member of the Today’s Wound Clinic editorial board.