Key Insights On Mapping Wounds With Ultrasound

By Martin Wendelken, DPM, RN, Oscar Alvarez, PhD, Lee Markowitz, DPM, Christopher Comfort, MD, and Linda Waltrous, RN

   During the last few years, improvements continue to abound in wound care treatments and therapeutics. Specialized dressings, circulation boots, monochromatic infrared therapy, skin substitutes and negative pressure therapy along with variety of vehicles to deliver silver are only a few of the advances. There have also been emerging developments in the diagnostic arena, including thermography, infrared temperature devices, pressure detection mats and devices to test for sensory defects and neuropathy.    Despite all of these advances, standard wound care (sharp debridement, offloading, moist dressing and compression) still provides a great starting place for treatment of both acute and chronic wounds. In a study on the healing rate of 203 diabetic foot ulcers, Sheehan, et. al., discovered that the percent change in wound area from baseline at four weeks is a robust predictor of healing diabetic foot ulcers at 12 weeks. They concluded that in 30 days if an ulcer had an area reduction of less than 53 percent (using standard care), then the wound was not likely to heal at 12 weeks. Accordingly, at this point, one should consider an alternative or more aggressive treatment.    The ability to predict if a wound is going to close in 12 weeks using standard care should not be understated. This can have a huge impact on the wound care community at all levels including the patient and his or her family, the caregiver and facility, as well as insurance companies and Medicare.    In general, the technology of wound care has focused on treatment advances. However, little has been achieved in wound assessment. Elaborate flow charts have established treatment plans and the formulation of best practice scenarios based upon outcomes research. Fortunately, significant progress has been reported and DPMs are salvaging limbs with much greater success.

Digital Photo Planimetry: What You Should Know

   Quietly in the background, there have been a few advances in diagnostics and wound measurements. A new computer photo planimetry program (PictZar®, CDM BioVisual Technologies) has been shown to be easy to use while providing highly accurate wound measurements. Diagnostic ultrasound provides practitioners with the ability to discover occult pathology and give exact depth measurements of a wound using the Wound-Mapping™ Ultrasonic Assessment Method.    The wound mapping technique is a diagnostic procedure that offers the potential for even better results. Not only does it provide new and never before available information for the clinician, it reveals this information in real time when the patient will benefit most.    Digital photo planimetry provides image documentation and surface measurements to monitor the patient’s results with specific treatment regimens. Simple accurate data directs the clinician toward what is working best for the patient. When the services one is providing are helping to close wounds, the wound care team stays motivated and on track.    Planimetry is the mensuration of plane surfaces as opposed to sterometry or the mensuration of volumes. There are a number of necessary reasons to take photographs of wounds and measure wounds beside the aforementioned ability to predict healing. A photograph provides excellent documentation with the ability to produce a wound history by archiving serial pictures of the pathology or skin lesion.    Additionally, photographs serve as an objective monitor of the wound healing process. With the addition of accurate measurements on the photograph, this imaging can be a “yardstick” to measure the effectiveness of specific treatment regimens. Today, clinicians use wound measurements as an objective basis for reimbursement for a variety of dressings, skin replacements, negative pressure therapy and surgical debridement.

Which Wound Measurement Method Is Best?

   There are a number of methods for determining wound dimensions. The most popular method is simple linear measurements (length x width). When taking these measurements, one should note the widest width and the longest length perpendicular to the width line. One would then calculate the area by multiplying width by length. Unfortunately, this is the least accurate method as this measurement is based on a rectangle while wounds are a variety of shapes. Errors can exceed 50 percent using this method.    A second method is tracing the wound on a transparent acetate sheet. This is a better approach (with a +/- 20 percent error rate) but it is not without problems. Steam forms below the film surface, glare blocks visibility of the wound and there is an increased risk of wound contamination when performing tracings. Tracing also may be painful and this method takes time to count the squares (in cm) after placing the acetate sheet over a grid to determine wound area. It is well documented that the inter-rater reliability of wound tracings (two people tracing the same wound) yields large differences in wound areas. A recent advancement in wound tracings provides for a digital tablet that counts the number of squares in centimeters. However, a second tracing over the original tracing on the device is necessary and this increases the risk of error.    Digital photo planimetry software provides for the mapping of wounds on a computer using a mouse, notebook tablet with pen or USB tablet with pen. Planimetry captures images of wounds without regard to distance. However, getting as close as possible provides better images and measurements. The image has a ruler in the picture and one can use this for easy calibration. Once it is calibrated, the computer generates measurement data, captures it and adds it to the image for easy reading. One may save the data to Excel® to calculate the percent change in the area of the wound in addition to providing a wound history and/or statistical analysis of changes in the wound parameters.    Those who use this software can generate reports for referrals or to send to insurance companies and Medicare for reimbursement purposes. Best of all and unlike with tracings, others may verify the data because the original picture is always available for review. PictZar has been shown to have intra-rater reliability of 98.3 percent or less than a 1.7 percent error rate.    Photo digital planimetry has a few limitations. One limitation is that the clinician must take the photograph perpendicular to the wound.    A manuscript detailing PictZar digital planimetry software and comparing intra- and inter-rater reliability to traditional tracings has been submitted to a peer- reviewed journal.

A Closer Look At Diagnostic Ultrasonography For Wound Assessment

   Diagnostic musculoskeletal ultrasound in podiatry has been in use for nearly a decade. In the late 1990s, Martin Wendelken, DPM, RN, began his quest to introduce the modality to the general profession. It has now been a few years since the introduction of the aforementioned wound mapping technique to the podiatric community. A number of practitioners are now incorporating the novel technique into wound assessment protocols.    Understanding musculoskeletal diagnostic ultrasound is necessary in order to interpret the images acquired when using the wound mapping technique. As a noninvasive procedure, ultrasound examination is quick and painless. Ultrasound’s noninvasive properties make it a perfect modality for wound care. The technique employs a sterile film, which covers the wound and prevents cross-contamination between the transducer and the wound. The technique also utilizes the HydroStep® Standoff system, providing improved image quality and comfort for the patient. This system has a removable standoff pad, which is disposable and again prevents the transfer of pathogens between the transducer and a wound.    This imaging modality in the physician’s hands offers a complete real-time picture, providing information that may direct or facilitate changes in treatment regimens. Podiatrists may institute such changes immediately without having to wait for a scheduled exam or obtain results such as those from an MRI. The physician would perform the exam until he or she is satisfied that the wound and entire tissue surrounding the wound has been completely inspected. The exam along with the images captured (via USB memory stick, hard drive or printed to thermal paper) provide a variety of important clinical information directly to the clinician.    Occult pathology that one discovers may include abscess, sinus tracts and undermining. The imaging modality may also reveal the extent of invasion of local tissues including muscle tendon, ligaments, bone and joint capsule. One may also discover deep tissue injury via this non-invasive approach. This technique provides continuous imaging of soft tissue planes and avoids the risk of missing pathology caused by making “slices,” which may inadvertently skip over a disease area.    Ultrasonography does not exclude patients with metal implants or claustrophobia nor does it expose them to ionizing radiation or magnetic fields. Additionally, in this environment of healthcare cost controls, an ultrasound examination is a fraction of the cost of expensive MRI exams.

What About Wound Depth?

   Another benefit of utilizing this technology is assessing wound depth. One can easily and non-invasively obtain the accurate wound depth. Today, the vast majority of practitioners are still probing the wound for depth, sinus tracts and undermining. This technique is painful to the patient and may increase the risk of infection by probing to bone. The Wound-Mapping Ultrasonic Assessment Method, using current scanners approved for this application, can provide measurements to a hundredth of a millimeter (0.001 cm).    Currently, there is no other modality for assessing wound depth that is painless, non-invasive and portable. In addition, no other modality in this arena has an equivalent safety profile or can come close to the measurement accuracy afforded by this technique. The technology even enables one to measure the thickness of the wound bed that might be covering bone or other vital structures. With ultrasound, one may find a wound length and width, providing the wound does not exceed the width of the transducer. Also, the device may capture a wound profile using other included measurement parameters.    The measurements and diagnostic images recorded provide a 21st century approach to wound evaluation. Having insight into these parameters provides the practitioner with the tools to make immediate educated decisions involving patient care.

Case Study: When A Patient Presents With A Diabetic Neuropathic Wound

   In order to simplify and clarify the use of these technologies in the office setting, consider the following case study.    A patient with diabetic neuropathy presents for evaluation of a foot ulcer under the first metatarsophalangeal joint (MPJ). The ulcer has been present for over a month and the patient has been treating the wound with his own home remedy.    The initial exam includes a history and physical exam, an initial photo of the wound and an initial photo of the foot. The patient also undergoes surgical debridement of the wound and we took a second photo of the post-debridement wound. We performed an ultrasonic assessment of the wound, including all adjacent soft tissue and the cortical surface of the first MPJ, first ray and the entire hallux. The X-ray included two or three views.    The initial digital photograph includes an image of the wound and its general location. All too many times, there is confusion as to the exact location of the presenting chief complaint. A second photograph of the wound, prior to debridement, also provides documentation as to the condition of the wound when the patient initially presented to the clinician. As we are all well aware, home treatment includes anything from aspirin to zinc oxide. Such remedies often cover up the area of pathology. One should take a third photograph of the wound after cleaning and debriding the wound. The clinician would use this last digital photo for the initial photo involving digital planimetry measurements.    Having completed the exam, the clinician prescribes a treatment plan based on a thorough evaluation of the patient and his or her wound condition.    There are always some concerns related to testing. Our main concern is over utilization and how often would one perform an exam. One should take digital photographs at every visit. If the initial exam reveals no acute process (abscess, cellulitis, invasion of joint capsule, etc.), the clinician would perform digital ultrasound examination in about a month. However, if an acute process is apparent or there is an indication that the patient’s condition has changed, weekly studies may be warranted.    When it comes to patients with diabetic neuropathy, a chronic wound is a potentially dangerous condition that carries high risk to the patient and huge costs to insurance companies. This condition warrants the best evaluation tools available in order to detect and prevent the possibility of an underlying osteomyelitis, abscess or looming ascending cellulitis in a timely manner.

In Conclusion

   Imaging of the wound using diagnostic ultrasound opens a whole new world of non-invasive wound assessment. For those who attain and utilize these special skills, the rewards are many for both the clinician and patient. Depending on the results of the exam, clinicians may note the extent of the wound depth as it invades into tissues below the wound surface. One will easily discover the deepest part of the wound and the extent of its lateral invasion into local tissues.    The patient benefits from this painless non-invasive procedure knowing that the clinician has examined the area both visible and invisible to the eye. An immediate feeling of trust and cooperation ensues between the patient and physician. The data and acquired images from diagnostic ultrasound and planimetry provide more information and documentation about the wound along with the local wound environment than ever before.    For the first time, two imaging technologies, ultrasound and planimetry, synergistically work together. The ability to map wounds using diagnostic ultrasound enables clinicians to monitor exact depth and wound bed thickness along with detecting the presence of occult pathology. The digital planimetry provides the means to surface map and monitor wound measurements to ensure a reduction in wound area (or the lack thereof).    Together, planimetry and ultrasound support state-of-the-art and evidence-based medicine techniques. These two technologies are now available on a single diagnostic device that may soon become FDA-approved for these applications. Dr. Wendelken is the Research and Development Director of Medical Staff at the Center for Palliative Wound Care at Calvary Hospital in Bronx, N.Y. Dr. Alvarez is the Administrative Director of Research at the Center for Palliative Wound Care at Calvary Hospital in Bronx, N.Y. Dr. Markowitz is a member of the medical staff at the Center for Palliative Wound Care at Calvary Hospital in Bronx, N.Y. Dr. Comfort is the Medical Director of the Center for Palliative Wound Care at Calvary Hospital in Bronx, N.Y. Ms. Waltrous is the Outpatient Services Manager at the Center for Palliative Wound Care at Calvary Hospital in Bronx, N.Y.

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