Evaluating the Safety and Efficacy of Fractionated Carbon Dioxide Therapy in Postoperative Lower Extremity Wound Healing

Background and Significance

With an aging population, the prevalence of cutaneous malignancies continues to pose
significant burden in terms of morbidity and economic cost. It is estimated that 5.4 million
new cases of non-melanoma skin cancers, i.e squamous cell carcinoma (SCC) and basal cell
carcinoma (BCC), are diagnosed each year. As the incidence of skin cancer increases, the
prevalence of postoperative lower extremity wounds also increases. Epidemiologic studies
consistently find up to 10% of BCC and 20% of SCC occur on the lower extremity in both men
and women, and the largest portion of malignant melanoma cases occurs on the legs of women.
Lower extremity ulcers are a common postoperative complication of melanoma, BCC and SCC
treatment, and impose an undue health care burden by negatively impacting patient quality of
life and increasing costs. Recent reports suggest that lower extremity ulcers cost $10,000
per patient per year, and patients often reported social isolation and depression, thus
making an improved treatment protocol for healing lower extremity wounds essential.

After an acute injury, normal wound healing is usually complete within four weeks and can be
divided into 4 phases: coagulation, inflammation, formulation of granulation tissue, and
remodeling or scar formation. The initial steps of coagulation and inflammation involve the
inhibition of bleeding through activation of the coagulation cascade, release of growth
factors and cytokines such as platelet-derived growth factor and transforming growth factor
β, and recruitment of macrophages and fibroblasts. This facilitates removal of foreign bodies
and bacteria while preparing the wound site for new tissue. Around 5-7 days inflammation
subsides via apoptosis of proinflammatory cells followed by formation of granulation tissue
through dermal and epidermal cell migration to the wound bed. Granulation tissue has a high
metabolic demand that is supplied by angiogenesis (proliferation of new blood vessels).
Angiogenesis occurs due to local hypoxia during acute tissue injury which stimulates the
release of several factors such as vascular endothelial growth factor and fibroblast growth
factor 2. Lastly matrix remodeling and scar formation result in the restoration of primarily
normal epidermis by replacing the extracellular matrix containing collagen III to primarily
collagen I and myofibroblast induced tissue contraction.

Lower extremity ulcers exhibit increased infection risk compared with other body sites, and
are rarely amenable to surgical closure due to a lack of suitable local skin and poor tissue
vascularity. As a result, many of these defects are allowed to heal via secondary intention
healing (SIH).The lower extremity suffers from poor perfusion and hypovascularity, both of
which impair wound healing in this anatomic site. Therefore, post-surgical wounds on the
lower extremities frequently convert into chronic wounds, defined as wounds that fail to heal
within four weeks and show no sign of improvement within eight weeks. This protracted healing
course drains the medical system of resources and subjects the patient to significant
discomfort and distress. The major problems reported from patients include pain, immobility,
sleep disturbances, lack of energy, limitations in work and leisure activities, worry,
frustration, and lack of self-esteem. Given the problems associated with allowing lower
extremity ulcers to heal by second intent, strategies that improve ulcer healing would be
beneficial, improving patient quality of life and preventing further complications.

Ablative fractional carbon dioxide lasers, such as the CO2RE® (Syneron Candela Corp, Wayland,
MA), offer a multi-depth pulse technology that delivers a precise fractionated beam pattern
to treat the epidermis and dermis simultaneously. This precision technology creates areas of
superficial and deep ablation and coagulation to activate remodeling at several tissue
depths. The CO2RE® is FDA-approved and has demonstrated efficacy in post-surgical scar
treatment, although it has not been studied in acute, lower extremity ulcers.

While the use of AFLs for wounds is novel, there are sufficient reported studies to suggest
it may be an efficacious intervention to facilitate the healing of lower extremity surgical
wounds. AFLs create microscopic wounds that can reach greater dermal depths than previously
attainable with fully ablative devices, and adjacent untreated skin may facilitate rapid
healing. Histopathologic studies of normal skin treated with AFL demonstrate altered kinetics
of growth factor and cytokine release, expression of heat shock proteins and matrix
metalloproteinases. In 3D human organotypic full-thickness skin models, carbon dioxide AF
therapy resulted in reduced expression of matrix metalloproteinases, and downregulation of
pro-inflammatory cytokines. Therefore, carbon dioxide AFL may offer significant advantages
over traditional non-ablative laser technologies.

Mohs Surgery

The treatment for BCC and SCC is often surgical. Mohs Micrographic Surgery (MMS) is a
surgical procedure in which skin cancer cells are removed. Once all visibly cancerous tissue
is removed, the tissue is examined under a microscope to evaluate for the presence of cancer
cells at the tissue edges. This allows the surgeon to determine if all of the cancer has been
removed. After examining the specimen, multiple thin sections of tissue are removed around
the margins of the wound and then examined under a microscope. If abnormal cells remain,
further tissue excision is required. This process is continued until no cancerous cells
remain. This technique allows for preservation of maximum amount of normal tissue and the
pathologic confirmation of complete cancer excision. MMS is used when there is a high risk of
recurrence, when the skin cancer is located in a sensitive area such as the nose or lower
extremities, or the cancer is an aggressive subtype. Complications of MMS include infection,
hypertrophic scar formation, hypergranulation tissue, and impaired wound healing that can
result is ulcers persisting up to 7 months.

Innovation

This project tests the highly innovative hypothesis that use of the AFL is both safe and
efficacious for the treatment of post-surgical ulcers. This laser technology has demonstrated
efficacy for treatment of lower extremity scars, but has not been adequately evaluated in
ulcers. Due to a unique pattern of injury induced by fractional technology where healthy
tissue in the vicinity of the ulcer is spared, the use of this technology may demonstrate
significant benefits as compared to traditional non-ablative lasers and low level light
systems previously used to treat ulcers.

Although our proposed study is highly novel, the feasibility of our proposed protocol is
supported by the fact that the fractional carbon dioxide laser has been shown to improve
wound healing in scar-related wounds and in post-traumatic wounds of the lower extremity.
Based on this data, treating acute lower extremity ulcers with ablative fractional carbon
dioxide laser is expected to improve healing times in lower extremity ulcers occurring as a
result of cutaneous surgery. This work may lead to the use of ablative fractional laser to
support the body's regenerative capacity on the lower extremity, improving patient quality of
life and conserving healthcare resources. The investigators therefore hypothesize that
ablative fractional laser treatment therapy after cutaneous surgery is a safe and efficacious
treatment for lower extremity wounds.

In addition to the novelty of our proposed hypothesis, our study benefits from technical
innovation in adjudicating ulcer healing, which has previously not been combined with carbon
dioxide laser technology.

Preliminary Studies

The first report of carbon dioxide AFL utilization in wounds was by Schumaker et. al in 2012.
In their report they described three patients treated with a 10.6-um carbon dioxide AFL
system for multiple traumatic scars related to blast injury. Incidentally they noted that
chronic wounds in the treatment sites resolved within 2 weeks of initial therapy. Phillips
et. al observed similar results in elderly individuals with post traumatic lower extremity
ulcers. Their report demonstrated greater than 60% resolution of chronic lower-extremity
ulcers 3 weeks after a single treatment with carbon dioxide AFL therapy. Most recently
Krakowski et. al demonstrated near complete resolution of two chronic wounds by two months in
pediatric patients after treatment with CO2 AFL at a pulse energy of 50 mJ and treatment
density of 5%.

MMS performed on the nose, like lower extremities, are occasionally allowed to heal by second
intent and can thus be predisposed to prolonged healing. Our preliminary studies demonstrate
the effects of carbon dioxide AFL on these wounds. Two patients receiving MMS on the nasal
ala were studied. One patient receiving carbon dioxide AFL therapy on his postoperative wound
while the other did not. After three weeks the patient's postoperative wounds were assessed.
The patient receiving laser therapy had complete epithelialization of his wound, while the
patient with no treatment had incomplete epithelization. These results suggest the hypothesis
that the carbon dioxide AFL may be a safe, efficacious treatment for ulcers of the lower
extremity.

Design:

Our study is a prospective, double-blinded, randomized, placebo-controlled trial evaluating
the efficacy of fractionated carbon dioxide therapy in postoperative lower extremity wound
healing. This study, including analysis and submission for publication, will occur from July
2018 to June 2019. A cohort of 68 patients will be recruited from July 2018 to September
2018. Eligibility criteria will include patients older than 18 years, those with a lower
extremity wound as a result of Mohs Micrographic Surgery at Saint Louis University
Dermatology Des Peres, and a postoperative wound greater than 5mm in diameter. Patients must
be able to understand the informed consent, willing to come to the office for treatments and
capable of following post-treatment instructions. Exclusion criteria will include pregnancy,
immunosuppression, uncontrolled diabetes (defined as >7% A1c in the last 3 months),
peripheral vascular disease, venous insufficiency, or no desire/unable to undergo laser
therapy.

After informed consent is obtained, a screening visit will be performed on their Mohs surgery
day and patient eligibility will be determined. Then, patients will be randomized 1:1 to a
treatment or control group via computer software. One arm will receive carbon dioxide AFL
immediately postoperatively on the wound base. The second arm, which will serve as control,
will receive sham laser therapy. Both patients will be given identical postoperative wound
care instructions, including vaseline applied to the wound, a piece of telfa to overlay the
wound, and paper tape to secure the dressing. Additionally, patients will be advised to avoid
baths and application of any other products to their wound. These supplies will be given to
the patients to eliminate wound care supplies as a confounding factor. Patients will be given
a diary to record observations about their postoperative wound and to note any adverse
events.

Blinding

There will be one unblinded member of the team in this study which will be the clinician
performing laser therapy or sham therapy, who will therefore not be involved in any data
collection, but will be responsible for reporting any adverse events per IRB protocols at our
institution. Other members of the research team member will be blinded to patient group
assignment, and these members of the research team will collect data (see below) at
subsequent visit. Additionally, patients will be blinded to treatment group. This will be
achieved by having patients wear safety glasses which blind them and the wound site still
anesthetized from the operation. Data collection will be done by a separate research team
member who is blinded to the treatment groups.

Patient Visits and Data Collection

Patients will be seen at 7 separate visits. This will include weekly visits post-operatively
for the first 4 weeks to monitor safety and efficacy endpoints and additionally at 8 and 12
weeks post-operatively. The patient's initial visit will include preoperative screening for
eligibility, informed consent procedure, and recording of past medical history and physical
exam. Once the patient is deemed eligible, enrolled, and signed informed consent, they will
be randomized to either carbon dioxide AFL therapy or sham laser therapy. After the patient
undergoes Mohs surgery with the resultant ulcer (the defect that typically forms after Mohs),
the patient will undergo either carbon dioxide laser versus sham laser therapy.

The investigators will measure ulcer size, presence or absence of complete healing, wound
temperature, a digital photograph, wound site pain, quality of life, and adverse events at
each visit. Ulcer size will be recorded by placing transparent acetate paper with a grid over
the wound site. This will then be traced with fine point marker. The cubic centimeters will
be recorded along with the width (longest axis of the ulcer) and length (axis perpendicular
to the width). Healing will be determined by one of the licensed research team members and
will be defined by complete epithelialization in the absence of scab/eschar. Wound
temperature will be recorded by non-invasive infrared thermographic camera. A digital
photograph will be taken with a camera that has an attachment ensuring the same distance and
angle at every visit. Wound pain will be graded on a scale from 1-10 with 1 being no pain to
10 being the worst pain of the patient's life. Quality of life will be determined by ED-5Q
questionnaire. Adverse events will be recorded by eliciting an oral history and review of the
patients diary. Adverse events will be recorded as presence of absence of specific outcomes.
Outcomes that patients will be directly questioned about include: crusting (scaly or
thickened scar), swelling, burning sensation, xerosis at treatment site, pruritus at
treatment site, infection, bleeding, hypertrophic or keloid scarring, burns, or color changes
at treatment site. These data points will be collected at every visit, and adjudicated by a
member of the research team blinded to the treatment group. This member will be a licensed
research team member.

Placebo treatment will consist of directing the laser system at the floor instead of the
patient's wound site. The patients will be wearing safety glasses and will have their wound
site still anesthetized from the operation therefore unaware if they are receiving the
therapy. This group will serve as the control group to the treatment arm in the study.

Inclusion Criteria:

- Older than 18 years

- Lower extremity wound as a result of Mohs Micrographic Surgery at Saint Louis
University Dermatology Des Peres

- A postoperative wound greater than 5 mm in diameter

- Able to understand the informed consent, willing to come to the office for treatments
and capable of following post-treatment instructions.

Exclusion Criteria:

- Pregnancy

- Breast feeding

- Immunosuppression

- Uncontrolled diabetes (defined as >7% A1c in the last 3 months)

- peripheral vascular disease

- venous insufficiency

- decompensated heart failure (NYHA class IV)

- peripheral neuropathy involving the treatment site

- active cancer at the time of study enrollment excluding curatively treated skin cancer

- Any underlying or current medical condition which, in the opinion of the Investigator,
would interfere with the evaluation of the subject. or no desire/unable to undergo
laser therapy.

Immunosuppression will be defined as patients with HIV, AIDS, who have received an organ
transplant, allogeneic bone marrow transplant, or peripheral stem cell transplant, and any
other patients taking chronic doses of systemic immunosuppressive medication within 6
months prior to randomization. Examples of immunosuppressive medications include
Tacrolimus, Azathioprine, Prednisone, or Methotrexate.