Efficacy of Laser Debridement on Pain and Bacterial Load in Chronic Wounds

Efficacy of the Er:YAG Laser Debridement on Patient-Reported Pain and Bacterial Load in Chronic Wounds

Bacterial load is frequently associated with impaired healing of chronic wounds. As well, sharp debridement is often associated with pain, causing patient distress, and thereby occasionally contributing to inadequacy of debridement, leading to a delay in wound healing. The purpose of this study is to assess the efficacy of the Sciton Laser in reducing bacterial load and patient distress in patients with chronic wounds, in efforts to expedite the wound healing process.

Chronic wounds are a debilitating affliction, affecting a substantial portion of the population worldwide and incurring staggering healthcare economic costs (1,2). Included among chronic wounds are venous leg ulcers, which are known to cause considerable pain, and can impact patient quality of life, thereby complicating wound care (3). The exact pathophysiology and etiology of the prolonged course of chronic wounds are poorly understood, but are thought to be multi-factorial in nature. Given the exposure of chronic wounds to the environment, they harbor a diverse microbial flora. Specifically, there is evidence that biofilm produced by these microbes are a large contributor to their non-healing nature (4). Debridement is considered an integral part of wound management with its ability to remove necrotic tissue and bacterial biofilm, in addition to stimulating release of cytokines and growth factors that promote wound healing (5). However, sharp debridement, the gold standard in wound care, is often ineffective for painful wounds. The effect of lasers on wound healing have been well-studied both in in vitro and in vivo models. Beneficial effects of low-level laser therapy in wound healing in animal and human studies has been established. However, extrapolation of this data is limited by study design and light dosimetry (6). Laser energy used for surgical excision is a lesser-known debridement technique that has been largely limited to burn scar treatment (7,8,9,10). Lasers are electro-optical devices that emit a focused beam of intense monochromatic light in the visible and infrared radiation spectrums. Since their start in the 1960s, lasers have been successfully utilized in many fields of medicine. Lasers for wound debridement began in the 1970s, with the successful report of a continuous-beam carbon dioxide (CO2) laser used for skin graft preparation of infected decubitus ulcers (11). Laser debridement is based on the controlled vaporization of the superficial layers of the wound bed. This results in the removal of the tissue containing unwanted microbial and necrotic particles. The laser type and the number of passes performed determine the depth of tissue ablation (12). Unlike other methods dependent on the clinician's manual control, laser debridement is electronically controlled, improving precision and reducing the risk of healthy tissue damage. Advantages of laser debridement include precision and uniformity of tissue ablation, which reduces trauma to the wound bed, improving patient comfort. To reduce thermal damage to healthy tissue, several improvements in laser technology have been made over the years. By utilizing a pulsed-beam system, laser energy is delivered in high-power, rapid succession pulses, resulting in short duration and high temperature exposure of target tissue, thereby minimizing thermal injury. Erbium:YAG (Er:YAG) lasers, with a wavelength of 2940-nm are widely used in the dermatologic community for skin resurfacing, for anti-aging and acne-related purposes (13). Skin ablation with the erbium laser is very precise, and allows for accurate assessment of the resurfacing depth (12,14,15). Since Er:YAG laser energy has greater than twelve times more water absorption efficiency than CO2 lasers, water in the tissue is rapidly expanded to eject the charred debris from the wound surface without leaving behind a necrotic eschar (12,16,17). The Er:YAG laser provides distinct advantages in precise ablation control and the reduction of residual necrotic tissue burden with minimal procedural discomfort, making the Er:YAG laser the most suitable device for laser wound debridement. Preliminary studies demonstrate remarkable patient pain reduction after laser debridement, resulting in more thorough removal of necrotic tissue and biofilm/bacterial load. Additionally, the extent of laser debridement is determined by the laser settings, as opposed to the individual operator's dexterity and skill, thereby providing better control over the wound bed preparation, producing more predictable and reproducible outcomes.

A portion of the patients will be randomized to sharp debridement first, then laser for the second debridement. The other portion will undergo this in the opposite order.

The investigator is blinded to which patient is receiving sharp or laser debridement as his/her first treatment.

During the first treatment, laser debridement will be performed at 200-um until punctate bleeding is visualized. During the second treatment, sharp debridement will be performed via a scalpel/curette until punctate bleeding is visualized. Tissue biopsies will then be obtained from the wounds prior to the first treatment, immediately after the first treatment, immediately prior to the subsequent treatment, and immediately after the second treatment. These will then be sent to Pathogenius for molecular analysis of wound microflora using polymerase chain reaction and sequencing. Pain will be assessed during debridement by recording the Numerical Rating Scale for pain assessment.

During the first treatment, sharp debridement will be performed via a scalpel/curette until punctate bleeding is visualized. During the second treatment, laser debridement will be performed at 200-um until punctate bleeding is visualized. Tissue biopsies will then be obtained from the wounds prior to the first treatment, immediately after the first treatment, immediately prior to the subsequent treatment, and immediately after the second treatment. These will then be sent to Pathogenius for molecular analysis of wound microflora using polymerase chain reaction and sequencing. Pain will be assessed during debridement by recording the Numerical Rating Scale for pain assessment.

Laser debridement entailed usage of an Er:YAG laser, employing the JOULE® machine (Sciton, Inc., Palo Alto, California). Full-field ablation was performed using the 2940 nm Er:YAG Contour TRL Resurfacing® application with the following settings: fluence - 50 J/cm2, spot overlap - 50%, pattern repeat - 0.5 seconds, spot size - 3-mm (Figure 1). Debridement was carried out until all fibrinous and/or necrotic tissues were removed, and healthy, bleeding tissue was visualized.

Using a scalpel/curette, each patient's chronic wound is debrided until healthy, viable tissue is noted.

Visual Analogue Scale (VAS) is a measurement instrument that tries to measure a characteristic or attitude that is believed to range across a continuum of values and cannot easily be directly measured. It is used in our study to measure the intensity or frequency of pain. We have used Numerical Rating Scale (NRS), variant of VAS, which is a validated, uni-dimensional measure of pain intensity reported on an 11-point numeric scale. The scores were reported from "0" to "10," with "0" representative of "no pain," and "10" representative of the "worst possible pain".

Bacterial load in wound as per tissue biopsy, pre- and post-laser debridement. CFU = Colony Forming Units.

Patient-reported preference of debridement type one week after study completion, reported as the count of participants that preferred either method.

The mean wound size increased immediately after debridement in both Groups, compared to the mean wound size before the debridement.

The mean percent change in wound size 1-week post-laser debridement was -20.8% ± 80.1%, as compared with -36.7% ± 54.3% 1-week post-sharp debridement (p = 0.6).

Inclusion Criteria: Aged eighteen years or older Having a chronic wound (as defined by lack of at least 50% reduction in wound surface area over a period of four weeks) No clinical evidence of active wound bed infection No exposure of any vital structure (i.e., tendon, bone, vessel) Has signed the informed consent form prior to any study protocol related procedure Willing and able to adhere to protocol requirements Exclusion Criteria: Any unstable medical condition that would cause the study treatment to be detrimental to the subject, as judged by the Principle Investigator Documented medical history of significant cardiac, pulmonary, gastrointestinal, endocrine (other than Diabetes Mellitus type 1 or 2), metabolic, neurological, hepatic or nephrologic disease would impede the subject's participation, as judged by the Principle Investigator Documented medical history of immunosuppression, immune deficiency disorder, or currently using immunosuppressive medications Having clinical presentation of active osteomyelitis Pregnancy or lactation Participation in another clinical study involving ulcers within thirty days prior to enrollment

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