Decreasing Intraoperative Skin Damage in Prone Position Surgeries

Preventing pressure injuries (PrIs) from developing during surgery is difficult due to insensitivity and immobility of the patient and the positioning needed for safe surgical access. Intraoperative acquired pressure injury (IAPI) rates are reported from 4% to 45% (1). IAPI rates vary due to differences in defining PrIs, surgical positions and because tissue damage that occurs in surgery may not be visible on the skin surface initially with the resulting PrI presenting several days post operatively (2,3). The sustained pressure, deformation, and shear forces on the tissues combined with changes in blood flow due to blood loss, vasopressor and anesthesia use, and temperature changes present unique risk factors for PrI development during surgery (1). Reducing PrI damage during surgery requires preventive strategies to decrease the mechanical forces of pressure and shear on the tissues loaded in the unique positions required for surgical access. In the supine position for surgery, use of silicone foam dressings on the sacrum and heels with pressure reducing devices on the operating table have decreased IAPIs (4, 5).

The prone position for surgery has been shown to be a risk factor for IAPIs in multiple studies (1,2,4,14). Yet, there is limited data on IAPIs for surgeries in the prone position with Luo and colleagues reporting incidence at 4.7% and Yoshimura et al showing an 11% incidence (4,15). Preventing PrIs among patients undergoing spinal or orthopedic surgery in the prone position is especially challenging because of positioning required for surgical access and limited availability of pressure reduction surfaces for prone positioner operating tables (2,15). The face, chest, and iliac crest are all loaded on small operating table surfaces in the prone position. These anatomic locations have limited soft tissue for compression and small surface areas and because of this, distribution of pressure and shear forces over a large surface area is not possible. Thus, the intensity of the pressure and shear force over these anatomic areas is high. Shear force is particularly problematic as tissues change due to variations in blood volume and flow, anesthesia and vasopressor use, and initiation of the inflammatory response during the surgical procedure all of which may increase shear forces on the tissues (1,2,16). Use of silicone foam dressings on the iliac crest and chest has been shown to reduce IAPIs in the prone position for spinal surgery (15). Most recently, use of silicone foam dressings has been suggested for use to decrease PrIs in patients with acute respiratory distress syndrome (ARDS) from COVID-19 who are placed in prone position to manage respiratory distress (17,18). Issues with use of silicone foam dressings intraoperatively is keeping the dressing in place while positioning for surgery preoperatively, protecting the skin and allowing for movement and changes in the tissues intraoperatively, and safe nontraumatic removal immediately postoperatively. A new dressing technology (Mepilex Border Flex® (MBF)) provides increased conformability of the dressing to the skin with the ability of the dressing to move in all directions (e.g., 360-degree flexibility) with even slight body movements while using a silicone-based adhesive allowing for atraumatic removal.

The investigators will examine use of MBF dressings on the chest, iliac crest, and face (chin, cheeks, forehead) of patients undergoing surgery in a prone position using a prospective, non-randomized pre/post-intervention clinical trial. The specific aims are to:

1. Compare IAPI, erythema, and skin damage (e.g., friction abrasions, moisture associated skin damage (MASD)) incidence of patients undergoing surgery in a prone position with use of standard care to use of MBF dressings placed on chest, iliac crest, and face with standard care.
2. Compare subepidermal moisture (SEM) values (a biophysical measure of inflammatory tissue changes) of patients undergoing surgery in a prone position with use of standard care to use of MBF dressings placed on chest, iliac crest, and face along with standard care.
3. Explore cost estimates for use of MBF dressings placed on chest, iliac crest, and face for surgery in a prone position.

Three outcome measures will be compared between patients undergoing prone surgery with standard care (no dressings, pressure reduction positioning on the operating table) and those with standard care and use of MBF dressings placed on chest, iliac crest, and face: (1) incidence of erythema and PrIs on anatomic locations from visual skin assessment, (2) incidence of moisture associated skin damage (MASD) and friction abrasions on anatomic locations, and (3) SEM measures indicative of PrI damage.

The investigators will also complete a 6-month retrospective medical record review of patients who underwent prone surgeries from February 1, 2018 through July 31, 2018 to determine a historical PrI facility incidence rate. The year 2018 was chosen to avoid changes associated with the COVID-19 pandemic.

The investigators will obtain written informed consent to participate in the study directly from patients who are able to provide informed consent.

Participants will be recruited from patients in the neurological and the orthopedic surgery groups scheduled for prone surgery UCLA Santa Monica Medical Center. Participant inclusion criteria are over 18 years of age and able to provide informed self-consent. Exclusions to participation include less than 18 years old, inability to provide informed consent, and scheduled for surgery in a position other than prone position.

The study data collection period is anticipated to be 6 months, 3 months of pre-intervention baseline assessments followed by 3 months of intervention assessments.

During pre-intervention baseline (3 months) participants will undergo visual skin assessment and SEM Scanner readings at face (chin, cheeks, forehead), chest and iliac crest, conducted by the research staff, preoperatively, immediately following surgery in the Post Anesthesia Recovery (PAR) Unit, on transfer to the floor unit, post-operative day 3 and post-operative day 5 or discharge from hospital (whichever occurs first).

During intervention (3 months) participants will undergo visual skin assessment and SEM Scanner readings at face (chin, cheeks, forehead), chest and iliac crest, and then placement of MBF dressings to the face, chest and iliac. MBF dressings will be removed in the PAR unit, on transfer to the floor unit, post-operative day 3 and post-operative day 5 or discharge from hospital (whichever occurs first).

Research staff will collect all data after training in all protocols by the PI. Data collection includes medical record abstraction, visual skin assessments, and SEM Scanner measures. Each is described below.

The electronic medical record will be abstracted for demographic data (gender, age, race/ethnicity) and medical data (height, weight, body mass index, comorbidities such as diabetes, hypertension, peripheral vascular disease and, smoking status, medical diagnoses, Braden Scale for predicting Pressure Sores (Braden) score, use of any PrI preventive strategies such as support surface use, repositioning schedules), surgery type, surgery length, use of vibration machines or other instruments in surgery, length of time in PAR unit, anesthesia used, use of vasopressors during surgery, estimated blood loss, volume of fluids provided during surgery, blood pressure during surgery, American Society of Anesthesiologists physical status score and documentation of any skin damage including PrIs, MASD, and friction abrasions.

A 6-month retrospective medical record review of patients who underwent prone surgery between February 1, 2018 through July 31, 2018 will be done to determine the historical PrI incidence for UCLA Santa Monica Medical Center. The retrospective medical record review will include data as noted above.

Visual skin assessment training of research staff will emphasize stage 1 PrIs and deep tissue injury (DTI) Research staff will assess skin health through direct visual assessments preoperatively or within 1 week of scheduled surgery, immediately after surgery in PAR unit, on transfer to the floor unit, post-operative days 3 and 5 or discharge whichever occurs first. Participants will be positioned in bed in a supine position for visual assessments. Eight anatomic locations will be assessed: right and left chest at nipple line, iliac crest, and cheeks, mid forehead and chin. Skin will be assessed for discoloration (redness), erythema, PrI, MASD, and friction abrasion. Areas of visual skin discoloration will be palpated for blanchability using finger palpation and defined as blanchable versus non-blanchable. Erythema will be graded as minimal, moderate, or severe discoloration. DTI will be defined as severe skin discoloration (purple or maroon in light skin tones and black to blue-grey in dark skin tones) with or without blanching. Stage 1 PrIs will be defined as moderate skin discoloration (all skin tones), with non-blanching (non dark skin tones). PrIs more severe than stage 1 will be classified using the EPUAP/NPIAP/PPPIA's 2019 staging system (1) and assessed using the Bates-Jensen Wound Assessment Tool (BWAT) (32).

The SEM readings will be obtained on clean dry skin directly over each anatomic location using the SEM Scanner (Bruin Biometrics, Los Angeles, CA), a handheld dermal phase meter that requires light skin touch and provides SEM readings in 3 seconds (range 0-7 picoFarads (pF)) concurrently with the visual skin assessments. The SEM Scanner uses dielectric parameters, high-frequency low power electromagnetic waves of 32 kHz are transmitted via an electrode that is manually placed on the skin surface. In the skin, the induced electrical field interacts mainly with water molecules closest to the electrode with depth of interaction depending on the diameter of the circular electrode (in this study at a depth of 4mm) (19-21). The portion of the electromagnetic energy that is not absorbed by tissue water is reflected and measured by the device and displayed in the measuring unit. SEM values are displayed in picoFarads. Reliability of the device has been previously reported (33).

Descriptive statistics will be used to describe the sample. Chi square (categorical data), t-tests (continuous data) and Analysis of Variance (ANOVA) will be used as appropriate to compare demographic and medical data between the two study groups and to compare the total sample to the retrospective historical sample.

Costs of the dressings will be described.