The authors used a prospective self-controlled study design to investigate the effect of prophylactic dressing on the development of pressure injuries in patients undergoing spinal surgery.
Participants. Sixty-four (64) patients admitted to the neurosurgical clinic of K Tertiary General Hospital in Seoul, South Korea, for surgery of the lumbar or thoracic vertebrae in the prone position between February 12 and September 1, 2018, were recruited for this study (Figure 1). The detailed criteria for participant selection were patients who 1) were age 19 years or older and scheduled for spinal surgery in the prone position on the Wilson frame who agreed to participate in this study, 2) expected to undergo surgery lasting 2.5 hours or longer, 3) had no chest or iliac crest wound when admitted to the hospital, and 4) expected to undergo thoracic or lumbar vertebrae surgery but not cervical vertebrae surgery.
The exclusion criteria were as follows: 1) not agreeing to participate in the study or being younger than 19 years, 2) undergoing cervical spine surgery in the supine position, 3) having an estimated surgery time less than 2.5 hours, and 4) having wounds on the chest or iliac crest. The selection criterion for operative time was determined as 2.5 hours based on the findings of a previous study,15 which showed that the likelihood of pressure injury doubles if surgery lasts longer than 2.5 hours.
A significance level of α = .05 and power of .80 were used in G*Power 3.1 (http://gpower.hhu.de) to calculate the proper sample size for 2-group proportion testing (chi-square test). The minimum sample size for this study was determined to be 93.
Instruments and assessment. To assess the degree of postoperative skin damage caused by pressure injury, this study adopted the international guideline on ulcer classification from the European Pressure Ulcer Advisory Panel, National Pressure Injury Advisory Panel, and Pan Pacific Pressure Injury Alliance.1 The finger-press method was used to distinguish stage 1 pressure injuries from blanchable erythema and non-blanchable erythema. This was performed by gently pressing the reddened area for 10 seconds and observing whether the pressed site turned white. A healthy reaction was recorded if the site turned white immediately; a stage 1 pressure injury was recorded if the site remained red.
Procedures. The skin condition of patients admitted to the operating room was evaluated by an experienced researcher (a neurosurgeon). Then, dice were rolled to determine where to place the dressing. If an odd number appeared, then a preventive dressing (Mepilex border, 15 × 20 cm) was attached to the right chest and right iliac crest area. If an even number appeared, then the preventive dressing was attached to the left chest and iliac crest area (Figure 2). The conventional method was employed at the control site, using a disinfectant cloth to cover the Wilson frame and the memory foam provided with it to prevent contamination by direct contact between the patient’s skin and the Wilson frame as well as to prevent direct pressure on the skin (Figure 3).
Immediately after surgery, the first skin condition evaluation was performed for the chest and iliac crest area. The second skin condition evaluation was conducted 30 minutes after surgery. Participants with a pressure injury that was found in the second skin evaluation underwent a third skin evaluation on all chest and iliac crest areas after 1 week.
Data collection. A total of 64 patients were enrolled. Fourteen (14) patients were excluded, leaving 50 for analysis (Figure 1).
Blood tests (white blood cell count, hematocrit, platelets, hemoglobin levels, C-reactive protein level, erythrocyte sedimentation rate, creatinine, blood urea nitrogen, glutamic oxaloacetic transaminase [aspartate aminotransferase], glutamic-pyruvic transaminase [alanine aminotransferase], prothrombin time [international normalized ratio], activated partial thromboplastin time, albumin, glucose, hemoglobin A1c, total cholesterol, and low-density lipoprotein) were performed before hospitalization. Systolic blood pressure, diastolic blood pressure, age, height, weight, body mass index, hypertension, heart disease, diabetes mellitus, and Braden scale scores were based on hospitalization records measured by the attending nurse at the time of admission to the hospital.
Surgery-related variables were set based on risk factors that might affect pressure injuries that might occur in the operating room, and were recorded using anesthesia recording paper after surgery.15
Patient age was grouped as follows: 44 years and younger, 45 to 64 years, and 65 years and older. Body mass index was grouped as less than 18.5 kg/m2, 18.5 to 22.9 kg/m2, 23 to 24.9 kg/m2, and ≥ 25 kg/m2. The Braden scale scores were grouped as 6 to 12 points, 13 to 14 points, 15 to 18 points, and 19 to 23 points. Additionally, the operative time and anesthesia times were grouped as 150 to 239 minutes, 240 to 400 minutes, and ≥ 401 minutes. All groups were used to evaluate pressure injury risk.
Data analysis. Data were analyzed using SPSS/WIN 23.0 (IBM SPSS, Inc., Chicago, IL). The participants’ general, disease-related, and surgery-related characteristics were examined using frequency analyses and descriptive statistics. Categorical variables were analyzed according to frequency and percentage, whereas continuous variables were analyzed according to mean and standard deviation. Continuous variables included disease-related characteristics such as blood test results, mean blood pressure during surgery, and heart rate. Finally, a chi-square test or Fisher’s exact test was performed to evaluate the frequency of pressure injuries in the chest and iliac region after surgery. A pressure injury was determined to be present when the ulcer was stage 1 or higher.
Ethical considerations. To protect research participants, an approval from Kangbuk Samsung Hospital’s Institutional Ethics Review Board was obtained before this study (IRB 2018-01-026). Only participants who had submitted written informed consent were included in the study, and they were told that they may withdraw themselves whenever they wished.