Study design and sample. This descriptive study was conducted using a convenience sample of patients who were hospitalized in the tertiary ICU of the internal medicine department of a university hospital in İzmir, Turkey, between April and December 2015. All patients admitted to this unit at the start of the study and who met the study criteria were eligible to participate. The inclusion criteria for the study stipulated study participants must be at least 18 years old, have an expected hospital stay of at least 5 days, have no PU on admission to the unit, and have a Braden score ≤12, which indicates high risk.
Nursing care. The care nurses provided to protect and maintain skin integrity complied with the instructions stated in the hospital quality certificates that were developed based on the 2009 National Pressure Ulcer Advisory Panel (NPUAP) guideline.4
Demographic and clinical characteristics form. Data collected included patient age (categorized as 38 to 64 years, 65 to 74 years, and 75 to 90 years), gender, body mass index (normal weight: 18.5-24.9 kg/m2, overweight: 25-29.9 kg/m2, obese: ≥30 kg/m2), diagnosis, systolic and diastolic blood pressure, body temperature, hemoglobin level, sacral skin temperatures in the supine and lateral positions, PU stage, time when the PU was first noted after admission, and Braden Risk Assessment Scale score, as well as room temperature, mattress type (alternating pressure air mattress, continuous lateral rotation alternating pressure air mattress, viscoelastic mattress), and length of follow-up (days). Blood pressure, body temperature, and sacral skin temperatures were measured once daily; patient serum hemoglobin levels were extracted daily from the medical records by the researcher. If a PU developed, it was assessed and recorded as Stage 1 through Stage 4, as defined in the NPUAP guideline.4
Braden Risk Assessment Scale. The scale has 6 subscales: sensory perception, moisture, activity, mobility, nutrition (rated from 1 to 4), and friction and shear (rated from 1 to 3). The total score ranges from 6 to 23; lower scores indicate higher risk (patients with scores of 15 to 18 points are at mild risk, 13 to 14 at moderate risk, 10 to 12 at high risk, and ≤9 points at very high risk).15,27,28 Risk assessment commenced within the first 24 hours of admission to the ICU and was repeated daily.
Sacral skin temperature measurement. Participant sacral skin temperatures were measured using the PlusMed Infrared Temporal Artery Thermometer (model pM 1-802; Istanbul, Turkey). The thermometer was supplied by the manufacturer and calibrated twice by an authorized technical service separate and independent from the manufacturer, once before the study began and again during the study (measurements ranged from 36˚ C to 39˚ C˚ ± 0.2˚ C). In addition, linearity and accuracy were verified on 30 healthy persons by using a mercury thermometer as a reference.24 The mean differences between the 2 thermometer types was 0.1˚ C ± 0.05˚ C (range 0.0˚ C – 0.2˚ C); the Pearson correlation coefficient was 0.962, P = .000.
Disposable paper rulers were used to determine sacral skin area and the thermometer distance from sacral skin surface on patients. When the patient was in the lateral position, the sacral area was determined in line with the vertebral column, 5 cm above the coccyx.24 The thermometer was held vertically 10 cm from the sacrum according to the manufacturer’s suggestion. At each measurement period, consecutive measurements were performed at 1-second intervals until the temperature difference between 2 measurements was 0˚ C, and the results of the measurements then were recorded.
The participants’ sacral skin temperatures were measured within the first 24 hours of admission (day 1) in the ICU and continued consecutively at 24-hour intervals between 5:00 pm and 7:30 pm until the patient developed a PU or died, was discharged, or was no longer having a position change.
Sacral skin temperatures were measured when patients were placed in the lateral position immediately after 120 minutes of being in the supine position (referred to as supine position sacral skin temperature measurement) and immediately following 30 minutes in the lateral positions (referred to as lateral position sacral skin temperature measurement) and recorded. When the sacral skin temperature was measured, the room temperature also was measured and recorded with the infrared thermometer in surface temperature mode. The measurements were taken by the researcher who positioned the patients.
PU protocols. Standard hospital protocol that stipulated patients should be repositioned every 2 hours; provided a support surface; protected from moisture, friction, and shear; and have a bath every day was applied to all participating patients. Patients using an alternating pressure air mattress or viscoelastic mattress were placed in the right lateral, supine, and left lateral positions every 2 hours by the researcher with the help of the support team. When a continuous lateral rotation alternating pressure air mattress was in use, the position change intervals were set to 1 hour because the device rotates at a 1-hour maximum.
Data analysis. Data were entered from paper-and-pencil questionnaires into the SPSS, version 22.0 (IBM Corp, Armonk, NY), for statistical analysis. Descriptive and inferential statistics were used to analyze the data. For the descriptive statistics, mean values and standard deviation, frequencies, and percentages were used. Descriptive characteristics, sacral temperature averages, PU development, and the difference between sacral skin temperatures in terms of gender were analyzed using the Student’s t test. The one-way analysis of variance test was used to assess the differences between sacral skin temperatures in terms of age, body mass index, and mattress type. Patients that developed PUs were followed-up for between 4 and 12 days; patients who did not develop a PU were followed-up until they died, were discharged, or no longer had their position changed for between 5 and 22 days. For most (66.5%), PUs developed within the first 5 days (day 1 to day 5); sacral skin temperatures of all the patients within the first and fifth days were used to examine the effect of sacral skin temperature on PU development.
The relationship between body temperature and sacral skin temperatures on day 1 and day 5 was assessed using the Pearson product moments correlation and Spearman’s rank correlation coefficient (Spearman’s rho). Results were evaluated at 95% confidence interval; P <.05 was considered significant.
Ethical considerations. Before the study was conducted, approvals were obtained from the Scientific Ethics Committee of Ege University Nursing Faculty (dated 07.03.2014 and numbered 2014-29) and the hospital where the study was to be conducted. Patients or their relatives were given verbal and written information about the study; persons who agreed to participate in the study gave their written informed consent. The participants were told they could withdraw from the study at any time and that their credentials would be kept confidential and would not be shared with any third party. First letters of name and surname and the last 3 digits of the protocol number of each patient were combined to give a code to define and verify the patient. This ensured patient confidentiality.