Risk for surgical positioning injuries: scale validation in a rehabilitation hospital.

Objective: to validate the Risk Assessment Scale for the Development of Injuries due to Surgical Positioning in the stratification of risk for injury development in perioperative patients at a rehabilitation hospital. Method: analytical, longitudinal and quantitative study. An instrument and the scale were used in the three perioperative phases in 106 patients. The data were analyzed using descriptive and inferential statistics. Results: most patients showed high risk for perioperative injuries, both in the scale score with estimated time and in the real-time score, with a mean of 19.97 (±3.02) and 19.96 (±3.12), respectively. Most participants did not show skin lesions (87.8%) or pain (92.5%). Inferential analysis enabled us to assert that the scale scores are associated with the appearance of injuries resulting from positioning, therefore, it can adequately predict that low-risk patients are unlikely to have injuries and those at high risk are more likely to develop injuries. Conclusion: the scale validation is shown by the association of scores with the appearance of injuries, therefore, it is a valid and useful tool, and it can guide the clinical practice of perioperative nurses in rehabilitation hospitals in order to reduce risk for injuries due to surgical positioning.


Introduction
Surgical positioning is a key factor in the performance of safe and efficient operative procedures, and it aims to provide the best anatomical exposure for surgery, although there are risks to patients that result from the position adopted on the operating table. All positions present risks that may be exacerbated, as the patient is under anesthesia and, in most cases, unable to alert the team about his or her discomfort (1)(2) .
Fixed positioning associated with prolonged surgery time can cause bone pressure points against the operating table and cause temporary or even permanent damage to the patient (2)(3) .
Pressure injuries (PIs) due to surgical positioning are considered complications, and they have a multifactorial etiology. Despite technological advances, they are still a challenge for clinical practice. The adoption of adequate protective measures is compromised by the difficulty that the surgery team has in the early assessment of risk in surgical patients (4) .
With the premise of promoting safe and quality care, comfort and individuality for each patient, perioperative nurses are responsible for planning nursing actions that can reduce and prevent complications resulting from the anesthetic-surgical procedure, thus minimizing potential risks. Therefore, they must provide adequate surgical positioning, with the equipment and devices that are available and appropriate to help the performance of the procedure and, thus, implement effective interventions (2)(3) .
In order for interventions to be effective in preventing skin injuries, they must be related to pressure relief while and immediately after the patient remains on the operating table, and examples of effective devices for such prevention are dry viscoelastic polymer mattress toppers and gel pads (5) .
In the national literature, studies show the occurrence of PI related to surgical positioning, such as one involving 199 surgical patients with the presence of PI in 20.6% of the sample. In most cases (98.6%), the injuries were in stages 1 and 2 (6) . Another study, conducted in a university hospital, showed the occurrence of 25% PI in a total of 148 patients who underwent elective surgery (7) .
Even more worrying results are shown in a study conducted with 50 patients evaluated when admitted to the operating room (OR) and immediately after the surgical intervention, identifying that 37 patients (74%) had stage-1 injuries and that on only one patient were protection resources used (8) . Another study identified that out of 115 patients who underwent elective surgery, 46 (40%) had pain due to surgical positioning, and 25 (21.7%) developed PI (2) .
Injuries related to peripheral nerves or peripheral neuropathies are an uncommon complication of surgery, with estimates ranging from 0.02% to 21% (9) . A systematic review of 23 studies that evaluated sensory changes or nerve damage after an abdominoplasty reported that most injuries occurred when surgery included more than one type of procedure and also suggested that patient risk increased with surgery time (10) .
Early risk assessment, including the use of a combination of a validated risk assessment instrument, skin assessment and clinical judgment, is crucial (11) .
Recently, a study showed the importance of establishing a specific risk scale for surgical patients, since the same study compared existing scales which assess PI development and showed that they were not so effective as they did not identify the critical factors of the perioperative period (2) .  for the patient, as it promotes a calm environment for the start of procedures (12) .
The study was carried out at the SF and in the wards that receive inpatients in the pre-and postoperative periods from January to February 2018. The permanent staff on the service's nursing team, which provides direct care for surgical patients, comprised 24 nurses, 13 nursing technicians and three nursing assistants, totaling 40 employees. Among nurses, one was responsible for receiving each patient at the SF and monitoring anesthetic procedures; therefore, he/ she was directly responsible, together with the other team members, for the patient's positioning and ELPO application, thus being a differential in the perioperative care provided.
To calculate the representative sample size, the GPower 3 software was used with the following parameters: two-tailed correlation test, 80% test power, 5% error probability and average effect size.
Thus, the number of 82 participants was obtained to seek the internal validity of the study. It was a convenience sample, and 106 patients participated in the study, that is, a larger sample than the estimated minimum was achieved.
The target population in the study consisted of surgical patients undergoing elective procedures, of both sexes, aged 18 years or over, from any surgical specialty. Patients undergoing a second surgical procedure within the data collection period and patients undergoing emergency procedures were excluded.
The data source was primary, and a data collection instrument (the same as that used by ELPO's author) (2) as well as ELPO were applied. In the instrument, with five sub-items each. The score ranges from one to five points and the total score from seven to 35 points.
Patients with up to 19 points are considered to be at low risk, and those with 20 points or more are at high risk. The higher the score according to which a patient is classified, the greater the risk for developing injuries due to surgical positioning (2) .
Prior to data collection, a nurse from SF, who was previously trained, was invited to assist during the preoperative visit stage. Then, a pre-test involving represents his or her pain (13) . In the intraoperative period, ELPO was applied, and At the end of each day, each patient's score was checked, and the points generated by the items on the scale were evaluated so that there were no differences of opinion. ELPO was applied with the estimated surgical time, which was considered in this study as ELPO 1.
It was, then, applied again with the real positioning time and designated as ELPO 2. This procedure enabled the comparison of the means obtained in each score, since one of the most significant risk factors is the time that patients remain on the operating table, as they may be subjected to intense and prolonged pressure during long surgical procedures, which creates a risk for developing PI (2,14) .
In the postoperative period, the researcher   As for pain related to surgical positioning, eight (7.5%) complained of pain located in the shoulders (n=3), arm (n=2), right side of the chin and right side of the chest (n=1), neck (n=1) and sacral region (n=1). In evaluating this variable, 92.5% (n=98), that is, the majority, did not report any pain due to surgical positioning.
During the pre-test, it was necessary to group the available resources and equipment and the way they are distributed to assemble the Support Surfaces (SS) for each type of patient so that the nursing team could understand it. Thus, they were distributed within each item proposed by the scale (Table 2).
Regarding the type of SS used to position the patient, of the 106 procedures analyzed, 63 (59.4%) used a foam operating table mattress (conventional) + foam cushions (Table 3).

Discussion
When evaluating patients undergoing elective surgery, it was found that the mean age was 46.36 years (±16.32) and that the mean BMI was 27.79 (±4.81).
The literature shows that the incidence of complications increases proportionally to age, with less tolerance to prolonged positioning. It also increases proportionally to obesity because, depending on the type of position, it favors the compression of the diaphragm and hinders chest expansion (15)(16) . Changes in BMI (underweight, overweight or obesity) influence the appearance of injuries caused by surgical positioning (1) .
Another aspect found was that the majority of patients did not report pain, had intact skin, with no history of PI or physical limitations. Physical limitation was established so that, at the time of positioning, there would be available resources and the surgical position would be in accordance with the patient's tolerance.
As for the presence of comorbidities, a factor in which most patients had two or more associated diseases, it is noteworthy that some diseases imply the fragility of the patient's body systems, such as vascular and respiratory diseases, neuropathies and even malnutrition, and the more severe they are, the greater the risk for developing injuries (8) .
Diabetes mellitus causes impaired tissue perfusion to the patient due to decreased blood flow, which makes healing difficult and is considered a risk factor for the occurrence of perioperative lesions due to www.eerp.usp.br/rlae 7 Nascimento FCL, Rodrigues MCS.
positioning (17) . Corresponding to the characteristic of the hospital where the study was conducted, the surgical specialty of orthopedics showed a higher frequency of surgeries.
Some positions were analyzed during the intraoperative period, the most frequent being the against the operating table (18) .
When the patient is in the supine position, with his or her arms in bracers, they must be supinated (with the palms facing upwards), the bracers must be levelled with the mattress and the arms must be abducted at an angle less than 90° in order to avoid possible discomfort and improper positioning (3) .
The prone position can cause complications that are considered potentially serious due to vascular compression, hemodynamic changes, increased abdominal pressure and PI (19) .
Long periods of immobilization and pressure exposure cause anoxia, tissue necrosis and consequent skin damage; therefore, the duration of the anestheticsurgical procedure in the intraoperative period is characterized as one of the most significant risk factors and as a contributor to the appearance of injuries due to surgical positioning (3) . The longer the surgery, the greater the chance of developing PI, and the prevalence rate of PI in patients who undergo surgery lasting more than three hours is 8.5% or more (20) . The risk for the patient's developing this type of injury increases by 1.07 every hour of surgery (21) .
The type of anesthesia is another significant risk factor in the intraoperative period, since it depresses pain receptors, influences the level of depression of the nervous system and relaxes the muscles, causing the patient's defense mechanisms to no longer provide protection against pressure, stretching, muscular effort and/or damage resulting from the exacerbated rotation of the limb, making it susceptible to pressure injury and pain (5) .
In order to provide adequate and safe positioning to the patient, it is necessary to use supports and cushions as well as decrease height during leg elevation; however, the availability and appropriate selection of support surfaces (SS) are mainly required (5) .
SS are specialized devices used in order to redistribute pressure. They are designed for the management of tissue pressure by reducing the shear force and controlling the local microclimate. Thus, they must be chosen according to patients' specific needs and surgery type (22) .
Failure to use SS during the intraoperative period increases the risk for injuries resulting from surgical positioning, as found in a systematic review (22) .
However, SS are not regularly used on surgical patients due to political, economic and social issues faced in the country, thus, in many public services, such SS are not available, which interferes in the prevention of these injuries (5) .
In the study, the SS used for the patients were The national literature shows evidence of a relatively high incidence of injuries resulting from surgical positioning, mainly PI. In this study, reactive hyperemia, a type hyperemia that is blanchable to finger pressure and that usually disappears in less than an hour, was considered, since the lack of pressure relief results in tissue ischemia or anoxia, thus causing PI (15) .

Conclusion
The ELPO applied in this study proved to be a valid and useful instrument for assessing the risk of developing injuries resulting from surgical positioning in adult perioperative patients at a rehabilitation hospital, as shown by the association of ELPO 1 and ELPO 2 with the appearance of injuries due to surgical positioning.
In clinical practice, the use of ELPO in rehabilitation hospitals will promote the improvement of perioperative care if it is included in a nursing care protocol aimed at the adequate and safe positioning of surgical patients.