Assessment scale of risk for surgical positioning injuries 1

ABSTRACT Objective: to build and validate a scale to assess the risk of surgical positioning injuries in adult patients. Method: methodological research, conducted in two phases: construction and face and content validation of the scale and field research, involving 115 patients. Results: the Risk Assessment Scale for the Development of Injuries due to Surgical Positioning contains seven items, each of which presents five subitems. The scale score ranges between seven and 35 points in which, the higher the score, the higher the patient's risk. The Content Validity Index of the scale corresponded to 0.88. The application of Student's t-test for equality of means revealed the concurrent criterion validity between the scores on the Braden scale and the constructed scale. To assess the predictive criterion validity, the association was tested between the presence of pain deriving from surgical positioning and the development of pressure ulcer, using the score on the Risk Assessment Scale for the Development of Injuries due to Surgical Positioning (p<0.001). The interrater reliability was verified using the intraclass correlation coefficient, equal to 0.99 (p<0.001). Conclusion: the scale is a valid and reliable tool, but further research is needed to assess its use in clinical practice.


Introduction
Surgical positioning is a relevant procedure, executed by all professional involved in patient care (nursing, anesthetic and surgical team) during the intraoperative period. Therefore, the patient's particularities should be taken into account, as well as the surgeon's preferences for the best exposure of the surgical site, the surgical technique to be applied and access needed for medication administration and the patient's monitoring and ventilation by the anesthesist. Hence, the implementation of interventions based on recent evidence is crucial to guarantee safe and comfortable surgical positioning, with a view to preventing complications in the tegumentary, neurological, vascular and respiratory systems (1)(2)(3) .
In this context, perioperative nurses' activities are fundamental. These professionals should be familiar with the anatomic and physiological alterations the surgical positioning and the equipment and devices available to be of help in the execution of the procedure cause in the patient's organism, permitting the planning and implementation of effective interventions to guarantee the prevention of complications that can arise due to the prolonged stay of the patient in each type of surgical position (4) .
The main complications related to surgical positioning include musculoskeletal pain, skin and peripheral nerve injuries and compartment syndrome (4) .
Studies have been published in the literature about the occurrence of injuries deriving from surgical positioning.
In a descriptive study to identify the risk factors for the emergence of this type of lesion, the results evidenced that, in the research sample (n=50), 74% of the patients were affected by pressure ulcer (stage I) (5) .
In another study, the results indicated that, out of 172 participants, 12.2% were affected by surgical positioning injuries, and five patients presented more than one type of injury (26 injuries in total), that is: 9.9% patients referred severe pain in pressure points, 4.7% suffered peripheral nerve injuries and 0.6% erythema (6) .
In the literature, there is a lack of data on the incidence of peripheral nerve injuries due to surgical positioning. In a descriptive study, including 2,304 patients submitted to colorectal surgery, 0.3% presented this type of injury, five of whom underwent open surgery and three minimally invasive procedures (videolaparoscopy) (7) .
At the health services, the use of a risk assessment scale can help the nurse to identify factors predisposing to the development of injuries and the implementation of prevention measures and, consequently, to the improvement of health care (8) .
To offer support through research that contributes to improve care delivery to surgical patients, in this study, the objective was to construct and validate a risk assessment scale for surgical positioning injuries in adult patients. To collect the data, besides the application of the ELPO (version 2), the following tools were used: tool 1 (built by the researchers) to register pre and postoperative information, which contained data on the patient identification, skin inspection and pain records.

Method
To measure the pain intensity, the Numerical Scale was employed and, to assess the risk of developing pressure ulcer in the preoperative phase, the Braden Scale was adopted.
The Braden scale is used to assess the risk of developing pressure ulcer in the global context. This scale consists of six domains: sensory perception, humidity, activity, mobility, nutrition, friction and shear. In this study, the version Paranhos adapted to Brazil in 1999 was employed. The participants were classified according to the Braden scale score for the risk of pressure ulcer, as follows: very high risk (patient scoring nine or less), high risk (patient scoring equal to or between 10 and 12), moderate risk (patient scoring 13 or 14) or at risk (adult patient scoring 15 or 16 and elderly patient scoring 17 or 18) (9) .
Before the data collection, the nurse invited for the inter-rater reliability phase of the scale was trained.
Then, a pretest was undertaken with 10 patients (not included in the sample) to adapt the dynamics of the data collection, which happened in the first semester of 2013 and took five months.
The data were collected as follows: preoperative period -after confirming the surgery schedule, the patient was selected based on the inclusion criteria. To calculate the Content Validity Index (CVI), th number of answers to the subitems scored as 4 (I agree) and 5 (I completely agree) was added up for all scale items and divided by the total number of answers the experts had provided (10) .   In the predictive criterion validity, the comparison of the mean ELPO (version 2) scores between the groups in pain due to the surgical positioning and without pain showed a difference by more than three points (group with pain, higher average), which was statistically significant (p<0.001). In addition, in the logistic regression analysis with a 95% confidence interval, adopting the presence or not of pain as the outcome and the ELPO scores as the predictor, the odds ratio corresponded to 1.28 (OR=1.28), that is, for each additional point on the ELPO, the patient's chance of pain due to the surgical positioning increases by 28%.
The mean ELPO (version 2) score in patients who did not develop PU amounted to 18.55 and, for patients who developed this type of injury, to 23.08, that is, a difference by almost five points between the groups, with statistical significance (p<0.001). The logistic regression analysis indicated an odds ratio of 1.44 (OR=1.44), which means that, for each additional point on the ELPO, the chance of developing PU increases by 44%.
In the comparison of the ELPO (version 2) scores, assessed by the two independent raters (researcher and invited nurse), the minimum, maximum and means were identical between the observers and the variance amounted to 14.81 and 14.58, respectively. Adopting a 95% confidence interval, the ICC corresponded to 0.994 with p<0.001, that is, statistically significant and considered excellent (11) .

Discussion
In the preoperative phase, the use of assessment scales that include internal and external risk factors for the emergence of injuries can help the nurse to identify patients at higher risk. Through the use of this tool, this professional can plan the implementation of effective solutions in the intraoperative period (e.g. the use of effective pressure relief devices) to prevent the patient from suffering injuries due to surgical positioning (12) .
Based on the international and Brazilian literature, there is a lack of studies on risk assessment scales for the development of injuries due to surgical positioning.
Hence, the elaboration of the ELPO was based on recent evidence and its development covered aspects related to different injuries the perioperative nurse can assess. In addition, the selection of the items included in the scale follows expert recommendations on the theme (4,6,(13)(14) . Lopes CMM, Haas VJ, Dantas RAS, Oliveira CG, Galvão CM.
The comparison between the CVI calculated for the ELPO with another recent study (15)  To assess the predictive criterion validity in this study, the types of injuries investigated in relation to the patient's surgical positioning were the presence of pain (6) and the development of PU (9,14,16) . The results indicated that higher ELPO scores predict the presence of pain and the occurrence of PU, that is, patients with higher ELPO scores have a greater chance of presenting pain and developing postoperative PU due to the surgical positioning.
In that sense, perioperative nurses' application of the ELPO to adult patients can support nursing care planning, guiding intraoperative actions to prevent pain due to the surgical positioning and PU.
The inter-rater reliability analysis demonstrated almost identical results for the two observers in the application of the ELPO. The reliability or trustworthiness of a quantitative measure is one of the main criteria to assess its exactness (11) .

Recommendations for the use of ELPO in clinical practice
The ELPO is a simple scale that is easy to apply. To use it, the nurses should be familiar with its items and subitems in order to speed up the registration of the scores during its intraoperative application. To enhance patient care during surgical positioning, educative programs for nursing, anesthesia and surgical teams are recommended, addressing the best practices for this procedure, including a preoperative visit to get to know each patient's particularities and provide for the support devices and surfaces needed for the surgical positioning the patient will remain in during the intraoperative period.
Concerning the study limitations, the application of the ELPO was restricted to a single hospital. Therefore, further research is needed to assess its use in clinical practice, which will offer support to verify whether the use of this tool can promote positive results in the prevention of injuries due to surgical positioning.

Conclusion
The ELPO is a valid and reliable tool to assess the