RISK OF INJURY DEVELOPMENT DUE TO SURGICAL POSITIONING: AN OBSERVATIONAL STUDY

Risk


INTRODUCTION
In 2021, 4,203,024 surgical procedures were performed through the Unified Health System (Sistema Único de Saúde) in Brazil 1 .Regardless of the categorization into small, medium or large, surgeries involve multiple steps, and safe surgical positioning of the patient is essential, sometimes underestimated 2,3.Patient positioning should allow access to the surgical site, monitoring, ventilation, and medication administration.It is a multidisciplinary activity that requires knowledge of anatomy, physiology, pre-existing health conditions, technology, safety, possible risks and complications 2,4 .Among the complications, musculoskeletal pain, permanent loss of vision, nerve injuries and pressure injuries (PI) stand out. 3,5,6.
The development of lesions is related to intrinsic, extrinsic and specific intraoperative risk factors.The extrinsic factors are pressure, friction, shear, humidity and heat.Intrinsic factors are related to individual and clinical aspects of the patient, such as age, weight, nutritional status, comorbidities, physical status according to the scale of the American Society of Anesthesiologists (ASA), immobility, loss of sensitivity, reduced motor capacity, incontinence urinary or fecal infection, low hemoglobin levels, and surgical risk.Specific intraoperative factors include surgical position, anesthetic-surgical time, type of anesthesia, type of surgery, hypothermia and use of support surfaces [7][8][9][10][11][12] .
Identifying the risk of developing injuries supports care planning, decision-making, review of practices, adoption of appropriate care and strengthening of patient safety culture 12,13 .The Risk Assessment Scale for the Development of Injuries Due to Surgical Positioning (ELPO), the Munro Scale and the Scott Triggers Tool stand out as validated and reliable apenas na região sacra.Conclusão: Verificou-se maior risco para desenvolvimento de lesão em decorrência do posicionamento cirúrgico e baixa incidência de lesão por pressão.A enfermagem perioperatória deve incorporar à prática assistencial ferramentas validadas de mensuração de risco para um cuidado seguro, individualizado e de qualidade aos pacientes cirúrgicos.Hubo un mayor riesgo de desarrollar lesiones debido al posicionamiento quirúrgico y una baja incidencia de lesión presión.La enfermería perioperatoria debe incorporar herramientas validadas de medición del riesgo en la práctica asistencial para una atención segura, individualizada y de calidad a los pacientes quirúrgicos.
Risk of injury development due to surgical positioning: an observational study instruments for assessing the risk of perioperative injuries.12.The latter contains the patient's serum albumin value as a variable, a procedure not routinely performed in Brazil.
Concerning perioperative injuries due to surgical positioning, this study focuses on PI.It should be noted that PI is an indicator of the quality of care 14,15 associated with pain, increased length of stay, physical and emotional consequences, interference in social relationships and patients' quality of life, and the high institutional costs involved in the treatment 14,16 .
Although studies indicate incidences of PI due to surgical positioning ranging from 37.7 to 77% in Brazil 6,12 , with a more significant predominance of stage 1 lesions in the sacral and calcaneal regions, the research emphasizes the lack of knowledge about the prevention of PI by the perioperative nursing team 17 .
In this context, this study is justified for the expansion of the theme, identification of risk factors and risk score for injuries resulting from surgical positioning, planning and implementation of preventive strategies for PI by the perioperative nursing team and institutional management.Thus, it aims to classify the risk of developing injury by surgical positioning.

METHOD
An observational, longitudinal, prospective study with a quantitative approach, guided by the Strengthening the Reporting of Observation Studies in Epidemiology (STROBE) tool, carried out in the operating room and the surgical inpatient unit of a medium-sized hospital in the city of Rio de Janeiro (RJ), in July and August 2022.
Patients of both genders, aged 18 years or older, who underwent elective surgery were included in the study.Patients undergoing dental surgery were excluded.
For the calculation of the sample, the following were considered: incidence of injuries resulting from surgical positioning of 50%, the precision of 5% and confidence interval of 95% 12 , the average of monthly surgeries referring to the years 2019, 2020 and 2021 and the finite population of 190 surgeries, resulting in a total of 128 participants.The recruitment process was non-probabilistic.
For the recruitment of patients, the surgical map made available the day before the surgery, was consulted.With the identification of the patient and hospitalization unit, a research team member went to the respective bed to invite them to participate in the study, guide the research, and read and collect the signature of the Free and Informed Consent Form (FICF).Afterward, data regarding the sociodemographic and clinical characterization and the accuracy of the information confirmed in the medical record were collected.Weight and height variables were consulted on the daily map of the hospital nutrition sector.The body mass index (BMI) was calculated based on the parameters recommended by the World Health Organization (WHO): underweight (BMI < 18.5 kg/m 2 ), eutrophic (BMI ≥ 18.5 and < 25 kg/m 2 ), overweight (BMI ≥ 25 and < 30 kg/m 2 ) and obesity (BMI ≥ 30 kg/m 2 ).For older adults, the Lipschitz classification was considered: thinness (BMI < 22 kg/m 2 ), eutrophic (BMI 22-27 kg/m 2 ) and obesity (BMI > 27 kg/m 2 ).
Intraoperatively, data from the anesthetic-surgical procedure were collected.Physical status classification according to the ASA scale was extracted from the anesthetic chart.
The ELPO version 2 scale was applied immediately after the patient was anesthetized and positioned on the operating table and reapplied when there was a change in positioning, type of anesthesia and duration of surgery.The ELPO is a scale developed and validated in Brazil for assessing the risk of developing injuries due to surgical positioning.It has as variables surgical position, time, type of anesthesia, support surface, position of limbs, comorbidities and patient age.When delimiting the score of each item, the highest score corresponding to the answer should be considered.For example, for a diabetic and obese patient, only the obesity item with the highest score will be assigned a score 4 .
The scores can range from 7 to 35 points with those factors added together.The higher the score, the greater the risk.The cutoff points determined by the scale's authors were used to stratify the risk of developing injury due to surgical positioning (score up to 19 points, lower risk; and score equal to or greater than 20 points, higher risk) 4 .
Data collected on clinical variables were used to calculate the most prevalent comorbidities, predefined as cancer, diabetes, vascular disease, hypertension, neuropathy, venous thrombosis and other comorbidities.
Sé ACS, Oliveira EBS, Lima LLM, Oliveira RCS, Trivino GS, Lobato IS, Medeiros FM, Pestana LC, Gonçalves RCS, Gonçalves EF, Freitas VL In the postoperative period, to identify the development of PI, stomal therapist nurses evaluated the full extension of the patient's skin through inspection and palpation at three different times (24, 48 and 72 hours after the surgical procedure).For PI classification, the clinical guidelines recommended by the National Pressure Injury Advisory Panel (NPIAP) were adopted, with the following names: stages 1, 2, 3, 4, non-classifiable injuries, deep tissue and injuries related to medical devices.
The collected data were entered into the Microsoft Excel® program and analyzed using the Jamovi statistical software.
Categorical variables were analyzed using absolute and relative frequency distributions, and quantitative variables, using measures of central tendency (mean and median) and variability (amplitudes and standard deviation).Data were organized into contingency tables and submitted to Fisher's exact test or Pearson's χ 2 test and the odds ratio measure of association, as appropriate, to verify the association of sociodemographic, clinical and anesthetic-surgical procedure variables with the risk score.The significance level considered was 5% (α = 0.05).
This study was carried out following Resolution nº 466/2012 of the National Health Council, and the Research Ethics Committee approved the research project under opinion nº 5,492,043.

RESULTS
Some 136 patients who underwent elective surgical procedures met the criteria for inclusion in the study, with one being excluded at the time of data organization due to a need for more information in the data collection instrument.Thus, the final sample consisted of 135 participants.Of these, most were male, adults and self-declared brown, as shown in Table 1.
Participants aged 60 years or older were classified as elderly.The average length of stay of the patient in the operating room was 2 hours and 47 minutes (standard deviation -SD = 1h34min), a minimum of 45 minutes and a maximum of 9 hours and 28 minutes, with the average duration of the anesthetic-surgical procedure being 2 hours and 29 minutes (SD = 1h32min), a minimum of 34 minutes and a maximum of 9 hours and 28 minutes.
The analysis of age groups identified higher risk scores in the elderly compared to adults (Fig. 1).
The fact of being elderly increased by 9.47 times the probability of being classified as a higher risk for the development of injury resulting from surgical positioning, as well as patients with systemic arterial hypertension (SAH) and diabetes mellitus (DM), with an increase of 3.07 and 2.47 times more likely to be classified as at higher risk for injury, respectively, according to Table 4.
Of the 135 participants, 39 (28.89%) remained hospitalized after the surgical procedure for more than 72 hours.
Regarding the length of stay of the others, 16 (11.85%)were discharged within 24 hours after the surgery, 55 (40.74%) between 24 and 48 hours and 25 (18.52%)length of stay over 48 hours and less than 72 hours.Notably, of the participants classified as higher risk (ELPO), 49 (70%) were discharged before 72 hours.
The development of PI due to surgical positioning was observed in only one participant (0.74%), adult, brown, eutrophic, ASA III, classified as lower risk (ELPO), submitted to general and regional anesthesia to perform resection of the neoplasm in the kidney.The lesion was observed on the third postoperative day, in the sacral region, in stage 1.

DISCUSSION
The results identified a more significant number of male, adult and brown participants, as a survey carried out with surgical patients in Ceará 13 and divergent from studies carried out in the States of Minas Gerais 12 and Bahia 18 .
Concerning the risk of developing injuries resulting from surgical positioning, there was a prevalence of patients classified as higher risk, with higher scores in the elderly population, but age should not be considered an isolated risk Risk of injury development due to surgical positioning: an observational study factor for the occurrence of injuries of the skin, with different results described in the literature regarding the ELPO risk score, prevalence of P I and age group 6,18 .
Regarding body composition, both age groups showed alterations: mostly overweight and obese adults; and the elderly at the extremes of obesity and thinness.Low weight contributes to the accentuated exposure of bony prominences 8 ; the increase in adipose mass can compress blood vessels, reduce tissue perfusion and favor the appearance of lesions 3 .In this study, patients with altered or eutrophic BMI did not present statistically significant differences in risk classification for developing lesions, contrary to findings in another Brazilian study 6 .An integrative review highlighted divergences between body composition and the occurrence of PI in adults and the elderly.Still, it emphasized that more body fat may be a protective factor for the elderly, and a reduction in body water may be associated with a greater risk of developing lesions 19 .
Most patients were classified as ASA II, as well as other studies with elective surgical patients 6,7,12 , but unlike patients who underwent cardiac surgery, classified as ASA III 18 , according to the mild or severe systemic diseases presented at the time of the preoperative evaluation 20 .
Still, on health status, the most prevalent comorbidities were SAH, cancer and DM.There was a statistically significant difference between the risk of developing a lesion resulting from surgical positioning and SAH and DM.These comorbidities increased the probability of being in the highest-risk group and, consequently, developing injuries.This finding corroborates an American research, which pointed out that the probability of developing PI in hypertensive patients increased 28 times compared to non-hypertensive patients.10,and meta-analysis indicated twice the probability of developing PI related to surgery in diabetic patients 21 .
As it is a general hospital, the specialty of general surgery performs the largest number of surgical procedures.A statistically significant difference was found for a lower risk of developing a lesion in patients at the referred clinic and for a higher risk in urology patients.It is assumed that the findings are related to the lithotomy position, which is more used in urological procedures when compared to general surgery, with a higher prevalence of the supine position.Surgical positioning is a risk factor for developing injuries, each with specific pressure points. 17 the ELPO scale, lithotomy is the position with the highest risk score4, which may cause nerve damage (obturator, lateral femoral cutaneous, sciatic, peroneal and femoral), deep venous thrombosis and compartmental syndrome of the lower limbs 7 .In this study, the supine position was the most adopted, according to other studies, whose results ranged from 71.50 to 100% 6,18 , and unlike another study that identified the Trendelenburg positioning as the most prevalent, in 43.2% of patients 12 .
It is up to the multidisciplinary team involved in perioperative care to position the patient to allow access to the surgical site, in addition to comfort, privacy, physiological alignment, body stabilization, and support of extremities and joints, with minimization of pressure points 5 .
Regarding anesthesia, general anesthesia combined with regional anesthesia was the most prevalent, exposing patients to the risk of developing PI due to immobility, blockage of pain sensitivity in pressure areas, increased pressure in places of bony prominence, occlusion of blood flow and tissue ischemia 5,8 .
The most used support surface was a foam mattress and cotton cushions, mainly in the occipital region, in a circular shape, made manually with a bandage of crepe and cotton.This result differed from that described in a Brazilian study, with the use of a viscoelastic polymer mattress in 100% of the patients. 18e support surfaces are mattresses, overlays or pillows made of gel, viscoelastic polymer or foams, to redistribute body pressure and control shear and tissue friction 12,22,23 .
Despite the consensus on the importance of using support surfaces in surgical patients to prevent complications such as PI and compartment syndrome, studies show disagreement regarding the effectiveness of certain materials in the distribution of interface pressure, characterized by compression of soft tissues at the interface between prominences bone and surgical surfaces, making clinical decision-making difficult for the selection of the most appropriate resource [22][23][24] .
Sé ACS, Oliveira EBS, Lima LLM, Oliveira RCS, Trivino GS, Lobato IS, Medeiros FM, Pestana LC, Gonçalves RCS, Gonçalves EF, Freitas VL A recent systematic review found no statistically significant difference between the standard operating table mattress and low-technology support surfaces.Still, the opposite was observed compared to high-and low-technology support surfaces, with high technology being more effective 25 .
It is noteworthy that the varied terminologies referring to supplies, lack of institutional protocols, political issues, deficit of economic resources and lack of knowledge of managers and professionals about the products can hinder the availability of support surfaces for surgical patients 12,23,24 .
The opening of the upper limbs smaller than the 90º angle was the most adopted position of the limbs, widely used for non-invasive pressure monitoring and administration of fluids, medications and blood components.It should be ensured that the angle used in this study is maintained, minimizing the occurrence of nerve injuries.The cuff should be positioned at the height of the operating table to avoid straining the brachial plexus, and the patient's arms should be aligned with the palms facing upwards to decrease pressure on the ulnar nerve 5,17 .
The average anesthetic-surgical time was 149 minutes, lower than that of the research carried out in Brazil, with an average time of 202 minutes6, and that of the survey in North America, with an average time of 365 minutes 9 .Anestheticsurgical time is significant for the development of lesions due to the risk of tissue damage; for each additional hour of surgical time, the risk of developing PI increases by 48% 9 .
It was identified, in only one participant, the occurrence of PI as a result of surgical positioning.The literature highlights that PI can be observed from the immediate postoperative period to five days after surgical positioning 6,7 .
However, 71.11% of patients were discharged before 72 hours postoperatively, making it impossible to identify possible other injuries.
Failure to follow up with patients classified as being at greater risk for developing injuries due to surgical positioning implies underreporting of injuries, failure in early identification and adequate treatment.In an American outpatient surgical unit, patients with a higher risk of skin lesions are guided and followed up after hospital discharge.The possible body areas that suffered pressure during surgical positioning and post-anesthetic recovery are highlighted, and, in the presence of alterations related to skin color, appearance, consistency and temperature, pain and/or itching, contact with the health unit is indicated 7 .
Finally, it is emphasized that the perioperative nursing team has an essential role in protecting the skin of patients 9 through preoperative assessment for risk classification of injuries related to surgical positioning, use of support surfaces for pressure redistribution, application of prophylactic dressings in areas subject to pressure, friction and shear, safe practices for surgical positioning and follow-up of the patient in the postoperative period to identify the lesion 5 .
Limitations of the study include the impossibility of following up with all patients in the postoperative period for 72 hours due to hospital discharge to identify the development of PI through surgical positioning; and the association of the outcome with risk scores.

FINAL CONSIDERATIONS
The study identified the prevalence of male patients, adults, self-declared brown, with altered BMI and classified as ASA II.Regarding the risk of developing perioperative injury due to surgical positioning, the majority presented a higher risk.Age equal to or greater than 60 years, hypertension, DM and urological procedures were statistically significant risk factors for developing lesions.There was a low incidence of PI due to surgical positioning.As a result of hospital discharge, most patients could not be followed up within 72 hours of the postoperative period to identify possible injuries.
Identifying the risk of developing injuries due to surgical positioning is the first strategy for clinical decision-making and implementing preventive care for injuries related to the perioperative period, minimizing impacts on patients' health and quality of life, emotional distress, pain, length of stay and hospital expenses.The perioperative nursing team should incorporate validated risk measurement tools into care practice for individualized, safe and quality care.

Table 3 .
Distribution of study participants (n = 135) according to the variables of the Risk Assessment Scale for the Development of Injuries Due to Surgical Positioning, Rio de Janeiro (RJ), Brazil, 2022*.
*Systemic arterial hypertension was computed as a vascular disease; the options Trendelenburg position, local anesthesia and support surface viscoelastic mattress + viscoelastic cushions were omitted because they were not observed.

Table 4 .
A risk score of the Risk Assessment Scale for the Development of Injuries Due to Surgical Positioning (ELPO) and clinical, sociodemographic and surgical specialty variables, Rio de Janeiro (RJ), Brasil, 2022.The risk score of the Risk Assessment Scale for the Development of Injuries Due to Surgical Positioning (ELPO) by age group, Rio de Janeiro (RJ),Brasil, 2022.
*statistically significant result (p ≤ 0.05); ...: numerical data is not applicable; # χ 2 test; @ Fisher's exact test; $ data not presented in the contingency table, which makes the calculation impossible; BMI: body mass index.