Clinical REVIEW Pressure risk during the perioperative period focusing on duration and hypothermia The perioperative period for many patients may be the time when they are at highest risk of developing pressure . The author’s literature search identified 24 risk factors which may be contributory factors to pressure ulcer development in the perioperative period. This article focuses on the evidence surrounding surgery duration and hypothermia. Although the findings of the studies reviewed are limited, they highlight the need for preventive interventions to limit these risks. The author concludes that pressure ulcer prevention must be a major concern for staff working in theatres.

Joan Rogan

ulcers as there are other causative equipment used (Stevens et al, 2004). factors. A literature review produced It is not certain how effective risk KEY WORDS a large volume of studies which assessment tools are as different Pressure ulcers identified a number of risk factors studies have found them to be both Risk factors in addition to pressure which may effective and ineffective at predicting Duration of surgery have an impact on the development risk (Flanagan, 1995; Lewicki et al, 1997; Hypothermia of pressure ulcers. Kelley (1995) Karadag and Gumuskaya, 2003). Only suggests pressure ulcers which begin one risk assessment tool (Waterlow, in the operating room have a more 1994) includes surgery as a risk factor complex aetiology than those in for pressure ulcers. medical patients, due to circulatory he perioperative period may and metabolic changes which occur This article will review two risk be the time for many patients during surgery. factors associated with surgery — Twhen they are at most risk of duration of surgery and hypothermia. developing pressure ulcers. It is unclear Risk factors identified can be from the literature what percentage divided into two groups: those which Duration of surgery of pressure ulcers actually begin in are in existence before surgery such as In order to cause ischaemia, the operating theatre. The preoperative comorbidities, advancing external pressure must exceed ranges from 8.5% (Aronovitch, 1999), age, , smoking (Papantonio et capillary pressure to obstruct blood to 66% (Versluysen,1986). Although al, 1994), peripheral vascular disease flow. The threshold pressure at several studies have suggested that the (Hoshowsky and Schramm, 1994), which capillaries close is frequently risk of pressure ulceration is greater in poor nutritional status, low body quoted as being 32mmHg (Landis, older patients, a study by Aronovitch weight, low serum albumin and total 1930). However, this is misleading (1999) demonstrated a 9.3% incidence protein levels (Kemp et al, 1990); as the study involved young healthy in patients between the ages of and those which occur as a direct students who would not compare 20 and 40 years. result of surgery such as immobility with older or frailer patients. Ek et (Schoonhaven et al, 2001), tissue al (1984) identified pressures as low The Department of Health (1993) tolerance (Scott, 1998), interface as 11mmHg being capable of causing defines pressure ulcers as areas pressure (Nixon et al, 1998), shear, capillary closure. In addition, during of skin discolouration or damage friction (Defloor, 1998), intensity and surgery many patients are placed which persists after the removal of duration of pressure (Schoonhaven et in anatomically unnatural positions, pressure and which are likely to be al, 2001), hypothermia (Scott, 1998), such as the ‘fossa’ position where due to the effects of pressure on the (Kemp et al, 1990), the patient is seated at an 80º angle tissues. This definition would seem extra corporal circulation (Lewicki with the head and leaning to be only partly true in relation to et al, 1997), type of anaesthesia against the operating table, which can interoperatively-acquired pressure (Bliss and Simini, 1999), surgery type put additional pressure on areas that (Aronovitch, 1999) drug would not normally be accustomed to Joan Rogan is Tissue Viability Nurse, Belfast City Hospital (Schoonhaven et al, 2002) and weight-bearing.

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Although high interface pressure is an having a lesser pressure-reducing ability, repositioning patients every two to important factor, the length of time spent the total pressure reducing ability of the three hours to prevent pressure ulcer on the operating table may also play a operating room table pad was decreased, formation. They interpreted this as significant part. Duration is determined by thus a higher pressure was obtained an indication that the likelihood of the length of the surgery. An early study creating a negative effect (Campbell, 1989). developing pressure ulcers in the by Kosiak in 1959 identified that low first three hours of surgery would pressures over a long period of time as The following studies included duration be small. well as high pressures over a short period of surgery as a possible risk factor for of time could lead to pressure damage. pressure ulcer development — Campbell The mean average age of the (1989); Kemp et al (1990); Hoshowsky and patients was 61 years (range 15–89 Scott (2005) states a patient lying on Schramm (1994); Papantonio et al (1994); years). Duration of surgery ranged a hard surface will get pressure damage Grous et al (1997); Lewicki et al (1997); from four to more than 9 hours. sooner than if he or she was lying on a Aronovitch (1999); Schoonhaven et al The patients’ skin was assessed softer surface. The standard theatre table (2002), and Stevens et al (2004). However, preoperatively and every day post- has a thin mattress and a hard surface none of the studies assessed duration of operatively for 14 days. In order which means the patient’s body weight surgery as an exclusive factor. to enhance the reliability of the has to be distributed over this small area, observer’s data was not collected resulting in high interface pressures. In Schoonhaven et al (2002) by the nurses caring for the patients addition, Campbell (1989) demonstrated conducted a clearly defined study but by the researcher and three the practice of placing sheets and drapes involving 208 patients from nine observers. Training had been given under the patient can increase the specialties who had surgery which to the researchers and inter-rater total amount of pressure by 16mmHg. lasted in excess of four hours. The reliability was assessed as being The operating room table pad was authors choose this duration time high. The observers were trained determined to provide a certain amount to reflect the recommendations of in data collection especially in the of pressure reduction. As each layer of the Panel for the Prediction and observation of pressure ulcers cloth or material was added (turn sheets, Prevention of Pressure Ulcers in according to a named classification incontinence pads, warming blankets) each Adults (1992) which recommended (Haalboom et al, 1997).

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In this study group 21% (n=44) ulcers who underwent surgery lasting years with an average age of 51.8 of patients developed a total of 70 6–7 hours fell to 7.4%. This outcome years (m=4; f=1). The author did not pressure ulcers within 48 hours of may not be statistically significant and identify any comorbidities other than surgery. These varied in severity could be attributed to other variables the patients required . from grade one (23 patients) to within each individual patient. As in The types of surgery are not recorded. necrosis (two lesions). This study also the Schoonhaven et al (2002) study, The post anaesthesia sacral readings highlighted the presence of atypical the majority of ulcers were stage increased on average 27.5% over the lesions which other authors have one (76%) with 16% being stage two pre-anaesthesia sacral readings and acknowledged as arising post-surgery and 8% being ungradeable. There are increased 30–35% in the post-surgery (Vermillion, 1990; Scott, 2005). Thirty- limitations to this study as the author phase. The difference was determined four patients developed lesions which does not indicate if training had been by the duration of the surgery. If it was did not fit the description of pressure given and the inter-rater reliability had less than 2.5 hours the average reading ulcers as defined in the literature. The not been assessed. They also did not was a 30% increase, if more than 2.5 authors describe these as being bright mention the grading system used. hours the average increase was 35%. red with sharply defined borders This indicated that the duration of which blanched to light pressure. In a retrospective study, Stevens et surgery was a definite risk factor. While In some patients they caused pain al (2004) identified pressure ulcer risk this is a small study its outcomes are and numbness and despite pressure factors from 382 charts of patients still concerning. relief, lasted 13–21 days. These who had specifically undergone varying were excluded in the study analysis. urological surgery during the previous Hoshowsky and Schramm (1994) A number of patients developed 10 years. The mean age was 47 years in a prospective study involving 505 pressures ulcers which were preceded (range 11–73 years). Duration of patients assessed a number of variables by blanchable erythema. Of these, 11 surgery varied from 30 minutes to which included comorbidities, type of became stage one lesions and three 21.55 hours. Fifty-five patients (14.4%) operating table surface and duration became stage two lesions. A total developed pressure ulcers, the majority of surgery. The authors used a points of 23 grade two lesions were not of which (64%) were grade one. The system analysis tool (Hemphill, 1986) preceded by blanchable or stage one authors concluded that there was which expressed in terms of odds ulceration. These results challenge an increased risk of pressure ulcer ratios the likelihood of the different the assumption that non-blanching development associated with duration variables (along with the patient’s erythema is a ‘safe’ observation of surgery and lateral positioning. general condition) to affect the (Schoonhaven et al, 2002). development of pressure ulceration. Campbell (1989) conducted a small The mean age was 47 years (range While the authors observed an project study involving five patients 13–86 years). Eight surgical types were increase in pressure ulcer development undergoing vascular surgery. Her main identified. Duration of surgery was corresponding to the duration of objective was to measure anatomical recorded as being less than one hour surgery, the pattern is not entirely pressure points at different operative for 28.7% (n=145) of the subjects, 1–2 conclusive — 4.8% developed lesions stages. The author measured the hours for 29.9% (n=151), 2–4 hours for following 5–6 hours surgery; 19% patients while in the supine position 26.5% (n= 134), 4–6 hours for 10.5% following 6–8 hours surgery and 47.6% at three different stages of their inter (n=53), 6–8 hours for 3.2% (n=16) to following surgery that lasted more than operative period — pre-anaesthesia, greater than eight hours 1.2% (n=6). nine hours. The number of patients post-anaesthesia and on completion One author performed preoperative who developed lesions following 8–9 of surgery before being transferred assessments and the other carried out hours of surgery actually decreased from the operating table. Using a postoperative assessments. to 9.5%. This would correspond to Gaymer® pressure gauge, pressure figures identified in an earlier study by points were measured on the occipital, Patients were assessed immediately Aronovitch (1999) which reviewed scapulae, thoracic spine, sacrum and postoperatively and only 16.8% (n=85) 1,128 patients nationwide, who both . Each pressure point was patients developed stage one lesions. underwent surgery lasting in excess of to be measured twice in each of the Of all the variables assessed, the one three hours. three phases and an average recorded. single predictor of pressure ulceration However, only the sacral reading was was surgical duration — 2.5–4 hours In this study 11 surgical specialties monitored in phase 3 (immediately doubled the risk; greater than four were represented. The percentage of post-surgery) as the patients could not hours tripled the risk. The risks were patients developing ulceration following be turned enough times to obtain the increased in the presence of vascular 3–4 hours surgery was 5.8%; 4–5 other readings. disease and when the patient was aged hours was 8.9%, 5–6 hours 9.9% and over 40 years. 13.2% in patients undergoing surgery Five patients all undergoing vascular lasting in excess of seven hours. The surgery below the waist were included While detailing other variables, number of patients developing pressure in the study, aged 54 years to 72 the authors identified that duration

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of surgery was significantly associated specified. In this study group, 27.2% et al, 2001). The studies identified two with the development of pressure (n=37) developed ulcers, 43% (n=16) methods of maintaining normothermia ulcers. Other studies do not confirm of which remained grade one, while during surgery; a forced air warming this relationship (Kemp et al, 1990; 57% (n=21) progressed to grade system and an under blanket system. Papantino et al, 1994; Grous et al, 1997; two and three. Surgical duration time Grous et al (1997) suggested that Lewicki et al, 1997). varied from less than five hours to warming blankets or devices placed 16.75 hours. The mean time for those under the patient inter-operatively Three studies assessed patients developing ulcers was six hours and stimulated increased blood supply specifically undergoing . the number of lesions did not increase to tissues already compromised by In a prospective study by Kemp et al with duration (figures were not increased pressure. This increased (1990) 125 patients were assessed for specified). The authors concluded blood supply results in a compromised a number of risk factors. Mean age was that duration on its own was not a vasodilatory response that may hasten 58 years (range 23–84 years). Fifteen risk factor. tissue damage. Campbell (1989) patients (12%) developed a total of 23 suggested that higher temperatures pressure ulcers. Six were grade one, A small study by Grous et al results in increased metabolic activity six grade two and one grade 3. Grade (1997) involving 33 patients from five which in turn produces increased waste one ulcers were defined as areas of surgical specialties undergoing a surgical products, thereby adversely affecting erythema which did not resolve after duration period in excess of 10 hours peripheral perfusion. A 1°C rise in skin 30 minutes. Lewis and Grant (1925) did not find duration significant. The temperature causes a 10% increase reported that hyperaemic reaction was average length of surgery was 17 hours in tissue metabolism (Fisher et al, proportional to the duration of the with a range of 10–33.5 hours. This 1978). If the circulation to the tissue occlusion, lasting half to three-quarters study will be discussed later in relation is already compromised the further of the occlusion time. This might to hypothermia. demand for oxygen and nutrients may indicate that grade one ulcers may be unsustainable and lead to increased have been over-predicted as duration The outcomes of these studies are susceptibility to ischaemic injury (Fisher of surgery varied from 45 minutes contradictory. The main reason is the et al, 1978). to 22 hours. The average length populations that were being studied. of surgery for those patients who Differing surgery types, age groups, The aim of this descriptive study by developed pressure ulcers was eight (some included children) and also the Grous et al (1997) was to identify risk hours and several patients (numbers varying interpretation of stage one factors contributing to pressure ulcer not specified) developed ulcers after scores have resulted in the studies development in patients undergoing two hours. Using discriminate analysis, being largely incomparable. prolonged surgery, defined as lasting in the authors found length of surgery excess of 10 hours. The emphasis was alone was not a risk factor. However, Hypothermia on the effects of the warming devices when combined with advancing age Hypothermia is a major risk factor placed beneath patients during surgery. and extra corporeal circulation, it did associated with significant morbidities. It was a small study of 33 patients, become a risk factor. The surgical patient is very much at who the authors described as being risk of developing this condition due to ‘generally healthy’. Their age range Lewicki et al (1997) studied 337 the effects of anaesthesia, preoperative was 14–76 years with a mean age of patients also undergoing cardiac fasting, preoperative sedation and 53.5 years. Preoperative Braden risk surgery. The mean age was 62 years exposure (McNeil, 1998). In an attempt assessment scores ranged from 17–23 (range 22–86 years). Of these patients, to maintain core temperature, the with a mean of 21.9 indicating low 4.7% (n=16) had developed a total of body’s natural reaction is to constrict risk for pressure ulcer development. 22 pressure ulcers. Thirteen were grade the peripheral blood vessels supplying Comorbidities were not determined. one and five grade two. Four were the skin but consequently, reducing the Five surgical specialties were involved atypical and were not included in the oxygen, nutritional and waste metabolic in the study. The majority of the study. The average duration of surgery activities to the skin. This, combined patients (n=28) were in the supine for patients developing pressure ulcers with unrelieved pressure, may in itself position. The other positions used was 6.21 hours compared with 6.02 present a risk factor for pressure ulcer were lateral, lithotomy and jack-knife. hours for those who did not develop development. Various procedures are Devices used in an attempt to maintain ulceration. The authors therefore used to try and maintain normothermia. normothermia varied from warming concluded that duration of surgery was Warming therapy would appear to be a blankets to stabilising positioners placed not a significant risk factor. frequent choice. under the patients. Two patients had no devices. Warming blankets were Papantonio et al (1994) studied Two studies specifically looked at used for 20 patients (67%). Skin was 136 adult patients undergoing cardiac the relationship between hypothermia assessed preoperatively and at 48 surgery. The mean age of the subjects in surgical patients and pressure ulcer hours postoperatively by one of the was 61.9 years with the range not development (Grous et al, 1997; Scott assessment team.

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Fifteen patients (45%) developed was occipital, and while these are skin. The ulcers were positioned on at least one pressure ulcer. Eight had most likely due to pressure, they are the sacrum (n=12), (n=9) and grade one and seven had grade two not in an area that would be affected buttock (n=5). The researchers found in varying locations. Nine were on the by a warming blanket. The authors’ a significant correlation between small buttocks, two on the sacrum, one on recommendation was that warming body size (based on BMI) and the the scapula, one on the anterior chest blankets should not be used during lowest core temperature suggesting wall, one on the right ear and one was surgery. Given the potential morbidity that body fat had an impact on the occipital. The authors used the National associated with hypothermia, this maintenance of body temperature. Pressure Ulcer Advisory Panel (1989) statement should be rephrased so that Significantly a greater number of grading, but also stated that the lesions other methods could be considered. patients receiving general anaesthesia had the appearance of ‘surgical burns’. (10.4%; n=19) developed pressure All ulcers were noted within 48 hours The aim of a prospective, ulcers compared with those receiving of surgery. Of the 15 patients who randomised control trial by Scott et al regional anaesthesia (4.4%; n=6). In developed pressure ulcers 75% had in 2001 was to determine if there was general, older patients were more used warming blankets. The authors did a correlation between hypothermia likely to develop pressure ulcers, but not identify any other significant factors and pressure ulcer development. The this was not statistically significant in predicting pressure ulcer formation. study involved 324 patients (41–89 (p=0.27). The duration of surgery was They felt the negative outcomes years) who were randomised into not found to be significant. This was a produced by the warming blankets two groups. Group one received the clearly designed study with significant necessitated the discontinuation of the standard perioperative care and group outcomes not only in favour of using trial, advocating that warming blankets two the standard perioperative care this method of warming therapy should not be used. plus a warming therapy system as during surgery but also showed its well as their IV fluids being warmed. ability to reduce the incidence of A number of questions have arisen Both groups had similar characteristics. pressure ulcers. about the validity of this study. First, the Based on the findings of previous numbers involved in the study were authors, the researchers decided not Summary small (33 patients). While the patients to use an under blanket, but chose Campbell (1989) describes the were said to be healthy it would a forced air over-blanket. All patients interoperative period for many appear that a significant number had were scheduled to undergo major patients, as being the time that they a diagnosis of cancer given that the surgery, defined as necessitating at least are at the highest risk of developing main surgery type was related to head a five-day postoperative stay in hospital. pressure ulcers during their entire and neck cancer (67%). The duration Five surgical specialties were identified. hospital stay. The number of risk of surgery time (the longest was 33.5 Comorbidities relating to peripheral factors identified would confirm that hours) would indicate that very major vascular disease, diabetes, heart disease statement. Unfortunately the author interventions were involved. It is also and smoking were identified, as was could not identify a consensus on the not clear from the study if the same body mass index. Duration of surgery predictive risks for inter-operative warming device was used uniformly. varied from 45–365 minutes (6 hours). pressure ulcer development from the While the patient’s skin was assessed Core temperature was measured by studies reviewed. This is because the both pre- and postoperatively by tympanic thermometers, described by various researchers have used different one of the assessors, there is nothing the authors as being the most accurate. study designs mostly concentrating on to identify whether it was the same Patients were followed-up for five days a number of different variables rather assessor and what their knowledge postoperatively and their skin assessed than one specific risk factor. They have base, inter-reliability skills were, nor if by the principle researcher, who was also used different pressure ulcer they were blinded. There is no record blinded to the treatment group, on days classifications and incomparable patient to state what type of mattress the one, three and five. The study omitted groups. While the methodology in some patient was nursed on postoperatively to record if any other pressure-relieving studies has been very precise, it is less and if the patient was able to be equipment had been used. so in others. The quality and experience repositioned. It is possible that some of those making the skin assessments in of these lesions could have developed The study found the incidence of some studies have raised questions to during this period and therefore not pressure ulcers almost halved through the validity of the recorded outcomes. have been directly as a result of the the use of warming therapy. In total 8% This has resulted in inconclusive results warming blanket. The location of (n=26) of the study group developed with no preoperative or interoperative some of the lesions in relation to the pressure ulcers; 65.4% (n=17) in factors being indisputably linked to positions used do not totally correlate. the standard group, 34.6% (n=9) in pressure ulcer formation during surgery. One was on the anterior chest wall the warming group. Ulcers were not which may suggest that it could have graded, but defined as persistent The one agreement is pressure been caused by an ECG lead. One (lasting in excess of 24 hours) non- ulcer development in the perioperative lesion was on the ear and the other blanching erythema or a break in the period is a serious problem which

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Defloor T (1998) The risk of pressure sores; a patients. Part 2: Self learning package. Br J conceptual scheme. J Clin Nurs 8: 206–16 Theatre Nurs 8(5): 25–33 Key Points Defloor T, De Schuijmar JDS (2000) Morrison M (2001) The Prevention and Preventing pressure ulcers: an evaluation of Treatment of Pressure Ulcers. Mosby, London 8 Many patients are at greater four operating table mattresses. Appl Nurs Res 13(3): 134–41 National Pressure Ulcer Advisory Panel risk of developing pressure (1989) Pressure ulcers: incidence, ulcers in the perioperative Department of Health (1993) Pressure Sores: economics, risk assessment. Consensus period. A Key Quality Indicator. HMSO, London development conference statement. Decubitus 2(2): 24–8 Ek AC, Lewis DL, Zetterqvist H, Svensson 8 There are many factors that PG (1984) Skin blood flow in an area of at National Pressure Ulcer Advisory Panel are implicated in the increased risk for pressure sore. Scand J Rehabil Med (NPUAP) (1989) Pressure Ulcer Stages. www. 16: 85–9 npuap.org (Last accessed 13th May 2006) risk including duration of surgery and hypothermia. Fisher S, Szymke TE, Apte SY, Kosiak M Nixon J, Mc Elvinney D, Mason S, Brown (1978) cushion effect on skin J, Bond S (1998) A sequential randomised temperature. Arch Phys Med Rehabil 59: controlled trial comparing a dry visco–elastic 8 The author could not identify 68–72 polymer pad and standard operating table a consensus on the predictive mattress in the prevention of post–operative Flanagan M (1995) Pressure Sore Risk pressure sores. Int J Nurs Stud 35(4): 193–203 risks for inter-operative Assessment. Education Leaflet. Care pressure ulcer development Society, Huntington Panel for the Prediction and Prevention of from the studies reviewed. 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