The effect of various combinations of turning and pressure reducing devices on the incidence of pressure ulcers
Introduction
Turning is generally considered to be an important and effective way of preventing pressure ulcers. A pressure ulcer is an ulceration caused by excessive pressure being applied to a tissue over an extensive duration (Pfeffer, 1991). Regular position changes reduce the length of time during which the tissue is under pressure and decrease the likelihood of the development of pressure ulcers.
Almost no research has been undertaken on the turning interval necessary in this respect. The first study relating to turning dates from 1962. In this study, Norton, McLaren and Exton-Smith compared the incidence of pressure ulcers between two groups of hospitalised elderly women. One group consisted of 100 women. They were turned every 2–3 h, every 4 h or two, three, four times a day. The turning schedules varied during their hospitalisation . The other group of 148 women received standard preventive care chiefly consisting of massage with local applications such as soap and zinc creams. The incidence of pressure ulcers in the group which received turning was 9%, while in the other group 26% of the residents developed pressure ulcers. It is unclear on what basis the nurses decided which residents were eligible for turning, at what time(s) during their hospitalisation this was carried out and how frequently the residents were turned.
A PubMed search for the period from 1984 to 2002, in which the keywords “pressure ulcer(s)” or “pressure sore(s)” were used in combination with “turning” or “repositioning” produced 65 references. The effect of the frequency of turning on the occurrence of pressure ulcers was only investigated in one of these studies. Knox et al. (1994) compared the effect of changing position after 1, 1.5 and 2 h. This study was conducted on 16 healthy elderly subjects, 11 with a Caucasian skin type and 5 with a dark skin type. They were placed in a position for 2 h, then in another position for 1.5 h and finally in yet another position for 1 h. The positions used, the sequence of which was randomised, were supine position, lateral position 90° right and lateral position 90° left. Temperature and change in skin surface colour, interface pressure and pain were recorded. The skin temperature had increased more after 2 h of immobilisation than after 1 h or 1.5 h. No significant differences were found with regard to interface pressure and colour. The experimental subjects found staying in the same position for 2 h more uncomfortable than for 1 or 1.5 h. The results are difficult to generalise owing to the limited number of subjects, the difficulty of detecting skin colour changes in subjects with a black skin type and the short duration of the study.
On the basis of expert opinion, the Agency for Health Care Policy and Research (Panel for the Prediction and Prevention of Pressure Ulcers in Adults, 1992) recommends turning at a minimum interval of 2 h. The Dutch consensus guideline (Bakker, 1992) refers to turning every 3 h. The European Pressure Ulcer Advisory Panel (EPUAP) does not comment on the necessary interval and states that the ‘frequency of repositioning should be consistent with overall goals’ (EPUAP, 1998).
The turning interval has an important bearing for its feasibility in practice and on its actual use. Turning patients every 2 h or even every 3 h is highly labour-intensive (Helme, 1994).
On a standard (non-pressure reducing) institutional mattress usually constructed of cold foam only about 10–20% of the body is supported. The average interface pressure of a person weighing 80 kg (176 lb) is between 30 and 60 mmHg. The maximum pressure under bony prominences can be much higher. Therefore, many pressure-reducing mattresses have been designed to conform to the body contours, thus increasing the area of the body supporting its weight and avoiding local point pressure (Jester and Weaver, 1990; Weaver and Jester, 1994). Stewart (1997) defines pressure-reducing mattresses as those which reduce tissue interface pressure as compared to a conventional institutional mattress and are unable to consistently maintain interface pressure below capillary closure pressure (the minimum pressure needed to obtain a complete occlusion of the capillary). In recent years the variety of such pressure-reducing mattresses has grown considerably (Clark, 1991; Conine et al., 1990; Daechsel and Conine, 1985; Hofman et al., 1994; Krouskop et al., 1986; Ooka et al., 1995; Rondorf Klym and Langemo, 1993; Seiler et al., 1986; Solis et al., 1988; Thompson Bishop and Mottola, 1992; Whitney et al., 1984; Whittemore, 1998; Willems, 1995). Mattresses can reduce pressure considerably. Defloor (2000) measured the interface pressure on 62 healthy volunteers lying in 10 different positions. He found that the use of a viscoelastic polyurethane foam mattress reduced the pressure by 20–30% in comparison to the interface pressure measured on a standard institutional mattress.
Two factors are important in the causation of pressure ulcers: the amount of pressure and the duration of pressure. A high amount of pressure during a short period of time will cause irreversible tissue damage, and will result in the development of pressure ulcers. It seems logical to assume that pressure has to be exerted during a much longer time before pressure ulcers will develop, if the amount of pressure is reduced.
Against this background we conducted a trial comparing four preventative schemes to assess the effects of turning with different intervals on the development of pressure ulcers. The following schemes were used during a 4-week period in a four-arm experimental design:
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turning every 2 h on a standard institutional mattress;
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turning every 3 h on a standard institutional mattress;
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turning every 4 h on a viscoelastic polyurethane foam mattress;
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turning every 6 h on a viscoelastic polyurethane foam mattress.
Ethical considerations make it impossible to withhold preventive measures from at-risk patients. Both turning every 2 h and turning every 3 h may be considered as control conditions (Bakker, 1992; Panel for the Prediction and Prevention of Pressure Ulcers in Adults, 1992).
An observation period of 4 weeks is frequently used in pressure ulcer research (Bergstrom et al., 1996; Burd et al., 1992; Chan et al., 1997; Hunter et al., 1992; Langemo et al., 1991; Van Marum et al., 1992; Williams, 1972).
The study was approved by the Ethics Committee of Ghent University Hospital.
Section snippets
Subjects
Geriatric nursing home patients were recruited because the length of stay in these wards would far exceed the 4-week duration of the study, the pressure ulcer risk of patients would be relatively high and the individual risk of pressure ulcers would fluctuate little over a period of 4 weeks. Inclusion criteria were:
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a Braden score of less than 17 or a Norton score of less than 12;
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informed consent of patient/family.
Because of the rather low predictive value of pressure ulcer risk assessment
Results
In total, 838 patients were randomised to the 2-h turning scheme (n=65), 3-h turning scheme (n=65), 4-h turning scheme (n=67), 6-h turning scheme (n=65), and standard-care group (n=576).
During the study 23 patients died and 30 were admitted to the hospital. The observations were incomplete in the case of 24 patients (Fig. 1).
Of the 838 included patients, 761 patients completed the 4-week study period. The mean age of those 610 women and 151 men was 84.4 (SD 8.33) years, the mean Braden score
Discussion
Approximately 43% (838/1952) of the patients in the 11 institutions who took part in the study were considered to be at-risk to develop pressure ulcers. A large number of patients are therefore found to be in need of preventive measures. The workload of nurses and economic cost of prevention should not be underestimated. Haalboom (1991) estimated the cost of prevention at per patient per day. Xakellis et al. (1995) came to a mean cost of $2.98 (SD 5.3) ( (SD 4.55)) per person and
Conclusions
The study examined the effect of different turning intervals on the occurrence of pressure ulcers. The use of turning in combination with pressure-reducing positions and materials did not reduce the incidence of non-blanchable erythema (pressure ulcer grade I). Turning every 4 h on a pressure-reducing mattress in combination with pressure-reducing positions and cushions resulted in a significant reduction in the number of pressure ulcer lesions (pressure ulcer grades II–IV). This makes turning a
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