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ORIGINAL ARTICLE

Prevention of pressure ulcer:interaction of bodycharacteristics and differentmattressesTheodoros Moysidis, Wolfgang Niebel, Katharina Bartsch, Irene Maier,Nils Lehmann, Michael Nonnemacher, Knut Kroeger

Moysidis T, Niebel W, Bartsch K, Maier I, Lehmann N, Nonnemacher M, Kroeger K. Prevention of pressure ulcer:interaction of body characteristics and different mattresses. Int Wound J 2011; 8:578584

ABSTRACTWe analysed the effect of different body features on contact area, interface pressure and pressure distribution ofthree different mattresses. Thirty-eight volunteers (age ranged from 17 to 73 years, 23 females) were asked tolie on three different mattresses in a random order: I, standard hospital foam mattresses; II, higher specificationfoam mattresses (Viscorelax Sure); III, constant low pressure devices (CareMedx, AirSystems). Measurementswere performed in supine position and in a 90 left- and right-sided position, respectively, using a full-body mat(pressure mapping device Xsensor X2-Modell). Outcome variables were contact area (CA) in cm2, mean interfacepressure (IP) in mmHg and pressure distribution (PD) estimated as rate of low pressures between 5 and 33 mmHgon each mattress in percent. Mean CA was lowest in the standard hospital foam mattresses and increased in thehigher specification foam mattresses and was highest in the constant low pressure device (supine position: 491 86 cm2, 615 95 cm2, 685 116 cm2). Mean IP was highest in the standard hospital foam mattresses and lowerbut similar in the higher specification foam mattresses and the constant low pressure devices (supine position:

223 15 mmHg, 176 17 mmHg, 176 22 mmHg). Models were estimated for CA, IP and PD includingthe independent variables height, weight and waist-to-hip-ratio (WHR). They show that body morphology seems toplay a minor role for CA, IP and PD, but very thin and tall patients and very small and obese people might benefitfrom different mattresses. Our data show that CA increases with increasing specification of mattresses. Higherspecification foam mattresses and constant low pressure devices show similar IP, but constant low pressure devicesshow a wider pressuredistribution. Body morphology shouldbe considered to optimise preventionfor singlepatients.

Key words: Interface pressure Mattresses Pressure ulcer Waist-to-hip-ratio

Authors: T Moysidis, MD, Department of Angiology, HELIOS

Klinik Krefeld, Krefeld, Germany; W Niebel, MD, Department of

General and Transplant Surgery, University of Duisburg-Essen,

Germany; K Bartsch, Department of Angiology, HELIOS Klinik

Krefeld, Krefeld, Germany; I Maier, Clinical Nurse Manager,

University of Duisburg-Essen, Germany; N Lehmann, Insti-

tute for Medical Informatics, Biometry and Epidemiology, Med-

ical Faculty, University of Duisburg-Essen, Essen, Germany;

M Nonnemacher, Institute for Medical Informatics, Biometry

and Epidemiology, Medical Faculty, University of Duisburg-

Essen,Germany; K Kroger, Department of Angiology, HELIOS

Klinik Krefeld, Krefeld, Germany, Initiative Chronische Wunden.

e. V., Luenen, Germany

Address for correspondence: Professor K Kroeger, MD,

FASA, EFMA, Klinik f ur Angiologie, HELIOS Klinik Krefeld,

Lutherplatz 40, 47805 Krefeld, Germany

E-mail: [email protected]

INTRODUCTION

Pressure ulcer also known as bedsores, pres-Key Points

the awareness for prevention

of pressure ulcers and for early

detection increased in the past

decades and pressure relief is

the most mandatory concept to

prevent pressure ulcers

thus, pressure-relieving beds,

mattresses and seat cushions

are widely used as aids of

prevention in both institutional

and non institutional settings

sure sores or decubitus ulcer is a generally

preventable complication of immobility. The

awareness for prevention of pressure ulcersand for early detection increased in the past

decades and pressure relief is the most manda-

tory concept to prevent pressure ulcers (13).

Thus, pressure-relieving beds, mattresses and

seat cushions arewidely used as aids of preven-

tion in both institutional and non institutional

settings. Technical analysis concentrates on the

quantification of the applied pressure at the

patientsupport interface and the limitations

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578 2011 Blackwell Publishing Ltd and Medicalhelplines.com Inc International Wound Journal Vol 8 No 6

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Characteristics of mattresses

and variability of current techniques, mea-

surement systems and data presentation (47).

A recent Cochrane analysis concluded that

higher specification foam mattresses rather

than standard hospital foam mattresses can

reduce the incidence of pressure ulcers in

people at risk but the relative merits of alter-nating and constant low pressure devices

are unclear (8,9). Many risk factors predis-

posing patients to develop pressure ulcer are

described and implemented in a variety of

risk scores (3,10,11). However, there are less

data regarding the interaction of body shape

and specific mattresses. A study of individu-

als with spinal cord injuries had shown that

peak seat-interface pressure was highest in the

thin elderly group, which had the lowest BMI

(body mass index) levels. Differences in the

peak seat-interface pressures were less as BMI

increased (12).

Key Points

we hypothesised that body

morphologyhas differenteffects

on interface pressure depending

on the specification of different

mattresses

thus, we analysed the effect ofdifferent body features on con-

tact area (CA), interface pres-

sure (IP) and pressure distri-

bution (PD) of three different

mattresses

38 volunteers (age ranged from

17to73years,23females)were

asked to lie on three different

mattresses in a random order

the participants were asked

to stay on each mattress for

5 minutes until the pressure

measurement was started

We hypothesised that body morphology has

different effects on interface pressure depend-

ing on the specification of different mattresses.

Thus, we analysed the effect of different body

features on contact area (CA), interface pres-

sure (IP) andpressuredistribution (PD) of three

different mattresses.

METHODSAt the University Hospital of Essen, Germany,

healthy volunteers (students, visitors andemployees) were asked to participate in this

study. People were selected to cover a wide

range of age, weight and height (Table 1).

Finally, 38 volunteers (age ranged from 17 to

Table 1 Characteristics of body morphology of the 23 females

and 15 males enrolled in the project

Variable Mean SD Range

Age (years) 419 160 1773

Height (cm) 1714 112 150199

Weight (kg) 749 151 47130

BMI (kg/cm2) 255 49 1745

Body surface area (m2) 19 02 1425

Chest circumference (cm) 998 102 79133

Waist circumference (cm) 923 155 67134

Hip circumference (cm) 1034 116 88149

Waist-to-hip-ratio 089 009 071106

Leg length (cm) 944 94 74114

Shoe size (German size) 408 31 3549

BMI, body mass index.

73 years, 23 females) were asked to lie on three

different mattresses in a random order:

I. A standard hospital foam mattress, which

was the standard mattress in the hospital till

2005 (weight 12 kg, thickness 14 cm, density

35 kg/cbm).

II. A higher specification foam mattress(Viscorelax Sure, Hapeka, Buhl, Germany),

which was bought for some departments, that

is, the Department of Oncology, with a higher

frequency of patients a risk. The mattress is in

the superstructure of viscoelastic foam and the

base of high-quality open-pore polyether foam.

Sinking into the viscoelastic foam reduces the

hammock effect and provides an optimum

pressure relief and functional support of the

spine. Mattress forms at body temperature and

thus adapts itself to the body contours (weight

17 kg, thickness 17 cm, density 80/40 kg/cbm).

III. A constant low pressure device (Care

Medx, AirSystems), which may be ordered

for special risk patients. The modular mattress

system has20 airchambers. It hasan individual

pressure profile control for four body regions

(head, chest, pelvis and foot). The upper is

made of nylon.

All three systems were placed near each

other in the same room. The participants were

asked to stay on each mattress for 5 minutes

until the pressure measurement was started.

Measurements were performed in supine posi-

tion and in a 90

left- and right-sided posi-tion, respectively. The participants were asked

to take off thick or constricting clothing but

remained dressed. Most of them wear a shirt

and pants.

A full-body mat [pressure mapping device

Xsensor X2-Modell (Fa: FSA, type Ultra-Thin,

Software Version 40.)] was used to record the

pressures over the complete body (7). Outcome

variable were CA in cm2, IP in mmHg and PD

estimated as rate of low pressures between 5

and 33 mmHg on each mattress in percent.

Sensitivity of the Xsensor X2-Modell is

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Table 2 Contact areas and pressures measured while lying on the rear and in the left and right side, respectively, on the three

different mattresses

Mattresses I II III

Supine position

Contact area (cm2) 491 86 615 95

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Table 4 Results of the final linear regression analysis in supine position

Weight Size Waist/hip ratio Intercept R2

Surface area

I 507583

40236129

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with the Cochrane analysis (8). Thus, our

study concept can be assumed to be valid.

The repeatability of a technique for measur-

ing interface pressures has been assessed by

Allen et al. Pressure measured using a Tal-

ley SA500 Pressure Evaluator (Omega Medical

Systems, Pottstown, PA) under six anatomi-cal sites was found to vary significantly more

between days than between repeats on the

same day (P < 002) (14).

Key Points

ourdatashow that CAincreases

with increasing specification of

mattresses

constant low pressure devices

differ from higher specification

foam mattresses by a widerpressure distribution

body morphology should be

considered to optimise preven-

tion for single patientsSimilar studies have been carried out before,

but they focused on IP and did not analyse the

influence of body morphology in detail (1418).

Hockersen et al. compared IP in the Ortho-

derm Convertible II (Bio-Clinic Inc., Toronto,

Ontario, Canada) low air-loss mattress, in a

Stryker PMS(StrykerInc., Kalamazoo, MI)bed;

the FluidAir Elite (KCI Inc., San Antonio, TX)

air-fluidised bed; the Pegasus Airwave mat-

tress (Pegasus Airwave Inc., Boca Raton, FL) in

a Stryker PMSbed anda standard hospital mat-

tress in a Stryker PMS bed (17). They showed

that the Pegasus Airwave mattress total IP val-

ues of the anatomical regions (total body, torso

and hips) of the body are lower than those

of the other three tested mattresses. The total

body and hip pressure resulting from pres-

sure maturation was significantly less in the

Pegasus Airwave mattress than in the hospital

bed, the air-fluidised bed and the low air-loss

bed. Allen et al. measured IP interface pressure

in four continuous airflow mattress overlays[Clinirest (SSI Medical Services Inc, Yonkers,

NY), FirstStep (KCI)] and alternating pressure

air mattresses [Airwave (Pegasus) and Nimbus

(Huntleigh Healthcare Limited, Bedfordshire,

UK)] (14). Their data suggest a clinical benefitat

the occiput and heel using an alternating pres-

sure air mattress and a benefit in using a con-

tinuous airflow mattress overlay at other sites.

In contrast to the literature we focus on body

morphology. Thicker people have relatively

smaller BSA than thinner people presenting

with the same weight. BSA is the theoretical

limitation of CA. Thus, almost spherical-

shaped bodies should have higher IP than

thin cuboid bodies of the same weight.

These assumptions retrieve themselves in our

final models estimating the CA and IP on

the different mattresses. Weight is the most

important variable of course, but size and

WHR play a role too as they describe the

spherical shape of the body. The last two

variables become more important in the higher

Table 5 Estimated CA, IP and pressure distribution in supine

position for two different body shapes based on the models in

Table 4

CA (cm2) IP (mmHg)

Pressure distribution (%

between 5 and 35 mmHg)

Patient A: weight 90 kg, size 160 cm, WHR 1 5I 589 227 781

II 660 184 885

III 870 171 962

Patient B: weight 90 kg, size 190 cm, WHR 091

I 567 227 783

II 715 178 890

III 779 185 898

CA, contact area; IP, interface pressure; WHR, waist-to-hip-ratio.

specification foam mattresses and constant low

pressure devices, because they allow the body

to cave in. As we showed in Table 5 very thin

and tall patients should benefit from higherspecification foam mattresses, whereas small

and obese people should benefit from constant

low pressure devices. This influence of body

morphology on IP and pressure distribution

might be considered in future developments of

pressure-relieving mattresses.

LIMITATIONSAlthough this study has a clear design and

deals with objective measurements, some lim-

itations have to be mentioned. The number of

participants is rather small and does not neces-sarily cover the whole range of variables with

the same frequency. Repetitive measurements

on the same mattresses could have shown

variability in the data. Longer resting periods

on the different mattresses could have given

insight into temporary changes of pressure

distribution.

CONCLUSIONOur data show that CA increases with

increasing specification of mattresses. Con-

stant low pressure devices differ from

higher specification foam mattresses by a

wider pressure distribution. Body morphology

should be considered to optimise prevention

for single patients.

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