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Implication of cytokines in the aggravation of malnutrition and hypercatabolism in elderly patients with severe pressure sores

Age and Ageing, Jan, 1995 by M. Bonnefoy, L. Coulon, J. Bienvenu, R.C. Boisson, L. Rys

Introduction

Pressure sores remain a considerable problem in geriatric medicine [1] owing to their frequency and severity. The pressure-time product is of fundamental importance in initiating ischaemia and tissue necrosis [2-4]. Once present, the pressure sore may be considered as a largely autonomous object, with its own evolution, but nutritional status, and particularly protein malnutrition, is an important cofactor in the process of tissue breakdown [5-8] or healing [7]. Severe pressure sores may be comparable with injury processes known to induce production of acute-phase proteins by the liver [9]. This process may aggravate the underlying malnutrition promoting a vicious circle.

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To test this hypothesis we investigated the production of cytokines (IL-1, IL-6 and TNF) responsible for the dramatic increase in synthesis of acute-phase reactants [10-13] and the secretion of cortisol [14] (known to interact with cytokines) in malnourished elderly patients with severe pressure sores living in a long-term care unit.

Methods

Patients: Nineteen consecutive bedridden elderly patients with pressure sores (stage III or IV according to SHEA's classification [15, 16]), living in a long-term care unit, entered the study. Twelve elderly bedridden patients without pressure sores, living in a long-term care unit, but with identical risk for pressure ulcer development according to the Norton Scale [3] were also studied. We also enrolled 12 elderly control patients with good activity and mobility living in the same unit.

No subject had other documented septic or inflammatory foci.

Study protocol: IL-1, IL-6, and TNF circulating levels together with IL-1, IL-6 and TNF production in an ex vivo model were measured. Blood cortisol levels were determined on samples withdrawn at 08 h 00. Nutritional status was evaluated using anthropometric measurements, biochemical analyses, and delayed-hypersensitivity skin testing.

Anthropometric measurements: Anthropometric measures are an important part of nutritional assessment of elderly people. Our results will be compared with reference data available for people aged 75 years and older. Several anthropometric reference data for elderly people living in the United States have been published [17, 18], but few reference data are available from Europe [19].

Anthropometry of elderly people presents particular difficulties [20] owing to mobility problems, abnormal kyphosis, and muscular contractures. For bedridden patients, duplicate measurements were made with the patient supine using a measuring-tape stretched from crown to heel. For patients with contractures, recumbent knee height was used to estimate stature [21]. Weight was calculated with an electronic scale (Support System International[R]). The mid-arm circumference (MAC) and the triceps skin-fold (TSF) were measured at the mid-point between acromion and olecranon processes, according to the method defined by Lohman et al. [22]. The MAC was measured with a flexible tape, and the TSF with Harpenden skin-fold calipers.

Biochemical analyses: Blood samples were collected after overnight fasting. The usefulness of albumin and prealbumin as nutritional markers has already been validated [23]. In addition, acute-phase proteins (APP) which are consequences of sepsis and severe injury [9] are known to be prognostically important [24].

C-reactive protein (CRP), albumin and alpha-1 acid glycoprotein (AAG) were measured by kinetic immunoturbidimetry with a Behring Turbitimer. Prealbumin and retinol binding protein (RBP) were quantified by an immunoturbidimetric assay using the Fara centrifugal analyser (Roche Analytical Instruments) and commercially available antiserum (Behring for RBP and Atlantic Antibodies for prealbumin). For each protein, between-run coefficient of variation was less than 5% within the analytical range. Transferrin was not measured, as it is known to be influenced by iron levels [25].

Immunological status: Delayed hypersensitivity was determined by skin testing with multitest Merieux[R]. Seven antigens were used (Tetanus, Diphtheria, Streptococcus C, Tuberculin, Candida, Trichophyton, Proteus). The induration area was measured 48 h after intracutaneous injection. The sum of mean diameters (A + B)/2 of positive reaction was calculated. The reaction was considered as anergic when induration was below 2 mm. Lymphocyte and monocyte counts were also determined.

Cytokines production (IL-1-IL-6 and TNF): A whole-blood ex vivo model was used [26]. Blood is drawn into a heparinized tube (Kabi ref. 82 23-12-63/9) tested for absence of endotoxins by the chromogenic kabitest; 675/[[micro]liter] of whole blood are pipetted into a 5 ml propylene sterile tube; 75[[micro]liter] of RPMI 1640 (control, no stimulation) or 75[[micro]liter] of LPS (10 ng/ml of E. coli 055: B5, SIGMA, dissolved in RPMI) are added and vortexed gently. The tubes are incubated for 5 h at 37 [degrees] C in presence of C[O.sub.2] stopped by adding 2250 [[micro]liter] of RPMI and centrifuged for 10 min at 3000 g. Supernatants are frozen in aliquots at -80 [degrees] C for cytokine measurement. Cytokines quantitation has been performed using an ELISA method [TABULAR DATA FOR TABLE I OMITTED] (EASIA Medgenix) on blood samples and on supernatants of stimulated monocytes.

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Implication of cytokines in the aggravation of malnutrition and hypercatabolism in elderly patients with severe pressure sores

Age and Ageing, Jan, 1995 by M. Bonnefoy, L. Coulon, J. Bienvenu, R.C. Boisson, L. Rys

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