Impact of a Nutritional Formula Enriched in Fish Oil and Micronutrients on Pressure Ulcers in Critical Care Patients

By Miriam Theilla, RN; Betty Schwartz, PhD; Jonathan Cohen, MBBCh, FCP; Haim Shapiro, MD; Ronit Anbar, RD; Pierre Singer, MD

Disclosures

Am J Crit Care. 2012;21(4):102e-109. 

In This Article

Methods

Patients

This interventional, controlled, randomized study was conducted in a 12-bed general ICU of the Rabin Medical Center, Petah Tikva, Israel, a tertiary care, university- affiliated hospital. The sample consisted of all adult patients admitted to the ICU who were expected to require nutritional support for at least 5 days and who had evidence of grade II or higher pressure ulcers (ie, damage of the epidermis extending at least into the dermis), according to the classification of the National Pressure Ulcer Advisory Panel,[1] that were present either at the time of admission to the ICU or developed during the ICU stay. Exclusion criteria included conditions associated with markedly impaired immunity and/or wound healing, such as AIDS, auto immune disorders, and treatment with immunosuppressive medications. The study design was approved by the appropriate institutional internal review board, and informed consent was obtained from all patients before their enrollment.

Study Treatments

Eligible patients were randomly allocated to 2 groups according to a computer-generated random list: the study group, which received an enteral nutritional formula enriched in fish oil and antioxidants (Oxepa, Abbott Nutrition, Columbus, Ohio) and the control group, which received an isonitrogenous nutritional formula (Jevity, Abbott Nutrition). Patients who could not tolerate enteral nutrition (as indicated by a gastric residual volume >500 mL) received parenteral nutrition in the form of OliClinomel N6–900 (Baxter Healthcare Ltd, Maurepas, France). Patients in the study group who required parenteral nutrition also received Omegaven (Fresenius Kabi AG, Bad Homburg, Germany) as the source of fish oil. Table 1 gives the macronutrient and micronutrient composition of the various formulas. Treatment allocation was concealed from the study statistician but not from ICU staff, patients, or the assessor of ulcer severity.

The quantity of nutritional formula prescribed was determined on the basis of the nonfasting resting energy expenditure, as measured by indirect calorimetry (Deltatrac II, Datex-Ohmeda, Helsinki, Finland). Resting energy expenditure was assessed every 7 days, and the calorie prescription was adjusted as needed. Assessment of gastric residual volume and the consequent adjustment of nutritional support were performed according to established ICU protocols. Glucose levels were monitored every hour, and, when necessary, patients received a continuous infusion of insulin; the goal was to maintain the glucose level between 60 and 150 mg/dL (to convert to millimoles per liter, multiply by 0.0555). All other aspects of patient management were determined by each patient's attending physician. Treatment regimens for grade II pressure ulcers for all patients consisted of hydrogel dressings (Granuflex, ConvaTec Ltd, Ickenham, United Kingdom) when secretions were minimal, alginates (Kaltostat, ConvaTec Inc, Skillman, New Jersey, or SeaSorb, Coloplast, Minneapolis, Minnesota) when secretions were moderate, and specialty absorptives (Kaltostat, ConvaTec Inc, Skillman, New Jersey) when secretions were excessive. Treatment regimens for grade III pressure ulcers consisted of composite dressings (TenderWet, Paul Hartmann AG, Heidenheim, Germany).

Outcomes and Data Collection

Effectiveness of treatment was defined as the degree of progression of existing pressure ulcers.

The following data were collected for all patients at the time of admission to the ICU: sex, age, body mass index (calculated as weight in kilograms divided by height in meters squared), primary diagnosis (surgical, medical, or trauma), and score on the Acute Physiology and Chronic Health Evaluation (APACHE) II. The amount of enteral formula, kilocalories, protein, and PUFAs delivered and energy balance (calories delivered daily minus resting energy expenditure measured weekly) were recorded on a daily basis. CRP concentrations were recorded weekly. CRP was assayed by using an Olympus 2700 Analyzer and a particle-enhanced immunoturbidimetric method with latex particles coated with monoclonal antibodies to CRP. The day-to-day variation for the measurement is 3.04% at 14.1 mg/L, 2.51% at 27.7 mg/L, and 1.18% at 0.83 mg/L (multiply by 9.524 to convert to nanomoles per liter). The test is linear within a concentration range of 0.08 to 80 mg/L, and the reference interval is less than 5 mg/L.

The severity of pressure ulcers at baseline (day 0), and the response to treatment (on days 7, 14, and 28) were assessed by using the Pressure Ulcer Scale for Healing (PUSH) tool.[9] With this noninvasive diagnostic tool, severity scores range from 0 (healed) to 17 (worst possible score). The score is a summation of 3 parameters, each of which is graded according to increments in severity: surface area, which is measured with a ruler designed for this purpose (0–10 points); amount of exudate (0–3 points: none, light, moderate, or heavy); and tissue type (0–4: closed, epithelial tissue, granulation tissue, sloughing, or necrotic tissue). The changes in the direction and magnitude of the score over time provide a validated indication of whether or not the wound is healing. The PUSH score was obtained by a single investigator (M.T.) in all patients. When a patients had more than 1 pressure ulcer, only the largest ulcer with the most exudation was assessed in the study.

Data Analysis

On the basis of the study of Makhsous et al,[10] the standard deviation of the change in the PUSH score can be estimated at 1.8. The difference in mean improvement between the groups in their study[10] was also 1.8. In our study, a sample size of 40 was deemed sufficient to detect such a difference with a power of approximately 85%. Differences in baseline data and patient characteristics were assessed by using Wilcoxon and independent t tests for nonparametric and parametric variables, respectively. The changes in the severity of pressure ulcers to treatment were analyzed by using repeated-measures analysis of variance. Data were analyzed by using SPSS 17 for Windows (IBM SPSS, Armonk, New York). Results were considered significant at P < .05.

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