Longitudinal changes in phase angle by bioimpedance in intensive care patients differ between survivors and non-survivors.

BACKGROUND & AIMS: Intensive care (ICU) patients suffer from metabolic stress, creating a catabolic state which might disturb nutritional status and body composition. Alterations in body fluid compartments by disease or massive volume resuscitation could invalidate bioimpedance hydrometry. Still bioimpedance might give other information. METHODS: 52 ICU patients (35 male, 17 female, mean age 66 years), BMI 29,2 were assessed by bioimpedance spectroscopy. Phase angle (PhA) at 50 kHz was assessed. RESULTS: On first assessment PhA was 3.7 ± 1.0°. In 26 patients reassessed after median 5 days PhA was not significantly changed, although R 50 kHz and Xc 50 kHz both increased (p = 0.047), indicating diminishing overhydration. Body weight and body cell mass decreased by 1.8 ± 5.7 and 2.8 ± 7.5 kg (p = 0.13). Fat free mass and extracellular water decreased 4.5 ± 8.9 kg (p = 0.032) and 1.5 ± 3.5 kg (p = 0.031), while CRP decreased 63 mg/l (p = 0.002). In 17 survivors PhA increased 0.62 ± 1.24° (NS), while in 9 non-survivors PhA decreased 0.24 ± 0.82° (p = 0.06), with 0.86° difference (p = 0.049) between groups. CONCLUSION: Phase angle by bioimpedance is very low in ICU patients and positive changes in PhA seems to reflect more favorable outcome. Bioimpedance by Body Scout appears unsuitable for the assessment of fat free mass or overhydration in ICU patients.

Bioelectric impedance spectroscopy underestimates fat-free mass compared to dual energy X-ray absorptiometry in incurable cancer patients.

BACKGROUND/OBJECTIVES: Weight loss is frequently seen in advanced cancer. Bioelectrical impedance spectroscopy (BIS) is a convenient method for estimating body composition. We examined in a prospective, comparative study if BIS could accurately estimate fat-free mass (FFM) in cancer patients compared to dual-energy X-ray absorptiometry (DXA). SUBJECTS/METHODS: The study was based on 132 consecutive incurable cancer patients with solid tumours in a University hospital outpatient clinic. Comparison of FFM from DXA and BIS with standard and revised equations. Bland-Altman plots, t-tests and linear regression analysis were used to evaluate agreement and differences between methods. RESULTS: BIS significantly underestimated mean FFM with 7.6+/-4.7 kg compared to DXA (P<0.001). Bias was significantly correlated to % weight loss (r=0.32), systemic inflammation as measured by C-reactive protein (r=0.29), malnutrition as assessed by low insulin-like growth factor-1 (r=-0.23) and inversely to the per cent body fat estimated by DXA (P=-0.61) and body mass index (BMI; r=-0.30). Revised BIS equations taking BMI into account reduced bias significantly but still with great individual variation. CONCLUSIONS: BIS by standard equations grossly underestimates FFM compared to DXA in cancer patients. This bias is related to weight loss, malnutrition and systemic inflammation. Revised equations improved FFM estimates, but with large individual variation. Thus, BIS with standard equations is not suitable to estimate FFM in patients with cachexia, inflammation and malnutrition.

Biochemical indices to evaluate nutritional support for malignant disease.

Malignant diseases are often complicated by malnutrition, and nutritional support is often indicated. Nutritional support should be evaluated primarily by improved clinical outcome. During nutritional support as artificial nutrition, monitoring is of paramount importance. Several biochemical markers are frequently used to monitor nutritional status. Most widely used are serum levels of albumin, transferrin, and transthyretin which are subnormal in malnutrition. Unfortunately, monitoring nutritional support by biochemical indices in malignant disease is complicated by the pathophysiology of cancer related malnutrition. Systemic inflammation is central in this context as it perturbs most of the traditional biochemical indices, and is inversely correlated to survival. In addition, systemic inflammation explains variations in body composition. Thus, the most important biochemical index to be measured in malignant disease is the assessment of systemic inflammatory response, preferably by high-resolution CRP, and if normal, common biochemical indices such as albumin, transferrin or transthyretin might be used. Preferentially, indices with high turnover should be used. IGF-1 is an index well suited for assessing nutrition support in conventional malnutrition, but its use in malignant disease is still unproved. If APPR is prevalent, methods detecting changes in body composition, performance or physical activity might offer better options to evaluate nutritional support.

Nondigestibility characteristics of inulin and oligofructose in humans.

The ileostomy model is considered to be a reliable model to reflect small bowel absorption. Studies in ileostomy subjects have shown that inulin and oligofructose pass through the small bowel without degradation and without influencing the absorption of nitrogen, fat, starch, calcium, magnesium or zinc. Inulin and oligofructose do not have any considerable effect on cholesterol absorption or bile acid excretion.