New bioelectrical impedance formula for patients with respiratory insufficiency: comparison to dual-energy X-ray absorptiometry

Abstract

Severe respiratory insufficiency causes patients to be intolerant of physical effort and to be frequently limited in their daily activity and results in an imbalance between food intake and nutritional needs. Undernutrition and overnutrition can both affect the quality of life and survival of patients with pulmonary disease. Protein-energy malnutrition can lead to quantitative, qualitative and functional alterations of muscle [1,2] and this affects muscle function, including respiratory muscle in patients with already limited respiratory reserves. Optimal adaptation of nutrition support through the assessment of fat-free mass (FFM) and fat mass (FM) in patients with chronic respiratory insufficiency can avoid or minimize muscle wasting or obesity. For these reasons, the nutritional assessment should include body composition measurements which are based on objective rather than subjective criteria of nutritional evaluation. Body composition can be measured by a number of techniques, including hydrodensitometry, isotope dilution, and whole-body counting of potassium-40 [3]. However, these methods are not easily applicable in ill subjects.More recent methods for the determination of the FFM are dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). DXA has been validated against independent methods, including a gamma neutronactivation model [4,5], total body potassium and hydrodensitometry [6] and is becoming one of the reference methods for body composition analysis, but requires sophisticated technology. BIA is a method of measuring body composition which is easy, noninvasive and inexpensive [7]. BIA measurements have been validated in healthy adults [8][9][10]. The relationship between body impedance and body composition is dependent on age and sex [11,12]. Over 20 different formulae permit the calculation of the FFM and FM based on BIA measurements and have generally been validated in healthy, young adults. SCHOLS et al. [13] proposed a BIA formula validated against deuterium dilution for patients with chronic obstructive pulmonary disease (COPD) (n=24), which included weight and height 2 /resistance (ht 2 /R) as independent variables. Recently, PICHARD et al. [14] were unable to obtain clinically relevant correlations between FFM calculated by 12 BIA formulae [8,9,11,[15][16][17][18][19][20][21], including SCHOLS et al. [13], and DXA-determined FFM, and suggested that a specific formula should be developed for patients with chronic severe respiratory insufficiency. These results suggest that the bioelectrical impedance analysis formula specific to patients with severe respiratory insufficiency give a better correlation and smaller mean differences than 12 different bioelectrical impedance analysis formulae described in the medical literature. A prediction equation, validated against dual-energy X-ray absorptiometry and based on subjects with similar clinical characteristics, is more applicable to the patients with respiratory insufficiency than a formula developed for healthy subje...

Bedside methodsversusdual energy X‐ray absorptiometry for body composition measurement in COPD

“…By contrast to their original equation, this provides sex-specific equations for COPD patients and may explain why the agreement between BIA and DEXA is better in the present study than in that of PICHARD et al [16]. More recently, a prediction equation for COPD patients using DEXA as a reference method has been published [18]. Perhaps not surprisingly (as the equation used was derived from data within the study), the limits of agreement between DEXA and BIA reported in this latter study were narrower than in the present one.…”

Effects of 2 Exercise Training Programs on Physical Activity in Daily Life in Patients With COPD

“…12 Exercise capacity was evaluated with 3 tests: the 6-min walk test, 13 with the reference values from Troosters et al 14 ; incremental symptom-limited cycle ergometry, 15 following a program previously described 16 ; and constant-workcycle ergometry (endurance time). Body composition was assessed with bioelectrical impedance 17 and we used the specific values described by Kyle et al 18 Respiratory muscle force was measured with the maximum inspiratory and expiratory pressures, 19 with the reference values from Neder et al 20 Peripheral muscle force was assessed with the onerepetition maximum test. Functional status was assessed with the London Chest Activity of Daily Living (LCADL) scale 21 and the Pulmonary Functional Status and Dyspnea Questionnaire Modified Version (PFSDQ-M).…”

Three-year follow-up study of respiratory and systemic manifestations of chronic obstructive pulmonary disease

“…Body composition was evaluated by bioelectrical impedance (BIA 101A; RJL systems, USA) according to the guidelines of the European Society for Parenteral and Enteral Nutrition (ESPEN) (12). Fat-free mass (FFM, kg) was calculated using a group-specific regression equation developed by Kyle et al (13). The FFM index (FFMI = FFM/height 2 ) was also calculated.…”