Validade da obtenção da água corporal total por impedância bioelétrica multiespectral face à diluição de deutério sob influência da ingestão de cafeína

• Autor(a) principal: Gaspar, Inês Filipa Tavares
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/26505
• topic: Bioelectrical impedance analysis; Body composition; Clinical trial; Coffee ingestion; Dilution techniques; Hydrometry; Mass spectrometry; Methodology; Total body water; Validation; Água corporal total; Análise por impedância bioelétrica; Composição corporal; Espectrometria de massas; Estudo clínico; Hidrometria; Ingestão de cafeína; Metodologia; Técnicas de diluição; Validação; Domínio/Área Científica::Ciências Médicas::Outras Ciências Médicas

Background: The objective is to analyze the validity of bioelectrical impedance multispectral (BIS) in ACT against the reference method (deuterium dilution) in a crossover design with administration of 5mg/kg caffeine or 5mg/kg placebo. Methods: It includes 30 participants, without smoking habits, low caffeine consumption (<100 mg·day−1) and aged between 20 and 39 years (BMI = 23.19 ± 2.54 kg/m2). A cross-over randomized trial with 2 conditions (5 mg·kg−1·day−1) of caffeine and placebo (maltodextrin) of 4 days each, with a washout period of 3 days was performed. ACT was evaluated by dilution of deuterium oxide from mass spectrometry and using BIS. Results: For both conditions, a strong correlation was found between the reference method and BIS (placebo: R2 = 0,931, p<0,01, caffeine: R2 = 0,905, p<0,01). Mean differences between methods were -0.014 for placebo and 0,064 for caffeine. The 95% limits of agreement ranged from -2.708 to 2.681kg for placebo and from -2.630 to 3.527kg for caffeine, with a CCC of 0.962 and 0.945, respectively. No significant correlations were found between the mean and the difference of the methods for any condition (placebo: R = 0,268, p = 0,153, caffeine: R= 0,350, p = 0,058). Conclusion: Regardless of caffeine or placebo intake, TBW obtained by BIS was valid at the group level with acceptable individual accuracy, compared to deuterium dilution.