title: Energy expenditure in mechanical ventilation: is there an agreement between the Ireton-Jones equation and indirect calorimetry?
abstract: OBJECTIVE
  Assess the agreement between the energy expenditure measured by indirect calorimetry and that estimated by the Ireton-Jones formula of critically ill patients under assisted mechanical ventilation.
  
  
  METHODS
  Participated in the study individuals able to interrupt ventilation support, admitted at the center of intensive care of the Hospital de Clínicas de Porto Alegre - RS, between August 2006 and January 2007. Energy expenditure was measured by indirect calorimetry using a specific monitor, as well as estimated by the Ireton-Jones formula. Values found were analyzed using the Student's t test and the Bland and Altman method and expressed in mean, ± standard deviation with a significance level of p<0.05.
  
  
  RESULTS
  The study included forty patients with a mean age of 56±16 years and APACHE II score of 23±8. Energy expenditure measured by indirect calorimetry was of 1558±304kcal/24h, while that estimated by Ireton-Jones was of 1689±246kcal/24h. There was a significant statistical difference between means of energy expenditure measured and estimated of the same individual (p<0.004). The agreement thresholds between indirect calorimetry and the Ireton-Jones equation were of -680.51 to 417.81 kcal.
  
  
  CONCLUSIONS
  Energy expenditure estimated by the Ireton-Jones formula did not present good agreement with that measured by indirect calorimetry, however, considering aspects related to availability of the equipment, this equation may be useful in the nutritional planning for critically ill patients.
authors.affiliation: Universidade Luterana do Brasil, Torres, RS, Brasil.
authors.forename: Laura Jurema Dos
authors.initials: LJ
authors.lastname: Santos
authors.affiliation: Programa de Residência Multiprofissional em Saúde, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Laíse
authors.initials: L
authors.lastname: Balbinotti
authors.affiliation: Universidade Estadual de Campinas, Campinas, SP, Brasil.
authors.forename: Anne Y Castro
authors.initials: AY
authors.lastname: Marques
authors.affiliation: Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Sônia
authors.initials: S
authors.lastname: Alscher
authors.affiliation: Departamento de Medicina Interna, FAMED, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Sílvia Regina Rios
authors.initials: SR
authors.lastname: Vieira