Energy expenditure during weaning from mechanical ventilation: Is there any difference between pressure support and T-tube?☆☆☆★★★
published online 09 July 2010. Corrected Proof
Abstract
Background
The objectives of this study were to compare patients' energy expenditure (EE) during pressure support (PS) and T-tube (TT) weaning from mechanical ventilation (MV) through indirect calorimetry (IC) and to crosscheck these findings with the results calculated using Harris-Benedict (HB) equation.
Methods
This study is a randomized crossover controlled trial. Patients with clinical criteria for weaning from MV were randomized to PS-TT or TT-PS, with EE measurement for 20 minutes in PS and TT through IC. Energy expenditure was estimated through HB equation with and without activity factor. Statistical analysis used the Student t test for paired samples and Pearson correlation coefficient, as well as Bland-Altman method.
Results
Forty patients were included. The mean age and Acute Physiology and Chronic Health Evaluation II score were 56 ± 16 years and 23 ± 8, respectively, with predominance of male patients (70%). Mean EE of patients in TT (1782 ± 375 kcal/d) was 14.4% higher than in PS (1558 ± 304 kcal/d; P < .001). In relation to the EE obtained with the HB equation, the mean (SD) value calculated was 1455 (210) kcal/d, and when considering the activity factor, it was 1609 (236) kcal/d, all of them presenting correlation with the values from IC in PS (r = 0.647) and TT (r = 0.539). However, the limits of agreement between the measured EE and the estimated EE suggest that the HB equation tends to underestimate the EE.
Conclusion
Comparison of EE in PS and in TT through IC demonstrated that there is increased EE in the TT mode. The results suggest that the HB equation underestimates the EE of patients in weaning from MV.
aPostgraduate Program in Health Sciences: Cardiology and Cardiovascular Sciences, Medical School, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2400 - 2° andar, 90035-003 Porto Alegre, RS, Brazil
bIntensive Care Unit, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, 90035-903 Porto Alegre, RS, Brazil
cUniversidade Luterana do Brasil - Torres, Rua Universitária, 1900, 95560-000 Torres, RS, Brazil
dIntensive Care Unit, Hospital Mãe de Deus, Rua José de Alencar, 286, 90880-480 Porto Alegre, RS, Brazil
eIntensive Care Unit, Hospital Cristo Redentor, Rua Domingos Rubbo, 20, 91040-000 Porto Alegre, RS, Brazil
Corresponding author. Tel.: +55 51 9978 1067.
☆ The support was provided by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq-Brazil; National Council of Scientific and Technological Development) and Fundação de Incentivo a Pesquisa e Eventos (FIPE-HCPA; Foundation of Incentive to Research and Events). The monitor used in the study was kindly provided by Medicalway, with no financial charges to patients, investigators, and involved institution.
★ Competing interests: The authors declare that they have no competing interests.
★★ Authors' contributions: All authors made substantial contributions to the study conception and design, data collection, analysis and interpretation of data, as well as drafting of the manuscript. All authors read and approved the final manuscript.
ABSTRACT