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.
Subject(s)
Energy Metabolism , Ventilator Weaning/methods , Adult , Aged , Biometry , Calorimetry, Indirect , Cross-Over Studies , Female , Humans , Male , Middle Aged , Reproducibility of Results , Ventilator Weaning/instrumentationABSTRACT
O uso da continuous positive airway pressure (CPAP) no tratamento do edema agudo de pulmão (EAP) cardiogênico tem sido estudado por alguns autores. Recentemente, a utilização da ventilação não-invasiva com dois níveis de pressão (BiPAP) vem sendo estudada nessa situação clínica; entretanto, os resultados são controversos. Dessa forma, foi realizado, através do MEDLINE, um levantamento dos ensaios clínicos randomizados publicados em língua inglesa que analisaram a utilização do BiPAP em pacientes com EAP cardiogênico, obtendo-se um total de 11 trabalhos. O BiPAP mostrou-se útil no manuseio do EAP, apresentando benefícios similares à CPAP. Nos pacientes hipercápnicos, o BiPAP surge como uma importante estratégia de suporte ventilatório não-invasivo. Porém, faz-se necessário um estudo com grande número de pacientes para esclarecer certas dúvidas ainda persistentes.
The use of continuous positive airway pressure (CPAP) in the treatment of acute cardiogenic pulmonary edema (CPE) has been studied by some authors. Recently, the use of bi-level positive airway pressure (BiPAP) has been studied in this clinical situation, although the results have been controversial. We searched MEDLINE in order to find randomized trials published in English that analyzed the use of BiPAP in patients with CPE. Eleven trials were found. BiPAP was useful in the management of CPE, showing similar benefits to those of CPAP. In hypercapnic patients, BiPAP appears to be an important strategy of noninvasive ventilatory support. However, large trials are necessary to clarify certain doubts that still remain.
