Electrical impedance tomography to evaluate air distribution prior to extubation in very-low-birth-weight infants: a feasibility study

OBJECTIVES: Nasal continuous positive airway pressure is used as a standard of care after extubation in very-low-birth-weight infants. A pressure of 5 cmH2O is usually applied regardless of individual differences in lung compliance. Current methods for evaluation of lung compliance and air distribution in the lungs are thus imprecise for preterm infants. This study used electrical impedance tomography to determine the feasibility of evaluating the positive end-expiratory pressure level associated with a more homogeneous air distribution within the lungs before extubation. METHODS: Ventilation homogeneity was defined by electrical impedance tomography as the ratio of ventilation between dependent and non-dependent lung areas. The best ventilation homogeneity was achieved when this ratio was equal to 1. Just before extubation, decremental expiratory pressure levels were applied (8, 7, 6 and 5 cmH(2)0; 3 minutes each step), and the pressure that determined the best ventilation homogeneity was defined as the best positive end-expiratory pressure. RESULTS: The best positive end-expiratory pressure value was 6.3 ± 1.1 cmH(2)0, and the mean continuous positive airway pressure applied after extubation was 5.2 ± 0.4 cmH(2)0 (p = 0.002). The extubation failure rate was 21.4%. X-Ray and blood gases after extubation were also checked. CONCLUSION: This study demonstrates that electrical impedance tomography can be safely and successfully used in patients ready for extubation to suggest the best ventilation homogeneity, which is influenced by the level of expiratory pressure applied. In this feasibility study, the best lung compliance was found with pressure levels higher than the continuous positive airway pressure levels that are usually applied for routine extubation.

CPAP em selo d'água versus CPAP com fluxo variável em recém-nascidos com desconforto respiratório: um ensaio controlado randomizado / Bubble CPAP versus CPAP with variable flow in newborns with respiratory distress: a randomized controlled trial

OBJETIVO: Avaliar a eficácia e segurança da pressão positiva contínua na via aérea (CPAP) utilizando aparelhos de fluxo variável e fluxo contínuo em selo d'água, quanto a falha do CPAP, ocorrência de escape de ar, tempo de uso de CPAP e de oxigênio e tempo de internação em unidade de terapia intensiva e hospitalar em neonatos com desconforto respiratório (DR) moderado e peso de nascimento (PN) > 1.500 g. MÉTODOS: Quarenta recém-nascidos que necessitavam de CPAP foram randomizados em dois grupos: um grupo tratado com fluxo variável (FV) e outro com fluxo contínuo (FC). O estudo foi realizado entre outubro de 2008 e abril de 2010. Foram registrados dados demográficos, falha do CPAP, ocorrência de escape de ar, tempo de uso de CPAP e de oxigênio, entre outros. Os desfechos categóricos foram analisados com o teste do qui-quadrado ou exato de Fisher e as variáveis contínuas com o teste de Mann-Whitney, com significância de p < 0,05. RESULTADOS: Não houve diferença quanto aos dados demográficos, falha do CPAP (21,1 e 20,0% para o FV e o FC, respectivamente; p = 1,000), síndrome de escape de ar (10,5 e 5,0%, respectivamente; p = 0,605), tempo de CPAP [mediana: 22,0 h, intervalo interquartil (IIQ): 8,00-31,00 h e mediana: 22,0 h, IIQ: 6,00-32,00 h, respectivamente; p = 0,822), e tempo de uso de oxigênio (mediana: 24,00 h, IIQ:7,00-85,00 h e mediana: 21,00 h, IIQ:9,50-66,75 h, respectivamente; p = 0,779). CONCLUSÃO: Em recém-nascidos com PN > 1.500 g e DR moderado, o CPAP nasal com fluxo contínuo apresentou os mesmos benefícios do CPAP nasal com fluxo variável.

OBJECTIVE: To evaluate the efficacy and safety of nasal continuous positive airway pressure (NCPAP) using devices with variable flow or bubble continuous positive airway pressure (CPAP) regarding CPAP failure, presence of air leaks, total CPAP and oxygen time, and length of intensive care unit and hospital stay in neonates with moderate respiratory distress (RD) and birth weight (BW) > 1,500 g. METHODS: Forty newborns requiring NCPAP were randomized into two study groups: variable flow group (VF) and continuous flow group (CF). The study was conducted between October 2008 and April 2010. Demographic data, CPAP failure, presence of air leaks, and total CPAP and oxygen time were recorded. Categorical outcomes were tested using the chi-square test or the Fisher's exact test. Continuous variables were analyzed using the Mann-Whitney test. The level of significance was set at p < 0.05. RESULTS: There were no differences between the groups with regard to demographic data, CPAP failure (21.1 and 20.0% for VF and CF, respectively; p = 1.000), air leak syndrome (10.5 and 5.0%, respectively; p = 0.605), total CPAP time (median: 22.0 h, interquartile range [IQR]: 8.00-31.00 h and median: 22.0 h, IQR: 6.00-32.00 h, respectively; p = 0.822), and total oxygen time (median: 24.00 h, IQR: 7.00-85.00 h and median: 21.00 h, IQR: 9.50-66.75 h, respectively; p = 0.779). CONCLUSION: In newborns with BW > 1,500 g and moderate RD, the use of continuous flow NCPAP showed the same benefits as the use of variable flow NCPAP.