Comportamento da mecânica do sistema respiratório após o uso de 0,5 a 2 segundos de pausas inspiratórias utilizando taxa de fluxo inspiratório de 40 e 60 l/min

Abstract

Introduction:The aim of this study was to assess the behavior of the different intervals of respiratory pause, achieved through the occlusion maneuver at the end of inspiration, and its consequences on resistance, and on static and dynamic complaisance of the respiratory system (RS), in patients mechanically ventilated, without pulmonary pathologies. Methods: Analysis of the RS mechanics was made with 40 and 60 l/min flows with constant flow square wave. The determined pause intervals were: 0.5, 1, 1.5 and 2 seconds. The following data were collected: peak pressure, plateau pressure, current exhaled volume and intrinsic peep. With their integration, it was possible to analyze the behavior of resistance and of dynamic and static complaisance of the RS, using Oneway ANOVA, with Turkey test. Results: The sample was composed of 21 patients with 40 l/min flow and 23 patients with 60 l/min. The values of complaisance and resistance don’t differ significantly according to the values of respiratory pause considered. However, in both flows the study was capable of detecting a significant and positive correlation between the pause interval and the intrinsic peep. But only in the 40 l/min flow group there was an increase in the percentage of peak variation. Conclusion: The pause of 0.5 second isn’t sufficient to calculate the RS complaisance and resistance values, considering that there was no statistical difference in these values in relation to the increase in respiratory pause up to 2 seconds.