Electrical impedance tomography in evaluating the effects of non-invasive ventilation in the post-operative cardiac surgery: randomized controlled clinical trial

Abstract

Introduction: Noninvasive ventilation has been widely used to prevent pulmonary complications after cardiac surgery. Electrical Impedance Tomography(EIT) has been highlighted as a tool to monitor the distribution of regional pulmonary ventilation. However, there are few studies available on the use of this tool in evaluating the effects of noninvasive ventilation(NIV). Objectives: To compare the effects of noninvasive ventilation with oxygen therapy(OT) on pulmonary aeration and ventilation in patients in the immediate postoperative period of cardiac surgery; Hypothesis: the use of non-invasive ventilation in patients in the postoperative period of cardiac surgery results in greater ventilation and greater aeration during and after intervention compared to the control group. Methods: Patients were randomized into two groups: NIV and OT (control). The evaluation was performed through EIT. Results: 16 patients were randomized, 9 in NIV group and 7 in OT group. Greater global end expiratory lung impedance (pulmonary aeration) was observed during NIV when compared to OT group (0,20±0,08 and 0,23±0,10 vs. -0,14±0,01 and -0,21±0,02, p value 0,009 and 0,013 respectively); but there was no maintenance of this improvement after intervention. There was also a greater variation of global impedance (ventilation) change during intervention (7,96 vs. 4,17, p value 0,03). Conclusion: There was increased global aeration and ventilation during noninvasive ventilation in patients in post-operative cardiac surgery, but there was no maintenance of aeration improvement after its interruption. Grants: FACEPE, CNPq and CAPES.