During mechanical ventilation, atelectasis may appear. Atelectasis seems to be caused by reduced lung volume and small airway collapse. The collapse of healthy anesthetized and acutely injured lungs of patients is well described and the main mechanical treatment of such collapse conditions is built upon positive end-expiratory pressure (PEEP). The aims of this study were to investigate the hemodynamic and respiratory effect of the adding PEEP in patients with healthy and damaged lungs during

more »

... hanical ventilation. Methods: In 24 patients with healthy and 28 patients with damaged lungs at constant ventilation, PEEP was decreased from 5 to 0 cmH2O and then increased to 15 in steps of 5 cmH2O every 10 minutes. We prospectively evaluated the effects of PEEP on the respiratory and hemodynamic indexes of this patients during ventilation and then, SPO2, peak inspiratory pressure, plateau airway pressure, tidal volume, static and dynamic compliance, heart rate and blood pressure (systolic, diastolic, and mean) were recorded. Findings: Increasing PEEP levels from 0 to 15 cmH2O improved oxygenation in both patient with healthy and damaged lungs; but increasing PEEP levels decreased heart rate and systolic, diastolic and mean arterial blood pressure, although this changes were not significant. Increasing PEEP increased respiratory indexes with statistically significant difference between two groups (P < 0.001). Conclusion: Because of increasing the respiratory indexes by increasing PEEP levels in both damaged and healthy lungs without significant hemodynamic effects, this maneuver can be propose to improve oxygenation and respiratory indexes during constant ventilation in both patients with healthy and damaged lungs.