Respiratory and hemodynamic changes during lung recruitment maneuvering through progressive increases and decreases in PEEP level

Abstract

ObjectiveTo evaluate the respiratory and hemodynamic changes during lung recruitment maneuvering (LRM) through stepwise increases and decreases in PEEP level. Design and settingA retrospective study in a 17-bed ICU was carried out. PatientsTwenty-one patients with acute respiratory failure and bilateral pulmonary infiltration. InterventionLRM was carried out, consisting of stepwise increases in PEEP (4cmH2O every 3min), with fixed ventilation pressure, until reaching a maximal value of 36cmH2O PEEP (ascending branch), followed by progressive decreases in PEEP (2cmH2O every 3min) until establishing the open-lung PEEP at the value associated to maximum respiratory compliance (Crs) (descending branch). Continuous hemodynamic monitoring was performed using an esophageal echodoppler probe. ResultsCrs gradually decreased in the ascending branch of the LRM, and progressively increased surpassing the initial value after establishing the open-lung PEEP in the descending branch, reducing the ventilation pressure and increasing the SpO2/FiO2 ratio. Hemodynamic changes primarily consisted of a fall in cardiac output and left ventricular preload, together with an increased heart rate and cardiac contractility. At comparable levels of PEEP and mean airway pressure, these changes were more pronounced during the descending branch of the LRM. Conclusions(1) LRM increased Crs, improving oxygenation and decreasing ventilation pressure; (2) the main hemodynamic consequence was the drop in cardiac output and left ventricular preload; and (3) the unequal hemodynamic derangement in both branches, at the same level of PEEP and mean airway pressure, showed that, along with intrathoracic pressure, other factors such as Crs and hypercapnia may have influenced the hemodynamic consequences of this type of LRM.