Lung Alveolar Recruitment Research Articles

Effects of early postoperative lung recruitment maneuver on pulmonary oxygenation in patients undergoing off-pump coronary artery bypass grafting

Objective To evaluate the effects of early postoperative lung alveolar recruitment (LRM) on pulmonary oxygenation in patients undergoing off-pump coronary artery bypass grafting (OPCABG).Methods One hundred and twenty-six ASA physical status Ⅱ or Ⅲ patients of both sexes,aged 44-70 yr,of NYHA class Ⅱ or Ⅲ patients,scheduled for elective OPCABG,were randomly allocated into 2 groups (n =63 each):control group (group C) and LRM group.In group LRM,LRM was performed using pressure control method at 1 and 2 h after operation based on conventional mechanical ventilation.Both distending pressure and positive end-expiratory pressure were 20 cmH2O.Peak airway pressure was limited to 40 cmH2O and maintained at this level for 30 s,and then the original mode of ventilation was restored.At the end of operation,at 3 h alter operation and immediately after weaning from mechanical ventilation,blood samples were collected from the radial artery for blood gas analysis and oxygenation index was calculated.The development of postoperative hypoxemia,atelectasis,pulmonary infection,delayed removal of endotracheal tubes,and prolonged duration of intensive care unit stay,and ventilation time were recorded.Results LRM was stopped in no patients for unstable hemodynamics.Compared with group C,oxygenation index was significantly increased at 3 h after operation and immediately after weaning from mechanical ventilation,the incidence of postoperative hypoxemia,atelectasis,pulmonary infection,and delayed removal of endotracheal tubes was significantly decreased,the ventilation time was shortened,and no significant change was found in the incidence of prolonged duration of intensive care unit stay in LRM group.Conclusion Early postoperative LRM can improve pulmonary oxygenation in patients undergoing OPCABG. Key words: Positive-pressure respiration; Respiratory function tests; Coronary artery bypass surgery, off-pump; Postoperative complications

A micro-CT analysis of murine lung recruitment in bleomycin-induced lung injury

The effects of lung injury on pulmonary recruitment are incompletely understood. X-ray computed tomography (CT) has been a valuable tool in assessing changes in recruitment during lung injury. With the development of preclinical CT scanners designed for thoracic imaging in rodents, it is possible to acquire high-resolution images during the evolution of a pulmonary injury in living mice. We quantitatively assessed changes in recruitment caused by intratracheal bleomycin at 1 and 3 wk after administration using micro-CT in 129S6/SvEvTac mice. Twenty female mice were administered 2.5 U of bleomycin or saline and imaged with micro-CT at end inspiration and end expiration. Mice were extubated and allowed to recover from anesthesia and then reevaluated in vivo for quasi-static compliance measurements, followed by harvesting of the lungs for collagen analysis and histology. CT images were converted to histograms and analyzed for mean lung attenuation (MLA). MLA was significantly greater for bleomycin-exposed mice at week 1 for both inspiration (P<0.0047) and exhalation (P<0.0377) but was not significantly different for week 3 bleomycin-exposed mice. However, week 3 bleomycin-exposed mice did display significant increases in MLA shift from expiration to inspiration compared with either group of control mice (P<0.005), suggesting increased lung recruitment at this time point. Week 1 bleomycin-exposed mice displayed normal shifts in MLA with inspiration, suggesting normal lung recruitment despite significant radiographic and histological changes. Lung alveolar recruitment is preserved in a mouse model of bleomycin-induced parenchymal injury despite significant changes in radiographic and physiological parameters.