Functional Residual Capacity and Alveolar Recruitment in Single-lung Ventilation: a Randomized Study

In thoracic surgery, the incidence of postoperative pulmonary complications is higher than for other surgeries. Indeed, thoracic surgery has the specificity of being carried out with single-lung ventilation and is thus a source of intraoperative atelectasis which persists postoperatively and gives rise to pulmonary complications, particularly infectious ones. During one-lung ventilation, mediastinal and abdominal compression on the ventilated lung leads to a drop in functional residual capacity (FRC) which will in turn lead to collapse of the small airways leading to the formation of atelectasis. Strategies exist to limit the appearance of atelectasis. One of the intraoperative strategies is alveolar recruitment. Alveolar recruitment is a dynamic process that can be defined by a transient increase in transpulmonary pressure beyond the critical opening pressure. Physiologically, alveolar recruitment corresponds to the re-aeration of poorly or non-aerated lung areas. In single-lung ventilation, intraoperative alveolar recruitment maneuvers are not performed systematically to prevent the formation of atelectasis. The General Electric Carescape R860 ventilator allows intraoperative monitoring of end-expiratory closing lung volume (EFVP), which corresponds to the CRF associated with positive expiratory pressure (PEEP). This spirometry incorporated in the ventilator continuously monitors the intraoperative variation of VPFE, thus making it possible to detect any significant decrease which would favor the formation of intraoperative atelectasis. Early detection of VPFE can therefore allow the anesthetist-resuscitator to initiate intraoperative alveolar recruitment maneuvers adapted to the patient. Alveolar recruitment maneuvers are then personalized and based on precise monitoring of the evolution of the VPFE. The effectiveness of recruitment maneuvers can be evaluated and quantified (with the Lung Ultrasound Score (LUS)) postoperatively using pleuropulmonary ultrasound