Assessment of the Incidence of Expiratory Flow Limitation in Patients Undergoing Thoracic Surgery

Background and rationale of the study: During general anesthesia, the residual functional capacity (FRC) is reduced. If the FRC is lower than the minimum volume necessary to maintain the airway opening (closing capacity, CC), a pulmonary parenchyma derecruitment leads to the phenomenon of expiratory flow limitation (EFL). In recent years, new methods are being studied to assess EFL. In the study by Marangoni E, et. al., has been shown how the sudden subtraction of 3 cmH2O to the value of the tele-expiratory positive pressure (PEEP test) is sufficient to establish the presence of the EFL.

The presence of EFL measured by this method seems to correlate, in abdominal surgery, with the development of post-operative pulmonary complications. In the area of anesthesia in thoracic surgery, neither the incidence nor the relevance of the EFL are known, so a study is needed that evaluates both.

The aim of the study is to determine the incidence of expiratory flow limitation in patients undergoing thoracic surgery and ventilated in bi and monopolmonary mode.

The protective ventilation is a mechanical ventilation with a current volume (TV) of 6-8 mL / kg among to the ideal body weight (IBW), PEEP of 3-5 cmH2O and a FiO2 <80%.

The aim of this study is to evaluate the incidence of EFL in patients undergoing thoracic surgery, planned by thoracoscopy and thoracotomy in election, and to correlate this parameter with the onset of postoperative pulmonary complications. The final aim will be to verify if it is possible to identify a better approach, through the personalization of mechanical ventilation during the surgery, to reduce mortality, morbidity and hospital stay after thoracic surgery.