Interpretation and use of intraoperative protective ventilation parameters: a scoping review

Thirty years ago, the traditional approach to mechanical ventilation consisted of the normalization of PaCO(2) and pH at the expense of using a tidal volume (V(T)) of 10–15 mL kg(-1). But then, the use of 6–8 mL kg(-1) became a dogma for ventilating patients either with acute respiratory distress syndrome (ARDS) or without lung disease in the operating theatre. It is currently recognized that even low tidal volumes may be excessive for some patients and insufficient for others, depending on its distribution in the aerated lung parenchyma. To carry out intraoperative protective mechanical ventilation, medical literature has focused on positive end expiratory pressure (PEEP), plateau pressure (P(aw plateau)), and airway driving pressure (ΔP(aw)). However, considering its limitations, other parameters have emerged that represent a better reflection of isolated lung stress, such as transpulmonary pressure (P(L)) and transpulmonary driving pressure (ΔP(L)). These parameters are less generalized in clinical practice due to the requirement of an oeso-phageal balloon for their measurement and therefore their cumbersome application in the operating theatre. However, its study helps in the interpretation of the rest of the ventilator pressures to optimize intraoperative mechanical ventilation. This article defines and develops protective ventilation parameters, breaks down their determinants, mentions their limitations, and offers recommendations for their use intraoperatively.