ABSTRACT
Positive end-expiratory pressure (PEEP) has been an important component of mechanical ventilation for over 50 years, yet PEEP selection remains highly debatable in the critical care community. Despite numerous studies trying to answer the ‘PEEP question’, there are often conflicting opinions when it comes to recommendations based on clinical trials [1]. Tree major studies (ALVEOLI, LOVS, EXPRESS) assessing higher versus lower PEEP in combination with low tidal volume (Vt) for acute respiratory distress syndrome (ARDS) failed to show decrease in mortality, although a meta-analysis of the three trials suggested a survival benefit for a subgroup of patients with severe ARDS [2]. It is universally accepted that higher PEEP may be helpful in ARDS patients where recruitability is expected but proves harmful in other groups of patients contributing to ventilation induced lung injury (VILI). Therefore, as many authors have suggested that not only one PEEP does not fit all, but also looking for the ‘best’ PEEP has little meaning because within mechanical power, it is just one part of the whole [3]. Since the introduction of PEEP into clinical practice, researchers have been focusing on finding the single most suitable PEEP that usually corresponded to best lung mechanics (i.e., highest compliance of the respiratory system) or oxygenation. However, we would like to challenge this idea and introduce another approach to PEEP research in critically ill lungs. We hypothesize, that patients with nonhomogeneous lungs could be supported on mechanical ventilation using multiple and alternating levels of PEEP. In the following paragraphs, we will list and elaborate on several reasons supporting our hypothesis of potential benefits of using multiple alternating PEEP levels.