Respiratory decompensation with proning - when prone positioning can worsen respiratory mechanics

Prone positioning recently gain- ed more popularity from its use in COVID-19 management. It is gene--rally considered to improve respiratory mechanics via increased lung compliance. In surgery, prone positioning is typically encountered when it is a necessity to access certain posterior anatomic structures. Though certain post-operative complications from prone positioning are well known (e.g., postoperative vision loss), the potential intraoperative complications that it can have for respiratory com-pliance and O2 saturation, in the setting of general anaesthesia, are perhaps less familiar, as only a few studies showed improved respiratory mechanics in the setting of ge-neral anaesthesia [1-3] and one study showed that prone positioning led to a 30-35% drop in respiratory compliance under general anaesthesia [4]. As the following case illustrates, proning is a critical point in the intraoperative course as it can sometimes lead to negative respiratory sequelae disrupting homeostasis.