The continuum from extreme conditions to the intensive care unit.

Just by changing their lifestyle, humans are challenging the respiratory system to an extent never previously reached; by exposing it to extreme conditions. In an article in this issue of the European Respiratory Review, ADIR and BOVE [1] have deciphered the conditions that may promote lung injury when the respiratory system is exposed to low atmospheric pressure, high pressure surrounding the body and extreme exercise. The intensive care unit (ICU) can also be seen as an extreme environment for the respiratory system. This is because ICU management is required for the most severe forms of acute lung disease, in particular acute respiratory distress syndrome (ARDS), and the components of the management may be extreme, such as prone positioning [2] or extracorporeal lung oxygenation [3]. Therefore, I would like to discuss some aspects of hypoxaemia and mechanical ventilation that occur in the ICU, and which closely link to the cases described by ADIR and BOVE [1].