This new issue of Annals of Translational Medicine is dedicated to the discussion of issues concerning the heart-lung interactions in critically-ill patients. This is indeed a key subject for several reasons: (I) many patients in the ICU are submitted to positive pressure ventilation; (II) the possible application of heart-lung interactions to bedside old but still very actual physiology makes for exciting study; (III) development of critical care echocardiography allows physicians to easily and accurately evaluate heart-lung interactions in the ICU; (IV) heart-lung interaction in itself may be responsible for hemodynamic compromise in patients with respiratory failure and one of the way to support these patients is to “play” with the ventilator by modifying the respiratory settings; (V) studying heart-lung interactions allows hemodynamic monitoring—a core of what some experts call “functional hemodynamic monitoring”. The best illustration of this concept of functional hemodynamic monitoring is the evaluation of the fluid-responsiveness status by testing the response of the cardiovascular system to a cyclic positive airway pressure.
