Cardiopulmonary Consequences of Post Thoracic Surgery Pulmonary Hypertension: Cause or Consequence of Lung Edema?

The major complication of post-thoracic surgery is a severe disturbance of lung extravascular water that is the main cause of morbidity and mortality and therefore still represents an unmet medical challenge. Accordingly, the need to devise novel therapies ought to go through a more thorough understanding of the pathophysiological mechanisms. This review presents an updated description of the time evolution of this process providing the pathophysiological reason for its explosive development. Despite various names (“idiopathic edema”, acute lung injury -ALI, atelectasis, ARDS), a common patho-physiological pathway can be traced for respiratory dysfunction in post-operative thoracic surgery. We will present the evidence for the loss of control on the volume of extravascular lung water from the new perspective of the derangement and disorganization of interstitial proteoglycans, a family of link molecules controlling microvascular permeability and mechanical stability of the extravascular matrix. We analyze in detail specific conditions of lung water disturbance pertaining to cardiac surgery, lung transplant and lung resection surgery. In particular, we will discuss the functional link between lung edema formation and increase in pulmonary vascular resistances, and wish to develop the concept that pulmonary hypertension and right ventricle overload ought to be regarded as the consequence of a decrease in vascular bed reflecting microvessels compression in the edematous tissue both in the acute phase as well as in the fibro-proliferative repair process.