Primary Graft Dysfunction after LungTransplantation

Abstract

The human body requires oxygen to perform aerobic processes 1-3. The lungs are the respiratory organs that not only supply oxygen to the blood, but also remove carbon dioxide from the body. The right lung is most commonly made up of three lobes (superior, middle and inferior) relatively separated by fissures, while the left lung consists of two lobes (superior and inferior). Every lobe is again divided in several bronchopulmonary segments, which are the largest subdivisions of a lobe and named according to the segmental bronchi supplying them. The bronchial tree consists of a conducting zone (bronchi, bronchioles and terminal bronchioles) and a respiratory zone (respiratory bronchioles and the alveolar duct). The alveolar ducts terminate in the alveolar sac which gives rise to several pulmonary alveoli. The conducting zone not only transports gases, it also plays a role in the host defense system, and it warms and humidifies inspired air. It has its own circulation, known as the bronchial circulation, which comes from the descending aorta and drains into the pulmonary veins. Gas exchange occurs in the respiratory zone. A pair of normal lungs contains between 400 and 700 million alveoli. If stretched, this contains an area of 70 m2. The pulmonary circulation has its origin in the pulmonary trunk, that carries deoxygenated but carbon dioxide rich blood to the lungs. The pulmonary trunk divides in a right and left pulmonary artery that enter the pulmonary cavities at the pulmonary hilum. After branching several times, the pulmonary arteries terminate in capillaries that surround the alveolus. After gas exchange by diffusion, oxygenated blood enters the pulmonary veins that terminate in the left atrium, flows into the left ventricle, where it is pumped into the systemic circulation.