The Respiratory Tract in Pediatric Critical Illness and Injury

The principal role of the respiratory system is to permit ef? cient exchange of respiratory gases (O and CO ) with the environment. The respiratory system is unique in that it is constantly 2 2 exposed to a barrage of foreign substances from both the internal environment (at any one point in time, approximately one-half of the cardiac output is received by the lungs) and the external environment (with each breath, the respiratory tract is exposed to pollens, viruses, bacteria, smoke, etc). Accor