The aim of this chapter is to provide an outline of the underpinning theory and relevant information needed to deliver safe and effective, family centred, evidence based care to the child or young person who presents with breathing difficulties. In is anticipated that at the end of this chapter you will be able to: ● Understand the anatomy and physiology of the respiratory system. ● Discuss the concept of visual assessment of breathing, including monitoring and recording of respiratory rate, oxygen saturation levels, and peak expiratory flow rates. ● Explain oxygen therapy and the use of airway adjuncts. ● Reflect upon methods and equipment used for suctioning. ● Discuss tracheostomy management, care of intrapleural drainage, and endotracheal tubes. ● Apply the concepts and principles outlined relevant to the hospital and community setting. This is the system through which oxygen is breathed in from the external environment, either by the nose or mouth, and a waste product (carbon dioxide) is excreted. The respiratory system consists of respiratory passages, which carry air via the nose to the lungs, and a network of blood capillaries in the lungs. The respiratory passages include the nose, pharynx, larynx (voice box), trachea, two bronchi (one bronchus to each lung), and copious bronchial tubes, which divide and lead to millions of alveoli (tiny air sacs). There are two lungs either side of the heart in the thoracic cavity. They are made up of bronchial tubes, alveoli, blood vessels, and nerves (McCance & Heuther, 2006). Air containing oxygen (O2) and carbon dioxide (CO2) is breathed into the lungs. This fills the alveoli. It is separated from the blood in capillaries by two semi-permeable membranes. These make up the walls of the alveoli and capillaries. Oxygen is at a higher concentration in the alveoli. It therefore passes from the alveoli into the blood. Carbon dioxide is higher in concentration in the blood, so it passes from the blood into the alveoli. Oxygen is carried in the blood in haemoglobin (red blood corpuscles). Breathing is the regular inflation and deflation of the lungs, maintaining a steady concentration of atmospheric gases in the alveoli (MacGregor, 2000).