Respiratory problems that increase the resistance to airflow, increasing the work of breathing, are known as obstructive lung disorders. Resistance is influenced by the diameter of the lower respiratory airways. The walls of the respiratory tree are supported by cartilage to prevent collapse, smooth involuntary muscle and a mucous membrane inner lining. The narrow lumen of the terminal bronchioles has no cartilage, just smooth muscle. In health, little resistance is offered by these bronchioles as they are so numerous, but the narrow lumens can be easily disrupted by secretions and inflammation, increasing airways resistance and work of breathing. The smooth muscle cells in the respiratory tract lining are supplied by branches of the sympathetic and parasympathetic nervous system, which work together to regulate airways diameter. Asthma and COPD are obstructive lung disorders commonly encountered by nurses working in an acute care environment. Characteristics of each are summarised in Figure 17.1.

The UK has one of the the highest number of people in the world affected by asthma.¹ This chronic inflammatory airways disorder is triggered by many factors (Box 17.1). Symptoms include wheeze, breathlessness, chest tightness and cough. Airways swelling, secretion accumulation and airway hyperresponsiveness (twitchiness of the airway muscles) (Figure 17.2) results in airflow obstruction that is variable and reversible. Patients may be symptom free for long periods, punctuated by a few acute episodes. Treatment can be successful with patient education and self-management, but nurses need to be vigilant as acute episodes can be rapid and potentially life threatening.