L1 – Respiratory tract infections

What do we mean when we say upper respiratory tract infection and lower respiratory tract infection?

Lower respiratory tract infections (LRTIs) involve the lower airways (see picture below) and include illnesses such as bronchiolitis, bronchitis/chest infection and pneumonia.  The terminology can be confusing and there is a lack of a clear universally agreed definition.  LRTIs can be due to viral or bacterial infection, are often but not always accompanied by fever, and can be preceded by typical viral URTI (upper respiratory tract infection) symptoms.  It is not possible clinically to tell the difference between a bacterial or viral cause, so we often do consider treating with antibiotics, especially if the child has a fever and we are looking to manage at home.  The way an LRTI presents will vary depending on the age of the child, the causative organism and the main site of infection. 

You can see from this diagram what structures a urti would involve and structures involved in a lrti.