24% of candidates passed this question.

This is a core topic within respiratory physiology. There was a very low pass rate for this question. Expected components of the answer included: a definition of WOB as a product of pressure and volume or force and distance including the units of measurement; followed by a detailed explanation of the following three broad components – elastic resistance, viscous resistance and airflow resistance. Further marks were awarded to situations where the energy for expiration increases beyond stored potential energy as well as the impact of respiratory rate and tidal volume on different aspects of the WOB. For example, the changes in TV will have relatively greater impact on the elastic component, whereas RR will impact the resistance component. Additional marks were awarded for describing the efficiency of breathing. A common area where candidates missed out on marks was producing a diagram of WOB without a description; many diagrams were often incorrectly drawn or had no axes labelled. There were many incorrect definitions or respiratory equations provided without any link to the written answer. Factual inaccuracy and limited depth of knowledge were also prevalent in poorly performing answers. Marks were not awarded for a description of the control of breathing.