Anaesthesia Fundamentals | Physiology | Physiology of nausea and vomiting

Physiology of Nausea and Vomiting
Session Overview
Description
This session describes the physiology of nausea and vomiting. Topics covered include swallowing reflex, barrier pressure, agonist/receptor systems, afferent and efferent pathways and causes and consequences of postoperative nausea and vomiting.

Learning Objectives
By the end of this session you will be able to:

• Describe the normal swallow reflex
• List factors which influence barrier pressure
• Draw a basic diagram explaining the interaction between the vomiting centre and chemoreceptor trigger zone
• Describe the phases of the vomiting reflex
• Discuss the different mediators and their receptors involved in nausea and vomiting
• Discuss the risk factors for nausea and vomiting in both adults and children
• Describe the consequences of nausea and vomiting of relevance to the anaesthetist

Nausea and vomiting are commonly encountered in anaesthesia, intensive care and pain medicine. They can occur secondary to disease processes or as a side-effect of surgical intervention or medicines.

Vomiting is co-ordinated through the brainstem which receives multiple afferent signals. Several transmitter/receptor systems are involved.

Because animal studies have provided much of our knowledge in this area, the neural mechanisms involved in nausea remain poorly understood.