Hypothalamic-pituitary-adrenal (HPA) axis: function and control mechanisms in children undergoing cardiac surgery
Funder: British Heart Foundation
Sponsor: University Hospitals Bristol
We aim to study the stress response to cardiac surgery and cardiac catheterisation in children and babies.
Cardiac surgery triggers a major inflammatory response. The ‘inflammatory response’ is a set of reactions which when localised (such as a twisted ankle) can promote rapid healing of the injured part. When the injury is larger however (such as major surgery, burns or infection), this set of reactions can affect all tissues of the body leading to generalised inflammation that can result in the body’s organs failing and in some cases death. One of the hormones that can protect against an uncontrolled inflammatory response is the steroid hormone ‘cortisol’. Some hospitals give synthetic steroid type drugs to all children having cardiac surgery in an attempt to reduce this inflammatory response. However, it is currently unclear if this is needed or not. While too little cortisol leads to a large inflammatory response, too much cortisol leads to poor wound healing, high blood sugars and changes in the body’s metabolism. Humans produce their own cortisol in a diurnal rhythm (it is high when you first wake in the morning and lowest in the late evening). If you measure it frequently enough however, you can show that this rhythm actually consists of much more frequent pulses of cortisol (an ultradian rhythm). No-one has ever investigated the changes in the ultradian rhythm of cortisol around the time of cardiac surgery in neonates, infants and children.
There is good reason to believe that both the size and frequency of these pulses is important for the best function of cortisol. It has been shown by our group that these pulses change dramatically after adult heart surgery. The current study is designed to see what happens to these pulses when children and babies undergo cardiac surgery. We will compare this ‘surgical’ cohort with a group of children undergoing non-surgical cardiac investigations. Once we know what is ‘normal’ we will then be in a position to make better decisions about when and if extra steroid therapy is needed in paediatric cardiac surgery.
Chief Investigator: Professor Gianni Angelini
Study coordinator: Terrie Walker-Smith