Cortisol profiles in the critically ill after cardiac surgery
Sponsor: Bristol University
REC Number: 12/SW/0186
Some patients do not recover well from cardiac surgery and become critically ill on life support machines. One of the causes of this is an uncontrolled inflammatory response. The inflammatory response is what causes your sprained ankle or cut hand to become red and swollen. It gets red because the blood vessels get bigger and it gets swollen because fluid leaks out of the blood vessels and into the tissues. This is helpful if it is a small area, but when it is across the whole body, such as after cardiac surgery it can be problematic and potentially life-threatening.
We all produce a hormone called cortisol (a steroid) that helps protect against an uncontrolled inflammatory response. It is thought that there are some people who do not produce enough cortisol or do not produce it in the right pattern. Doctors often give synthetic cortisol type drugs (corticosteroids) to patients when they are critically ill to reduce this inflammatory response. However, if they are used in too large a dose, these drugs can have significant side effects such as immunosuppression, poor wound healing and a diabetic state. Cortisol is released in discreet pulses throughout the day, called an ultradian rhythm.
The Cortisol 2 study is investigating what happens to these pulses of cortisol in people who are critically ill. We are recruiting patients who have had cardiac surgery and go to the cardiac intensive care unit (CICU). We are taking blood samples over 24 hours to measure cortisol and describe its ultradian rhythm. Once we know what is ‘normal’ during critical illness, we can begin to design tests to see which patients might benefit from steroids and if so, give them in a more tailored way.
Chief Investigator: Prof Stafford Lightman