Grant: Project Grant

In Canada, approximately 40,000 people suffer from a cardiac arrest annually, with an approximate 5% survival rate. Those that do survive typically suffer a severe brain injury related to a lack of oxygen supply when their heart was not beating - in other words during the cardiac arrest. Low oxygen levels in the brain are related to a high risk of death and as a result many of these patients receive blood transfusions in an attempt to increase the amount of oxygen delivered to the brain. However, some research has demonstrated that transfusions may not help patients in certain clinical contexts, although this has yet to be investigated in post cardiac arrest patients. Therefore, it is important to understand how blood transfusions affect the brain's ability to adapt to low oxygen levels and the related impact on how much oxygen is delivered to the brain. The objective of our project is to determine how blood transfusions impact the brain's ability to adapt to low oxygen levels. Normally, when the brain encounters low oxygen levels, due to a low amount of oxygen in the blood, the amount of blood flowing to the brain increases so that the total amount of oxygen that is delivered is maintained at an adequate level. However, this important function where blood flow to the brain is increased may not be as effective following a blood transfusion. Therefore, we aim to determine how a transfusion impacts the brain blood flow and oxygen delivery response to low blood oxygen levels in healthy participants. This will enable us to determine what chemical messengers may or may not be involved in how blood transfusions affect brain blood flow regulation. We also will examine how transfusions affect blood flow and brain oxygenation in patients that have had a cardiac arrest and now suffer from a related brain injury.