Effect of Sodium Nitroprusside on Cerebral Blood Flow
Status:
Completed
Trial end date:
2017-12-04
Target enrollment:
Participant gender:
Summary
The brain has a high energy demand and requires continuous blood flow. The blood flow to the
brain appears to be unaffected by small changes in blood pressure, but brain blood flow may
be reduced by a large reduction in blood pressure. Large reductions in blood pressure are
common during anesthesia or bleeding. It is unclear, however, how a given reduction in blood
pressure affects blood flow to the brain.
In this study, medicine called sodium nitroprusside is used to dilate blood vessels and
reduce blood pressure in twenty healthy young men. The study will evaluate whether blood flow
to the brain is affected when sodium nitroprusside is used to induce a moderate and a large
reduction in blood pressure. Blood flow to the brain is evaluated using ultrasound on the
neck.
During breathing, oxygen is inhaled and carbon dioxide is exhaled. Carbon dioxide increases
brain blood flow whereby changes in respiration can affect the blood flow to the brain.
Sodium nitroprusside causes mild hyperventilation, whereby more carbon dioxide is exhaled,
which will contribute to a reduction in brain blood flow. Thus, the study will also evaluate
how brain blood flow is affected by hyperventilation and by breathing a mix of air and carbon
dioxide.