Project details

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Cerebral and renal blood flow autoregulation during major surgery with continuous invasive and non-invasive blood pressure monitoring: the AutoFlow study

Keywords:
hemodynamic monitoring blood flow autoregulation Blood pressure

Researchers:
J.J. Vos
I.N. de Keijzer
Prof. dr. T.W.L. Scheeren

Nature of the research:
Bi-center observational study for the development of a predictive algorithm of disturbed cerebral and renal blood flow autoregulation

Fields of study:
anesthesiology surgery

Background / introduction
The brain is able to autoregulate cerebral blood flow in order to minimize brain injury when hemodynamic changes occur. The brain is generally able to compensate for cerebral perfusion pressure (CPP) values between 50 and 150 mmHg, although this may vary between individuals. When no increased intracranial pressure is suspected, mean arterial pressure (MAP) can be used to estimate CPP. Cerebral autoregulation is unable to compensate CPP/MAP values out of this range and this will result in postoperative neurologic complications. Cerebral oxygenation, as a surrogate measure of cerebral blood flow, can be measured using the near-infrared spectrometry (NIRS). In combination with blood pressure measurements, as substitute for CPP, autoregulation curves can be created.
Like the brain, the kidneys also have an autoregulation system to protect itself from hemodynamic disturbances. Currently, the trend in hemodynamic monitoring is to progressively use less invasive monitoring tools. Therefore, the aim of this study is to develop an algorithm based on cerebral and renal oxygenation values and invasive blood pressure measurements in patients undergoing elective surgery requiring continuous invasive hemodynamic monitoring and compare this to the non-invasively obtained blood pressure measurements.
Research question / problem definition
The primary objective is to develop an algorithm based on cerebral and renal oxygenation values and invasive blood pressure measurements and compare the latter to non-invasive blood pressure measurements. The secondary objective of this study is to assess the agreement of the following:
• MAP at the upper and lower limits of renal blood flow autoregulation from invasive and non-invasive blood pressure measurement.
• MAP at upper and lower limits of cerebral blood flow autoregulation from invasive and non-invasive blood pressure measurement.
• systolic, diastolic, and mean arterial pressure derived from invasive and non-invasive measurements
The specific topic for the thesis can be discussed.
Workplan
We are looking for a motivated student who is interested in Anesthesiologie, particularly in the field of hemodynamic monitoring. You will be able to attend multiple major surgical procedures and have a unique insight in our field. You will be supervised directly by a PhD candidate, eventually you will be asked to obtain informed patient consent and collect data independently. There are opportunities for a MD/PhD program or PhD afterwards. The Ethics approval is expected for September 1st, 2021.
References
Armstead W. Cerebral Blood Flow Autoregulation and Dysautoregulation. Anesthesiol Clin. 2016;34:465–77.
Moerman A, De Hert S. Why and how to assess cerebral autoregulation? Best Pract Res Clin Anaesthesiol. 2019;33(2):211–20
Carlström M, Wilcox CS, Arendshorst WJ. Renal autoregulation in health and disease. Physiol Rev. 2015;95(2):405–511.
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