An interventional study of current versus high pump flow in Cerebral Autoregulation, Cardiopulmonary Bypass and Mean Arterial Pressure, sponsored by Clinique de la Sauvegarde. Completed at 1 site in France. Open to participants aged 18 Years to 90 Years. Per ClinicalTrials.gov, last updated 2023-09-14.
Sponsored by Clinique de la Sauvegarde · Not applicable, Interventional, and Diagnostic
Cerebral autoregulation is defined by the capacity of the brain to maintain a constant cerebral blood flow (CBF) despite variations of arterial pressure. However, when the arterial pressure is below a critical threshold, cerebral blood decreases.
This critical threshold is called the lower limit of cerebral autoregulation (LLA).
Cardiopulmonary bypass is a unique environment wherein systemic blood flow is totally controlled by the cardiopulmonary bypass pump. High pump flows combined with low arterial pressures has been shown to not compromise neurologic postoperative outcomes.
Our hypothesis is that that LLA may depend on the cardiopulmonary bypass flow, ie the LLA may decrease when the cardiopulmonary bypass flow increases, explaining why low arterial pressure may be well tolerated.
Cerebral tissue perfusion is partly ensured by cardiac output and arterial pressure. In cardiac surgery, and especially during bypass surgery, one of the main objectives is to maintain sufficient blood flow and an optimal mean arterial pressure (MAP) to limit the deleterious consequences of organ hypoperfusion. To have a physiological regional organ blood flow, some organs, such as the brain, need a minimum MAP threshold (the lower limit of autoregulation, LLA) to ensure a constant cerebral blood flow (CBF). This is known as the cerebral autoregulation (CA). As the brain is at high risk of ischemia and definitive functional consequences in case of cerebral hypoperfusion, maintaining MAP above the LLA of the brain limit the deleterious postoperative neurological outcome.
CA can be determined by continuously calculating the correlation between MAP and CBF. CBF is assessed by continuous monitoring of the middle cerebral artery velocity (mV). moving Pearson correlation coefficient between 30 consecutive, paired MAP and cerebral blood flow velocity values will be calculated to generate the mean velocity index (Mx). The Blood pressure in the autoregulation range is indicated by an Mx value that approaches zero (there is no correlation between flow velocity and MAP), whereas an Mx approaching 1 indicates dysregulated cerebral blood flow (flow velocity and MAP are correlated). A value of 0.4 is accepted as the threshold of CA corresponding to the LLA.
During cardiopulmonary bypass (CPB), MAP is physiologically related to bypass flow and systemic vascular resistance. The adjustment of MAP during CPB is therefore achieved by the administration of vasoconstrictors or vasodilators as well as by the variations of the pump flow.
This research assumes that a change in the pump flow rate will lead to a change in the LLA. Therefore, if the flow rate is higher, it is possible that the LLA will be lower.
In this randomized trial, two different rates of pump flow will be compared with respect to LLA testing.
Regional brain oxygen saturation, assessed by near-infrared spectroscopy will also be monitored during surgery.
Clinique de la Sauvegarde is the lead sponsor of 3 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
the pump flow will be constant during this randomized phase
Procedure: current versus high pump flow
the pump flow will be constant during this randomized phase
Procedure: current versus high pump flow
during each phase of randomized pump flow, arterial pressure will be increased from 40 to 90 mmHg with vasodilators and/or vasoconstrictors
measurement of MAP LLA (mmHg)
Determination of MAP LLA according to the calculation of the mean velocity index
Time frame: 15 to 25 min during the procedure
Plan to share: No
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Clinique de la Sauvegarde