Parameters of Cerebral Perfusion

Summary

The purpose of this study is to determine whether cerebral blood flow and cerebral tissue oxygenation is most dependent on cardiac output or on mean arterial pressure in patients undergoing cardiac surgery with the use of cardiopulmonary bypass.

Conditions

• Cerebral Perfusion
• Cerebral Oxygenation
• Cardiopulmonary Bypass

Interventions

OTHER

50-100ug phenylephrine before CPB

In this intervention we will administer 50-100 μg phenylephrine to the patient before CPB is started. This intervention will take place when the patient shows hypotension (MAP \<60mmHg, according to protocol22). Because of the increase in PVR there will be a baroreceptor-reflex-mediated decrease in CO. On-line, we will quantify the percentage decrease in systemic blood flow (i.e. CO) by using the Modelflow algoritm incorporated in a non-invasive beat-to-beat finger blood pressure monitor. This will allow us to obtain a reference for the decrease in CO to use in the next interventions. Our hypothesis is that CO will decrease because of the baroreceptor-reflex. During this intervention NIRS and TCD MCA will be recorded.

OTHER

50-100ug phenylephrine during CPB

In this intervention we will induce only 1 component of the changes at intervention (1), being the increase in MAP of approximately 20 mmHg by administrating 50-100 μg phenylephrine. The CPB enables us to maintain a constant CO and thus eliminating the baroreceptor-reflex. During this intervention NIRS and TCD MCA will be recorded.

OTHER

decreasing CPB flow

With this intervention we will only create a change in CO, which enables us to eliminate the effect of blood pressure. We will modify CPB flow to achieve the CO decrease (in %) measured at intervention (1) meaning: pre-CPB after the bolus of 50-100 μg phenylephrine. In the case of unexpected increase (in %) of CO measured at intervention (1), we will still decrease CPB flow so we will be able to analyse decrease as well as increase in CPB flow. During this intervention NIRS and TCD MCA will be recorded.

OTHER

Decreasing CPB flow AND 50-100ug phenylephrine

In this intervention we will simulate the 'normal' physiological state when administering phenylephrine. We will modify CPB flow to achieve the percentage change CO as observed during intervention (1) as well as administrate 50-100 μg phenylephrine. We expect to see similar outcomes as in intervention (1). During this intervention NIRS and TCD MCA will be recorded.

OTHER

Increasing CPB flow

In this last intervention we will create an increase in MAP without using phenylephrine but only by increasing CO. This enables us to eliminate a possible direct α1-adrenergic effect on the cerebral vasculature. MAP will be raised approximately 20 mmHg by increasing CPB flow 20%. During this intervention NIRS and TCD MCA will be recorded.

Sponsors & Collaborators

• UMC Utrecht

  lead OTHER

Study Design

Allocation

NA

Purpose

BASIC_SCIENCE

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2016-01-31

Primary Completion

2017-03-17

Completion

2017-03-17

Countries

• Netherlands

Study Locations