Autoregulation of cerebral blood flow in patients after cardiac arrest

Out-of-hospital cardiac arrest (OHCA) is the leading cause of death in
industrialized countries. Rates of survival with favourable neurological
outcome are low. Although in the past decades more patients have a return of
spontaneous circulation (ROSC), overall prognosis has not substantially
improved and only a minority of patients survive with a favorable neurological
recovery. The poor prognosis of patients after ROSC is related to the
development of the so called post-cardiac arrest syndrome. Crucial in the ICU
treatment after cardiac arrest is creating an optimal environment for cerebral
recovery and limiting the secondary brain damage occurring during the
post-cardiac arrest syndrome. Modulating these pathophysiological processes may
prevent secondary neurological damage and possibly improve the survival rate.
The cerebral blood flow (CBF) is mainly controlled by the brain itself by
metabolic activity, cerebrovascular reactivity and pressure autoregulation.
After cardiac arrest, ROSC does not automatically restore normal cerebral
circulation. The amount of brain damage after cardiac arrest strongly depends
on the recovery of the cerebral circulation. The state of the autoregulation in
patients after cardiac arrest is not well known.
The optimal target blood pressure in patients after cardiac arrest is highly
individually determined and the level of autoregulation will play a key role in
determining this optimal target pressure.
Aim of the proposed study is to take the first step into individualized optimal
blood pressure targeting in patients after cardiac arrest. Determination of the
state autoregulation during the post cardiac arrest syndrome is an essential
step in this process, as it determines the effect of blood pressure on cerebral
blood flow.

Primary Objective:
to determine the strength of the dynamic autoregulation of patients after
cardiac arrest during the post cardiac arrest syndrome.

Secondary Objectives:
to observe the natural course of the autoregulation during the first year after
the arrest and to compare different techniques of dynamic cerebral
autoregulation

Observational study

Due to the nature of the disease (coma after cardiac arrest) the patients will
be at least temporarily incapacitated. Intensive cerebral monitoring of these
patients is considered as part of standard patient care. The different
techniques of measurement of cerebral autoregulation are well established and
validated. Currently, these techniques are being introduced into standard
patient care, because they provide valuable and relevant clinical information.
The tests proposed in this study (THRT and change in the position of the bed)
are non-invasive, well-tolerated, with a minimal burden or risk for the
patient, who is established in advance by physical examination and ultrasound
that there are no abnormalities in the carotid artery.The tests do not
influence standard patient care in any way.