Cerebral Hemodynamics and Oxygenation in Critically Ill Patients

Cerebal Hemodynamics and Oxygenation in Critically Ill Patients : Characterization and Effects of Therapeutics

Critically-ill patients frequently experience marked changes in mean arterial pressure and carbon dioxide partial arterial pressure, the two major determinants of the cerebral blood flow. In addition, many therapeutics (fluids, vasopressors or inotropes administration, blood transfusion, prone positioning...) can influence these two determinants of cerebral blood flow and thus cerebral blood flow, especially in patients with altered cerebral autoregulation. Nevertheless, cerebral hemodynamics and oxygenation, as well as the effects of the different therapeutics on it have been poorly studied in critically-ill patients. In addition, it has been suggested that impaired cerebral blood flow and impaired cerebral microcirculation may be involved in the pathophysiology of septic encephalopathy in patients with sepsis and/or septic shock. In this study, we aimed to characterize and investigate the effects of different therapeutics on cerebral hemodynamics and oxygenation in critically-ill patients.

Inclusion Criteria :

• Patients under mechanical ventilation and sedated within the first 72h of ventilation onset
• Indication to one of the studied therapeutics left at the discretion of the attending physician Exclusion criteria
• Age < 18 years
• Pregnancy
• Inability to obtain a Doppler signal
• Medical history or clinical evidence of neurological disease
• Known severe carotid stenosis (>70%)
• Significant cardiac arrhythmias
• Care-limitation decision.