Comparative effects of propofol vs dexmedetomidine on cerebrovascular carbon dioxide reactivity in patients with septic shock

• Published in: British journal of anaesthesia : BJA Vol. 100; no. 2; pp. 224 - 229
• Main Authors: Kadoi, Y., Saito, S., Kawauchi, C., Hinohara, H., Kunimoto, F.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2008; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Aged; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; blood flow; Blood Flow Velocity - drug effects; brain; brain, blood flow; carbon dioxide; Carbon Dioxide - metabolism; carbon dioxide, measurement; Cerebrovascular Circulation - drug effects; Conscious Sedation - methods; Dexmedetomidine - pharmacology; Humans; Hypnotics and Sedatives - pharmacology; measurement; Medical sciences; Middle Aged; Middle Cerebral Artery - diagnostic imaging; Middle Cerebral Artery - physiopathology; Propofol - pharmacology; Prospective Studies; Respiration, Artificial; sedation; Shock, Septic - physiopathology; Ultrasonography, Doppler, Transcranial; sedation; brain, blood flow; carbon dioxide, measurement; α2-Adrenergic receptor; Shock; Human; blood flow; carbon dioxide; Agonist; Carbon dioxide; Sedation; brain; Blood flow; Encephalon; Infection; General anesthetic; Dexmedetomidine; Anesthesia; α-Adrenergic receptor agonist; Propofol; measurement; sedation
• ISSN: 0007-0912; 1471-6771; 1471-6771
• DOI: 10.1093/bja/aem343

The use of sedative drugs is reportedly related to altered cerebrovascular CO2 reactivity. The present study examined the comparative effects of propofol vs dexmedetomidine on cerebrovascular CO2 reactivity in patients with septic shock. A total of 20 patients with septic shock who required mechanical ventilation were included in this study. Sedation during mechanical ventilation was maintained using either propofol or dexmedetomidine. A 2.5 MHz pulsed transcranial Doppler probe was attached to the head of the patient at the right temporal window for continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). After establishing baseline values of Vmca and cardiovascular haemodynamics, end-tidal CO2 was increased by decreasing ventilatory frequency by 5–8 bpm. The absolute and relative CO2 reactivity values in patients with septic shock were lower for both propofol and dexmedetomidine than those for control groups, with significant differences between these values in the two septic shock groups (absolute CO2 reactivity in septic shock under propofol: 2.6 (sd 0.3) cm s−1 mm Hg−1; absolute CO2 reactivity in septic shock under dexmedetomidine: 2.0 (0.3) cm s−1 mm Hg−1; P<0.01). This study showed that cerebrovascular CO2 reactivity was lower under dexmedetomidine sedation than under propofol sedation during almost identical sedation in patients with septic shock.