Evaluation of near infrared spectroscopy for detecting the β blocker-induced decrease in cerebral oxygenation during...

Area of Science:

• Anesthesiology
• Cardiovascular Physiology
• Neuroscience

Background:

• Beta blockers can decrease cerebral oxygenation, potentially increasing stroke risk during surgery.
• Perioperative hemodilution further impacts oxygen delivery.
• The utility of cerebral tissue oxygenation monitoring in this context is unclear.

Purpose of the Study:

• To investigate if near-infrared spectroscopy (NIRS) can detect beta blocker-induced reductions in cerebral oxygenation.
• To assess if this detection is dependent on hemodilution severity and/or beta blocker dose.
• To evaluate the clinical utility of tissue oxygenation index (TOI) monitoring.

Main Methods:

• Animal model study using landiolol and esmolol.
• Progressive hemodilution induced by hemorrhage and fluid resuscitation.
• Administration of escalating beta blocker doses.
• Monitoring of hemodynamic variables and tissue oxygenation index (TOI) via NIRS.

Main Results:

• Both landiolol and esmolol dose-dependently reduced heart rate, mean arterial pressure, and cardiac output.
• Cerebral oxygenation, measured by TOI, decreased in a dose-dependent manner during hemodilution.
• Cerebral oxygenation returned to baseline after beta blocker infusion cessation.

Conclusions:

• Short-acting beta blockers reduce cerebral oxygenation during hemodilution.
• NIRS-derived TOI can identify these reductions.
• TOI monitoring may be valuable for patients on beta blockers during high-bleeding-risk surgery.