Effect of Hypotensive Anesthesia on Cerebral Perfusion and Blood Antioxidant Levels and HIF 1a

The aim of this study to evaluate the patients who underwent controlled hypotensive anesthesia under standardized depth of anesthesia; preoperative and postoperative blood HIF 1a, TAS, TOS measurement and cerebral perfusion evaluation with NIRS and to investigate tissue hypoxia secondary to hypotensive anesthesia and the changes of the mediators at the tissue level and which blood pressure parameters are related.

Controlled hypotension is the voluntary reversible reduction of arterial blood pressure. Hypotensive anesthesia is a method of anesthesia in which blood pressure is reduced in a controlled manner, especially in certain surgeries. İt reduces intraoperative bleeding and need for blood transfusion and provides a clean surgical vision in narrow-field surgeries or with high bleeding potential. Hypotensive anesthesia can be performed according to mean blood pressure (MBP) or systolic blood pressure (SBP). A non-invasive cerebral oximeter is used to see the changes in the brain due to high oxygen-dependent metabolism during induction and maintenance of anesthesia. Hypoxia inducible factor (HIF) is a transcription factor involved in cell adaptation mechanism activated in response to hypoxia. The biological activity of HIF 1 is determined by the expression and activity of the HIF 1a subunit. Total antioxidant status (TAS) shows the total effect of all antioxidants in the human body and total oxidant status (TOS) shows the total effect of oxidants. Near Infrared Spectroscopy (NIRS) allows continuous and non-invasive monitoring of cerebral oxygenation. HIF 1a, TAS and TOS are laboratory markers that predict tissue oxygenation and perfusion. Hypotensive anesthesia can be performed according to both MBP and SBP. However, in our study that follow-up MBP is more advantageous/protective, although it is not supported by very strong data. The investigators recommend hypotensive anesthesia compared to MBP; but further studies are needed.