Modeling the Effect of EtCO2 on Cerebral Oxygenation

Pharmacodynamic Modeling of the Effect of End-tidal Carbon Dioxide on Cerebral Oxygen Saturation in Beach Chair Position Under General Anesthesia

The aim of this study was to investigate the relationship between the end-tidal carbon dioxide (EtCO2) and cerebral oxygen saturation (rSO2) and to identify the covariates in the pharmacodynamic relationship between EtCO2 and rSO2.

Even though mild hypercapnia in the beach chair position (BCP) under general anesthesia was effective in reducing cerebral desaturation, there is no comprehensive data with regard to the dose-effect relationship of EtCO2 on rSO2 in the BCP under general anesthesia. Pharmacodynamic modeling can be useful in describing this relationship in which concurrent mean arterial pressure changes and disease state can be considered as covariates. Therefore, we investigated the relationship between the EtCO2 and rSO2 and identified the covariates in the pharmacodynamic relationship between EtCO2 and rSO2.

Inclusion Criteria:

• Age ≥19 years who were scheduled to elective arthroscopic shoulder surgery in BCP under general anesthesia

Exclusion Criteria:

• Previous cerebrovascular disease, orthostatic hypotension, and the American Society of Anesthesiologists physical status IV or V