The steep Trendelenburg position (STP) provides an advantage in laparoscopic procedures as it optimizes the surgical image. In laparoscopic operations, the need for CO2 pneumoperitoneum (PP), together with this non-physiological position, raises concerns about the patient's physiological homeostasis. Although most patients seem to tolerate the combination of STP and PP, this method carries risks of ICP (intracranial pressure) and brain perfusion. The head-down position increases arterial pressure as well as CVP, thereby disrupting cerebral venous drainage and increasing hydrostatic pressures in the cerebral vascular system. This increases cerebrovascular resistance and decreases cerebral blood flow by increasing ICP and cerebral edema. Systemic CO2 absorption from pneumoperitoneum causes hypercarbia. Hypercarbia can increase cerebral blood flow through cerebral vasodilation.

Seventy-four percent to 95% of cerebral venous drainage in the supine position is provided by IJVs. Studies have shown that IJVs, which are responsible for most cerebral venous drainage, exhibit changes in diameter and blood flow due to TP. These studies were generally conducted on moderate TP and on healthy volunteers. In this study, we aim to evaluate the effects of a steep Trendelenburg position (25°) and pneumoperitoneum on IJV blood flow in patients undergoing operation under general anesthesia

Inclusion Criteria:

ASA I-II physical status age between 18 and 65 years planned gynecological laparoscopic surgery. -

Exclusion Criteria:

history of head and neck surgery history of cerebrovascular disease ASA III-IV physical status

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ASA I-II physical status, age between 18 and 65 years, and planned gynecological laparoscopic surgery.