The main objective of this study is whether preloading before positioning would be effective for less hemodynamic instability. The study also analyzes that patients with preloading will decrease postoperative nausea and vomiting, better surgical satisfaction and shortened the duration of surgery and anesthesia.

Keeping patients in normovolemic state and hemodynamically stable in anesthesia and intensive care practice are important goals of anesthesiologist. It is known that hypotension that develops after taking patients to the beach chair position has a negative effect on cerebral oxygenation. Aggressive fluid regimes using to prevent hypotension can cause glycocalyx damage, edema and organ dysfunction. Also hypertension seconday to vasopressor therapy can cause bleeding at the surgical site and impaired surgical visualization during the arthroscopic shoulder surgery.

In the literature, there are studies examine whether the hypotension is the result of decreased cardiac output or decreased systemic resistance and what should be the optimal treatment , but as far as investigators know, there is no study about effects of preloading before the beach chair position on hemodynamic parameters.

Inclusion Criteria:

• undergoing elective arthroscopic shoulder surgery in the BCP,
• age older than 18 years and younger than 65 years,
• the American Society of Anesthesiologist (ASA) physical status of I or II,
• accepting the study protocol.

Exclusion Criteria:

• preoperative arrhythmia,
• significant heart failure
• valvular heart disease,
• preexisting cerebrovascular disease,
• deciding to switch to open surgery,
• vasopressor infusion during the surgery,
• using angiotensin converting enzyme inhibitors (ACEI) orangiotensin receptor blockers (ARB) as antihypertensive medication.

Single-blind