The Effect of Controlled Hypotension

Controlled hypotension is currently used in spinal surgery to reduce bleeding at the surgical site, improve the surgeon's visibility, and decrease intraoperative blood loss. Although controlled hypotension is considered a beneficial method from a surgical perspective, it is important to be cautious about its side effects. One such side effect is cerebral perfusion insufficiency, which can be managed by monitoring cerebral circulation through regional cerebral oxygen saturation (rSO2).

In the literature, various definitions of controlled hypotension exist. It is commonly defined as maintaining the Mean Arterial Pressure (MAP) between 50-65 mmHg, Systolic Arterial Pressure (SAP) between 80-90 mmHg, or reducing MAP by 30% compared to baseline values. In our study, we plan to maintain the MAP within the range of 55-75 mmHg and compare the effects of two different MAP levels on perioperative cerebral oxygen saturation, anesthetic and surgical parameters, and postoperative cognitive functions.

The aim of this study is to compare the effects of controlled hypotension at specific MAP ranges on cerebral oxygen saturation.

Inclusion criteria

• Aged 18-65 years
• ASA I-III risk group
• BMI between 18-40
• Baseline blood pressure below 140/90 mmHg
• Scheduled to undergo spinal surgery (2-4 level instrumentation)

Exclusion criteria

• Below 18 or above 65 years old
• Advanced comorbidities
• ASA IV or higher
• Baseline blood pressure above 140/90 mmHg
• History of bleeding diathesis
• Use of anticoagulant medications
• BMI below 18 or above 40
• History of previous spinal surgery