The study compares the effect of thigh high compression stockings on cerebral desaturation events in patients undergoing shoulder arthroscopy in the beach chair position with a BMI greater than or equal to 30.

On the day of surgery, enrolled patients whom have signed consent for participation in the study will be randomized to receive thigh high compression stockings with SCDs or SCDs alone. The importance of the investigation, proposed methodology, and potential risks of participation will be addressed. In the pre-operative holding area, a cerebral oximeter (INVOS 5100C, Covidien) will be placed on the skull as directed by the manufacturer. The sensors will be placed on the skull bilaterally in order to assess perfusion in both hemispheres. Cerebral oximeter is a non-invasive, transcutaneous tool that can be used to measure cerebral tissue oxygenation. The tool uses nearinfrared spectroscopy to measure the percentage of hemoglobin saturated with oxygen in the microcirculation of tissue within approximately 2-3cm below the skin. The technology is approved by the FDA in the anesthesia setting to monitor cerebral oxygenation and is commonly used in cardiothoracic surgery and its use has been validated in the surgical setting.11 A baseline cerebral tissue oxygen saturation (rSO2) will be recorded. All patients will be anesthetized using a standardized protocol. Once anesthesia has been induced, thigh high compression stockings will be applied to the appropriate group followed by SCDs. All patients in the study will wear sequential compression devices on both legs for thrombosis prophylaxis regardless of randomization. The patient will then be raised into the beach chair position and secured in the normal fashion and the planned surgery will begin. Intraoperative rSO2 data will be continuously recorded throughout the case. The system will be set to alarm when the rSO2 decreases greater than 20% from baseline. These events will be recorded throughout the case as CDEs. To avoid cerebral vascular injury, these events will be treated with a protocol by anesthesia including ephedrine, phenylephrine, and the patient may be returned to the supine position if needed. When surgery is complete, patients will be recovered in the post-anesthesia care unit. The study will be conducted at three facilities within the Loyola system: the Loyola Ambulatory Surgery Center at Oakbrook (LASCO), the Ambulatory Surgery Center at Loyola (ASC), and at Gottlieb Memorial Hospital (GMH). Personnel will include the attending surgeon, orthopaedic surgery residents, and anesthesia staff assigned to each case, all of whom will be fully educated on the study and protocols.

Inclusion Criteria:

• • All patient over age 18

  • BMI > 30
  • Undergoing shoulder arthroscopy in beach chair position

Exclusion Criteria:

• • Age < 18 years

  • BMI < 30
  • Known and documented >90% occlusion of carotid artery
  • Prior neck surgery
  • Women who are pregnant

IPD will not be shared

Patients are not made aware of their study group or the presence of intraoperative cerebral desaturation events