Total Shoulder Arthroplasty Near-infrared Spectroscopy

Completed

Interventions: Device: Casmed Fore-Sight Elite
Device: Non-invasive Cardiac Output Monitor (NICOM)

Brief Summary: The purpose of this study is to measure cerebral oxygenation and cardiac output of total shoulder replacement patients undergoing general anesthesia (GA) and positive-pressure ventilation (PPV).

We hypothesize that cerebral desaturation occurs frequently during GA with PPV, but is rare during GA and spontaneous ventilation. We also hypothesize that cardiac output usually is well maintained under GA in the sitting position when epinephrine is used, but that decreased cardiac output increases the risk of cerebral desaturation.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Patients younger than 18 years older and older than 99
Patients not intending to receive general anesthesia and peripheral nerve block
Indication for endotracheal tube
BMI ≥ 30
Ejection Fraction (if known) < 50%
Known significant restrictive or obstructive pulmonary disease
Patients with a history of transient ischemic attack (TIA) or stroke
Patients with recent signs or symptoms of myocardial ischemia
- Current stress test positive for ischemia
Intolerance to study medications
pre-existing contraindication to regional anesthesia
- infection at block site
- pre-existing neurological injury to operative limb
Non-English speaking patients

Arm && Interventions

Group	Intervention	Description
Near-infrared spectroscopy	Casmed Fore-Sight Elite	Casmed Fore-Sight Elite and Non-invasive Cardiac Output Monitor (NICOM)
Near-infrared spectroscopy	Non-invasive Cardiac Output Monitor (NICOM)	Casmed Fore-Sight Elite and Non-invasive Cardiac Output Monitor (NICOM)

Primary Outcome Measures

Name	Time	Method
Number of Cerebral Desaturation Events	Day of surgery	The number of Cerebral Desaturation Events (CDE) that occured. CDE is defined as a reduction in cerebral tissue oxygen saturation of \>20% from baseline that lasts for 90 seconds or longer.

Secondary Outcome Measures

Name	Time	Method
Intravenous Fluid Volume	Day of surgery
Stroke Volume (SV)	Day of surgery	Stroke volume, the amount of blood pumped by the left ventricle of the heart with each contraction. Measured in milliliters.
Cardiac Output (CO)	Day of surgery	Cardiac output of patients as measured in liters per minute
Cardiac Index (CI)	Day of surgery	Average cardiac index for patients, a measurement of how efficient the heart is pumping. Measured in liters per minute per meters squared of heart size.
End Tidal Carbon Dioxide (ETCO2)	Day of surgery	a lower score is a better outcome.
Mean Arterial Pressure (MAP)	Day of surgery	mean arterial pressure and noninvasive blood pressure will be represented as a percentage of baseline after surgery. A lower percentage is a worse outcome.