Total Shoulder Arthroplasty Near-infrared Spectroscopy
Total Shoulder Arthroplasty Near-infrared Spectroscopy
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.
Inclusion Criteria:

 -  Patients 18-99 undergoing total shoulder arthroplasty

 -  Planned general anesthesia + brachial plexus nerve block

 -  Planned arterial catheter

 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