Dexmedetomidine vs Propofol TIVA (Total Intravenous Anesthesia) and Interscalene Block

The anesthesia provided during shoulder surgery commonly uses a combination of regional and intravenous (IV) anesthetic medications. The current drug of choice for IV sedation is Propofol. Although. it is a good anesthetic, incidence of intermittent apnea makes the use of it problematic in cases where the head of the patient is less accessible to the anesthesiologist, as is in sitting beach char position. Dexmedetomidine is a FDA approved drug, which has a very stable cardiovascular and respiratory profile. It has been successfully used for Neurological and Vascular cases and in Intensive care units. The primary objective of the present study is to use Dexmedetomidine for sedation, and compare the outcomes with Propofol sedation. The investigators' will enroll 50 patients for this study. Using a computer program the participants will be randomized into two equal groups to receive either Dexmedetomidine or Propofol.

The standard hospital procedure calls for the patient to undergo Interscalene block under ultrasound with or without nerve stimulation guidance prior to going to operating room (OR). The block utilizes a 40 ml mixture of 0.5% Ropivacaine and Lidocaine 1.5%. At this time the patient receives preliminary sedation with Midazolam 1mg IV and Fentanyl 50 mcg IV. The participant is then brought to the OR and prolonged sedation is initiated, randomly using either Dexmedetomidine or Propofol.

Dexmedetomidine infusion is initiated with a bolus of 1 mcg/kg is given over 10 min as patient is being positioned, and the sedation is maintained with Dexmedetomidine at 0.7- 1.0 mcg/kg/hr during the surgery. Propofol infusion is started at 100mcg/kg/min, and maintained with Propofol at 50-120mcg/kg/min, during the surgery.

In each group the investigators will record the incidence of respiratory depression/hypoxia, hemodynamic stability, frequency of airway manipulation, cardiovascular effects, need for anesthetic supplementation of Dexmedetomidine, post anesthesia care unit (PACU) discharge time, the need for postoperative pain medication, post operative complications, like nausea/vomiting.

Significant differences between the two groups will be evaluated using unpaired t-test for numerical variables, and Chi-square test or Z test for categorical variables.

The investigators hypothesis is that Dexmedetomidine will cause fewer episodes of intermittent apnea, and reduced need for supplemental medication for sedation, compared to Propofol

Inclusion criteria

Participants scheduled for shoulder arthroscopies in the beach chair sitting position.

Participants who received a successful interscalene block.

Exclusion criteria

Failed interscalene block. Refusal to participate in the study. Allergy to the study drugs. Participants that need a secure airway.