Dexmedetomidine and Hypoxic Pulmonary Vasoconstriction in Thoracic Surgical Procedure and One-Lung Ventilation(OLV)

Inclusion Criteria:

1. Subject is > 18 years of age.

2. Subject is American Society of Anesthesiologists (ASA) Physical Status I, II, III, or
IV.

3. If female, subject is non-lactating and is either:

- Not of childbearing potential, defined as post-menopausal for at least 1 year or
surgically sterile due to bilateral tubal ligation, bilateral oophorectomy or
hysterectomy.

- Of childbearing potential but is not pregnant at time of baseline and is
practicing one of the following methods of birth control: oral or parenteral
contraceptives, double-barrier method, vasectomized partner, or abstinence from
sexual intercourse.

4. Subject requires thoracic surgical procedure .

5. Subject (or subject's legally authorized representative) has voluntarily signed and
dated the informed consent document approved by the Institutional Review Board.

Exclusion Criteria:

1. Subject has received general anesthesia within 7 days prior to study entry, has
received any experimental drug within 30 days prior to study drug administration, or
has been previously enrolled in this study.

2. Subject has central nervous system (CNS) disease with an anticipated potential for
increased intracranial pressure, an uncontrolled seizure disorder and/or known
psychiatric illness that could confound a normal response to sedative treatment.

3. Subject has received treatment with an alpha-2 agonist or antagonist within 14 days
of the scheduled surgery/procedure.

4. Subject for whom opiates, benzodiazepines, DEX or other alpha-2 agonists are
contraindicated.

5. Subject has received an IV opioid within one hour, or PO/IM opioid within four hours,
of the start of study drug administration.

6. Subject has acute unstable angina, acute myocardial infarction documented by
laboratory findings in the past six weeks, heart rate < 50 bpm, SBP < 90 mmHg, or
third-degree heart block unless patient has a pacemaker.

7. Subject has known elevated SGPT (ALT) and/or SGOT (AST) values of > 2 times the upper
limit of normal (ULN) within the two months prior to screening, and/or a history of
liver failure.

8. Subject has any other condition or factor which, in the Investigator's opinion, might
increase the risk to the subject.

9. On vasodilators, i.e.,nitroglycerin, nitroprusside, or ACE inhibitors

10. on vasopressors, i.e, norepinephrine,epinephrine, or vasopressin