Oxygen dependence of > 2 L/min continuously throughout the day at baseline Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations (including current drug or alcohol abuse or dependence, or history of drug or alcohol abuse or dependence within the last year) that would limit compliance with study requirements Alcohol or drug dependence As per self report, participant has major depressive disorder, alcohol or drug dependence and Active drug/alcohol dependence or abuse history Inotropic dependence Chronic corticosteroid dependence (except replacement therapy) History of alcohol or other substance abuse or dependence within the year prior to registration Moderate or severe aplastic anemia defined by one of the following: peripheral blood neutrophils < 0.5 x 10^9/L; platelets < 30 x 10^9/L or platelet transfusion dependence; reticulocytes < 50 x 10^9/L in anemic patients or red cell transfusion dependence Substance or alcohol abuse or dependence, within 12 months prior to screening. Treatment for drug or alcohol dependence during the last year, or evidence of alcohol abuse so severe that the patient is judged potentially unable to comply with the protocol. Active alcohol dependence PRE-REGISTRATION: Chronic corticosteroid dependence that is unable to be weaned to discontinue. Active drug or alcohol use or dependence that would interfere with study compliance Inotropic dependence No history of or current active drug/alcohol dependence Active drug/alcohol dependence or abuse history Patient has an Alcohol Use & Dependence (AUDIT) score of < 10 Conditions, including alcohol or drug dependence, intercurrent illness, or lack of sufficient peripheral venous access, that would affect the patient's ability to comply with study visits and procedures Feeding tube dependence Conditions, including alcohol or drug dependence, intercurrent illness, or lack of sufficient peripheral venous access, that would affect the patient's ability to comply with study visits and procedures Current substance dependence, other than nicotine Conditions, including alcohol or drug dependence, intercurrent illness, or lack of sufficient peripheral venous access, that would affect the patient's ability to comply with study visits and procedures Active substance abuse or dependence Tracheotomy or oxygen dependence at time of MBS Substance abuse or dependence or met criteria within past year History of substance dependence in the past six months Patients cannot be homeless or have substance dependence Active alcohol dependence, defined as 2 or more positive questions on the CAGE alcoholism questionnaire Co-morbid delirium, dementia, or active and untreated psychotic, bipolar or substance-dependence disorder interfering with consent untreated alcohol or substance abuse or dependence, bipolar, or psychotic disorder No history of or current active drug/alcohol dependence History of or active drug/alcohol dependence or abuse History or current diagnosis of substance abuse or dependence No substance dependence within the past year; Substance dependence within the past year; History of alcohol or other substance dependence or current abuse History of alcohol or other substance dependence or current abuse Unstable psychiatric/medical conditions such as suicidal ideation, acute psychosis, severe alcohol dependence, or dementia Patients with a current dependence on alcohol (characterized by a physical addiction to alcohol that interferes with physical or mental health, and social, family or job responsibilities) History of alcohol or drug dependence in the past year Nicotine dependence assessed as > 4 (>= 2 for study 2) with the Fagerstrom Test for Nicotine Dependence Alcohol or illicit drug dependence within the past 12 months (by history and urine tests) Active drug or alcohol use or dependence that, in the opinion of the Site Investigator, would interfere with adherence to study protocol Active drug or alcohol use or dependence that, in the opinion of the site Investigator, would interfere with adherence to study requirements Current or recent (within 12 months) problems with drug use or alcohol dependence by self-report Alcohol dependence, abuse, or history of dependence/abuse by self-report Current or recent (within 12 months) problems with drug use or alcohol dependence by self-report Alcohol dependence, abuse, or history of dependence/abuse by self-report