Participants with an unstable major psychiatric disorder, as assessed by study clinician, or a diagnosis of alcohol abuse (more than drinks in a hour period) or substance dependence within the past year (as determined by a standard psychiatric interview) will be excluded unless otherwise approved by the PI or PIs designee Oxygen dependence of > 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 Meet criteria for the following psychiatric and/or substance use disorders as assessed by the MINI International Neuropsychiatric Interview (MINI): items C (current manic or hypomanic episode only), I (alcohol abuse - Alcohol Addendum - past months only; current alcohol dependence), J (substance abuse - Substance Abuse Addendum - past months only; current substance dependence), K (current psychotic disorder or current mood disorder with psychotic features); individuals who meet criteria for non-exclusionary psychiatric disorders that are considered clinically unstable and/or unsuitable to participate as determined by the principal investigator and/or study physician History of alcohol or other substance abuse or dependence within the year prior to registration Current alcohol dependence or drug abuse. Current alcohol dependence or drug abuse. Substance or alcohol abuse or dependence, within 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 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 Current alcohol dependence or drug abuse. Patient has an Alcohol Use & Dependence (AUDIT) score of < 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 alcohol dependence or drug abuse. 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 alcohol dependence or drug abuse. 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 or more positive questions on the CAGE alcoholism questionnaire Participant has current reported illicit drug or alcohol abuse or dependence 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 Meet criteria for the following psychiatric and/or substance use disorders as assessed by the Mini International Neuropsychiatric Interview (MINI): items C (current manic or hypomanic episode only), I (alcohol abuse - alcohol addendum-past months only; current alcohol dependence), J (substance abuse - substance abuse addendum - past months only; current substance dependence), K (psychotic disorder or mood disorder with psychotic features); individuals who meet criteria for non-exclusionary psychiatric disorders that are considered clinically unstable and/or unsuitable to participate as determined by the principal investigator History of alcohol or drug dependence in the past year Meet criteria for the following psychiatric and/or substance use disorders as assessed by the Mini International Neuropsychiatric Interview (MINI); items C (current manic or hypomanic episode only), I (alcohol abuse-Alcohol Addendum-past months only; current alcohol dependence), J (substance abuse-Substance Abuse Addendum-past months only; current substance dependence), K (current/lifetime psychotic disorder or current/lifetime mood disorder with psychotic features); individuals who meet criteria for non-exclusionary psychiatric disorders that are considered clinically unstable and/or unsuitable to participate as determined by the principal investigator and/or study physician Nicotine dependence assessed as > (>= for study ) with the Fagerstrom Test for Nicotine Dependence Alcohol or illicit drug dependence within the past 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 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 months) problems with drug use or alcohol dependence by self-report Alcohol dependence, abuse, or history of dependence/abuse by self-report any major current psychiatric impairment, including current alcohol/drug abuse/dependence