You will be shown inclusion or exclusion criteria for a clinical trial. Given these criteria, your task is to extract all unique entities of the following types: ["Observation", "Condition", "Procedure", "Drug", "Temporal", "Multiplier", "Qualifier", "Negation", "ReferencePoint", "Scope", "Value", "Mood", "Device", "Visit", "Measurement", "Person"].

Please return the output as a JSON object of the format: {"Condition" : ["breast cancer", ...], "Device" : ["ports", ...], "Drug" : ["Atenolol", ...], "Measurement" : ["blood pressure", ...], "Mood" : ["suspected", ...], "Multiplier" : ["more than two", ...], "Negation" : ["no", ...], "Observation" : ["history", ...], "Person" : ["male", ...], "Procedure" : ["surgery", ...], "Qualifier" : ["severe", ...], "ReferencePoint" : ["enrollment", ...], "Scope" : ["infection", ...], "Temporal" : ["one day", ...], "Value" : ["50%", ...], "Visit" : ["ICU", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

unstable condition, COPD exacerbation
mild (GOLD 1) or very severe COPD (GOLD 4)
requirement for oxygen therapy at low altitude residence
hypoventilation
pulmonary hypertension
more than mild or unstable cardiovascular disease
use of drugs that affect respiratory center drive
internal, neurologic or psychiatric disease that interfere with protocol compliance including current heavy smoking (>20 cigarettes per day), inability to perform 6 min walk test.
previous intolerance to moderate altitude (<2600m).
exposure to altitudes >1500m for >2 days within the last 4 weeks before the study.
pregnant or nursing patients
{"Condition": ["condition", "hypoventilation", "psychiatric disease", "gic or psy  that ", "intolerance", "pulmonary hypertension", "cardiovascular disease", "COPD exacerbation", "l, neuro  that ", "COPD"], "Device": [], "Drug": [], "Measurement": ["GOLD"], "Mood": [], "Multiplier": ["\u003e20 cigarettes per day"], "Negation": ["inability"], "Observation": ["smoking", "altitude"], "Person": [], "Procedure": ["oxygen therapy", "6 min walk test"], "Qualifier": ["more than mild", "very severe", "moderate", "mild", "unstable", "heavy"], "ReferencePoint": [], "Scope": ["more than mild or unstable"], "Temporal": [], "Value": ["\u003c2600m", "4", "1)"], "Visit": []}