- 1. Recent psychiatric hospitalization, suicide attempt, or history within the preceding month of electroconvulsive therapy 2. History of psychosis, eg, schizophrenia 3. History of recent seizures 4. Uncontrolled intracranial hypertension due to brain metastasis or hydrocephalus 5. Severe labile hypertension or poorly controlled cardiac arrhythmia 6. Chronic obstructive pulmonary disease (COPD) associated with hypercarbia