- Known co-morbid conditions likely to complicate therapy, e.g., end-stage cardiomyopathy, uncompensated arrhythmia, myopathy, liver disease severe enough to elevate bilirubin, history of pelvic or abdominal mass likely to compress inferior vena cava, IVC filters, dementia severe enough to prevent valid consent, end-stage AIDS, known thyroid deficiency, known renal insufficiency likely to impair meperidine (Demerol®) clearance