DDx -Post op (pain, anxiety, fever, hypovolemia), Stress, Fever, Pain, Hypovolemia (Shock, Dehydration, Third Spacing, Hemorrhage...), Hypoxia, MI, CHF, Acute Pulmonary Embolus, Pneumonia, Sepsis, Trauma, Arrhythmias (AFib, AFlumer, SVT, MAT, PAT, AV Nodal Reentrant Tachycardia, WPW, Bigeminy, VTach), Thyrotoxicosis, Pheochromocytoma, Medications (Epinephrine, Chronotropic Agents [Dopamine, Dobutamine, Levophed...], Beta-2 Agonists [Alupent, Ventolin, Serevent...], Aminophylline)