Angiotensin II in General Anesthesia

Hypotension in adult patients undergoing general anesthesia is common. Many of the body's normal mechanisms to maintain adequate blood pressure in the non-anesthetized state are significantly altered by anesthetic agents, which may lead to hypotension. This can lead to hypoperfusion of vital organs, organ damage, and states of increased metabolic duress. In response to this it has become standard of care to attempt to maintain blood pressure levels within 20% of baseline in most patients under anesthesia. Maintaining the baseline blood pressure is important as patients may have pathology such as coronary artery disease, carotid stenosis, and renal artery stenosis, and hypotension may compromise the perfusion of these organs. Vasodilation also plays a key role in hypotension due to general anesthesia. Therefore, the intravenous (IV) administration of Ang II may be an effective treatment of hypotension in this patient population.The objective of this study is to determine the infusion rate of Ang II that is necessary to return systolic blood pressure (SBP) to within 5% of baseline or greater in patients with essential hypertension taking ACE inhibitors, ARBs, or different classes of antihypertensive agents and further to determine the plasma levels of different RAAS components