The number of high-risk patients undergoing non-cardiac surgery has increased continuously over the last two decades. There is a paucity of data exist about the bioavailability of postoperative administrated beta-blockers. One study reported adequate plasma levels of Propanolol after administration via nasogastric tube but not after oral administration in patient undergoing thyroid surgery.Thus it is possible that patients maintained on oral beta blockers may in fact be experiencing a withdrawal syndrome. Because of the importance of avoiding withdrawal of beta blockers, intravenous administration may be the only alternative in cases where oral administration fails to achieve adequate plasma levels perioperatively. Furthermore, due to changes in pharmacodynamics, intravenous dosage may be the optimal way to achieve tight hemodynamic control. There is, however, no data on the post-operative hemodynamic effects of orally administered beta blockers in patients on chronic beta blockers.
