Vasopressin (and its congener, desmopressin) are exogenous preparations of the endogenous antidiuretic hormone.
Clinical uses of vasopressin have included treatment of diabetes and as an adjunct to treatment of gastrointestinal (GI) bleeding and esophageal varices.
New clinical indications for vasopressin include support of patients with septic shock and cardiac arrest (40 IU in 40 mL IV) secondary to ventricular fibrillation or pulseless ventricular tachycardia. Advanced Cardiac Life Support (ACLS) guidelines recommend vasopressin in place of the first or second dose of epinephrine during treatment of pulseless arrest.
Adenosine is an endogenous byproduct of ATP and has negative chronotropic effects on the SA node as well as negative dromotropic effects on the AV node when administered IV. The principal clinical use of adenosine is termination of paroxysmal supraventricular tachycardia (6 mg IV [100–150 µg/kg IV for pediatric patients]).
Phosphodiesterase inhibitors do not rely on stimulation of αor βreceptors. These drugs combine positive inotropism with vasodilator activity by selectively inhibiting phosphodiesterase.
Milrinone is a more potent phosphodiesterase inhibitor that lacks effects on platelets and may be useful for short-term IV therapy of congestive heart failure.
Digitalis Glycosides.Digoxin is administered principally to treat congestive heart failure and control supraventricular tachydysrhythmias such as atrial fibrillation. A therapeutic effect occurs within 10 minutes (0.25–1.0 mg IV for adults). Signs of digitalis toxicity (cardiac dysrhythmias, GI disturbances) must be inquired about when evaluating patients preoperatively. Digitalis toxicity is enhanced by hypokalemia or injection of calcium. Iatrogenic hyperventilation of the lungs with associated hypokalemia should be avoided during anesthesia. Most recommend continuation of digitalis therapy in the perioperative period, especially when the drug is being administered for heart rate control. Prophylactic preoperative administration of digitalis preparation is controversial but may be of unique value in elderly patients undergoing thoracic surgery.