Case Progression: ABCD Survey Airway—open Breathing—shallow Circulation—pulse rapid, very weak Defibrillation—? Key Concepts: This patient has unstable VT. He requires rapid synchronized cardioversion. Ask participants if there is any difference in how the ACLS protocols should be modified for this patient. Discussion Points: Low energy levels (25 to 50 J) for synchronized cardioversion are used initially in patients with digitalis intoxication. There is an increased likelihood of postcountershock rhythm deterioration in these patients. If preparation for synchronized cardioversion will require more than 30 to 60 seconds, provide unsynchronized shocks. If no response, then immediately reattempt cardioversion with 200 J; if no response, reattempt cardioversion with 360 J. After successful cardioversion, additional medical therapy is indicated: For treatment of unstable VT, the patient should receive 10 to 20 vials of Fab fragments (Digibind). Give a loading dose of lidocaine 1.5 mg/kg IV. If the patient responds, begin continuous infusion 4 mg/min until the Fab fragment therapy becomes effective. If there is no response to lidocaine, give 1 to 2 g magnesium sulfate diluted in 10 mL of D5W over 1 to 2 minutes. Give up to 5 to 10 g magnesium sulfate over 2 to 5 minutes if there is no response. If pharmacologic conversion occurs, start a continuous magnesium infusion of 1 to 2 g diluted in 50 to 100 mL D5W for the next 30 to 60 minutes. This interval allows sufficient time for the Fab fragments to be administered and take effect. How should your treatment progress? 10

What else should you do now ? Case Progression The patient returns to a normal sinus rhythm after 2 g of magnesium sulfate is given. He is alert and vital signs return to normal. Transfer to ICU is being arranged. Key Concept: Digoxin-specific antibodies bind to free digoxin with effects beginning within minutes. Complete reversal of digoxin-mediated effects occurs in approximately 30 minutes. The high cost of therapy requires a careful assessment of indications. Ask participants who should receive Fab. Is administration based on the serum digoxin level? Are serum digoxin levels monitored for therapy? Discussion Points: The amount of Fab administered is determined by the patient’s weight and serum digoxin level if known. The known or estimated milligrams of digoxin ingested can be used to calculate Fab fragment dose in acute ingestions. Note that serum digoxin levels rise dramatically after Fab is given. Serial digoxin levels are not used to follow therapy. What else should you do now ? 11