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Hypokalemic Arrest. Eric Lavonas, MD, FACEP Carolinas Medical Center Charlotte, NC. Patient presents with…. H/O schizophrenia Acute-on-chronic overdose 100 pills of a single medication Time of ingestion: ~45 min PTA No symptoms. Vital Signs. P 70 R 16 BP 120/80 T 36.1 C.
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Hypokalemic Arrest Eric Lavonas, MD, FACEP Carolinas Medical Center Charlotte, NC
Patient presents with… • H/O schizophrenia • Acute-on-chronic overdose • 100 pills of a single medication • Time of ingestion: ~45 min PTA • No symptoms
Vital Signs • P 70 • R 16 • BP 120/80 • T 36.1C
Now the Fun Begins • Sudden cardiac arrest • Wide complex tachydysrhythmia • No pulse • Unknown if Torsades de Pointes • Rapid defibrillation & intubation • P 60 • BP 70/50
Pre-Arrest Post-Arrest 200 msec 240 msec
Laboratory Abnormalities • Profound hypokalemia • Mild metabolic acidosis • Respiratory alkalosis from vent • Other minor abnormalities • Creatinine 1.2 mg/dl • Glucose 178 mg/dl
Post-Arrest Therapy • Dopamine • Poor response • Norepinephrine • BP improved • 4 gm MgSO4 • Potassium, potassium, potassium • 300 ml (154 mEq) hypertonic NaCl
200 80 Effect of Hypertonic Saline Before After
QT = .640s; QTc = .500 QT.440; QTc.469 QT Prolongation Before After
Inpatient Course • Potassium still low • Aggressive replacement over 11 hours • Weaned off pressors • Did well
Key Elements • Wide QRS • Prolonged QTc • Relative bradycardia • Hypokalemia
Key Elements • Wide QRS • Prolonged QTc • Relative bradycardia • Hypokalemia
Anti-Dysrhythmics • Class I: Block Na entry • Ia: Block Na in and K out • Ib: Block Na in • Ic: Block Na in, Ca in, and K out • Class II: β receptor antagonists • Class III: Block K out • Class IV: L-type Ca channel antagonists Vaughn-Williams EM and Singh BN, Cardiovasc Res 6:109 (1972)
Na channel blockade Ca in, K out Na in K out
Sodium Channel States • Resting (Closed) • Open • Inactivated (Closed) • Refractory
Frequency-Dependent Block • Class Ia: τrecovery 1-10 sec • Class Ib: τrecovery < 1 sec • Class Ic: τrecovery > 10 sec Weirich J, Antoni H, J Cardiovasc Pharmacol 15:998-1009 (1990)
Key Elements • Wide QRS • Prolonged QTc • Relative bradycardia • Hypokalemia
QT = .640s; QTc = .500 QT Prolongation
K efflux blockade Ca in, K out Na in K out
Key Elements • Wide QRS • Prolonged QTc • Relative bradycardia • Hypokalemia
Relative Bradycardia • β-receptor antagonists • Calcium channel antagonists • Digitalis and related glycosides • Central α-2 agonists • Cholinesterase inhibitors • Mitochondrial toxins (e.g. CN) • Sedative-hypnotics • End-stages of cocaine, TCA’s, etc.
Key Elements • Wide QRS • Prolonged QTc • Relative bradycardia • Hypokalemia
Hypokalemia • Increased urinary losses • Most diuretics • Renal toxins (toluene, aminoglycosides) • Licorice • Extra-renal losses (diarrhea) • Exchange with another cation • Sodium polystyrene sulfate (Kayexalate™) • Sodium penicillins
Hypokalemia • Intracellular sequestration • Enhanced entry • Catecholamines • Insulin/glucose • Barium salts • Thyrotoxicosis
Hypokalemia • Intracellular sequestration • Blocked release from IK channels • “Pure”:Dofetilide, Ibutilide
Hypokalemia • Intracellular sequestration • Blocked release from IK channels • “Pure”:Dofetilide, Ibutilide • “Less selective”: Disopyramide, flecainide, procainamide, quinidine
Hypokalemia • Intracellular sequestration • Blocked release from IK channels • “Pure”:Dofetilide, Ibutilide • “Less selective”: Disopyramide, flecainide, procainamide, quinidine
Hypokalemia • Intracellular sequestration • Blocked release from IK channels • “Pure”:Dofetilide, Ibutilide • “Less selective”: Disopyramide, flecainide, procainamide, quinidine • Amiodarone, bretylium, propafenone, sotalol
Key Elements • Wide QRS • Prolonged QTc • Relative bradycardia • Hypokalemia
The Sicilian Gambit Task Force of the Working Group on Arrhythmias of the European Society of Cardiology. The Sicilian gambit. A new approach to the classification of antiarrhythmic drugs based on their actions on arrhythmogenic mechanisms. Circulation 1991;84:1831-51.
Hints & Clues • Pill form • Medication • Prescription? Herbal? • Available in bottle of 100 • Cardiac arrest precedes AMS • Recovery in 26 hours
Closing in… Quinine Quinidine Disopyramide Chloroquine Antipsychotics Amiodarone Procainamide Sotalol
Closing in… Quinine Quinidine Disopyramide Chloroquine Antipsychotics Amiodarone Procainamide Sotalol GI Effects Tachycardia Tachycardia Tachycardia, sedation Onset delayed Onset delayed No Na Ch block; no hypoK
Chloroquine • Na channel blockade • Present at low heart rate • K efflux blockade • QT prolongation • Profound hypokalemia • Relative bradycardia • Hypotension
Patient presents with… • H/O schizophrenia • Acute-on-chronic overdose • 100 pills of a single medication • Time of ingestion: ~45 min PTA • No symptoms