Dextrose, hypokalemia and torsade de pointes

A 72-year-old female presented to emergency room with generalized weakness predominantly in lower limbs. She was apparently normal until 1 week ago after which she developed watery diarrhea, four to six times a day. Stool was non-bloody. There were no associated symptoms such as nausea, vomiting, fever or abdominal pain. Patient denied history of sick contacts, travel and use of laxatives. She had a past medical history of mild persistent bronchial asthma and uses albuterol (inhaler and nebulizer) as needed. Patient looked dehydrated. Her heart rate was 96 beats per minute and blood pressure was 136/76  mm of Hg. Neurological exam and the reminder of physical exam was normal. Because of generalized weakness and dehydration, she was started on intravenous dextrose plus normal saline. Later, she was found to be severely hypokalemic (serum potassium: 2.0 mEq/l, normal: 3–5 mEq/l), and in severe c ontraction metabolic alkalosis. Electrocardiogram showed normal sinus rhythm with a heart rate of 88 beats per minute and prolonged QT interval (520 ms) (Figure 1A). Corrected QT (QTc) interval was 630  ms. She developed torsade de pointes (Figure 1B) even before receiving potassium replacement. Repeat potassium level was 1.6 mEq/l and magnesium level was normal. She was successfully revived following electrical defibrillation. She received aggressive replacement of potassium intravenously with glucose free solutions. Echocardiography showed mildly decreased left ventricular sys...
Source: QJM - Category: Internal Medicine Source Type: research