The following is an interesting case taken from our Night Float rounds. You are called by the lab for a panic value of potassium = 7.6 from blood drawn 3 hours ago. The serum creatinine is 3.5 and the bicarb is 18 with a normal anion gap. You go to see the patient and find that he is a 58 year-old man transferred from an outside hospital for cardiac cath. He presented to the outside hospital two days earlier with a NSTEMI with evidence of CHF and was transferred to this hospital 12 hours ago. His most recent previous electrolytes, from yesterday, show a potassium of 5.1, a creatinine of 2.3 and a bicarb of 22. You find the patient agitated and restless. His BP is 90/60 (decreased from 120/75), pulse is 78, SO2 is 86% on room air, rales are evident by auscultation, and extremities are cool. ECG shows sinus rhythm with a wide QRS complex (0.14, increased from 0.09 upon admission). T waves are flattened (not peaked). What is your presumptive diagnosis? What do you do?