Acute Caremiddle twist
A 62-year-old woman attends the emergency department after tripping on a step. She has a grazed knee, is otherwise well, takes only atorvastatin and passes urine normally. Venous blood taken from the back of the hand with the tourniquet left in place shows potassium 6.7 mmol/L (3.5-5.2), sodium 139 mmol/L, creatinine 68 micromol/L and a normal full blood count; the laboratory comments that the specimen is haemolysed. An electrocardiogram taken ten minutes ago shows a normal PR interval, narrow QRS complexes and normally shaped T waves. Which one of the following should be done next?