Disclaimer
This article and the related comments are for educational and discussion purposes. They do not establish the standard of care in every patient’s situation. In each patient’s situation, the treating physician or other medical professionals must exercise their professional judgment. Similarly, these materials are not medical advice to patients, who must consult with their own physician or other medical professional.
A 56-year-old man was admitted to the hospital with a small bowel obstruction. The patient is an alcoholic, who lives in the streets of your city. On day 6 of admission, internal medicine is consulted to take over his care, because electrolytes are being hard to control despite aggressive repletion. On your evaluation, you find his blood sugar to be at 243 mg/ dL, potassium is 2.6, magnesium is 1.6 and phosphorus is 1.3.
You are concerned about the electrolytes, but also about the hyperglycemia and decided to start him on an aggressive insulin regimen. You placed the orders for the potassium, phosphorus and magnesium replacements. The patient received potassium first, followed by phosphorus and finally magnesium. Eight hours into the shift, a rapid response team is called. Upon arrival the patient is poorly responsive, diaphoretic, and found to have a wide complex tachycardia. During your examination, the patient loses his pulse and a code blue is called. CPR is initiated for two minutes, first dose of Epinephrine is given, the patient has been successfully connected to the monitor and he is found with a wide complex rhythm that alternates periodically from upward to downward. After three cycles of CPR the patient recovers circulation, can follow commands, therefore targeted temperature management is not pursued, and the patient is transferred to ICU.
What happened there? Let’s start dissecting what trigger this avoidable chain of events. First, always analyze what was the rhythm of the arrest. In this case the description fits Torsades de Pointes. What could have triggered this? At first glance one could say: the hypokalemia, associated with the hypomagnesemia; then you wonder: why did the electrolytes didn’t correct if you ordered the replacements? When dealing with hypokalemia and hypophosphatemia, in the setting of hypomagnesemia, you must correct magnesium first, otherwise the other electrolytes will never correct. A teaching opportunity to share with the nurses and everybody involved in the case of this patient, since magnesium was the last electrolyte to be replaced via IV. But the investigation should not stop there.
Why are this patient’s electrolytes so difficult to replace? What we are facing in this case is refeeding syndrome, the patient has all the risk factors: poor oral intake for several days both pre and during admission, now recently exposed to a diet ordered when his obstruction was improving. Refeeding syndrome is a complication that can be fatal and is frequently unrecognized in hospitals. It seems to be triggered by an insulin surge in response to carbohydrates exposure. It clinically manifests with delirium, ataxia, Wernicke’s encephalopathy, and seizures in more extreme cases. The hallmark of the disease is hypophosphatemia, associated with low potassium, magnesium, and high glucose. If the trigger event is an insulin surge, what would an aggressive insulin regimen do for these patients? Not surprisingly the next thing we knew about him was his cardiac arrest.
The way to prevent and treat is by giving Thiamine, B12 vitamin, multivitamins, and start the nutrition very slowly, in conjunction with the dietitian, specifically warning about the risk of refeeding syndrome, and with a preference from protein source of calories as opposed to carbohydrates. Aggressively replace the electrolytes, starting by magnesium. You want to avoid replacing calcium, since its replacement decreases phosphorus even further. Start with a nutrition regimen of 20 Kcal/ hour and slowly increase to 40 kCal/ hour only if the electrolytes are holding and clinically there are no further signs of refeeding, and then eventually get him to the goal rate of feedings. Patients can also develop refeeding syndrome even when exposed to D5W IV, therefore the capital importance of suspecting it early to start the prevention with Thiamine, B12 and multivitamins.