Hypokalemia in a pediatric patient on continuous renal replacement therapy: Answers

Reviewed his total potassium intake. He was NPO. His TPN had 0.4 mEq/kg/day of potassium that was unchanged from when he was on ECMO. All CRRT bags were verified and he had 3.5 mEq/L of potassium bath in CRRT fluids also unchanged from when he was on ECMO. No other source of potassium intake as he had mild hyperkalemia while on ECMO.

Quantified all his output. Over the last 24 h, he had an unchanged nasogastric output 120 mL/day. Similar to prior days, there was no reported diarrhea to suspect increased gastrointestinal losses. He was not on any diuretics that could increase his urinary losses and he was anuric.

Reviewed any potential causes that can increase intracellular uptake. He was not receiving insulin or any selective beta-adrenergics (i.e., albuterol, terbutaline). He was on a stable dose of IV epinephrine drip. His arterial pH was 7.37, and other labs were consistently similar compared with prior samples. No new medications were started. He did have hypothermia with a temperature of 94 °F (34.4 °C) that started after CRRT re-initiation. Then, it was noted to trend down to 90.9 °F (32.7 °C) with concurrent decrease in heart rate that same morning (Fig. 1). Bedsides, nurse reported a concern with CRRT machine heater. Upon investigating the heater, it was found that the patient had not been covered with an external warmer blanket since being transitioned from ECMO to CRRT. A warming blanket was placed on the patient and warmer sleeve was serially checked and determined to be heating the return line. Patient temperature rose to above 96 °F (35.6 °C) within 2 h of intervention with improvement in his heart rate, and his potassium was rechecked with improvement from 2.8 to 3.5 mmol/L without any IV potassium boluses. His potassium levels continued to remain stable ranging from 4.1 to 4.5 mmol/L. He did not have any further recurrence of hypokalemia on CRRT.