Q: All of the following electrolyte abnormalities occurs during Cardio-Pulmonary-Bypass (CPB) except? 

A) hypocalcemia
B) hyperkalemia, 
C) hypermagnesemia
D) hyperglycemia


Answer: C

Hypomagnesemia is frequently occurred during CPB due to two reasons

1. Diuresis 
2. Hemodilution with magnesium-free fluids during CPB

Therefore, it is a common practice to administer 2 grams of magnesium sulfate 2 g at the conclusion of CPB.


References:

1.  England MR, Gordon G, Salem M, Chernow B. Magnesium administration and dysrhythmias after cardiac surgery. A placebo-controlled, double-blind, randomized trial. JAMA 1992; 268:2395. 

2. Booth JV, Phillips-Bute B, McCants CB, et al. Low serum magnesium level predicts major adverse cardiac events after coronary artery bypass graft surgery. Am Heart J 2003; 145:1108.