How can hyperventilation treat hyperkalemia?

Acid-base. Hyperventilation drives the carbondioxide from the lungs , so you develop respiratory alkalosis which causes hypokalemia( low potassium).If someone has hyperkalemia and hyperventilation, they probably have some other underlying cause like metabolic acidosis which could be due to several reasons like severe diarrhea, kidney failure, infection.These are only few and one should consult nephrologist.