Dustin knocked Caden unconscious after the others had left. Then, he proceeded with the treatment.

Caden's condition had worsened due to practicing forbidden techniques. These techniques drained his vitality, damaged his circulatory pathways, and affected his internal organs.

Moreover, Rudolph's treatment had exacerbated his condition.

Hence, Dustin needed to use silver needles to stabilize Caden's life force. He then channeled his true energy to clear Caden's blocked circulatory pathways