중재 전 심박 변이도를 5분간 측정한 후, 코티졸 수준을 측정하기 위해 상완정맥으로부터 5㏄ 채혈하였다.
Heart rate variability was measured 5 minutes before intervention, then 5cc of blood was collected from the brachial vein to measure cortisol levels.