Effects of caffeine doses on cardiac activity using laser Doppler flowmetry

In this work, the effects of different caffeine doses on cardiac activity have been evaluated by frequency domain analysis of laser Doppler flowmetry signal. Using different data acquisition units, the blood perfusion on human forearm middle finger tip has been recorded. Blood perfusion has been recorded before and immediately after the consumption of all caffeine doses. Different caffeine doses contain different amount of caffeine but approximately same amount of sugar. Recorded and pre-processed data have been analyzed using frequency spectrum within the frequency range of cardiac activity. It is found that the consumption of caffeine free dose increases the cardiac activity. Besides, the consumption of caffeinated doses decreases the cardiac activity with respect to normal condition (before consumption). As the amount of caffeine consumed increases, the cardiac activity improves. Result shows 42.9%, 32.2% and 39.4% decrement in cardiac activity due to the consumption of 27 mg, 48 mg, and 64 mg caffeine respectively. The consumption of 80 mg caffeine dose significantly increases the cardiac activity. The outcome indicates the reduction of heart functions due to the consumption of lower caffeine dose.