Blavatsky
Original sense
Prana is the life-principle of the physical and astral man, a specialized working of the universal jiva. It is not the spirit, not the soul, and not a panacea. When prana withdraws, the body dies; the Ego is elsewhere. She related it to the breath but refused to reduce occult life to breathing exercises.
Prâna is the radiating force or energy of Atma as the Universal Life… its lower, because manifesting, aspect.
Mesmerism, odic force, and later ‘vital energy’ sit in this file. Hatha-yogic pranayama she treated as a lower and risky art compared with ethical and noetic training.