Normal aging: definition and physiologic changes

Aging is a process of the progressive functional decline with time, leading to disability, dependence, morbidity, and mortality. While the organ function in the elderly is relatively uncompromised under basal conditions, their ability to tolerate increased physiologic stress is reduced. And the extent and onset of the deterioration in functional reserve is quite diverse from patient to patient. The aging population is rapidly growing and their medical management is becoming one of the greatest challenges to anesthesiologists. The understanding of the normal physiologic changes with aging is essential to frame any discussion of perioperative management in the elderly. In this review, we will focus on the physiologic changes in neurologic, cardiac, pulmonary, renal, and hepatic function, and thermoregulation.