The cardiovascular system undergoes considerable changes with age and is responsible for most of the perioperative morbidity seen in the elderly. A decrease in arterial compliance leads to an increase in afterload. In response, the left ventricle hypertrophies over time and its compliance decreases. The inability of the left ventricle to relax during diastole is termed “diastolic dysfunction,” which can be quantified by echocardiography. Left ventricular filling then becomes increasingly dependent on preload and atrial contraction. Hence, maintaining sinus rhythm is important to ensure adequate left ventricular filling and cardiac output. The venous vasculature also loses some of its compliance and its ability to act as buffer against volume overload. This predisposes the elderly to pulmonary edema with excessive fluid administration.

Conduction system abnormalities are often seen in the elderly because of a decrease in the number and function of atrial pacemaker cells. The most commonly seen abnormalities are right bundle branch block (RBBB) and first degree heart block. The responsiveness of β-adrenergic receptors is also diminished, rendering the elderly unable to initiate compensatory increases in heart rate in response to hypovolemia. Therefore, the elderly are likely to develop orthostatic hypotension. Although cardiac output may remain unchanged, systolic blood pressure increases with age, whereas diastolic blood pressure increases until age 60–65 years and then plateaus or decreases (see Fig. 24.2). Valvular abnormalities are more common due to sclerosis and calcification, and more than 70 % percent of the elderly have an audible heart murmur.

The major changes that occur with aging can be broadly attributed to the following factors:

The larger proximal airways tend to dilate with age, causing an increase in dead space. The distal airways tend to collapse, causing an increase in closing volume and air trapping. The compliance of the chest wall decreases (due to stiffening of the costochondral joints). The intercostal spaces are usually decreased because of loss of musculature, which increases the work of breathing and decreases the ability to re-expand atelectatic regions of the lungs. It also hinders the ability to cough and adequately clear secretions.

A decline in renal function is seen in the elderly due to a decrease in glomerular filtration rate (GFR) and total renal blood flow (RBF). The serum creatinine may not reflect the extent of renal impairment as muscle mass declines in the elderly. Creatinine clearance can provide a much more accurate reflection of renal function in the elderly. The elderly are also predisposed to dehydration because of diminished compensatory mechanisms, including perception of thirst and the renal response to antidiuretic hormone (ADH) (Table 24.1).

With age, there is a decline in higher cognitive functions due to gradual loss of neurons. This loss is more pronounced in the gray matter than the white matter. Additionally, diminished levels of neurotransmitters (dopamine, serotonin and acetylcholine) predispose elderly patients to cognitive deficits which can be accentuated in the postoperative period. Sensory perception such as vision, hearing and taste also diminishes with age.