DECREASED BLOOD PRESSURE Elderly patients are at risk for hypotension and ischemia, which can lead to arrhythmias and congestive heart failure.

With more and more elderly patients presenting for same-day surgery, now's a good time to consider the unique risks of geriatric anesthesia. Not only have the organs in your older patients begun their steady decline of functional reserve, but also you're likely to see hypertension, diabetes, and coronary and cerebrovascular disease. From strokes to dementia, here's how to avert dangerous situations.

What to watch for
From a physiological standpoint, cerebral blood flow and volume are decreased in geriatric patients. This is due to a combination of reduced cerebral metabolism and vascular changes, which include atherosclerosis and decreased vessel wall compliance. What to watch for:

•Stroke. The risk of stroke doubles each decade after age 55. For men, the 10-year probability of having a stroke is 5.9% at age 55. The risk more than doubles to 13.7% at 70, and increases again to 22.3% at age 80.

•Dementia. The risk of dementia increases to 10% for patients 65 and over, and at age 80, 20% of patients have some degree of dementia.

•Hearing loss. Additionally, 20% of 50-year-old and 90% of 80-year-old patients experience some level of hearing loss, which can lead to social isolation and paranoid ideation.

Now let's look at this from an anesthetic standpoint. The MAC of inhalational agents and the dosage of intravenous anesthetics decrease with age. Maintaining normothermia may require additional efforts because of impaired thermoregulation. Older patients may not be able to tolerate decreases in blood pressure, and ischemia may ensue because of atherosclerotic cerebral and carotid vessels. You may need additional time and patience for the pre-operative evaluation, especially if your patients present with hearing difficulties and dementias.

Cardiovascular risks
Because elderly patients have decreased vessel elasticity, they often demonstrate increased systolic blood pressures and decreased diastolic blood pressures. The result? Increased pulse pressures. Moreover, resting and maximum heart rate both decrease because of a reduction in beta-adrenergic responsiveness and cardiac contractility. A general rule of thumb is that the maximum heart rate is equal to 220 minus age in years. So, an 80-year-old would have a maximal heart rate of 140.

Baroreflexes also become impaired, due to reduced arterial compliance, making it hard for elderly patients to maintain their cardiac output during hypotensive episodes by increasing their heart rate (cardiac output = stroke volume x heart rate). About 65% of 70-year-olds have hypertension, and 30% of 75-year-olds have coronary artery disease. At age 80, 70% experience congestive heart failure, and valvular disease has a prevalence of 40% for mild disease and 13% for severe disease in those aged 75 to 85.

From an anesthetic standpoint, elderly patients may experience more profound hypotensive effects from inhalational and intravenous agents. They may also require invasive monitoring, like an arterial line, and even minor cases may require more aggressive treatment with vasopressors. Patients with heart conditions are already in danger of not getting enough blood or oxygen flow, so the effects can be detrimental. As with those carrying neurological risks, your patients with cardiac disease will also not be able to tolerate decreases in blood pressure very well. Hypotension can then lead to ischemia with consequent infarction, arrhythmias and congestive heart failure.

Did You Know?

Patients who are 65 years or older undergo an estimated 15 million surgeries per year in the United States.

Other areas of impact
Oxygen uptake from the lungs becomes less efficient and results in a lower oxygen saturation and blood-oxygen partial pressure. Elderly patients are more sensitive to anesthetic agents and less capable of clearing secretions because of the impairment of hypercapneic and hypoxic respiratory responses, respiratory muscle strength/cough, vital capacity and ciliary function. This also has a possibility of delaying extubation. What does that mean? Your patients may require supplemental oxygen for longer periods in the recovery room. There is also an increased incidence of respiratory failure from co-existing diseases like COPD and left ventricular failure.

Your patients' renal functions can take a hit due to atrophy of afferent and efferent arterioles, atherosclerosis and comorbid disease. This means a decrease in renal mass, renal blood flow, creatinine clearance and glomerular filtration. The result can be a decrease in drug clearance and impaired fluid balance for which you'll need to account. Because the kidneys aren't clearing well, there is likely to be a prolonged effect of drugs. If you give the patient a drug that can be toxic, she's going to take an even bigger hit. Additionally, the kidneys may not be able to tolerate hypotension, meaning pre-existing renal function in your elderly patients can worsen.

Hepatic mass and blood flow can decrease due to cell loss. Consequently, geriatric patients are more likely to experience prolonged effects of opioids, benzodiazepines, local anesthetics and neuromuscular-blocking drugs.

You may also see decreased esophageal function and gastric motility, which can increase the risk of pulmonary aspiration in the perioperative period. Diabetic patients tend to digest food at a slower rate, and that food carries a risk of traveling into the lungs. As far as metabolic function goes, your geriatric patients are more likely to have insulin resistance and/or impaired insulin secretion. Because about 10% of 50-year-olds and 20% of 70-year-olds have diabetes, it's important to counsel your patients on how to take perioperative insulin and oral antihyperglycemics. It's a good idea to schedule these cases early to decrease fasting times and hypoglycemic episodes.

Lastly, be aware of the increased risk of infections due to changes in patients' immune functions, including pneumonia and urinary tract and wound infections. These patients are likely to experience decreased functional competence of NK cells, granulocytes, macrophages and impaired phagocytosis.