Anesthesia and the Elderly: Effects of Surgery and Anesthesia on the Elderly Patient

With the increasing average age of Americans, more and more patients presenting for surgery and anesthesia are older or elderly. Some surgeries are elective and others will be emergencies.

Many people are living longer and are doing so with relatively good health. Modern medicine has also made it possible to extend life, even while being treated for serious health conditions.

There are normal changes in how the body works as we age. In addition, older people have more serious health issues. All of these things must be taken into account when administering an anesthetic.

The overall effects of age on the heart lead to a more dramatic drop in blood pressure when anesthesia is induced. If the patient is also dehydrated or has very high or very low blood pressure to begin with, this drop can be even more pronounced and may become dangerous if not attended to and treated right away by the anesthesiologist. Care must be taken in drug selection and dosing for the induction of anesthesia, since the elderly patient's ability to compensate for these changes may be limited or impaired.

The anesthesiologist must also be aware the the time it takes for blood to circulate in the body takes longer in older people, so medicines given in the IV will take longer to take effect.

While the normal changes to the heart of aging are complex, the overall function of the heart may be fairly well preserved in the absence of heart disease. Surgery and anesthesia are a stress on the body, however, like moderate exercise. Under anesthesia, the effects of age on the heart may be more likely to be seen.

As we get older, we have a lower resting heart rate and a decreased ability to increase our heart rate during physical or physiologic stress. This can become important during surgery and anesthesia. If we aren't able to maintain our cardiac output (determined by the heart rate and the amount of blood pumped with the heart's contraction), it makes it much more difficult for our body's to compensate for the stress that may accompany surgery and anesthesia.

Of course, any preexisting cardiac disease further complicates this issue. The anesthesiologist must have a thorough understanding of cardiac physiology (both normal and abnormal) in order to plan the most effective--and safe--anesthetic possible in these situations.

Because oxygen levels may be lower, it may be advisable to use higher concentrations of oxygen while under anesthesia.

Careful selection of ventilator settings can help reduce overdistention and collapse of small airways. Airway pressures should be monitored and adjusted to compensate for changes in the ability of the lungs and chest wall to expand and relax.

Postoperative oxygen may be needed and all patients, but especially the elderly with preexisting lung disease, should be instructed to use an incentive spirometer (device to help reexpand the lungs by deep breathing). Walking early in the postoperative course also helps decrease pulmonary complications from anesthesia and surgery.

The lungs have a natural elasticity to them. This gives them the ability to expand and then recoil appropriately with breathing and to adapt to changes in the depth and pattern of breathing.

As we get older, the elasticity of our lungs decreases. The overall effect is that smaller airways can collapse. Those collapsed areas are then not available to help absorb oxygen into the blood and get the carbon dioxide (waste gas) out. The body may take longer to respond to changes in oxygen levels, and overall oxygen levels may be lower.

The chest wall, itself, may also become more rigid and the muscles of breathing may weaken.

Pneumonia may be more likely in the postoperative period.

Examination of the airway preoperatively is necessary to predict and prepare for any difficulties with intubation (placement of the breathing tube).

Precautions should be taken to prevent aspiration pneumonia.

• Administration of antacids before anesthesia to high-risk patients.
• Induction techniques that block acid from rising up from the stomach into the throat and then into the lungs (called "cricoid pressure or Sellinger maneuver- an assistant pushes on the hard cartilage on the front of the neck to push against the food pipe and close it off to keep acid down).
• Ensure that airway reflexes have returned by removing the breathing tube only once the patient is fully conscious.

The airway is the passageway to get air with it's vital oxygen to the inside of the body and get waste gas like carbon dioxide, out. The airway includes the mouth, nose, throat, voicebox (larynx) and windpipe. Related structures and the lungs may be included in this term, depending on the context.

In older people, there are changes in the airway that occur with normal aging. The jaw and neck may have limited mobility due to arthritis. This can make placement of the breathing tube more difficult.

In addition, reflexes like coughing and gagging may be impaired. If the upper airway cannot be cleared of secretions, then aspiration of these secretions into the lungs may be more of a potential complication. Aspiration pneumonia is a serious condition that may become life-threatening.

Metabolism in general, slows as we age. The ability and speed with which the liver and kidneys clear toxins and medications from the body may be significantly different in the elderly.

Anesthesiologists must understand the changes that occur and how each drug administered to an elderly patient is handled by the body. Older patients may need less medication if the drug is cleared more slowly.

Electrolytes such as potassium are also regulated by the kidney. If there are risk factors that impair kidney function, electrolyte abnormalities may be more likely and can lead to problems during and after surgery. Abnormalities with heart rhythm and muscle weakness are examples of complications of electolyte disturbances.

Older patients are more prone to mental decline after surgery and anesthesia. While postoperative cognitive dysfunction was presumed to be the result of general anesthesia's effects on the brain, studies have now shown that this decline can occur regardless of the type of anesthesia used. Current theories speculate that factors related to illness and the stress of surgery, along with changes that occur in a body trying to heal (inflammatory mediators and hormone changes) may contribute to this phenomenon.