Chapter 131 The Geriatric Patient

Robert A. Hart, Mark D. D’Alise, Edward C. Benzel

When planning either elective or emergent spinal surgery in elderly patients, the numerous physiologic changes associated with advanced age must be considered. Each organ system manifests specific changes that affect surgical decision making, preoperative evaluation, and intraoperative and postoperative management. This chapter addresses the unique aspects affecting spine care that must be considered in elderly patients.

Surgical morbidity and mortality have been shown to be greater in the elderly patient.¹ Although this subset of patients is very heterogeneous, the general decline in physiologic reserve and presence of coexistent disease are likely primarily responsible for this finding.^2,³ The spine surgeon should be able to recognize specific surgical risk factors and develop an appropriate treatment plan that accommodates the specific needs of elderly patients.

Organ Systems

Cardiovascular System

It has been reported that at autopsy 50% of patients older than 70 years of age have significant cardiovascular disease. The cardiac risk index, a commonly used assessment tool, incorporates myocardial infarction in the past 6 months, uncompensated congestive heart failure, aortic stenosis, nonsinus rhythm greater than five premature ventricular contractions per minute, diabetes mellitus, and age older than 70 years as major risk factors for postoperative cardiac complications of noncardiac surgery ⁴ (Box 131-1).

BOX 131-1 Cardiac Risk Index (Major Risk Factors)

Myocardial infarction in the past 6 months

Uncompensated congestive heart failure

Aortic stenosis

Nonsinus rhythm greater than five premature ventricular contractions per minute

Diabetes mellitus

Age greater than 70 years

The basic cardiovascular workup in patients older than 65 years of age should include a thorough history and physical examination and a baseline electrocardiogram. Myocardial infarction, unaccompanied by recognized symptoms, occurs in as much as 10% of elderly patients.⁵ Reports of syncope or dyspnea are the most suggestive symptoms of this event. Peripheral vascular disease is often present with coronary artery disease and may complicate the diagnosis of neurogenic claudication. Absent peripheral pulses or a history of transient ischemic attacks or stroke should lead to a more comprehensive cardiac workup.

In patients with unstable angina, elective spinal surgery is clearly contraindicated. Patients with well-controlled stable angina, however, have only a slightly increased risk for perioperative cardiac complications, and may therefore be considered for surgery.⁶ Moderate to severe congestive heart failure is associated with a significant perioperative risk.⁷^–⁹ Jugular venous distention and peripheral edema are suggestive signs, whereas a history of dyspnea on exertion and orthopnea are symptoms of a more severe form of congestive heart failure.

Respiratory System

Elderly patients are at particular risk for perioperative pulmonary complications for several reasons. Decline in pulmonary function and reserve, underlying chronic obstructive disease and bronchitis, lack of mobility or bed rest associated with spinal surgery, and airway obstruction all can lead to significant morbidity or mortality for these patients.^10,¹¹ In a series of 100 patients older than 70 years of age, approximately 40% of those without a history of lung disease had abnormal pulmonary function.¹² Pulmonary function tests (spirometry) should be obtained for patients older than 65 years of age or with a history of obstructive lung disease if a ventral approach is being considered.¹³

A forced expiratory volume in 1 second of less than 50% of the predicted value does not suggest an increased risk of postoperative mechanical ventilation, but combined with dyspnea at rest and arterial hypoxemia, it is an established risk factor.¹⁴ Room air arterial blood gas should be tested in elderly patients with lung disease, as well as those with a history of shortness of breath, poor exercise tolerance, orthopnea, or excessive smoking. Elevated partial pressure of carbon dioxide (Pco₂) reflects a loss of pulmonary reserve. A preoperative Pco₂ of greater than 45 mm Hg is associated with an increased incidence of postoperative pulmonary complications,¹⁵ and patients with a Pco₂ of greater than 50 mm Hg often require a period of postoperative mechanical ventilation.¹⁶

There is no well-defined lower limit of pulmonary function established by any criteria that strictly contraindicates surgery. Optimizing preoperative function certainly helps decrease the overall risks associated with lung disease. Equally important is an aggressive postoperative care plan, including early mobilization, incentive spirometry and coughing exercises, chest physiotherapy with postural drainage and nasotracheal suction, and use of bronchodilators and mucolytics as needed. Finally, an operative plan that avoids thoracotomy in patients with significant pulmonary compromise is well advised.

Renal System

Decline of renal function in the elderly is more consistent than that of other organ systems.¹⁷ In geriatric patients, serum creatinine levels may be artificially low because of decreased production, caused by a shrinking muscle mass. For this reason, creatinine clearance is the preferred test for patients suspected of having significant renal disease. The effect of chronic nonsteroidal anti-inflammatory drug (NSAID) use on the kidney may also contribute to the decline in renal function with advancing age. These drugs can decrease renal blood flow, adding to an already diminished glomerular filtration rate.¹⁸ This has clinical significance in the perioperative patient because water homeostasis may be difficult to achieve in elderly patients, leaving them prone to hyponatremia and volume overload. The use of isotonic fluids, restriction of free water, and careful administration of diuretics may be helpful.

Other Sources of Morbidity

Advanced age itself is a risk factor for deep venous thrombosis.¹ Given the risks associated with bleeding after spine surgery, many surgeons are hesitant to anticoagulate, even with deep venous thrombosis demonstrated by venous Doppler ultrasonography. Such patients can be considered for vena cava filter placement or delayed (5 to 7 days after surgery) anticoagulation. All patients should receive aggressive physical therapy with early ambulation and range-of-motion exercises. Pneumatic compression devices should be used on all patients during their period of bed rest.

Malnutrition is associated with increased morbidity and mortality in elderly surgical patients.¹⁹ Dietary supplements should be added to the hospital diet of patients with reduced postoperative caloric intake to achieve a protein intake of 1 to 2 g/kg/day.

Advanced age is also a risk factor for wound infection. A sixfold increase in clean wound infections has been reported in patients older than 66 years compared with patients younger than 14 years of age.²⁰ The use of routine perioperative antibiotics, minimizing operative times, appropriate postoperative wound care, and attention to nutritional status all may decrease this risk.

Constipation can also be a major problem in elderly postoperative patients. Immobility, decreased gastrointestinal motility, narcotic medications, dehydration, and lack of privacy of the bedridden patient may all contribute to this problem. Stool softeners, fiber-enriched diets, gentle laxatives, and enemas should be used early in the postoperative patient. Perhaps the best method of avoiding postoperative constipation is simply early mobility and physical therapy.