Abstract
This chapter deals with the specific issues that make the approach to neuroanesthesia in elderly (>65 years) patients different from that in younger individuals. The basic concepts of cerebral physiology and protection staying the same, a problem unique to the elderly is the lower reserve and threshold for organ failure with operative stress. Age-related changes that affect anesthesia are dealt with succinctly, followed by a review of tailoring of the preoperative assessment, intraoperative plan, and postoperative care for these patients. The need to maintain adequate cerebral and spinal perfusion pressures at all times and positions is emphasized. This is followed by a review of the important points of interest in different procedures including surgery for Parkinsonism and movement disorders. The increased morbidity and mortality of emergency neurosurgical procedures and the greater risk of postoperative aspiration, delirium and cognitive decline is discussed. Finally, the chapter ends with a mention of the need to assess the geriatric patient in toto and to select the right procedure and anesthesia for each according to the expected quality of life and surgical outcome.
Keywords
Aging, Cognitive decline, Delirium, Elderly, Functional reserve, Geriatric, Malnutrition, Neuroanesthesia, Neurocritical care, Neurosurgical outcome, Palliative care, Stereotactic surgery, Stress
Outline
Introduction 653
Implications of Surgical Stress and Anesthesia on the Elderly 653
Neurosurgical Concerns Unique to the Elderly 654
Preoperative Assessment for Geriatric Neurosurgery 654
Risk Stratification 655
Functional Assessment 655
Medications 656
Anesthetic History 656
Laboratory Tests 656
Intraoperative Management 656
Postoperative Management 658
Conclusion 658
References 658
Introduction
The world is getting grayer as a result of the improvements in technology and health care facilities. The burden of disease has increased with the mean age of the population as has the stress on overstretched health care resources the world over. As a greater number of older patients (>65 years) come for a greater variety of neurosurgical diseases and surgeries, it becomes imperative to understand the interplay between the aged brain, the neurosurgical stress, and the anesthetic drugs.
Implications of Surgical Stress and Anesthesia on the Elderly
Age as a number may not affect to a great extent the basal functions of the various organ systems in the body. What is affected, however, is the ability of these organ systems and physiologic processes to respond to and compensate for the stress and physiologic upheavals associated with surgery and anesthesia. The functional reserve of the aging body system is no longer capable of buffering the insults of disease and treatment as efficiently as in its younger days.
The Framingham Heart Study has documented a linear relationship of blood pressure with age, increasing from 30 to 84 years. The changes in the control mechanisms and mechanics of the various organ systems are responsible for a majority of the “unexpected” perioperative events in response to surgery and anesthesia in the geriatric patient. The important physiologic changes with age are listed in Table 38.1 . These changes in the cardiopulmonary, renal, and neuroendocrine systems make tachycardia, hypotension, hypoxia, hyponatremia, hypercarbia, confusion, delirium, and abnormal fluid electrolyte balance occur more often than in younger patients.
| Organ System | Associated Change | Pathophysiology |
|---|---|---|
| Cardiovascular |
|
|
|
| |
|
| |
| ||
| Pulmonary |
|
|
| Neurologic |
|
|
| Renal |
|
|
Neurosurgical Concerns Unique to the Elderly
By virtue of surviving longer with greater age-related comorbidities, drugs, and disabilities, the elderly patient may present to neurosurgery for a variety of indications ranging from tumor, trauma, cerebrovascular accident (CVA), spinal cord stenosis, metastatic disease, etc. There is dearth of data regarding the morbidity and mortality rates for neurosurgical procedures in the elderly patient, which makes clinical decision making and prognostication difficult. In a recent retrospective study, Chibbaro et al. analyzed their geriatric neurosurgical surgeries over the past 25 years and found a progressive increase in the proportion of neurosurgical cases in elderly patients with a drop in the mortality. The length of stay of these patients in the hospital, however, remained significantly higher than that of their younger counterparts.
Preoperative Assessment for Geriatric Neurosurgery
Preoperative assessment serves three major purposes: to examine and assess if the patient’s physiology can withstand the surgical stress associated with the suggested surgery (or an alternative), to determine whether/which medical intervention is indicated prior to proceeding, and to decide on the most appropriate anesthetic and surgical intervention for the patient. The geriatric patients are prone to certain unique risks like delirium, aspiration, falls, malnutrition, and delay in rehabilitation after surgery. Risk stratification from information available through population studies, history taking, and physical examination should be supplemented with results of laboratory tests and functional examination. Preoperative optimization strategies must be decided upon in the preoperative assessment.
Risk Stratification
There is not enough data or evidence for risk stratification in the geriatric patient for any particular type of neurosurgery. Indeed, in spite of the gradual decline in physiologic reserves, age itself (however extreme) is not a contraindication for surgery. Similarly no particular neurosurgical procedure can be generalized as “especially high risk” for the elderly. The perioperative events of a geriatric patient are a complex interplay between two entities—the patient (with his unique physiology) and the surgery (with its unique anesthetic, anatomic, and physiologic demands).
There are various risk stratification scores for perioperative morbidity and mortality with their own merits and limitations. The Geriatric Index of Comorbidity, the Charlson Index, and the Index of Coexisting Disease have been validated for this age group.
The physiological and operative severity score for the enumeration of operative mortality and morbidity—the Portland modification score—has been studied in the neurosurgical patient population undergoing elective craniotomy; it predicts postoperative in-hospital mortality faithfully across different patient populations and health care systems.
Functional Assessment
A thorough preoperative functional assessment helps the surgical and anesthetic team in getting an idea of the physiologic reserve of the patient. It also sets goals for returning a patient to his preoperative functional status after the surgery.
Cardiovascular system : Preexisting coronary artery disease, hypertension, or abnormal contractility increase the risk of perioperative adverse events—identification, optimization, and risk reduction strategies may improve outcomes. The American College of Cardiology/American Heart Association guidelines recommend risk stratification according to the following: the functional capacity of the patient as determined by the maximum oxygen uptake by treadmill testing or the cardiopulmonary exercise testing; the presence or past history of clinical predictors like unstable cardiac syndromes, decompensated heart failure, significant arrhythmias, and severe valvular disease as evidenced in electrocardiogram (ECG) or echocardiogram as applicable; the type of surgery wherein emergency surgeries in older people are classified into the high-risk category and head and neck surgeries are classified as intermediate-risk surgeries.
Pulmonary system : The physiologic changes of age in the pulmonary system result in blunting of the central reflexes and a decreased compliance of the thoracic wall resulting in increased work of breathing, decrease in maximum breathing capacity, and increased risk of hypoxemia or hypercarbia. Detailed functional testing or a simpler 6-min walk test may predict postoperative complications, as will history of smoking and obstructive lung disease. Smoking cessation for at least 6 weeks prior to elective surgery, preoperative breathing exercises, and directed cough training is recommended for patients at increased pulmonary risk. Chest X-ray, pulmonary function tests, and arterial blood gas testing may be indicated in patients at risk or in those posted for neurosurgery in a position, which will further impair lung function.
Previous history of prolonged ventilation in the intensive care unit (ICU) or of difficult airway should alert the anesthetist to plan and prepare for a difficult airway while providing a smooth intubation with minimal fluctuation in the intracranial pressures (ICPs).
Nervous system : Cerebrovascular disease, dementia, and Parkinson disease are more prevalent in the elderly patients and should be carefully assessed. The medications should be documented in the preanesthesia evaluation. Even mild varieties of cognitive impairment, preoperative depression, and alcohol dependence can make the postneurosurgical emergence and ICU stay hectic. Decreased visual or auditory prowess may result in emergence delirium. Screening for these conditions in the elderly neurosurgical population, although not studied well, has an intuitive advantage. The Mini Mental State Examination, Neurobehavioral Cognitive Status Examination, and the Cognitive Capacity Screening Examination have all been to be found useful in the neurosurgical patients (not specifically geriatric).
Renal function : Elderly population with hypertension and diabetes are more prone for preexisting renal failure and hemodialysis and should be evaluated accordingly. It is necessary to plan the perioperative fluid and electrolyte management meticulously. Patients on chronic hemodialysis may be dialysed a day prior to the scheduled surgery: serum potassium levels should be optimized on the day of surgery. Autonomic dysfunction calls for careful fluid loading and induction. Careful interpretation of serum markers (urea and creatinine) is needed—“normal” values in the presence of reduced muscle mass may mislead the clinician. Urinary tract infections, common and indolent in the elderly patient may lead to postoperative sepsis.
Others : A multidisciplinary approach to preoperative assessment of malnutrition, early initiation of postoperative feeding, adequate hydration, appropriate antibiotic, preemptive analgesia, perioperative thromboprophylaxis, and counseling of caregivers in the elderly patients during preanesthesia checkup may go a long way in improving postsurgical outcome.
Medications
As elderly patients are often excluded from drug trials data available on the pharmacology of various drugs is limited. This does not help the anesthetist, as the elderly perioperative patient is at high risk for polypharmacy and adverse drug interactions. It must be borne in mind while administering drugs to the elderly that they have a decreased lean body mass and total body water: the volume of distribution of most drugs and their rates of clearance is therefore altered. This is complicated by the changes in plasma proteins, alterations in cardiac output, and renal or hepatic clearance with increasing age—an increased free fraction of available drug may increase the pharmacologic effect of the administered anesthetic and other drugs. Age-related changes in the central nervous system (CNS) increase the clinical response to a variety of drugs used in anesthesia like propofol, opioids, etc. Propofol pharmacokinetics and dynamics reveal a linear decrease in its elimination clearance after 60 years of age. Independent of this decreased clearance, the elderly patients are 30–50% more sensitive to propofol than younger patients.
Anesthetic History
If available, anesthetic history should be studied for difficult airway, cardiovascular lability, response to fluid load, urine output, and requirement of pressors or antihypertensives intraoperatively. Emergence delirium or delayed awakening history may help to decide the mode of analgesia postoperatively.
Laboratory Tests
Adequate functional assessment will indicate areas that need further testing in the laboratory for quantification or documentation of baseline organ status. Hemoglobin level, coagulation profile and type and crossmatch may be needed in cases like meningioma surgery or in patients scheduled for emergency neurosurgery. Cardiopulmonary impairments would call for preoperative chest X-ray, ECG, and echocardiogram. As all perioperative laboratory tests, routine testing in elderly patients should only be undertaken if they are expected to bring about a change in patient management or anesthetic regime.
Intraoperative Management
General principles : Fast-acting induction and reversal agents, shorter acting drugs, and different intraoperative management techniques for geriatric anesthesia have failed to demonstrate mortality benefits. This in part could be due to the advances made in routine intraoperative and early postoperative care, which render relatively small changes such as that in time of recovery redundant in the perioperative period. Apart from the choice of anesthesia (there being few indications for regional anesthesia in neurosurgery except awake craniotomy) and physiologic management techniques, factors that are less studied but may be important to an elderly patient undergoing neurosurgery (or any other surgery) are perioperative temperature regulation, immunosuppressive effects of blood transfusion, perioperative complications due to deep vein thrombosis, and skin and soft tissue injuries due to intraoperative position.
For all neurosurgery involving the elderly patient, appropriateness of ICP and cerebral perfusion pressure (CPP) must be borne in mind: smooth induction and reversal techniques with avoidance of large fluctuations in blood pressure and maintaining normocapnia and normoxia are important. Invasive monitoring allows for a beat-to-beat control of ICP and CPP along with a close watch on cardiac output in elderly patients. Hypotension caused by most anesthetic agents suitable for neurosurgery may be treated with vasoconstrictor agents.
To allow for rapid reversal and assessment of postoperative neurologic status, short-acting agents like remifentanil and desflurane coupled with good analgesia need to be chosen.
Careful positioning with careful padding of pressure points and avoidance of extreme positions especially in prolonged neurosurgeries is important as the delicate skin and soft tissues in the elderly patients makes them very prone for nerve and soft tissue injuries and pressure sores.
Temperature monitoring, active warming, and mechanical prophylaxis for deep vein thrombosis may need to be planned and initiated in the preoperative period. Preoperative assessment of nutrition status and early initiation of feeding postoperatively with stress ulcer prophylaxis is more important in the elderly patients than in their younger counterparts.
Perioperative analgesia must be titrated carefully; respiratory compromise may be a risk preoperatively, but inadequate analgesia is seen more often postoperatively and plays a role in postoperative delirium.
Specific concerns in different surgical procedures include the following:
- 1.
Intracranial tumors
- a.
A growing intracranial space–occupying lesion may present late in the elderly due to a greater volume of spatial compensation resulting from increased ventricles and sulci.
- b.
Preanesthetic documentation of neurologic status and deficits is important.
- c.
Premedication must be chosen carefully depending on patients’ status and availability of close observation; oversedation may lead to respiratory depression and raised ICP.
- d.
Prolonged circulatory time in the elderly may delay the onset of induction and muscle paralysis; coexisting dehydration due to concurrent administration of osmotic diuretics may result in induction hypotension. Smooth induction and laryngoscopy avoiding stress response and hemodynamic alterations must be ensured. Anticipating a difficult airway or intubation and use of lignocaine to avoid the intubation response are important to prevent spikes in ICP. The same precautions need to be taken for a smooth extubation. Postoperative analgesics will need to be titrated with altered pharmacokinetics and pharmacodynamics of the elderly in mind.
- a.
- 2.
Aneurism surgery and CVA
- a.
Interventional neuroradiology and endovascular coiling are a preferred option where feasible.
- b.
Acute subarachnoid hemorrhage (SAH) may be associated with changes in the ECG, arrhythmias, volume shifts, and sympathetic overactivity. Bleed in the proximity of the hypothalamus may exacerbate or present as hypertension and diabetes. A guarded and careful management of the hemodynamic status balancing with the need to prevent vasospasm on one hand and cardiac decompensation on the other is important in the elderly patient with an SAH.
- c.
Use of controlled hypotension before clipping of aneurism may result in renal and cardiovascular adversities and has to be weighed against the purported benefits, being maintained for the minimum acceptable duration.
- d.
Cerebral vasospasm following SAH is conventionally treated with hydration and hypertension. Elderly patients with a higher risk of cardiopulmonary decompensation and hemorrhagic infarct may tolerate this poorly. Cerebral transluminal angioplasty and continuous selective infusion of intra-arterial vasodilators (papaverine, nimodipine, or verapamil) may be associated with lesser morbidity in cerebral vasospasm in these patients.
- e.
Early decompressive hemicraniectomy may improve mortality in elderly patients with large middle cerebral artery region strokes. Majority of the survivors needed assistance with most activities of daily living, however.
- a.
- 3.
Traumatic brain injury
- a.
A combination of concomitant hypertension, use of anticoagulants, and increased frequency of falls make subdural hemorrhage (SDH) more common in the elderly. Presentation is late due to a shrunken brain and delay in recognizing the subtle symptoms of confusion, amnesia, and falls in these patients. Local anesthetic techniques may be considered in elderly patients with SDH at a high risk from general anesthesia.
- b.
Preexisting cervical spine disease must be borne in mind in these patients during intubation and positioning for surgery.
- a.
- 4.
Surgery of the spine
- a.
Osteoporosis, preexisting arthritis, and delicate skin and soft tissues must be kept in mind along with the higher risk for hypotension when the elderly patient is turned prone. Adequate spinal perfusion pressures must be maintained.
- b.
Neutral neck position and keeping the abdomen and inferior vena cava free of compression will prevent hypotension, engorgement of the vertebral venous plexus, and a compromise of ventilation.
- c.
An increased risk of postoperative blindness especially in patients with concomitant vasculitis or in chronic smokers has been seen.
- d.
Systemic manifestations of diseases like rheumatoid arthritis will affect perioperative care.
- a.
- 5.
Functional stereotactic neurosurgery:
Elderly patients with Parkinson disease, chronic pain, and movement disorders are often good candidates for therapeutic electrical stimulation of the CNS. These procedures are usually done under monitored anesthesia care and minimum sedation as the patients need to be able to follow commands to ascertain the correct location and function of the stimulators. Care has to be taken about the effect of the anesthetic agents on the recordings from the microelectrodes. The anxiety and discomfort of elderly patients added to comorbidities and anesthetic agents may result in complications like hypertension, airway obstruction, and seizures. Good preoperative counseling, proper patient selection, and increased vigilance during the procedures will prevent or allow early identification and treatment of these events.
- 6.
Emergency neurosurgery
- a.
Emergent indications for neurosurgery in the elderly population forms a large proportion of all such procedures.
- b.
Emergency surgeries are performed in older patients, predominantly male, and have significantly longer length of stay in the hospital. Mortality is higher in the emergency neurosurgeries in the elderly patient, an event that may be attributable in varying proportions to the disease severity, patient physiology, and case selection.
- a.
Postoperative Management
Preexisting comorbidities such as diabetes and hypertension, the volume of the neoplasm, and local postoperative complications have been found to affect the postoperative course of geriatric patients after neurosurgery. Intensive monitoring including ICP and transcranial Doppler ultrasonography are useful for detecting intracranial complications at an early stage.
Respiratory complications : The elderly postoperative patient is at a higher risk of postoperative respiratory complications because of the associated physiologic changes of age and effects of altered consciousness associated with the neurosurgical pathology. Anesthetic agents, pain, analgesics, diminished mucociliary clearance, and fluid shifts make postoperative atelectasis more common. Decreased cough and pharyngeal reflex and associated cranial nerve palsies especially in posterior fossa and cervical spine surgery may increase the risk of postoperative aspiration. Meticulous analgesia, chest physiotherapy, and toileting along with protocols in the neuro-ICU to prevent aspiration are required.
Postoperative delirium and cognitive decline : Multiple factors play a role in the geriatric patients’ propensity to developing delirium and possible cognitive decline after anesthesia and surgery. Aggravation of age-associated anticholinergic deficiency due to anesthetic agents has a role to play, as do other factors like urinary tract infection, hypoxia, hypercarbia, hyperthermia, fluid shifts, and electrolyte imbalance.
Rehabilitation in the elderly patients after neurosurgery may be more prolonged and interspersed with infection, deep vein thrombosis, and other events. Good stepdown units, well-equipped hospices, and social support systems may improve the speed and extent of recovery and return to premorbid functional states.
Palliation in geriatric neurosurgery and neurocritical care : When faced with a position of having to decide the magnitude and type of intervention for an elderly patient suffering from a neurosurgical disorder of the brain or spine the questions that need to be answered are will the patient truly benefit from the procedure planned? Will the patient’s physiology withstand the rigors of anesthetic and surgical challenges? And will his quality of life improve or at least not deteriorate after the procedure?
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
