Sedation in the geriatric patient

LÓPEZ-JIMÉNEZ J, GIMÉNEZ-PRATS MJ. SEDATION IN THE GERIATRIC PATIENT. MED ORAL 2004;9:45-55.

SUMMARY

A review is made of the utility of iatrosedation and pharmacological sedation in the dental treatment of elderly patients. The adoption of such measures is required due to the increased prevalence of oral pathology, poorer stress tolerance and frequent association of systemic disease in such patients. A description is made of the recommended psychoactive drug administration routes according to the associated pathology and of the most frequent pharmacological interactions with the background disease. Drug sedation should always be accompanied by psychological measures to minimize the required drug dose, and by correct locoregional anesthesia.

Key words: Geriatric sedation, iatrosedation, intravenous sedation, oral sedation, inhalatory sedation, ambulatory general anesthesia.

INTRODUCTION

Although the geriatric period corresponds to individuals over 65 years old, there are two forms of aging: chronological and biological. The term "elderly" is associated with an age-related decrease in the physiological capacity of the individual (1-3).

The aging process comprises physiological and pathological changes which can modify the response of the individual to different stimuli, including stress or the administration of drugs. The American Society of Anesthesiologists (ASA) score classifies healthy individuals over age 60 as corresponding to ASA II. These subjects show a poorer tolerance of stress; consequently, although they are exposed to only minimum risks, caution is required to avoid anxiety and pain during the dental treatment of these patients (1). In this context, stress associated with dental treatment may be the main factor causing chronic illnesses to develop decompensation and complications in the form of acute exacerbations (ischemic heart disease, hypertensive episodes, diabetes, etc.)(2). There are no contraindications for pharmacological sedation in such patients, though psychological intervention to facilitate behavioral control should always accompany such sedation measures in order to reduce the required drug doses. The term "sedation" does not imply analgesia, as a result of which correct locoregional anesthesia must be provided in all cases (1,4,5).

Pharmacological hypnosis or sedation is particularly indicated for the dental management of medically compromised and apprehensive elderly patients (6).

Aging involves a reduction in metabolism and tissue elasticity, as well as a lessened functional reserve (1). In this sense, the cerebral blood flow of a 75-year-old is 80% that of a 30-year-old individual (1), while cardiac output decreases to 65%. Cardiovascular and respiratory function can also be altered in healthy geriatric individuals (1,6), while renal flow decreases up to 45%, and liver metabolism is also reduced (1,2). As a result, drug metabolization and elimination is slowed, with an increase in half-life and plasma concentration. Another aspect to be taken into account is the increase in fatty tissue at the expense of a reduction in lean body mass (muscle) with increasing age. As a result, the action of sedatives that accumulate in fatty tissue (e.g., benzodiazepines) is prolonged, and the associated adverse or side effects are both more frequent and more serious than in the rest of the population (1-3). Local anesthetic half-life is considerably prolonged, as a result of which special attention should focus on the possibility of interactions with the rest of the drugs these patients may be using for chronic disorders &endash; particularly taking into account that 41% of those over age 60 regularly consume some type of medication (2,6,7). The lack of a prior exhaustive multidisciplinary clinical evaluation of the patient is one of the main causes of complications (8). Eighty-five percent of the population over age 65 suffer some chronic disorder, and 42% suffer limitations in daily life activities as a result of such background illnesses (1,3). The most frequent pathologies are arthritis, hypertension, cardiovascular disease (particularly ischemic heart disease, which represents the first cause of mortality in this population group), and chronic obstructive pulmonary disease (COPD). While impaired liver or kidney function is comparatively less prevalent, it must be taken into account when prescribing drugs for such patients (1,3,9).

-ARTHRITIS: Arthritic patients have difficulties adapting to the dental chair, and typically use nonsteroidal antiinflammatory drugs (NSAIDs). As a result, more intense bleeding can be observed in the dental treatment of such patients; coagulation tests are thus required as a measure of caution (2).

-ARTERIAL HYPERTENSION: The emotional tension and stress associated with dental treatment increases patient blood pressure; sedation is thus particularly indicated in such situations (1,6). An important consideration is that antihypertensive drugs enhance the effects of sedatives. Consequently, low sedation doses should be administered initially, followed by a gradual increment according to the patient response observed. Since the most important complications of an acute hypertensive crisis are myocardial infarction, stroke, renal failure, congestive heart failure or lung edema, all procedures involving more than simple anxiolytic premedication should contemplate the administration of additional oxygen using a cannula or nose mask (1,6).

In patients with a history of high blood pressure and who either do or do not receive sedation, pre- and postoperative arterial pressure monitorization is essential (8).

In such patients sedation via the oral route or involving inhalatory nitrous oxide may be indicated (9). In subjects with severe hypertension (ASA IV) involving systolic pressure values of over 200 mmHg and/or diastolic pressures of above 115 mmHg, treatment should be provided in the hospital setting, with the adoption of intravenous sedative measures. This affords a safer approach to management, since it provides a more direct access for the administration of drugs in the event of an emergency (1,10).

At the end of treatment, the patient should take special care in getting up from the dental chair, due to the increased risk of a orthostatic hypotension episode. In order to prevent this problem, the patient should remain seated for a few minutes after the conclusion of dental treatment, until normal blood pressure is confirmed. The patient may then adopt a more raised sitting position for a few minutes before standing up (2).

Since antihypertensive drugs increment the effect of sedatives, the latter should be dosed more slowly &endash; the ideal administration routes being those which allow stepwise dose increments (e.g., inhalatory and intravenous). The oral route is especially indicated for anxiolytic premedication or for affording very superficial sedation (1).

-CARDIOVASCULAR DISEASE: Ischemic heart disease in particular constitutes the first cause of mortality in the developed world, affecting approximately 10% of the population (1,2). Sedation is especially indicated in these patients in order to combat stress, since endogenous catecholamine secretion increases heart rate and thus also myocardial oxygen demand &endash; this in turn constituting an added source of risk in patients with ischemic heart disease. The inhalatory route is the best option in such situations, in view of the added oxygen it can provide. Sedation via the oral or intravenous route is also indicated, taking care to monitor blood oxygen saturation (oximetry). It is advisable to use drugs that exert the least possible depressive effect upon the respiratory center, such as diazepam, midazolam or propofol (1,2). In such circumstances it is advisable to provide additional oxygen with a nasal cannula throughout the dental procedure, at a flow of 3-4 l/min., with sedation as superficial as possible &endash; regardless of the administration route employed. At no time should the blood oxygen levels (oximetry) be allowed to decrease. Anticholinergic agents such as atropine should be avoided, due to their collateral tachycardia-induced effects (1,2).

The drugs most widely used to treat ischemic heart disease are vasodilators and antiplatelet drugs. Such medication may in turn exacerbate postural hypotension, particularly when the patient gets up after treatment. Progressive patient incorporation is thus advised (2). Special caution is required in relation to the pressive amines used in local anesthetic solutions; the use of adrenaline in gingival retraction threads is contraindicated. As regards hemostasia, the bleeding and coagulation time must be evaluated. Sedation is particularly indicated in patients with cardiac arrhythmias, to prevent myocardial hypoxia secondary to stress-induced increments in cardiac frequency and inotropism. Hypotension should also be controlled, since it constitutes an added risk factor. Oximetric monitorization is essential when providing sedation of any kind, and additional oxygen supplementing using a nasal cannula or catheter is advised in those procedures involving more than simple anxiolytic premedication (11).

In patients with a history of arrhythmia, electrocardiographic monitorization should be carried out throughout the dental treatment procedure (12). The side effects of beta-blockers such as propanolol comprise asthenia, bradycardia, dyspnea and hypotension. Such medication should not be suspended without approval by the cardiologist, since a risk of ischemic heart problems would result. Lidocaine is used as a cardiotonic and antiarrhythmic drug, and would thus be the local anesthetic of choice (2,7).

-RESPIRATORY DISEASE: Respiratory pathology, fundamen-tally COPD (and usually involving chronic bronchitis) is the greatest source in incapacitation among the elderly. Bronchial secretions increase, with the appearance of inflammatory exudates; such situations are in turn exacerbated by irritants such as tobacco smoke or infections. These patients should be instructed to stop smoking, with the adoption of measures to prevent possible respiratory infections. Bronchodilators are the most widely used drugs, while diuretics are prescribed in the presence of associated congestive heart disease. Oxygen therapy is provided in the more severe cases (2,3).

The higher respiratory centers normally activate when carbon dioxide partial pressure rises. In patients with respiratory pathology in which the carbon dioxide concentrations are persistently elevated, respiratory stimulation takes place in response to lowered oxygen levels. This means that apnea may result if high oximetric readings are maintained in such patients. All sedatives are potentially able to cause respiratory failure, and must therefore be administered with great caution under such circumstances. Benzodiazepines or propofol are advised, in view of their lesser respiratory depressive effect. Barbiturates and opiates are contraindicated because of their increased tendency to cause bronchospasm and respiratory depression. Antihistamines and anticholinergic agents (atropine, scopolamine) are likewise not recommended, since they increase mucosal dryness and respiratory secretion viscosity (2).

Patient positioning during treatment should be evaluated, since these subjects tend to suffer orthopnea. The most comfortable breathing position is advised (normally the Trendelenburg position, with the back raised approximately 30-45 degrees)(13).

Anxiolytic premedication should be administered via the oral route. The inhalatory route can also be used, since apnea as a result of the increase in oxygen partial pressure is unlikely (1). Nevertheless, in order to prevent possible apnea, oximetric monitorization is indicated before the intervention, taking care to maintain constant levels throughout the treatment procedure (1). In patients with emphysema, nitrous oxide should be used with great caution, since the gas may accumulate within the dilated pulmonary spaces, with excessive persistence of the sedative effect. In such situations the advantages of stepwise dose adjustment would also be compromised. If intravenous sedation is decided, it should be provided in the hospital setting, with additional oxygenation (nose mask, 2-3 l/min.) and strict monitorization (13,14).

Pharmacological interactions may occur between beta-adrenergic bronchodilators and the pressive amines found in local anesthetic solutions. An evaluation should also be made of corticoid dose increments in those patients who already use such drugs for the control of mental and physical stress (2).

-KIDNEY DISEASE: Chronic renal failure is the most common reason for modifying the habitual dental treatment protocols. The management of chronic renal failure comprises dialysis or transplantation (2). Since the excretion of drugs which are eliminated through the kidneys is reduced in such patients, the corresponding blood drug levels will remain higher for longer time periods &endash; with the resulting risk of overdose. It is advisable to perform dental treatment on the day after dialysis, when the metabolic status of the patient is closest to normal. Sedatives such as benzodiazepines or opiates can be administered as usual without problems, as can amide-type local anesthetics, and their combination with vasoconstrictors is not contraindicated (2,7).

No concrete administration route is contraindicated, though the oral route is advised for affording superficial sedation or for anxiolytic premedication. The inhalatory or intravenous route would be the option of choice when deeper sedation is required (1).

-NEUROLOGICAL AND PSYCHIATRIC DISORDERS

Elderly people have a high prevalence of psychiatric problems associated to medical disorders. Depression affects 15-20% of this population subgroup (2,15). These individuals in turn show an increased prevalence of oral pathology, since the anxiety produced by the idea of having to visit the dentist prevents them from seeking treatment. Moreover, patients with neurological or psychiatric problems have greater difficulties for maintaining adequate oral hygiene, and tend to resort to polymedication, which in turn produces dry mouth and hence secondary oral problems (16,17).

In view of its frequency and behavioral implications, dementia is a problem to be taken into account. The disease is characterized by generalized intellectual, memory and personality deterioration, though without impaired consciousness (3,15). It is distinguished from mental retardation in that dementia is an acquired disorder and is normally progressive. Alzheimer's disease accounts for 70% of all cases of dementia, and its prevalence is known to increase with age from 3% in individuals in the 65-74 years age range to 40% in those over age 85 (2,17). In such situations neuron loss and neurological functional deterioration is five-fold greater than in normal aging (3,15-17). Depending on the degree of evolution of the disease, dysphoria states may be observed with unpredictable behavior. This is in turn decisive for selecting the route for administering sedation and in determining its depth. Intravenous dosing may be indicated, since it facilitates stepwise dose increments and requires less patient cooperation than the inhalatory route (1). There are no contraindications for the use of amide-type local anesthetics or vasoconstrictors, unless concomitant systemic disease is present (15).

Parkinson's disease is a degenerative disorder of the central nervous system attributable to a loss of dopadrenergic fibers in the basal ganglia of the brain (1). Eleven percent of all people over age 65 have the disease (2,3). The first symptoms may be a slowing in mental processes and behavioral changes, possibly accompanied in the early stages by depression. Progression is usually slow (2,15). In patients with consolidated Parkinson's disease, the facial expression is characteristically rigid, body movements are slow with a tendency towards stiffness, and trembling of the hands is observed (15). The mental functions are not impaired, however, and psychological management is therefore very important in such cases. As the illness progresses it is accompanied by depression, with the development of dementia in the more advanced stages (1,2,15). The definitive diagnosis can only be established at autopsy, identifying the corresponding cortical atrophy and increased size of the ventricles. A clinical diagnosis is therefore made based on the typical signs and symptoms of the disease (2,15-17).

The most common pharmacological interactions of the most widely used psychoactive drugs are summarized below:

(A) Tricyclic antidepressants: These drugs increase the depressive actions upon the central nervous system of all sedatives, reinforce the actions of other anticholinergic agents such as antihistamines and atropine, and enhance the sympathomimetic effects of other pressive amines such as adrenaline and noradrenaline. Tricyclic antidepressant overdose manifests with the appearance of anticholinergic effects, altered heart rate (tachycardia) and arrhythmias (2,7,15).

(B) Lithium: This agent is used to prevent acute manic states in bipolar disorders. The complications resulting from chronic lithium administration comprise thyroid depression and arrhythmias with T-wave alterations, as a result of which any sedative treatment should be accompanied by continuous electrocardiographic monitorization (7,13,15).

(C) Anxiolytic drugs: The most widely used anxiolytics are the benzodiazepines. In this context, all central nervous depressants exert additive or synergic effects when administered in combination. Low-dose benzodiazepines have anxiolytic effects, while on increasing the dosage central depression is also produced &endash; with sedation, general anesthesia, respiratory and cardiac depression, and the risk of death (1,2,7,15).

(D) Neuroleptics or antipsychotic agents (major tranquilizers): These substances produce sedative and tranquilizing effects, and attenuate aggressive behavior while inducing diminished patient interest in the surroundings. Side effects and overdose are more commonly found in the elderly and comprise slowed mental processing and drowsiness, anticholinergic action (dry mouth, postural hypotension, constipation, urine retention), extrapyramidal effects (uncontrolled large-amplitude movements), tachycardia and arrhythmias. When combined with antidepressants, they can induce intense anticholinergic effects. They also reinforce the actions of other sedatives (benzodiazepines, propofol, antihistamines, narcotics, alcohol) -a fact that may be particularly hazardous in patients with respiratory failure. The combination of major tranquilizers and adrenaline can induce hypertensive crises (1,2,7,15).

In patients with any other psychiatric pathology (phobias, schizophrenia, delirium, etc.), the degree of patient cooperation in relation to dental treatment, the magnitude of the latter, and the possible drug interactions must be appraised (2,15).

-LIVER DISORDERS: Since liver metabolism decreases with advancing age, drug dosage in the elderly should be reduced &endash; unlike the situation in children, where in terms of body weight equivalence larger doses are needed than in adults. Impaired liver function can lead to intoxication, overdose or prolonged action of psychoactive medication administered at the usual dosage. In situations of severe liver disease, the drug dose should be reduced approximately 50%. Amide-type local anesthetics with vasoconstrictors can be used, though the performance of nerve block is advised in order to reduce the dose requirements (1,2).

For sedation via the oral route, a particularly good choice is represented by the benzodiazepines, controlling the dose and ideally providing mild anxiolytic premedication; alternatively, deeper sedation can by achieved via the intravenous route, with stepwise dose adjustment. In both cases the duration of the effects is longer. Barbiturates and opiates are contraindicated, due to the intensity of their effects in situations of severely impaired liver function. The inhalatory route is advised for administration, since it involves no prior hepatic biotransformation (2). Short action benzodiazepines such as midazolam are the drugs of choice (1,18,19).

TREATMENT OF PAIN AND ANXIETY

In geriatric patients there are no absolute or specific contraindications to the use of local anesthetics, sedatives or general anesthesia, though a number of special considerations do apply, such as the extended half-life of both sedatives and local anesthetics. Caution is also required when using vasoconstrictors (1,2,1). Pharmacological sedation is particularly recommended for the dental treatment of elderly patients with associated medical problems or apprehension (6). The elimination of diazepam in the 20-year-old patient is completed within 20 hours, while in individuals over age 80 the duration increases to 90 hours (1).

In selecting the sedation route or depth, or the setting in which sedation is to be provided, a critical consideration is patient ASA status (i.e., medical risk assessment), the degree of patient cooperation, and the magnitude of the oral pathology requiring treatment.

SEDATION VIA THE ORAL ROUTE

Benzodiazepines are recommended, especially those which lack active metabolites, such as lorazepam (Orfidal®). Midazolam can also be used (Dormicum®) &endash; the latter being the sedative of choice when dental care is provided on an ambulatory basis, due to its short-lasting action, muscle relaxant effect, more intense amnesic action than diazepam, and few effects in terms of respiratory or cardiac depression (1,18-20).

On occasion of the first visit, very low doses are indicated, to observe the specific effects in each individual patient and thus progressively adjust the dose on successive visits (1).

SEDATION VIA THE INHALATORY ROUTE

Nitrous oxide is used in the ambulatory setting. It affords considerable advantages in elderly patients, since the technique is noninvasive, an antidote is readily available (oxygen), the action is easily reversible, stepwise dose adjustment is possible, and additional oxygenation is provided that may constitute a safety mechanism in all associated pathologies other than COPD (1,2). Some authors advocate the inhalatory route as the best option in all patients with ischemic cardiovascular disease (9,11).

INTRAMUSCULAR SEDATION

The intramuscular route is normally not indicated since stepwise dose adjustment is not possible and drug absorption is unpredictable. It could be used in situations of extreme patient anxiety and when intravenous administration (venoclysis) is not possible. Midazolam is advised in view of its low tissue irritability due to its solubility in water and ultra-short action (1,2). Drugs such as ketamine can be used for anesthetic induction to facilitate venoclysis and thus perform the entire procedure under conventional general anesthesia in aggressive patients where cooperation is nonexistent (1).

INTRAVENOUS SEDATION

It should be made clear that intravenous sedation is not synonymous of deep sedation. Intravenous dosing is the route of choice in patients with medical problems. Constant venous perfusion moreover allows stepwise dose adjustment, and great safety for drug or even antidote administration in the event of an emergency (1,10,14).

The intravenous route is the safest option, provided it is employed by an experienced professional. While stepwise dose adjustment is possible, it should be much slower in the elderly patient, due to the pharmacokinetic peculiarities involved in such individuals (18). The technique is very safe. In effect, in a study of 372 patients sedated via the intravenous route with midazolam for dental treatment, Runas et al. reported no serious complications (21). Umino described a case of atrial fibrillation in the extraction of a tooth in an elderly patient subjected to intravenous sedation, following the administration of lidocaine with adrenaline (1:200,000). The condition resolved spontaneously after 20 min. (22). In turn, Campbell, in a series of 200 patients in the 65-90 years age range and treated with fentanyl and midazolam or diazepam plus local anesthesia for dental treatment, reported no serious complications (23).

Where necessary, oxygen can also be provided during the procedure (1,10). The combination of analgesia and sedation via this route is very useful, administering morphic agents (fentanyl) with sedatives such as the benzodiazepines (midazolam) and local anesthetic (1,5). This approach is particularly recommended in patients at medical risk (14). D
Different combinations can be used with these drugs, though in all cases administration should be carried out by an anesthetist, and patient pre- and intraoperative monitorization and postoperative care until full recovery is essential to avoid accidents with sedation (1,8,24,25). Runas reported an average recovery time after intravenous sedation with midazolam of 94 minutes, though obviously discharge must be decided on an individualized basis once all the patient constants have been normalized, and regardless of the predefined times (21).

AMBULATORY GENERAL ANESTHESIA

It is essential to confirm the absence of severe systemic disorders when contemplating ambulatory general anesthesia, and the technique is moreover indicated only for short-duration procedures. Any sedation technique, in any patient, must be accompanied by due pre-, intra- and postoperative monitorization. Resuscitation measures, antidotes and a constant oxygen supply must be available (1,8,14,24).

Nkansah reported a mortality rate in association to ambulatory general anesthesia in dental treatment and oral surgery of 1.4 cases per million interventions. According to the author, this incidence is similar to that recorded for ambulatory dental care (26). D'Eramo recorded no deaths among 1,500,000 patients subjected to dental treatment under ambulatory anesthesia (27). Laryngeal or bronchial spasm is a complication almost always associated with general anesthesia (27).

DISCUSSION

Dental treatment under general anesthesia or deep sedation should only be contemplated in those cases where treatment cannot be provided on an ambulatory basis with simple local anesthesia (28). Advanced patient age does not constitute an absolute contraindication for such procedures; indeed, intravenous sedation is particularly indicated in elderly subjects with associated systemic disorders or apprehension in relation to dental treatments (6). Intravenous sedation with the required precautions is as safe as ambulatory local anesthesia, though considering that it is performed in patients at increased medical risk, it is comparatively even safer (9,21,23,26,27,29).

The immense majority of accidents or complications associated with the administration of psychoactive drugs are the result of: (a) A lack of knowledge of the patient, an incomplete clinical history, a lack of interconsultation with the internist, missing laboratory tests or complementary explorations; (b) Incorrect pre-, intra- and postoperative patient monitorization for the early identification of any possible metabolic decompensation before an emergency arises; and (c) A lack of knowledge of the sedatives used and their potential interactions (1,2,8,30). The medical constants to be controlled are: arterial pressure, oxygen saturation, heart rate, respiratory frequency and amplitude, constant electrocardiographic monitorization (in patients with heart disease), and the degree of communication with the patient - particularly in cases of conscious sedation (12,13,25,30). Thus, it is essential to evaluate the medical risk involved, based on an exhaustive clinical history, interconsultation with other specialists caring for the patient, and the complementary explorations required from the medical, ethical and legal perspective (1,8).

As regards the characteristics of the drug of choice for providing anxiolysis or mild sedation, the administered drug should offer very short action, with no active metabolites capable of unpredictably prolonging its effects, and an antidote should be available. These features are afforded by benzodiazepines via the oral, intramuscular and intravenous routes. The antidote in such circumstances in flumazenil (Anexate®). Inhalatory protoxide is also indicated &endash; the antidote in this case being oxygen. Among the benzodiazepines, midazolam is currently considered to be the drug of choice in ambulatory dental treatment, in view of its pharmacokinetic and pharmacodynamic characteristics. It moreover offers improved amnesic action versus diazepam (18). When good analgesia is required via the intravenous route, morphic agents such as fentanyl can be used - the antidote being naloxone (1,5,14).

In cases where deep sedation proves necessary, it is essential from the ethical and legal perspective to ensure that an anesthetist performs the procedure (25,30). In the absence of associated disease, a series of blood tests should be made before the intervention (complete blood count, leukocyte formula, coagulation tests, liver and renal function parameters), together with an electrocardiogram and a posteroanterior and lateral projection chest X-ray study (8).

Iatrosedation and local anesthesia are essential for providing treatment under sedation. Complications such as the case of atrial fibrillation described above have been associated to insufficient local anesthesia, deficient sedation and failure to maintain stable blood pressure, heart rate or oxygen saturation values (22).

On completing any procedure under sedation, it is important for the elderly patient to remain in the inclined position for a few hours, followed by gradual incorporation, to avoid the risk of orthostatic hypotension on standing up directly. Discharge should not be decided until all patient constants have returned to normal (8).

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