The Geriatric Patient

Patrick A. Nee

Diane M. Birnbaumer

THE CLINICAL CHALLENGE

Comorbid illnesses are common in the older population, and for any given illness or injury, older adults have a worse outcome. Aging causes progressive deterioration in physiologic reserve and these changes are exacerbated by preexisting chronic conditions, so the elderly are at increased risk of adverse responses to tracheal intubation.

Advanced age affects airway management decision making in three primary areas.

Decreased Cardio-Respiratory Reserve

Age-related changes in the lungs impair gas exchange, reducing oxygen tension at baseline. The normal PaO₂ falls by 4 mm Hg per decade after the age of 20. Total lung capacity does not change significantly, but functional residual capacity (FRC) and closing volume (CV) increase with age. CV increases more than FRC leading to atelectasis, especially in the supine position. Reduced sensitivity of central respiratory drive, weakened respiratory muscles, and altered chest wall mechanics impair the ability of the older adult to respond to hypoxia and hypercarbia. Consequently, oxygen saturation may fall rapidly in the face of a respiratory threat. Older patients also are at risk of pulmonary aspiration because of blunted airway reflexes, swallowing disorders, drug effects, and delayed gastric emptying.

The aging heart has reduced contractility and limited coronary blood flow, and dysrhythmias, such as atrial fibrillation, further impair the ability to increase cardiac output. This relatively fixed cardiac output impairs the physiologic response to the hypotensive effects of intubation drugs. Finally, the presence of cardiovascular or cerebrovascular disease reduces the patient’s tolerance of hypoxemia or hypotension.

Increased Incidence of Difficult Airway

Advanced age, per se, is a marker for difficult bag-mask ventilation (BMV) (see Chapter 2). Older patients also have an increased incidence of difficult direct laryngoscopy, although this is not a factor of age itself, but rather a result of impairment of neck mobility and mouth opening. Similarly, changes associated with aging and the cumulative effects of disease cause difficulty with the insertion of extraglottic devices (EGDs) and provision of a surgical airway.

Ethical Considerations

In airway management, as in all other aspect of resuscitation, the patient’s preferences regarding therapeutic interventions must be respected. Advanced age in and of itself is not a contraindication to advanced airway intervention. Poor outcomes relate more to functional limitation and comorbidities rather than chronologic age. In cases where life-sustaining interventions are either inappropriate or not desired, noninvasive ventilation can provide respiratory assistance and comfort.

APPROACH TO THE AIRWAY

As the elderly tolerate hypoxia poorly, intubation should be considered early in their management. A careful preintubation assessment will identify difficult airway predictors, such as poor mouth opening, absent teeth, stiff lungs and reduced cervical spine range of motion. Most often, the operator will be confident with respect to laryngoscopy, particularly if a video laryngoscope is used, and with respect to oxygenation using a bag and mask or EGD, so rapid sequence intubation (RSI) is usually the technique of choice.

Preoxygenation is particularly important as older patients may desaturate quickly because of age-associated changes in the heart and lungs and preexisting disease. For the same reasons, preoxygenation may not be as effective as in a younger, healthier patient. BMV may be required
to maintain oxygen saturation >90% after the induction agent and neuromuscular blocking agent (NMBA) are given, particularly if more than one laryngoscopic attempt is required. Although not studied in the elderly patient, passive oxygenation during apnea by the provision of oxygen at 5 L per minute flow through nasal cannulae may retard the rate of oxyhemoglobin desaturation.

During bag-mask ventilation (BMV), mask seal may be problematic because of facial wasting and edentulousness, and a two-handed two-person technique, with a nasal or oral airway, is advisable. Well-fitting dentures should be left in place during BMV and removed for intubation. Loss of elastic tissues promotes collapse and partial obstruction of the upper airway. Older patients may have oropharyngeal obstruction because of hematoma or cancer of the head or neck. Reduced lung compliance and chest wall stiffness may make oxygenation using a bag and mask or EGD difficult, and this may be worsened by coexisting chronic obstructive pulmonary disease (COPD) or heart failure.

When preintubation assessment identifies a difficult airway, the operator should choose the best possible device (usually a video laryngoscope) and ensure optimal patient positioning to create the greatest likelihood of success. Alternative airway approaches, including awake flexible endoscopy, may be chosen over RSI, as guided by the difficult airway algorithm (Chapter 3).

Surgical cricothyrotomy is the appropriate choice in a “can’t intubate, can’t oxygenate” situation, but this procedure may be difficult in the elderly as they are more likely to have distortion of the tissues as a result of cancer or radiotherapy.

Drug Dosage and Administration

Pretreatment

The pretreatment agents considered for older adults are the same as for younger adult patients: lidocaine and fentanyl. In general, lidocaine is recommended for patients with elevated intracranial pressure or reactive airway disease and does not require dose adjustment. Its use in the elderly has not been specifically studied.

Fentanyl mitigates catecholamine response to laryngeal manipulation. Although senescence may blunt these autonomic responses, critically ill hypoxic and acidotic older patients requiring intubation are at risk of stroke, myocardial infarction, or other vascular events. Although premedication with fentanyl may attenuate these responses, its use is not without risk. Older patients are more sensitive to the respiratory depressant and hypotensive effects of opioids. Consequently, fentanyl should be given slowly (over more than 2 to 3 minutes) as the last of the pretreatment drugs. In frail patients, or those with significant comorbidities, including the use of antihypertensive medications, it may be advisable to reduce the fentanyl dose to 1 to 2 µg per kg, or avoid its use altogether.

Paralysis with induction

Etomidate is the preferred agent in older patients because of its superior hemodynamic stability, but it will not adequately blunt the pressor response to laryngoscopy (see “Pretreatment” section). Thiopental and propofol may cause significant hypotension in critically ill patients. With any induction agent, the elderly are more prone to drug-induced hypotension, which may be persistent. Ketamine causes less cardiovascular lability and is useful in reactive airways disease, however, its sympathomimetic properties can be a disadvantage in patients with ischemic heart disease, cerebrovascular disease, elevated intracranial pressure, or Parkinson’s disease.

Succinylcholine is the paralytic agent of choice for RSI. Before using it in older patients, contraindications to succinylcholine should be sought by history from the patient or family members, physical examination (especially for neurologic disability), and review of clinical records, if possible. For example, a recent denervating stroke (3 days to 6 months) is associated with a high risk of drug-induced hyperkalemia. Where doubt exists, an alternative NMBA, ideally rocuronium, should be used. Chronic renal disease, including renal failure, is not a contraindication to succinylcholine use.

POSTINTUBATION MANAGEMENT

The principles of postintubation management, set out in Chapters 7

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