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Learning Scope #370
1 contact hour
Expires Nov. 7, 2013

You can earn 1 contact hour of continuing education credit in three ways: 1) For immediate results and certificate; take the test online; grade and certificate are available immediately after taking the test. 2) Mail your completed exam (or a photocopy) along with the $8 fee (check or credit card) to ADVANCE for Nurses, Learning Scope, 2900 Horizon Dr., King of Prussia, PA 19406. 3) Fax the completed exam to 610-278-1426. If faxing or mailing, allow 30 days to receive certificate or notice of failure. A certificate of credit will be awarded to participants who achieve a passing grade of 70 percent or better.

Merion Matters, Inc. is an approved provider of continuing nursing education by the Pennsylvania State Nurses Association (No. 221-3-O-09), an accredited approver by the American Nurses Credentialing Center's Commission on Accreditation. Merion Matters Inc. is also approved as a provider by the California Board of Registered Nursing (No. 13230) and by the Florida Board of Nursing (No. 3298).

The goal of this continuing education offering is to provide nurses with current information on monitored anesthesia care and the elderly they can apply to their practice. After reading this article, you will be able to:

1. Compare and contrast chronologic age to physiologic age in elderly patients.
2. Discuss how the aging process impacts organ function, drug response and drug metabolism in the elderly.
3. Describe nursing care priorities to decrease post-anesthesia complications in the elderly patient.

According to 2009 Census Bureau statistics, the elderly comprise 12.9 percent of the total U.S. population. Based on chronological age, an elderly patient is defined as 65 years of age and older. People are living longer because of advancements in medical care and healthier lifestyles. However, when planning care for the geriatric patient it is essential to consider the influence of physiologic age verses chronologic age, as physiologic age impacts organ function and the ability to respond to surgical stress.¹ A patient may have a chronologic age of 70 but the biological organ function of an 80-year-old due to the influence of genetic differences, presence of disease processes and lifestyle habits.¹

Since the elderly are the most rapidly growing segment of the total population, more geriatric patients will present for surgical procedures. It is critical for perianesthesia nurses to understand how the aging process impacts organ function, drug response and metabolism, and are cognizant of potential common postoperative issues among the elderly. This article will highlight the physiologic variations of aging, pharmacodynamic and pharmacokinetic changes, the medications administered for monitored anesthesia care (MAC) and perioperative nursing implications when caring for the elderly patient.

Although the aging process is frequently viewed from a chronological perspective, the impact of genetics, environmental factors and lifestyle choices influence organ function, which produces a pronounced degree of variability among the elderly population.¹ Aging produces numerous physiologic changes, which affect several organ systems throughout the body and are listed in the Table.

The physiologic changes listed in the Table influence the pharmacokinetics and pharmacodynamics of the drugs administered to the elderly patient. Aging produces pharmacokinetic changes due to alterations in vascular blood volume, plasma protein binding, change in percentage of lean to adipose tissue and decreased efficiency of metabolism and elimination. This, coupled with patient to patient variations, adds to the increased incidence of adverse drug responses in the geriatric patient.

Aging also produces a decrease in muscle mass, an increase in body fat and a decrease in body water. A decrease in total body water leads to a contracted blood volume in the elderly, which results in an initial higher plasma concentration of drugs and a potentially exaggerated response. Thus, the elderly patient will usually require a lower dose. Due to an increased volume of distribution, fat-soluble drugs administered to the elderly patient can have a prolonged elimination half-life, which can lengthen the duration of action and slow elimination.²

Although aging and the presence of comorbidities impacts anesthesia management, there is no one specific type that is best suited for the elderly patient, as it will be determined by the surgical procedure and the patient's comorbidities. MAC is commonly used in the elderly population. Various medications are utilized for MAC, including midazolam, fentanyl, propofol, dexmedetomidine, ketamine and remifentanil.

The dosages used for MAC are titrated to effect, which allows patients to respond to verbal commands or a gentle shake and to breathe on their own without mechanical assistance. MAC can be used in combination with local or regional anesthesia and is typically associated with simple procedures or minor surgery. The local anesthetics used in association with the surgical procedure will also provide some postoperative pain relief, but cannot be the primary source as they usually are short-acting in duration. The administration of a MAC anesthetic provides amnesia, analgesia or pain relief, and patient comfort during the surgical or diagnostic procedure.

The focus of this section will be on the medications administered for MAC and the postoperative nursing implications associated with providing care for the elderly patient.

Midazolam is a benzodiazepine used for its anxiolytic and amnestic effects. It has an onset of action between 2 and 2½ minutes and a short duration of action. Elderly patients may be very sensitive to the cardiovascular and respiratory effects of midazolam, demonstrating episodes of hypotension and respiratory depression; therefore, the dose should be reduced in this patient population. Postoperative delirium is a major concern associated with the administration of midazolam. The elderly patient may present to the post-anesthesia care unit (PACU) with somnolence, secondary to the administration of midazolam. These patients should receive supplemental oxygen via nasal cannula, and close monitoring of the patient's respiratory rate and oxygen saturation via a pulse oximeter is vital.

Fentanyl is a synthetic opioid frequently used for MAC because of its analgesic effects. The onset of action is almost immediate when administered intravenously and the duration of action is 30-60 minutes. Even when used in small doses (12.5-25 mcq IV), it can lead to respiratory depression when mixed with other anesthetic agents.³ Fentanyl can cause hypotension and respiratory depression, especially in the elderly, and consequently the dose should be reduced.

Propofol, a sedative-hypnotic, is a fast-acting IV agent that can be used for MAC. The onset of action for propofol is approximately 45-60 seconds with a half-life of 2-4 minutes. Propofol causes respiratory depression and a decrease in blood pressure and therefore the dose should be reduced in the elderly. Propofol has been reported to have antiemetic properties and at doses of 10-20 mg IV has been used successfully to treat postoperative nausea and vomiting.⁴ Because of its short half-life, there are usually no concerns in the postoperative period.

Dexmedetomidine is a highly selective alpha-2 adrenoceptor agonist that decreases anxiety and postoperative analgesic requirements. There is a limited amount of literature on the use of dexmedetomidine for MAC in the elderly patient. However, it is noted the most common side effects associated with dexmedetomidine in the postoperative period are hypotension, bradycardia and dry mouth.⁵

Ketamine is a dissociative agent that affects the thalamus and limbic system. The onset of action is short, with an elimination half-life of 2-4 hours. Ketamine is a derivative of phencyclidine and the patient may appear awake as their eyes remain open. Although hallucinations are a reported side effect, low doses of ketamine coupled with the administration of midazolam decreases the incidence of postoperative hallucinations. Ketamine does not cause respiratory depression but promotes bronchodilation and therefore it is preferred in elderly patients with a history of asthma.

Remifentanil is a potent opioid with a short onset and short duration of action. Elderly patients experience an increased sensitivity to remifentanil and the dose needs to be decreased by 50 percent.3 The elimination half-life is 9 minutes, as it is eliminated via the esterases (enzymes) in the blood. Due to remifentanil's unique metabolism, the drug does not accumulate regardless of the dose administrated. Because of its metabolism, the analgesic effects are rapidly eliminated, therefore patients will need additional opioid medications to treat postoperative pain.

Cardiac complications such as hypotension, hypertension or arrhythmias are common in the postoperative period. Careful monitoring of cardiovascular parameters including heart rate, rhythm and blood pressure is imperative. Elderly patients also have an increased risk of postoperative respiratory depression, which is due to the changes associated with aging, sensitivity to medications and postoperative hypoventilation. The patient should receive oxygen via nasal cannula and oxygenation saturation monitoring via a pulse oximeter.

However, due to the changes associated with the aging process, the dosage of opioids should be reduced and carefully titrated to limit the risk of respiratory depression and hypoxia. Nevertheless, pain must be adequately treated in the elderly population as inadequate pain control can delay recovery and increase the risk for postoperative complications.⁶ A multimodal approach may be beneficial when treating pain in the elderly during the postoperative period. By combining two or more medications, the healthcare provider will be able to reduce the dose of each drug administered, which will minimize the overall risk of side effects. American Society of Anesthesiologists (ASA) guidelines recommend the use of multimodal therapy when treating patients for postoperative pain relief. The guidelines advocate the use of NSAIDs, COX-2 inhibitors and acetaminophen around-the-clock for all surgical patients unless contraindicated.⁷

The use of NSAIDs may be effective for treating light-to-moderate pain. There is an increased risk of gastric complications in patients above 65 and that risk increases even further if the patient is over age 75.⁸

Acetaminophen may also be used to treat postoperative pain in the elderly; however,unlike NSAIDs, it has no associated anti-inflammatory properties, and is widely used based on its high safety profile. When used at the maximum recommended dose, it is usually well-tolerated. Acetaminophen also can be combined with opioids to treat postoperative pain in the elderly with minimal side effects. Recently, acetaminophen (OFIRMEV) IV was approved for use in the U.S. The IV dose is 1,000 mg administered over 15 minutes with a total 24-hour dose of 4 g. OFIRMEV is effective in managing mild-to-moderate pain and moderate-to-severe pain when combined with opioids.⁹ Contraindications for OFIRMEV include patients with severe active liver disease, severe hepatic impairment or a known hypersensitivity to acetaminophen.⁹

Postoperative confusion is a frequent problem among the elderly after general anesthesia associated with several risk factors such as OTC and prescribed medications, the presence of comorbidities, fluid and electrolyte imbalances, visual impairment, type and duration of surgical procedure, medications administered intraoperatively, and ineffective pain management.¹⁰ Although the incidence of postoperative confusion after MAC anesthesia is not noted in the literature, it should be noted that if significant doses of benzodiazepines were administered intraoperatively or risk factors linked to delirium are present then postoperative confusion is more likely to occur in the elderly patient. Nurses play a vital role in preventing and managing delirium by being aware of the risk factors and reorienting the patient to person, place and time. Explaining to geriatric patients they are in a hospital and just had surgery is an effective intervention.¹⁰

Due to advancements in medicine and healthier lifestyles, people are living longer. Geriatric patients can have numerous comorbidities and therefore may be taking several medications, which increases the risk for adverse drug reactions and postoperative confusion.

Medications administered intraoperatively can have a prolonged effect on the elderly with symptoms observed in the postoperative period. Numerous anatomical, physiological and cognitive changes also occur with aging, which affect perioperative management and outcomes. It is vital for nurses caring for elderly patients to understand of these key changes to ensure a safe, effective and successful perioperative experience.

To view the Course Outline and take the test online, click here.

For a printer-friendly version of the exam you can print out, complete and mail in to ADVANCE, click here.

References for this article can be accessed here.

Lew Bennett is assistant clinical professor and department chair, Division of Graduate Nursing, Nurse Anesthesia Department, at Drexel University, Philadelphia. The author has completed a disclosure form and reports no relationships relevant to the content of this article.