Geriatric Anesthesia: A Practical Guide

By Bharathi Gourkanti, Dinesh Chaudhry, Irwin Gratz and 2 more

Geriatric Anesthesia: A Practical Guide is a comprehensive reference on geriatric anesthesia. The book is divided into three sections. The first section covers the basics of both anatomical and physiological changes in senescence, and important polypharmacy considerations common in elderly patients. The next section covers anesthesia for cardiac and non-surgical patients. Various controversies and legal ethical issues that are particularly significant in the elderly such as advance directives, code status discussions, specific patient groups and shared decision-making prior to surgical interventions, are covered in the final section.

Key features

- 20 referenced chapters covering basic geriatric anesthesia considerations, cardiac and non-surgical patients and special topics, respectively

- Contributions and references from experienced anesthesiologists

- Emphasis on tailoring perioperative management depending on specific circumstances of patients

- Addresses novel and commonly overlooked topics related to the geriatric population

This book is a guide for both anesthesia providers and non-anesthesia medical providers, trainees and students. It equips them with necessary information to understand and devise anesthetic plans while being aware of postoperative complications and the respective treatment and management options.

Readership

Anesthesia providers and non-anesthesia medical providers, trainees and students.

• Language: English
• Publisher: Bentham Science Publishers.
• Release date: Apr 27, 2024
• ISBN: 9789815238877

Book preview

General Information

Andrea Villa¹, Bharathi Gourkanti¹, *

¹ Department of Anesthesiology, Cooper Medical School of Rowan University, Cooper University Health Care, Camden, NJ, USA

Abstract

The population is aging rapidly worldwide and as this occurs, the rate of surgical procedures in older people is increasing in conjunction with the required anesthesia services. Along with increased life expectancy, the disease burden is also expanding with advanced medical care. This chapter will explore the extent of worldwide aging demographics, the mechanics of aging, health care costs specific to geriatrics, and the significance of anesthetic considerations in a rapidly aging world.

Keywords: Geriatric population, Life expectancy, Demographics, Mechanics of Aging, Healthcare costs.

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* Corresponding author Bharathi Gourkanti: Department of Anesthesiology, Cooper Medical School of Rowan University, Cooper University Health Care, Camden, NJ, United States; E-mail: [e-mail]

INTRODUCTION

Worldwide, the population is aging rapidly. In 2004, there were 461 million people over the age of 65 and by 2050, it is estimated to be about 2 billion [1]. Given the increasing age of the population, it is no surprise that the percentage of people presenting for surgical procedures over the age of 65 is also increasing. People now have a longer life expectancy and therefore patients are presenting with increasingly complex medical histories and underlying comorbidities. Aging affects all systems and leads to diminished physiological reserves; therefore, it is imperative to consider all of these effects to minimize morbidity and mortality.

Presently, about 1/3 of surgical patients are over the age of 65 and the number only continues to rise [2]. In England for example, 2.5 million people over the age of 75 had surgery between 2014 and 2015, meanwhile only 1.5 million did between 2006 and 2007 [3]. Adults over the age of 65 account for over 40% of the surgical volume in the United States [4].

For elderly patients undergoing elective surgery, the operative mortality and prevalence of postoperative complications have increased [5]. Additionally, it is impossible to answer these patients’ questions sometimes such as What will my life look like if I have this procedure?, Will I develop any disabilities?, Will I be able to continue living independently?, and What quality of life can this surgery offer me?. Hence, it is of the utmost importance to carefully assess all the different aspects of this population when planning a surgical procedure.

DEMOGRAPHIC TRANSITION

For centuries, the debate on how population growth affects development has been ongoing with varied viewpoints. Overall, however, it is undeniable that improvements in health have largely altered mortality rates in the aging population worldwide. The demographic transition theory is basically one where societies have transitioned from pre-modern regimes of high fertility and high mortality to post-modern ones that have low fertility and low mortality [6]. More often than not, this theory is associated with the demographic transition model which was created by observing changes that were largely expected in the global north, especially northwest Europe. This model consists of four stages [7]:

Stage1: High-level Equilibrium

This stage consists of fertility and mortality being high which results in low population growth and low life expectancy.

Stage 2: Early Expansion

Fertility continues to be high such as in stage 1, but mortality declines. This leads to an increase in population growth as well as life expectancy.

Stage 3: Late Expansion

Fertility is not just no longer high, but begins to drastically decline, and mortality continues declining but at a slower rate than in stage 2. Because fertility has declined, population growth slows down from stage 2, and life expectancy continues to increase.

Stage 4: Low-level Equilibrium

There is a new balance between fertility and mortality to the point where mortality may fluctuate above the rate of fertility. Hence, population growth is slower and may eventually stagnate or decline because the birth rate supersedes the death rate.

This model was initially created with the expectation that it would become a universal model. However, multiple variations in demographic trajectories globally have not been able to fit well [7]. In the United States, nevertheless, a rising life expectancy leading to an aging population has prevailed and fertility rates have been lower [8].

Data shows that between 2000 and 2019, life expectancy has increased by more than 6 years [9]. Moreover, it is the fastest-growing population in healthcare and since 1975, the number of Americans over the age of 70 has more than doubled [10] and the projected global life expectancy only continues to rise. In the United States alone, the population that was 65 and older grew by over a third (34.2% or 13,787,044) during the past decade, and by 3.2% (1,688,924) from 2018 to 2019 (see table from United States Census Bureau below) [11]. In the next 10 years, it is estimated that 18 million people will turn 65 [4].

Currently, the global life expectancy average is 73.16 years [12] and this age will only continue to increase. By 2035, it is projected to be 75.49 years, by 2055 it will be 77.9 years, and by 2075, it is estimated to be 79.86 [12].

COMPARISON WITH THE GENERAL POPULATION

The clinical condition of frailty is the most problematic expression of an aging population [13]. It is what separates our geriatric subpopulation from the rest. Frailty is a state of increased vulnerability, a syndrome of decreased physiologic reserve and resistance to stressors [3]. Surgery alone is a stressor to which a previously frail, but balanced body, can succumb, and when one adds the associated perioperative stressors such as fasting, opioid analgesics, anesthetic agents, intraoperative blood loss, post-operative pain, nausea and vomiting, the unfamiliar hospital environment, immobility, an elderly patient’s road to recovery is fraught with challenges that may result in permanent functional decline [3]. In a cohort study of 432,828, across all levels of operative stress, frailty was associated with an increased 30, 90, and 180-day mortality even after low or moderate-stress procedures [14].

Interestingly, in a cross-sectional study performed in 2009, a non-linear relationship was found between the number of abnormal systems and frailty, independent of age and comorbidity [15]. Even more interesting was the fact that it was the number of abnormal systems rather than the number of abnormalities within each system, which was more predictive of frailty in the study [15]. Hence, suggesting that a dysfunction among different organ systems cumulatively is more impactful than having multiple dysfunctions within one single system [15].

Frailty is the leading cause of death in older people according to a 10-year prospective cohort study performed in 2010 [16]. This was followed by organ failure, cancer, other causes, advanced dementia, and finally sudden death [16]. Meanwhile, in 2010, according to the CDC, the leading cause of death in those 15-44 was unintentional injury [17]. It was not until the next age subgroup of 45-64 that unintentional injury was replaced by malignant neoplasms as the leading cause of death followed by heart disease [17]. From this information, one cannot deny that aging in the form of cumulative dysfunction takes a toll on the human body’s physiological reserve. In addition, as such, surgery and anesthesia cause greater adverse effects within this subpopulation compared to younger ones.

COMMON SURGERIES AMONG THE GERIATRIC POPULATION

The National Hospital Discharge Survey reported that in 2006, patients over the age of 65 underwent 35.3% of inpatient surgeries, and 32.2% of outpatient surgeries [18]. Among those over the age of 65, the five most common procedures were lens and cataract procedures, knee arthroplasty, hip replacement (total and partial), cholecystectomy, and common duct exploration, and spinal fusion [18]. Meanwhile, among those between 18-64 years, the top five most common were cholecystectomy and common duct exploration, hysterectomy (abdominal and vaginal), excision of semilunar cartilage of the knee, other OR procedures on joints, and other OR procedures on skin and breast [18]. The specific perioperative considerations for these will be outlined in Chapter 21. However, it is important to note that it is the age-related chronic conditions that typically result in these operations.

MECHANICS OF AGING

The basal function of most organ systems is relatively unchanged by aging; however, there is a decrease in the reserve and function of all these systems [10, 19]. The available response to acute stress is diminished as the body ages and its ability to retain homeostasis is impaired. Exactly how much the functional reserve is decreased in an elderly individual, is impossible to predict given the diversity of the population and their age-related physiologic changes. Moreover, aging is a multifactorial process involving a few prevailing theories of what those pathways or mechanisms are.

Although it is unknown which specific factors lead to primary aging, it is believed that an interplay between genetics and oxidant damage plays a major role [5]. Harman proposed in 1956, the Free Radical Theory, which postulated that degenerative diseases and aging could all be traced to the deleterious effects of free radicals on cell components [20]. About a decade after he proposed this theory, McCord and Fridovich discovered the enzyme superoxide dismutase whose sole purpose was to scavenge superoxide, and supported Harman’s theory that cells constantly produce free radicals [20].

In 2003, a study found that some metabolic genes that play a role in the TCA cycle act as tumor suppressors, and another study that same year discovered that the development of chronic diseases such as atherosclerosis, are slowed by genes that also slow the overall aging process [21, 22]. These findings suggest that Harman’s theory could be correct. Moreover, aerobic metabolism and the associated production of reactive oxygen species in many other studies have been shown to lead to aging. However, not much detail is known regarding significant intracellular targets of reactive oxygen species or how modifications to these processes could alter aging [20]. Despite knowing that free radicals are made continuously, it is still unknown whether this is merely a correlation with aging or the cause of it.

Macromolecular damage is another theory that has been shown to play a role in aging. Apparently, there is a time-dependent accumulation of DNA damage from environmental/iatrogenic, and spontaneous/endogenous genotoxic stress sources that likely play a role [23].

HEALTHCARE COSTS AMONG GERIATRIC POPULATION

It is no surprise that with an aging population comes increased costs of health care services which is why it is such a large policy issue worldwide. In the United States alone, between 1974 and 1984, expenditures on health care services for the elderly increased 14.5% annually [8]. Geriatric patients alone consume 50% of the US Federal Health Care Budget [19] and, they account for 44% of the total health care budget in Canada [24]. Per capita healthcare spending for the elderly is significantly higher than for the population as a whole [25]. In 2014, the elderly were the smallest population group (about 15%), but they accounted for 34% of all healthcare expenditures [12]. For comparison, that same year, children made up about 24% of the population and only about 11% of healthcare costs [12]. To further exemplify just how much is spent on the elderly, in that year, for those over the age of 65, healthcare costs per person was $19,098 as opposed to a child which was $3,749 and a person of working age was $7,153 [12]. The costs are clearly vastly different.

A study in Canada was performed to look at the healthcare costs in patients 70 years of age and older who had nonelective abdominal surgery between 2011 and 2012. Unfortunately, adverse events as a direct cause of these surgeries made up 44% of overall costs [27]. Moreover, the study took into consideration the fact that 22.6% of those who underwent these procedures ended up needing support/losing independence, which has other long-term healthcare expenses associated. The total cost of long-term health care expenses has not been analyzed, but its impact can be significant. In 1982, about 19% of the elderly which at the time represented about 4.6 million people, were limited in performing their daily activities and required help [8]. Despite advances in medicine since then, in 2014, it was estimated that about 1 in 4 elderly adults received living assistance from supportive care or nursing homes and nearly half of the entire elderly population had received some kind of help with daily activity even if not long-term [28]. Not only can this create a burden on these patients, but also on their families and Americans. Given the demographic transitions mentioned earlier, as the baby boom generation ages and modern-day fertility rates lower, the working population will bear the burden of supporting healthcare services.

Moreover, in 2021, the International Health Policy Survey found that one-fifth of elder Americans spent over $2,000 out of pocket in healthcare in the last year and these high costs led many to forgo receiving preventative healthcare [29]. It also found that many would not fill prescriptions or would skip their medications due to the high costs. It is likely that many who do not pursue medical care in a timely manner end up requiring major surgeries which their body cannot tolerate. These findings are beyond the scope of this book but highlight a huge concern that continues to be the focus of research and multiple policies.

CONCLUSION

Elderly people are an especially vulnerable section of the population when it comes to having procedures done. A prospective longitudinal cohort study performed in the US from 2011 to 2018 found that 1 in 7 older adults die within a year of undergoing major surgery [30]. Among the participants, the 1-year mortality among non-frail persons was 6.0% (95% CI, 2.6%-9.4%), among the frail was 27.8% (95% CI, 21.2%-34.3%), for those without dementia, it was 11.6% (95% CI, 8.8%-14.4%), and those with dementia, it was 32.7% (95% CI, 24.3%-41.0%) [30].

It is of the utmost importance to tailor anesthetic care to different needs of an elderly patient because even an excellent surgical candidate can be noted to decline after surgery. The associated stress can unmask problems that were previously unknown. It is not to say that age alone is an illness, but it is a contributing factor due to its association with changes in the organ's function that affect perioperative care. For example, there are various age-related conditions such as heart disease, high blood pressure, osteoporosis, shingles, cancer, and many others that are predominant among those over the age of 60. Age-related changes compromise the functional reserve of various organ systems, and their response to the physiological stress of surgery, anesthesia, and perioperative care. There are specific anesthetic outcomes that are seen among the elderly such as post-operative cognitive dysfunction and post-operative delirium. All of these issues will be discussed in this book.

REFERENCES

Anatomical and Physiological Changes in Aging

Magdy Takla¹, *, Michele Mele¹, Tina Takla²

¹ Department of Anesthesiology, Cooper Medical School of Rowan University, Cooper University Health Care, Camden, NJ, USA

² Nova Southeastern University, Davie, Fl, USA

Abstract

The human body is a complex connection of various systems, each affected by the internal and external environment. Each system relies on the other and changes in one can result in variations in all other organ systems. As humans age, their physical appearance changes, but the aging process also occurs below the skin. Each organ system is impacted by time, and an individual’s lifestyle can greatly impact his/her organ system. Various anatomical and physiological alterations that occur to the major organ systems due to aging and are relevant to an anesthesiologist are discussed below.

Keywords: Aging, Elderly, Central Nervous System, Cardiovascular system, Respiratory system, Renal system, Gastrointestinal and Endocrine, Musculoskeletal, Anesthetic management & techniques.

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* Corresponding author Magdy Takla: Department of Anesthesiology, Cooper Medical School of Rowan University, Cooper University Health Care, Camden, NJ, United States; E-mail: [e-mail]

INTRODUCTION

The geriatric population is a demographic that is rapidly growing and living longer. According to the statistics, there has been a notable rise in both elective and emergent surgical procedures. Indeed, as people age, their respiratory and organ functions tend to decline.

Perioperative care and management of geriatric patients are different from young patients due to various complications. The care geriatric patients receive during the perioperative period greatly impacts the side effects and complications of the surgery. Furthermore, instances of negative occurrences and extended stays in medical facilities are frequent in these patients [1, 2].

The likelihood of appropriate preoperative assessment, meticulous anesthetic technique, and careful postoperative management may decrease adverse events.

Central Nervous System

Anatomy

The nervous system is divided into two branches: central and peripheral nervous systems. The central nervous system (CNS) includes the brain and spinal cord, while the peripheral nervous system (PNS) consists of nerves that branch from the brain and spinal cord. There are excitatory and inhibitory synaptic inputs and the ratio of these two types determines whether there will be a neuronal event or not. These inputs can come from a voluntary pathway (controlled by the brain) or a reflex arc (controlled by the spine). Each motor pathway uses sensory, motor, and interneurons – starting with sensory neurons and ending with motor neurons [3].

The spinal cord is essential to the CNS, beginning at the medulla oblongata and running through the middle of the spine to the lower back. The spinal cord is segmentally organized. There are 31 segments, defined by 31 pairs of nerves exiting the cord. These nerves are divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve [4]. In a cross-section, the gray matter appears H-shape surrounded by the white matter. The unmyelinated axons and neuroglia cells are sensory neurons, interneurons, motor neurons, and neuropils that compose the gray matter in the spinal cord, whereas myelinated sensory and motor axons make up the white matter [5]. Although more research is required, studies have thus far shown that older patients had worse neurological outcomes following spinal cord injuries, and younger patients had better outcomes after decompression surgery for cervical myelopathy than older patients [6].

The brain contains billions of neurons that allow for proper function. Much like the spinal cord, there is gray and white matter and three layers of protection (the meninges) – dura, arachnoid, and pia maters. Unlike the spinal cord, the white matter is located on the inside with gray matter lines on the outside of the brain.  Shrinkage of the brain due to neuronal atrophy occurs as early as middle age. Older individuals lose about forty-five percent of their myelinated fiber length (white matter proportions), and smaller nerve fibers are most affected by age. Aging causes a decrease in the transport rate of materials needed for axon regeneration, resulting in an inability to regenerate axons following degeneration. There is also a significant decrease in brain plasticity as an individual grows older, which allows younger populations to have better outcomes after cerebral procedures/injuries [7].

Peripheral Nervous System

All the nerves that branch out from the brain and spinal cord form the peripheral nervous system. These nerves other than the brain and spinal cord are also negatively impacted by aging. Slower axonal regeneration, nerve conduction, and myelin expression are slower in older populations.

Degeneration of axons, less electrophysiological interactions, and decreased myelination or myelin abnormalities cause physiological alterations and a slower recovery response when the peripheral system suffers an injury.

PHYSIOLOGY

Brain

Physiological Changes

There is a decline in the weight and the volume of the brain. As we age, the weight and volume of our brain decline by around 5% per decade after the age of 40 [6].

Brain atrophy begins at an earlier age in men but occurs more rapidly in women once it has started [5].

Upon analysis of post-mortem brains, studies have indicated that as we age, we experience greater loss of white matter than grey matter. Additionally, granular degeneration of myelinated axons is commonly observed by the age of 40 (Fig. 1) [7].

Besides the decrease in brain weight and mass, there are cognitive changes associated with aging, in addition to a decrease in brain weight and mass.

Fig. (1))

Changes with the age of the neurological system [25].

Cardiovascular System

Arterial wall stiffness, wall thickness, and atherosclerosis are physiological changes in the older population. The cardiac output is reduced but the systolic function could remain intact. Aging causes a reduction in autonomic control over the cardiovascular system, this decrease makes the response to adrenergic stimulation decrease. The maximum heart rate and cardiac output also decrease due to aging (Fig. 2) [8].

Fig. (2))

Changes with age of the cardiovascular system [25].

In stressful situations, the baroreflex responses may not maintain hemodynamic stability completely, such as during orthostatic hypotension or administration of vasoactive drugs. Diabetes mellitus, hypertension, and ischemic heart disease are common in the elderly population, so brain and kidney autoregulation are impaired. The decrease in autonomic function may affect the stress response in the geriatric Population. Physiological stress response may also be impaired or limited because of the decreased autonomic function.

Increases in late systolic afterload leads to cardiac muscle hypertrophy, myocardial thickening, and diastolic dysfunction. Another common cardiovascular alteration due to aging is atrial fibrillation. This is a result of physiological changes, pharmacokinetics, and pharmacodynamics aspects of anesthetic agents. The response to induction agents results in an exaggerated effect on blood pressure. Atropine also becomes less effective due to a reduced response. Moreover, the diminished responses to hypovolemia are supplementarily confounded by sedative drugs and volatile anesthetics that impair baroreflex control mechanisms.

Respiratory System

In geriatric patients, respiratory muscles' weaken and chest wall compliance reduces ventilation, resulting in a decrease in maximal inspiratory and expiratory force. All functional capacities of the respiratory system are reduced and alveolar hypoventilation due to increased alveolar compliance and collapse of small airways may occur. Ventilation-perfusion mismatch due to air trapping and collapse of small airways may occur (Fig. 3).

Fig. (3))

Changes with age of the respiratory system [25].

An increase in residual volume and a decrease in the FRC lead to hypoxemia developing easily. Chronic obstructive pulmonary disease (COPD) rates increase with age. Additionally, pulmonary infection and atelectasis are more common in elderly patients [9].

Anesthesia Consideration

Administering premedication can heighten the possibility of aspiration for the patient. Additionally, the combination of residual anesthetic effects, prolonged neuromuscular blocking agents, and post-operative pain can contribute to respiratory complications.

The Renal System

The aging process causes steady deterioration in renal functions, which should be particularly monitored when treating a geriatric patient. Glomerular filtration rates become reduced, and the capability of producing concentrated urine, and preservation of renal function should be noted (Fig. 4).

Fig. (4))

Changes with age of the renal system [25].

There is no need for a particular fluid regimen for geriatric patients Monitoring urine output is important before and after major surgery and should be done regularly.

Compared to average patients, older populations may not tolerate hypo/hypervolemia well. While postoperative renal failure is rare, decreased nephron mass and renal blood flow may increase the risk of renal failure [10].

Anesthesia Consideration

The impairment of sodium ions handling, diluting capacity and concentrating ability predispose geriatric patients to dehydration and fluid overload. The ability to reabsorb glucose is decreased and the response to antidiuretic hormone and aldosterone is reduced.

Risk factors for acute postoperative renal failure include advanced age, diabetes mellitus, pre-existing renal insufficiency, major vascular surgery, and recent exposure to nephrotoxins. Sympathetic stimulation, pain, surgical stress, and the use of vasoconstrictive drugs may induce subclinical renal insufficiency.

Gastrointestinal and Endocrine

Geriatric patients have a noticeable decline in hepatic blood flow and liver mass. The decrease in liver mass leads to a proportional decline in hepatic function. Plasma Cholinesterase level decreases in elderly men and the production of albumin (Fig. 5).

Fig. (5))

Changes with age of the gastrointestinal and hepatic system [25].

It has been observed that oral nutritional supplementation before surgery has a positive impact on the levels of serum total protein. The use of this method results in a decrease in post-op complications. However, there was no observable improvement in postoperative mortality rates [11]. Increased insulin resistance decreases the ability to avoid hyperglycemia with glucose loads (Fig. 6).

Oxygen consumption declines with age and heat production decreases. This increases heat loss and hypothalamic temperature regulating centers may reset at a low level.

Fig. (6))

Changes with age of the endocrine system [25].

Musculoskeletal System

Geriatric patients are vulnerable to all types of degenerative diseases. This may limit their exercise tolerance and make assessing their fitness difficult. Aging and the complications that result from that process also make neuraxial blocks technically difficult to administer.

Older patients have a higher risk of experiencing fractures and dislocations as a result of weakened muscles and skeletal fragility. Patient positioning and pressure points protection must be performed with utmost care and vigilance before and during the procedure.

ANESTHESIA CONSIDERATIONS FOR GERIATRIC PATIENTS

Pre-operative Assessment

All geriatric patients should have pre-operative assessment and consultation in preparation for anesthesia. It is crucial to assess the mental status of patients before surgery as it can affect their cognitive abilities after surgery. Geriatric patients often take multiple medications, which can together impact and alter their hemostatic mechanisms [12].

Preoperative testing is not recommended for this patient group unless medical conditions are suspected or identified. Recent studies of routine preoperative testing in geriatric patients did not indicate whether certain preoperative screening tests have any clear benefit to the geriatric population. According to the guidelines drafted by the American Heart Association (AHA) and the American College of Cardiology (ACC), during preoperative cardiac assessment, evaluating the patient's activity level is crucial to determine if further evaluation is necessary [13]. The main factors that predict cardiac risk include significant arrhythmias, decompensated heart failure, uncontrolled coronary disease, and severe valvular disease.

Anesthesia Management and Techniques for Geriatric Patients Should Follow a Multidisciplinary Approach.

Anesthetic Management & Techniques

The type of anesthesia needed for surgery on geriatric patients should follow a multidisciplinary approach. Anesthesia should be given by experienced anesthesiologists who are qualified to accomplish perioperative care for all geriatric patients to ensure the best possible outcomes [14].

There is currently no conclusive evidence to support a single best type of anesthesia for geriatric patients. All anesthetic techniques have been applied. The duration, type, and medical condition, as well as the skill of the surgeon and anesthesiologist, are all important factors in surgery and influence outcome. A recent review highlighted the potential benefits of implementing regional versus general anesthesia as a primary anesthetic modality in certain patient groups. However, several reports on neuraxial blockade remain controversial due to poor study quality and lack of risk consideration [15, 16].

Postoperative morbidity and mortality, duration of hospital stay and costs as well as readmission rates have shown no differences in geriatric patients who received general anesthesia or regional anesthesia for hip surgery [17].

One of the most common anesthetic techniques is monitoring anesthesia care.

The advanced technology in diagnostic and interventional procedures has increased the demand for monitoring anesthesia care techniques. Geriatric patients who received only monitoring anesthesia care should be managed as if they have received general or regional anesthesia, this type of anesthesia should be provided by a certified anesthesia provider who should be ready to convert to any other type of anesthesia.

Sedative-hypnotic anesthetic agents such as propofol, benzodiazepines such as midazolam, and narcotics such as fentanyl or remifentanil are commonly used for monitoring anesthesia care. There may be some sensitivity to its pharmacologic effects among geriatric patients. It is important to decrease the initial dose of many classes of medications in older individuals to avoid undesirable effects. Propofol has a short half-life and high clearance. This leads to faster awakening as the primary agent, even after continuous infusion. However, it is important to consider that propofol has a dose-dependent effect on the cardiorespiratory system [18].

Midazolam decreases the ventilatory response to hypoxia, as well as reduces the slope of the carbon dioxide response curve.

Remifentanil is an ultrashort-acting drug. Its peak effect occurs within one to two minutes after bolus administration [19]. The unique distribution and metabolic properties of remifentanil facilitate the rapid resumption of spontaneous breathing.

General Anesthesia

General anesthetic agents typically depress cardiovascular and respiratory function and alter consciousness. The adverse effects of cardiorespiratory are dose related. Several negative effects occur in an unpredictable fashion and in a varying proportion of geriatric patients.

Hypoxia and oxygen desaturation happen quicker in geriatric patients which makes preoxygenation critical for this population. In general, the decision to use general anesthesia in elderly patients is based on the preferences of both the anesthesiologist and the surgeon.

Pharmacokinetic and pharmacodynamic changes in elderly patients can amplify anesthetic drug side effects and impact their effectiveness.

In elderly patients, the induction dose of an anesthetic agent is significantly reduced, and it is highly recommended to titrate anesthetic drugs. For elderly patients with cardiorespiratory conditions or hypertension, ketamine should not be used, general anesthesia is likely a better choice.

Geriatric patients experience slower clinical recovery from neuromuscular blockade when using nondepolarizing muscle relaxants. When tracheal extubation is planned, short or intermediate paralytic agents are preferred.

The laryngeal mask airway can be safely used in geriatric patients who are not given a paralytic agent, as it poses a low risk of aspiration. If the paralytic agent is not utilized, hypothermia should be avoided since it increases morbidity.

Regional Anesthesia

There are many benefits of regional anesthesia over general anesthesia, including fewer respiratory complications, thromboembolic events, and post-anesthetic cognitive changes. Regional anesthesia can be used alone or in combination with general anesthesia or monitored anesthesia care for surgery.

Regional anesthesia may diminish the requirements for analgesic and sedative drugs and it also preserves spontaneous ventilation and decreases postoperative complications following orthopedic, lower abdominal, and pelvic surgery [20]. However, geriatric patients’ sympathetic and cardiovascular alterations due to aging, as well as the reduction of the cardiovascular reserve may have untoward consequences. Moreover, the risk of complications and side effects of regional anesthesia is increased in older patients.

Peripheral Nerve Blocks

Geriatric patients can undergo peripheral nerve blocks without compromising airway safety or hemodynamic risk, resulting in satisfactory outcomes. Keep in mind the anatomical changes such as weak intervertebral disks and the spine, epidural space fat reduction, and fibrosis of the intervertebral foramina in these patients. In geriatric patients, the dose of local anesthetic agents should be reduced and administered gradually due to enhance its spread in the spinal column and epidural space. The dose of local anesthetic agents should be decreased for both neuraxial and peripheral nerve blocks. In addition, delayed metabolism and clearance in these patients should be taken into consideration. The central effect of opioids is enhanced in elderly patients with a greater risk of apnea. In addition, hypotension is usually induced by neuraxial blocks. If the patient is on an anti-coagulant or anti-platelet medication for cardiovascular or any medical condition, seek advice from the prescribing physician regarding its temporary discontinuation or modification prior to surgery.

Fluid Management

Close attention to fluid management both intraoperatively and postoperatively is essential in geriatric patients to avoid the undesirable effects of over or underhydration. The surgical patients may have been fluid-depleted for 6 to 8 hours before surgery; dehydration may often quickly deteriorate organ functions. The fluid deficit should be carefully considered during intraoperative fluid administration. In high-risk geriatric patients, numerous studies have shown that goal-directed hemodynamic therapy significantly decreased the rates of postoperative morbidity and mortality [21, 22].

Hypothermia

Close monitoring of body temperature under anesthesia is essential. Geriatric patients are at higher risk of hypothermia due to their low basal metabolic rate and alternating thermoregulatory mechanisms. Prolonged hospital stays, increased blood loss, wound infection, decreased drug metabolism, cardiac ischemia, and cardiac arrhythmias are the adverse effects of inter-operative and postoperative hypothermia. Numerous studies have demonstrated that maintaining a constant core temperature reduces cardiac morbidity. Various active and passive warming devices have been studied for their effects including a heated humidifier circuit or a forced air warming blanket on perioperative/postoperative hypothermic geriatric patients [23, 24].

Oxygen Therapy

The ability of geriatric patients to maintain and increase ventilation if needed declines. In addition, as people age, their protective reflexes such as swallowing and coughing are reduced. This can lead to recurrent aspiration and pulmonary damage, as well as a decreased central nervous system response to hypoxia and hypercarbia. During the second or third day after surgery, there is a higher likelihood of experiencing myocardial ischemia. A recommendation is for patients to be transported to the post-anesthesia care unit with 2-4 L/min of oxygen, even after minor ambulatory surgery.

Postoperative Respiratory Complications

Postoperative hypoxemia may occur in 20% to 60% of geriatric surgical patients. As people age, their respiratory muscle strength weakens, and their reflexes for coughing and swallowing decrease. This can lead to difficulty clearing secretions and an increased risk of pulmonary aspiration in geriatric patients. This hazard is made worse by sedation, narcotics, anesthetics, tracheal intubation, nasogastric tube placement, and surgery in the upper abdominal or head and neck regions. There are also other risk factors for respiratory complications, such as pulmonary thromboembolism, poor general health, atelectasis pneumonia, current infections, pre-existing cardiorespiratory diseases, renal impairment, and hypoalbuminemia. Upper abdominal and thoracic procedures can also contribute to complications. procedures in geriatric patients are an independent factor in worsening postoperative hypoxemia and other respiratory complications.

CONCLUSION

This chapter discusses the key anatomical and physiological deficits that begin to occur in the geriatric population (aged 65+), and the negative effects that these changes may have on procedures demanding anesthesia. Each body system is negatively impacted by aging as they are reshaped physically due to natural aging, stress, and other actions people undertake throughout their lives. Along with the structural differences/breakdowns, the body systems’ functions decrease substantially. These decreases in function and structure may result in detrimental outcomes, if not properly understood or handled correctly. Anesthesiologists have a duty to each patient to thoroughly comprehend how age impacts each organ system and proficiently adjust according to the diminishments caused by time in this population. Anesthesia considerations are described throughout the chapter and within each subsection to clearly guide physicians on proper procedure and practice.

REFERENCES

Pharmacology in Geriatric Anesthesia

Reuben D’Souza¹, George Hsu¹, *

¹ Department of Anesthesiology, Cooper Medical School of Rowan University, Cooper University Health Care, Camden, NJ, USA

Abstract

In terms of different pharmacokinetic and pharmacodynamic interactions, geriatric patients exhibit greater sensitivity to anesthetics. Therefore, understanding the differences in body composition, hepatic and renal function, changes in protein binding, and