Ahmed Galal, MD, MSc, FRCPC
Fellow in Allogeneic Bone Marrow Transplant,
University Health Network
Princess Margaret Hospital,
Toronto, ON.

Jeffrey Lipton, PhD, MD, FRCPC
Chief, Allogeneic Bone Marrow Transplant Program,
Princess Margaret Hospital,
Head, Chronic Myeloid Leukemia Group,
Associate Professor of Medicine,
University of Toronto,
Toronto, ON.

Introduction
Chronic myelogenous leukemia (CML), in addition to polycythemia rubra vera and essential thrombocytosis, are the most commonly diagnosed forms of the myeloproliferative disorders.^1-5 These diseases share several distinct features:

• They are clonal disorders of hema-topoiesis that arise in a hematopoietic stem or early progenitor cell;
• They are characterized by the dysregulated production of a particular lineage of mature myeloid cells with fairly normal differentiation;
• They exhibit a variable tendency to progress to acute leukemia.

Cytogenetic studies of bone marrow and peripheral blood in the benign myeloproliferative disorders are usually normal. However, CML is invariably associated with an abnormal chromosome known as the Philadelphia chromosome.⁶ CML accounts for 15-20% of adult leukemias. It has an annual incidence of 1 to 2 cases per 100,000, with a slight male predominance.

Michael Gordon, MD, MSc, FRCPC
Vice President of Medical Services,
Baycrest Centre for Geriatric Care,
Professor of Medicine,
University of Toronto, Toronto, ON.

The nurse and physician were very upset. They felt that Mrs. B.'s daughter was not respecting her mother's wishes to forgo CPR should she experience a cardiac arrest. A year earlier, when Mrs. B. entered the nursing home with late-stage Parkinson's disease, she had filled out an advance directive, naming her daughter, rather than her ailing husband, as her surrogate and indicating that, in the event of a cardiac arrest, she did not want to be resuscitated. Over the course of the year, as her disease progressed and she underwent repeated aspirations, it became evident that the end was in sight. Mrs. B.'s daughter told the staff that she would not accept the DNR order and, as the "lawful" surrogate, was requesting that "everything" be done should her mother have a cardiac arrest.

Dr. M. was distraught. Six months earlier, he and his younger brother and sister had, with some reluctance, agreed to the insertion of a PEG tube for their mother who suffered from late-stage Alzheimer disease and had stopped eating after a bout of pneumonia. They felt that by feeding her, she might have a chance at recovery and had not really thought through the long-term consequences of their decision.

Gena Piliotis, MD¹
William H. Geerts, MD^1,2
1Departments of Medicine and
²Health Policy, Management and Evaluation;
Sunnybrook & Women's College Health Sciences Centre,
University of Toronto, Toronto, ON.

Abstract
Venous thromboembolism is predominantly a disease of the elderly. However, geriatric patients often fail to receive appropriate thromboprophylaxis because of under-recognition of age as an important risk factor for thromboembolism and perhaps, in part, because of the perception of a greater potential for bleeding complications associated with anticoagulants. Although there is a paucity of literature specifically addressing thromboprophylaxis in geriatric populations, it is suggested that elderly patients with thromboembolic risk factors receive similar prophylaxis to that recommended for younger patients with the same risk factors. Routine prophylaxis should, therefore, be provided to elderly patients undergoing general, urologic and gynecologic surgery, neurosurgery, hip or knee arthroplasty, surgery for hip fracture, to those who experience major trauma, and to elderly patients with acute medical illnesses plus additional risk factors.

Sudeep Gill, MD, FRCPC
Fellow, Division of Geriatric Medicine,
University of Toronto, Toronto, ON.

Barbara Liu, MD, FRCPC
Kunin-Lunenfeld Applied Research Unit,
Baycrest Centre for Geriatric Care,
Sunnybrook & Women's College Health Sciences Centre,
Assistant Professor of Medicine,
University of Toronto, Toronto, ON.

An adverse drug reaction (ADR) is defined as any noxious or unintended reaction to a drug that is administered in standard doses for the purpose of prophylaxis, diagnosis or treatment.¹ ADRs are common in the elderly--it is estimated that 10-17% of hospital admissions for older patients are directly related to ADRs. Furthermore, one in every 1,000 older inpatients dies as a result of complications of medication use. Many of these ADRs result from potentially inappropriate--and therefore avoidable--drug prescribing practices. In this article, we explore the following topics: pharmacokinetic changes that accompany aging; symptoms and signs that may lead to recognition of ADRs; risk factors that predispose to ADRs; and finally, an approach to appropriate drug prescribing in the elderly.

Drug Pharmacokinetics
Pharmacokinetics involves drug absorption, distribution, metabolism and excretion. With normal aging, there is no clinically significant decline in absorption.

D'Arcy Little, MD, CCFP
Director of Medical Education,
York Community Services, Toronto, ON.

Introduction
The nurses inform you that the elderly woman in Bed 140-B is agitated, and is complaining that a ghost-like man has been frightening her in her room at night. She is recovering from hip surgery that took place the day before yesterday. When you examine her in the morning, she is drowsy. Later that afternoon she is awake but has difficulty attending to your questions. You begin a work-up for postoperative delirium.

At one time or another, all physicians have faced the challenge of treating a delirious elderly patient in hospital. Delirium is a common, serious, yet potentially preventable cause of morbidity and mortality that primarily affects the elderly and is very common in the elderly post-surgical patient.^1-3 The condition is characterized by a disturbance of consciousness and a change in cognition that develops over a short period of time and tends to have a fluctuating course over the day. It is caused by the direct physiological consequences of a general medical condition (See Table 1).^2,4 The following article will review the epidemiology and etiology of delirium with a view to presenting an approach to the prevention of postoperative delirium in the elderly surgical patient.

When to Use a Pacemaker

Naushad Hirani, BSc, MD
Medical Writer,
Geriatrics & Aging.

For over four decades, permanent implantable pacemakers have been routinely used for the treatment of bradyarrhythmias. In that time, the sophistication, capabilities and potential usefulness of pacemakers for a wide variety of indications have grown tremendously. Most pacemaker recipients are elderly; it is estimated that, currently, more than 70% of pacemaker recipients are over the age of 70. The reasons for this preponderance include the changes in the conduction system associated with normal aging, as well as the increased prevalence of coronary artery disease and primary conduction system disease that is observed as age increases.

Approximately two billion beats are required from an average heart over a typical lifetime. Most of these are initiated in the sinus node. With increasing age, the "P" cells that are the main component of the sinus node are progressively replaced by collagen. In addition, the distal portions of the conduction system, the His bundle and the bundle branches show an age-related loss in conducting cells without a concomitant increase in collagen.

Diagnosis and Management of Acute Coronary Syndromes

Nariman Malik, BSc, MD
Medical Writer,
Geriatrics & Aging

Coronary heart disease (CHD) is one of the leading causes of death in individuals over the age of 65¹ and, through a variety of syndromes, is responsible for symptomatic and asymptomatic functional abnormalities. The prevalence of cardiovascular disease increases with age and is a major cause of death and disability in the elderly population.² CHD is the most prevalent cardiac illness in this population: it accounts for 85% of all deaths due to heart disease in persons over the age of 65.³ By age 70, 15% of men and 9% of women have coronary artery disease (CAD) and are at an increased risk of suffering an acute coronary syndrome (ACS).⁴ By age 80, the severity of lesions becomes nearly equal for men and women.⁴ An estimated 40% of all individuals over the age of 80 have symptomatic cardiac disease.²

Despite advances in cardiology, CHD is still the leading cause of death in older individuals, especially those aged over 75.¹ Nevertheless, there is wide variation in the severity of coronary illness and in the functional status of elderly patients.

Pamala D. Larsen, PhD, CRRN
Associate Dean for Academic Affairs,
College of Nursing and Health Professions,
The University of North Carolina at Charlotte, NC, USA.

Although the elderly compose a significant percentage of the surgical patient population, postoperative pain management for this population has received little attention.¹ According to 1990 data, more than 4,000 documents are published annually about pain, but fewer than 1% focus on pain in the older adult.² Lack of published information and research about geriatric pain results in most patients' pain being managed by trial and error.

Considerable evidence suggests that pain is undertreated in older patients. This may be due in part to the misconception that pain sensation diminishes with increasing age or that the elderly patient cannot tolerate narcotic analgesia.³ The perception that older adults have less pain sensitivity than do younger patients is influenced somewhat by the silent myocardial infarctions and emergent 'painless' intra-abdominal surgical events that frequently occur in older adults.⁴ The research involving pain perception in the elderly client provides mixed results. These conflicting results make it difficult to fully establish the relationship or connection between aging and the sensory pain component.

Shabbir M.H. Alibhai, MD, MSc, FRCP(C)
Staff Physician, University Health Network,
Instructor, University of Toronto,
Toronto, ON.

The last few decades have seen major advances in the surgical management of numerous illnesses. As the proportion of the elderly in the general population continues to increase, the prevalence of many chronic conditions also increases. Given the number of available surgical therapeutic options to cure or palliate these chronic conditions, more and more elderly patients are undergoing surgery. Conventional wisdom suggests that, compared to younger or middle-aged patients, older individuals have a higher risk of perioperative and postoperative complications, including death. This increased risk has been attributed to aging itself. This article will examine this relationship in greater detail.

Dozens of studies have suggested that advanced age leads to an increased risk of experiencing surgical complications. This includes an increased risk of postoperative complications such as deep venous thrombosis, infections (including wound, urinary tract, and lung), delirium and mortality.¹ In preoperative assessment clinics, internists and anesthetists utilize risk indices or algorithms to determine an individual patient's surgical risk and potentially modifiable risk factors.

Stanley Muravchick, MD, PhD
Professor of Anesthesia and Vice
Chair for Clinical Affairs,
Hospital of the University of Pennsylvania,
Philadelphia, PA, USA.

Introduction
Recent advances in our understanding of the perioperative implications of aging have been due in large part to the establishment of clear distinctions between processes of aging and age-related disease. The implications of disease are clear to physicians caring for surgical patients of any age. However, many gerontologists consider increased susceptibility to stress- and disease-induced organ system decompensation to be a defining characteristic of geriatric medicine.¹ Even for healthy and fit older surgical patients, maximal levels of organ function decline rapidly. In fact, the difference between maximal and basal function provides the concept of functional reserve. Therefore, normal aging typically produces a progressive loss of the organ-system functional reserve (Figure 1) that provides the "safety margin" available for the additional demands for cardiac output, carbon dioxide excretion, or protein synthesis imposed upon the patient by trauma, disease, surgery and convalescence.