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Drug Allergy

Definition About 80% of adverse drug reactions are predictable and dose dependent, whereas about 20% are unpredictable and dose independent ( E-Fig. 234-1 ). These latter reactions include immediate and delayed drug allergies and hypersensitivities ( Fig. 234-1 ). Epidemiology Drug allergy has a spectrum of presentations and can be fatal. Any drug can induce allergic and hypersensitivity symptoms in the appropriate context and host. The…

Anaphylaxis

Definition Anaphylaxis arises when mast cells and possibly basophils secrete potent mediators that have effects on vasculature, smooth muscle, mucous glands, and nerves, thereby eliciting a systemic response. Although mast cells in any organ system may be involved, dictated in part by the distribution of the instigating stimulus, the principal targets are the cardiovascular, cutaneous, respiratory, and gastrointestinal systems, where mast cells are most abundant. Anaphylaxis…

Urticaria and Angioedema

Definition Acute and chronic urticaria, which involve the dermis, are caused by the excessive release of histamine from mast cells—sometimes acute and sometimes chronic, and sometimes with and sometimes without a trigger. Angioedema, which also involves subcutaneous tissue, can accompany histamine-driven urticaria or can be caused by excessive bradykinin, either as a result of hereditary angioedema or specific provoking agents. Histamine-Induced Acute and Chronic Urticaria Episodes…

Primary Immunodeficiency Diseases

Primary immune defects affect about 1 per 10,000 persons, but the prevalence rises to 1 per 400 to 1 per 5000 persons when selective immunoglobulin A (IgA) deficiency is included. , The prevalence has been increasing as the number of known defects has increased to about 450 different entities. Primary immune defects are now classified into nine categories ( Table 231-1 ). The functions of complement…

Approach to the Patient with Allergic or Immunologic Disease

Allergic diseases and disorders of the immune system affect multiple organ systems. This chapter addresses approaches to common allergic disorders and inborn errors of immunity. Specific disorders are discussed in detail in the chapters to follow. Allergic Disease Definition and Epidemiology Diseases characterized by hypersensitivity of the immune system and inappropriate reactions to common environmental, food, and drug substances are termed allergic diseases. In the sensitized…

Osteonecrosis, Osteosclerosis/Hyperostosis, and Other Disorders of Bone

Osteonecrosis Definition Osteonecrosis (aseptic, avascular, or ischemic necrosis of bone) refers to skeletal infarction. Bone infarcts may be asymptomatic, cause self-limited discomfort, or engender painful collapse of subarticular bone and resulting joint destruction. Epidemiology and Pathobiology Many conditions are associated with osteonecrosis ( Table 229-1 ). In adults, the most common causes are prior hip fracture, osteomyelitis ( Chapter 251 ), renal dialysis ( Chapter 117…

Paget Disease of Bone

Definition Paget disease of bone is a focal disorder of the skeleton characterized by increased and disorganized bone remodeling. Affected bones enlarge, become deformed, and are at increased risk for pathologic fractures. Epidemiology The prevalence of Paget disease is about 0.5% in the United Kingdom and United States. It also occurs in Western Europe and in people of European descent who have migrated to other parts…

The Parathyroid Glands, Hypercalcemia, and Hypocalcemia

Calcium Metabolism A healthy adult body has a total of 1 kg of calcium, about 99% of which is within the crystal structure of bone mineral and less than 1% of which is in soluble form in the extracellular and intracellular fluid compartments. In the extracellular fluid compartment, about half of the total calcium is ionized, and the remainder is principally bound to albumin or complexed…

Osteomalacia and Rickets

Definition Rickets can no longer be considered a historical disorder limited to third world countries or poor people. The COVID-19 pandemic and the loss of school dairy products in the United States has increased malnutrition and vitamin D deficiency. The primary function of vitamin D is to provide adequate levels of calcium and phosphorus by increasing their intestinal absorption, thereby making them available for normal mineralization…

Osteoporosis

Definition Osteoporosis is defined as a skeletal disorder that is characterized by compromised bone strength and that predisposes to an increased risk for fracture. The pertinent clinical outcomes of this disease include fractures, bone pain, loss of height, and physical deformity. The concept of bone strength is central to understanding the disorder because patients who suffer an osteoporotic or fragility fracture may or may not have…

Intimate Partner Violence

Definition Intimate partner violence is defined as any behavior that is within an intimate relationship or ex-relationship and that causes physical, psychological, or sexual harm. Such behaviors can include physical aggression, such as hitting, kicking, and beating; psychological violence, such as intimidation or constant humiliation; various controlling behaviors, such as isolation from family and friends, monitoring movements, financial control, and restricting access to services; and sexual…

Menopause

Definition Menopause is defined as the permanent cessation of menses and is the culmination of a process of reproductive aging that typically occurs in the fifth to sixth decades of life, with a median age of 52.5 years. Epidemiology Menopause is a universal phenomenon among women, and its lived experience varies by individual. The advent of menopause and the coincident loss of gonadal steroids significantly affect…

Chronic Respiratory Insufficiency

Chronic Respiratory Failure and Long-Term Mechanical Ventilation Denise M. Goodman Steven O. Lestrud Epidemiology There are continual improvements in invasive (ventilation through a tracheostomy) and noninvasive (mask ventilation) devices and management to care for those conditions predisposing to the need for chronic ventilation, such as acute respiratory failure, prematurity, and neuromuscular disease. Although difficult to determine the prevalence of chronic ventilation, estimates range from approximately 4 to 6/100,000…

Skeletal Diseases Influencing Pulmonary Function

Pulmonary function is influenced by the structure of the chest wall (see Chapter 400 ). Chest wall abnormalities can lead to restrictive or obstructive pulmonary disease, impaired respiratory muscle strength, and decreased ventilatory performance in response to physical stress. The congenital chest wall deformities include pectus excavatum, pectus carinatum, sternal clefts, Poland syndrome , and skeletal and cartilage dysplasias . Vertebral anomalies such as kyphoscoliosis can…

Bronchopulmonary Dysplasia

Bronchopulmonary Dysplasia Bronchopulmonary dysplasia (BPD) is a chronic lung disease of infancy and childhood that occurs primarily in preterm infants born at less than 32 wk gestation. BPD is characterized by alveolar hypoplasia, often with concomitant small airway dysfunction and impaired pulmonary vascular growth. Contributing factors to the development of BPD may include early gestational age, low birth weight, lung barotrauma, exposure to hyperoxia, lung inflammation, and…

Chylothorax

Chylothorax is a pleural collection of fluid formed by the escape of chyle from the thoracic duct or lymphatics into the thoracic cavity. Etiology Chylothorax in children occurs most frequently because of thoracic duct injury as a complication of cardiothoracic surgery (post Fontan surgery) ( Fig. 443.1 ). Other cases are associated with chest injury ( Fig. 443.2 ), extracorporeal membrane oxygenation, or with primary or…

Hemothorax

Hemothorax, an accumulation of blood in the pleural cavity, is rare in children. Etiology Bleeding into the chest cavity most commonly occurs after chest trauma, either blunt or penetrating. It can be the result of iatrogenic trauma, including surgical procedures and venous line insertion. Hemothorax can also result from erosion of a blood vessel in association with inflammatory processes such as tuberculosis and empyema. It may…

Hydrothorax

Hydrothorax is a transudative pleural effusion; typically, it is caused by abnormal pressure gradients in the lung. Etiology Hydrothorax is most often associated with cardiac, renal, or hepatic disease. It can also be a manifestation of severe nutritional edema and hypoalbuminemia. Rarely, it results from superior vena cava obstruction by neoplasms, enlarged lymph nodes, pulmonary embolism, or adhesions. It may occur from a ventriculoperitoneal shunt, central…

Pneumomediastinum

Air or gas in the mediastinum is called pneumomediastinum. Etiology Pneumomediastinum is typically caused by alveolar rupture which can be due to either a spontaneous or traumatic cause. A spontaneous pneumomediastinum can either be primary without an underlying etiology or can occur secondary to an underlying cause. Primary pneumomediastinum can be due to increases in intrathoracic pressure as is seen with a Valsalva maneuver, vomiting, Boerhaave…